Boiler Remote Monitoring for Thai Factories: Measurement Points, Regulations and RFP

When factories in Thailand that run steam boilers or thermal oil boilers ask us about introducing boiler remote monitoring, the starting point is usually one of three complaints: “We only find out the boiler has stopped when someone on the shop floor calls.” “We only notice fuel use went up when we see the invoice and compare it with last month.” “Head office in Japan has no way to see what is happening in the boiler room.” This is a common story at Japanese-affiliated plants that use a lot of steam around Bangkok, Ayutthaya, Chonburi, Rayong and Samut Prakan, in food and beverage, chemicals, rubber and plastics, textiles and dyeing, and painting and washing lines for auto parts.

This article is a practical guide for plant managers, facility and utility staff at those factories, and production engineering and facility management departments at head office in Japan. It sets out, for boiler remote monitoring, “what to measure, how to connect it, what to watch for under the law, what it costs, and how to order and accept it.”

This article makes one argument. Whether boiler remote monitoring succeeds is decided not by “being able to see the status on a screen,” but by whether the following 3 points were decided first.

• (1) The boundary between people and the law: the placement of a boiler controller, the annual safety test and the records required by the Thai Ministry of Labour’s ministerial regulation remain the factory’s obligations even after remote monitoring is introduced. Design remote monitoring as “a tool that supports the on-site controller”
• (2) The 3 numbers that determine efficiency: flue gas O2 (excess air ratio), flue gas temperature and blowdown rate. Monitoring that cannot capture these continuously can only tell you “it stopped / it is running”
• (3) A connection that does not touch the safety circuits: data from burner management (BMS) and combustion safety circuits should only be read via the display units or gateways provided by the manufacturer, and should not be operated remotely. Make it possible to cut the external connection at any time

On that basis, split measurement points into 3 layers, “regulation and records,” “efficiency” and “early signs of shutdown,” and build them into the RFP (request for proposal) and FAT/SAT (factory acceptance test / site acceptance test). That is the approach this article proposes.

Note that this article does not recommend any specific product or service or rank them. It is not legal or tax advice either. Because legal provisions can be amended, please check the latest content with the Department of Industrial Works (DIW) and the Department of Labour Protection and Welfare (กสร.). All amounts, hours and counts in the model calculation are hypothetical figures set for this article.

Why Consider Boiler Remote Monitoring Now

Production is growing, and steam loads are shifting

Recent figures for Thai manufacturing show production increasing. According to Reuters, the Ministry of Industry’s Manufacturing Production Index (MPI) rose 4.44% year on year in August 2026, beating the +1.0% market forecast in a Reuters poll. However, the ministry revised the calculation method at that time, for example by adding new electronic products and changing weights, so note that the figures cannot be compared directly with the old series. The ministry has raised its 2026 MPI growth outlook to 2.75-3.55%. S&P Global’s Thailand Manufacturing PMI was also at 54.3 in September 2026 (53.8 in August), its highest level since December 2025.

When production rises, the steam load on the boilers changes too. A factory that ran on 1 duty boiler may spend more hours running the standby unit, or the load may swing widely between day and night. When the load changes, combustion conditions change as well, so you cannot know whether the boiler is still burning efficiently “in the state it was tuned to at installation” unless you measure.

Look at what is behind the “frozen” energy price

Electricity tariffs were frozen. The Energy Regulatory Commission (ERC) decided to keep the average electricity tariff for September-December 2026 at THB 3.95/kWh (excluding VAT). However, this was the result of lowering the Ft charge by applying about THB 16,127 million in returned excess profits from the power utilities (claw back). Among the 4 options presented before the decision, one was an average of THB 4.73/kWh (+20%). The reports on the 4 options also noted that the assumed LNG spot price had been lowered to USD 17.6/MMBTU, that the accumulated burden advanced by the Electricity Generating Authority of Thailand (EGAT) stood at THB 31,268 million, and that the situation in the Middle East and other factors were sources of volatility.

This article does not give 2026 prices for industrial fuels (natural gas, LPG and fuel oil), because we could not confirm primary sources for them. However, the Federation of Thai Industries (FTI) cited persistently high energy and petrochemical feedstock prices as one of the factors weighing on its industrial confidence index for August 2026 (89.70). For boilers, where fuel accounts for a large share of cost, a difference of just 1 point in efficiency changes annual fuel cost substantially. Making that 1 point visible is an important role of remote monitoring.

Energy conservation rules and funding

A “designated factory” under the Energy Conservation Promotion Act is a factory that meets any of the following: power receiving capacity over 1,000 kW, transformer capacity over 1,175 kVA, or annual energy consumption over 20 million MJ. Such factories are required to appoint an energy manager, operate an energy management system and submit annual reports (according to the archive of the Energy Conservation Center, Japan [ECCJ]). Depending on size, factories with boilers can also fall under this scope. For factories that collect fuel and steam data for annual reports by hand, whether remote monitoring data can be used directly is one of the benefits of implementation.

On the funding side, in October 2025 the National Energy Policy Council approved a total spending framework of THB 15,000 million for the Energy Conservation Promotion Fund for fiscal years 2026-2028 (THB 9,000 million in the first year). Much of the first year is for the public sector, but low-interest loans for energy efficiency improvements by businesses and individuals are also listed. We could not confirm in published materials any specific program or subsidy rate for boilers. If you are considering using the fund, check the latest calls from the Department of Alternative Energy Development and Efficiency (DEDE) under the Ministry of Energy.

What Boiler Remote Monitoring Is: What It Can and Cannot Do

Monitoring “reads”; operation happens “on site”

In this article, boiler remote monitoring means a system that reads boiler operating data from a remote location (the factory office, a regional headquarters in Thailand, or head office in Japan), records it and gives notice of abnormalities. It does not include “remote operation,” such as starting or stopping the boiler or changing setpoints remotely.

There are two reasons. The first is safety. A boiler’s combustion safety circuit is the circuit that cuts fuel in the event of flame failure or low water level, and every additional path that can write to it from outside adds another entry point for operating errors or unauthorized access. The second is the law. As explained later, Thai law assumes that a controller is placed on site. If the system is designed for remote operation, “who is responsible for that operation” becomes unclear under the law.

Remote monitoring lets you do things like the following.

• Learn of running/stopped status and trips (flame failure, low water level, etc.) together with the time they occurred
• See trends in steam flow, fuel flow, flue gas O2, flue gas temperature and blowdown volume, and notice declining efficiency early
• Line up boilers across several units and several factories in the same format and compare them
• Assemble the data used for legal records and monthly reports without handwritten transcription

Conversely, there are things remote monitoring alone cannot do. Visually checking the water gauge glass, checking for abnormal noise, odors or leaks, confirming that safety valves operate, and the annual safety test are tasks performed by people on site.

Manufacturer-provided vs. in-house platform

There are two broad ways to introduce a boiler monitoring system.

The first is a remote monitoring service provided by the boiler manufacturer (manufacturer-provided). Below are examples from published information that show differences in how data is handled. These are not recommendations or comparative evaluations. We also could not confirm the terms or prices for these services in Thailand from published information.

What the table shows is that services differ in “whether data is kept on the boiler side or in the cloud” and “whether the manufacturer’s technicians can access settings remotely or access is read-only.” Neither approach is inherently right; you need to choose according to your own security policy and how you treat ownership of the data.

The second is to bring boiler data into the same in-house monitoring platform as electricity, compressed air and water (in-house platform). As factory-wide utility monitoring, its advantage is that boiler fuel and steam can be lined up on the same time axis as electricity consumption. Systems for keeping data long term are covered in our article on industrial historian selection, and how to order energy monitoring as a whole is covered in our article on the Thailand factory energy monitoring RFP.

In practice, a combination that keeps the manufacturer’s maintenance service while also bringing the data needed for efficiency and early signs of shutdown into the in-house platform is realistic for many factories. In that case, what matters is deciding in advance which value is authoritative when the same data is collected over two paths.

Split boiler monitoring measurement points into 3 layers

The figure above divides boiler measurement points into 3 layers.

• Regulation and records layer: running/stopped, steam pressure, water level, feedwater and boiler water quality, trip history. The data behind the controller’s records and monthly reports
• Efficiency layer: flue gas O2, flue gas temperature, fuel flow, steam flow, feedwater volume, blowdown volume, boiler water conductivity. The data that shows how much of the fuel is turned into steam
• Early signs of shutdown layer: number of flame failures and ignition failures, number of low water level alarms, number of burner starts and stops, feedwater pump operating status, blower current. The data where changes tend to appear before a shutdown

If you “just connect everything for now,” it often happens that only the regulation and records layer is in place and the efficiency layer has no sensors. That is because existing boilers often have no flue gas O2 analyzer or steam flow meter. If you split points into 3 layers and count up front which layers’ data you have now and which layers’ data you will add, estimates of cost and benefit are less likely to drift.

Thai Regulations to Know for Boiler Remote Monitoring

This chapter summarizes what we found from reading published laws and materials. It is not legal advice. Check the latest version of the provisions and how they apply to your company with the DIW and the Department of Labour Protection and Welfare (กสร.), or with a specialist.

Key points of the Ministry of Labour Ministerial Regulation B.E.2564 (2021)

On boiler safety, the Ministry of Labour issued the “Ministerial Regulation Prescribing Standards for the Administration and Management of Occupational Safety and Health Concerning Machinery, Cranes and Boilers B.E.2564” in 2021. It was published in the Royal Gazette on August 6, 2021 and took effect 90 days after publication. Its parent law is the Occupational Safety, Health and Environment Act B.E.2554 (2011), and the former Ministerial Regulation B.E.2552 (2009) was repealed. Thermal oil boilers are also covered.

The main requirements of the regulation, organized by their relationship to remote monitoring, are as follows.

The “test” here means inspection, trial and certification for use carried out by a person registered or a juristic person licensed under the OSH Act; until those are in place, as a transitional measure, it is to be carried out by an “engineer” as defined in the regulation. Chapter 3 also contains exemptions, such as small boilers with a very small water volume and hot water boilers meeting certain conditions. Whether your own boilers are covered is something you will want to confirm first.

Relationship with provisions under the Factory Act

The regulation contains a provision (Section 106) stating that if the boiler safety standards under the Factory Act (Ministry of Industry) are met, certain sections of the regulation (Section 105, Sections 107-111, Sections 113-115 and Section 117) are deemed to have been complied with. In other words, the Ministry of Industry (DIW) provisions and the Ministry of Labour provisions stand side by side, and complying with the Factory Act side satisfies part of the Ministry of Labour side.

On the Ministry of Industry side, there is a notification on “safety measures for boilers and thermal oil boilers” B.E.2549 (2006) and its amended version B.E.2559 (2016), and related notifications on boiler water properties and safety devices. However, in our research for this article we could not obtain the full text of the DIW notifications. For detailed requirements on the Factory Act side, such as the controller’s duties and the format of records, we recommend checking the original DIW documents.

Can boiler remote monitoring replace the controller?

This is the question asked most often when introducing boiler remote monitoring. As far as we read Chapter 3 of the Ministry of Labour regulation, we found neither an explicit provision that “the controller must always be present on site during operation” nor a provision that “remote monitoring can substitute for this.” Conversely, we have not confirmed any explicit provision that “remote monitoring is not permitted” either. At present, the accurate answer is that it is not clear under the law.

On the other hand, the regulation requires placement of a controller, periodic training for the controller, an annual safety test, and lighting that allows the on-site instruments to be read and a control panel visible even during a power outage. It is natural to read the current law as built on the premise that a controller is on site and checks conditions with the on-site instruments.

For that reason, this article recommends that you design remote monitoring as “a tool that supports the on-site controller.” Examples include sending abnormality notifications to the controller and the shift supervisor at the same time, and letting engineers at head office also see night-time trend changes that the controller can easily miss. If you are considering changing staffing, check with the DIW and the Department of Labour Protection and Welfare beforehand.

This matters because boiler accidents actually happen. On August 17, 2014, a boiler exploded at a dyeing factory in Samut Prakan Province, injuring 21 people. Police presumed the cause was a lack of water in the boiler. At the time, the Department of Labour Protection and Welfare stated that it would check whether a controller who had completed the statutory training had been placed and whether a safety test had been carried out by an engineer at least once a year (the legal basis at the time was the 2009 regulation). A system that gives remote notice of low water levels is useful, but only when there is an on-site controller and on-site safety devices.

DIW’s online boiler management system

The DIW operates a management system for boilers and thermal oil boilers (safety-boiler.diw.go.th). According to the published user manual, for factories it includes functions for equipment registration, annual inspections, temporary suspension and decommissioning, adding and removing controllers, and uploading monthly boiler reports and downloading forms, and there is also a function for inspectors to register safety test results. The system is described as part of a big data integration project between DEDE and the DIW.

Even if you collect remote monitoring data, producing the monthly report separately by hand means doing the work twice. If you confirm the items and format needed for uploading the monthly report and make sure the monitoring system can output them, the operational burden decreases.

Stack emission regulations and CEMS

Boiler stacks are also subject to air emission regulations. The standards table in the Ministry of Industry notification “Quantity of Pollutants in Air Emitted from Factories B.E.2549” sets limits for particulate matter, SO2 and NOx for each fuel type for sources involving combustion. Check the limits and correction conditions that apply to your boiler’s fuel in the original standards table published by the DIW. In addition, the notification on smoke requires an opacity of 10% or less on the Ringelmann smoke chart for boilers of 1 ton or more at Category 3 factories (excluding LPG-fired and natural gas-fired boilers).

Furthermore, under the Ministry of Industry notification “Installation of Special Equipment for Reporting Air Pollution from Factory Stacks B.E.2565” (Royal Gazette, June 10, 2022), covered factories are required to install continuous emission monitoring systems (CEMS) on their stacks and report to the DIW. According to DIW training materials, the installation deadline for existing factories was June 10, 2024 (extendable to December 31, 2027), and for new or expanded facilities it is before the start of operation. The parameters are NOx, SOx, TSP, O2, CO, TRS and temperature, 1-hour averages are reported continuously 24 hours a day, and a malfunction notification is required if the data capture rate falls below 80%. The Office of Natural Resources and Environmental Policy and Planning (ONEP) describes the scope as more than 600 large factories in 13 industries.

Which boilers are subject to CEMS depends on industry and size, so check the DIW notification to see whether your company is covered. If it is, stack O2 will also be measured for reporting. Whether the same analyzer can also serve as the O2 analyzer used for combustion management needs to be checked case by case, because the measurement position and the required accuracy may differ. CEMS implementation and the reporting setup are covered in detail in our CEMS guide to factory stack emission monitoring.

3 Indicators for Improving Boiler Efficiency: Flue Gas O2, Flue Gas Temperature and Blowdown Rate

The rules of thumb and calculation examples in this chapter come from energy efficiency technical materials (Steam Tip Sheets, 2012) by the US Department of Energy (DOE). They are guidelines that mainly assume natural gas-fired boilers in the US, and how well they apply varies with fuel type and equipment. The DOE’s calculation examples are “illustrative calculations,” not measured cases.

Flue gas O2: too much or too little air both cost you

DOE Steam Tip Sheet #4 treats flue gas temperature and flue gas O2 (or CO2) concentration as the main indicators of combustion efficiency. When there is not enough combustion air, unburned fuel, soot and CO are produced. Conversely, with too much air, the excess air is heated and thrown away up the stack, increasing heat losses. Flue gas O2 is the number that shows the amount of this “excess air” (the excess air ratio).

The same sheet contains a combustion efficiency table for natural gas. Extracting the values for a difference of 400°F between flue gas temperature and combustion air temperature (a temperature difference of about 222°C) gives the following (assuming complete combustion and no water vapor in the combustion air).

The DOE says that an excess air ratio of 10% is achievable in well-designed natural gas-fired boilers, and gives the rule of thumb that “boiler efficiency rises by about 1% for every 15% reduction in excess air or every 40°F (about 22°C) reduction in flue gas temperature.”

In the DOE’s illustrative calculation, for a boiler operating 8,000 hours a year and using 500,000 MMBtu of natural gas a year, tuning from an excess air ratio of 44.9% and a temperature difference of 400°F (efficiency 78.2%) to an excess air ratio of 9.5% and a temperature difference of 300°F (efficiency 83.1%) reduces fuel by 29,482 MMBtu a year, for savings of USD 235,856 a year at USD 8/MMBtu. This is an illustrative calculation based on US prices and conditions.

What matters is that combustion conditions change over time. The DOE sheet recommends monitoring flue gas O2 online to grasp trends in energy loss early and as an early warning of control failures. It also says that where fuel composition or steam load varies significantly, O2 trim control, which feeds flue gas O2 back to the burner control to adjust the air-fuel ratio automatically, should be considered.

Flue gas temperature: when it creeps up, suspect the heat transfer surfaces

Flue gas temperature shows how much of the combustion heat the boiler has passed to the water. If flue gas temperature slowly rises at the same load and the same O2, fouling of the heat transfer surfaces or scale buildup is suspected. Under the DOE rule of thumb mentioned above, 40°F (about 22°C) of flue gas temperature corresponds to about 1% of efficiency. With manual measurement once a month, this change is hard to distinguish from differences in load, so it is effective to record it continuously together with the load (steam flow).

Blowdown rate: the guideline differs by sheet

As boiler water evaporates, the dissolved solids in it become more concentrated, so part of the boiler water is drained (blowdown) to keep the concentration in check. The drained water is at the same temperature as the steam generated, so too much blowdown wastes the corresponding fuel and also increases makeup water and chemicals. This is why boiler blowdown control affects efficiency.

Even within the DOE materials, the range given for the blowdown rate differs from sheet to sheet. Written separately without mixing them, they are as follows.

• Steam Tip Sheet #9: The blowdown rate is typically 4-8% of feedwater. Up to 10% when makeup water solids are high
• Steam Tip Sheet #23: The blowdown rate is 1-8% of feedwater. It can reach 20% when makeup water solids are high
• Steam Tip Sheet #10: Boilers with continuous blowdown exceeding 5% of steam flow are good candidates for blowdown heat recovery

#9 also includes an illustrative calculation. For a 150 psig, 100,000 lb/h natural gas-fired boiler in continuous operation (efficiency 80%, fuel USD 8/MMBtu), reducing the blowdown rate from 8% to 6% with automatic blowdown control saves USD 62,913 a year in fuel and USD 9,718 a year in water and chemicals, for a total of USD 72,631 a year. This too is an illustrative calculation based on US conditions.

#23 points out that with manual surface blowdown, you know neither the concentration of dissolved solids in the boiler water nor the optimum blowdown rate. Automatic blowdown control measures boiler water with a conductivity probe, compares it with a setpoint and moves a control valve.

Conductivity and TDS

Boiler water concentration is generally measured continuously by conductivity. According to Spirax Sarco’s explanation, the allowable TDS (total dissolved solids) for shell boilers is about 2,000 ppm for small boilers and up to 3,500 ppm for large ones as a guideline, and multiplying conductivity (μS/cm) by 0.7 gives an approximate TDS (ppm, at 25°C). Conductivity increases by about 2% (relative to the value at 25°C) for every 1°C rise in temperature, so temperature compensation is needed. It also says that manual bottom blowdown tends to lead to operation where average TDS is well below the allowable value, in other words, too much blowdown.

The idea of managing blowdown by conductivity is very similar to water management in cooling towers. For how to approach sensor calibration and acceptance testing of blowdown control, our article on cooling tower water quality monitoring is also a useful reference.

Designing Measurement Points: What a Boiler Monitoring System Should Capture, and How Often

Measurement point list

The measurement points for a boiler monitoring system are organized by the 3 layers below. The intervals are design guidelines presented by this article. Adjust them to your boiler capacity, load fluctuations and communication conditions.

The blowdown rate is calculated from feedwater volume and blowdown volume (blowdown volume / feedwater volume). If blowdown volume cannot be measured directly, it can be estimated from conductivity and the open time of the blowdown valve, but in that case, state clearly on the screen that it is an estimate. How to choose and accept new flow meters for fuel and steam is summarized in our practical guide to flow meter monitoring.

“Time” and “missing data” matter more than the interval

In boiler monitoring, there are many situations where correct timestamps and being able to tell when data is missing matter more than the data interval. When a trip occurs, judging “whether the low water level alarm came first or the feedwater pump stopped first” requires the timestamps of each signal to be aligned. If the monitoring system’s clock and the boiler control unit’s clock are out of sync, you will misidentify the cause. Write into the specification that the gateway, the control unit and the server are synchronized to the same time reference.

The same goes for missing data. If fuel flow during a communication outage is recorded as “0,” that month’s intensity will look better than it is. Record missing data as missing, so that it can be distinguished on screens and in monthly aggregates.

Retention period and data ownership

Decide the retention period with use for legal records, annual energy conservation reports and year-on-year efficiency comparisons in mind. At a minimum, you will want to keep enough on hand to compare with the same month of the previous year. If you use a manufacturer-provided service, check before signing the contract where the data will be stored and whether you can extract the data when the contract ends.

Connect the downstream steam system as well

Even if the boiler is efficient, if steam leaks from steam piping or steam traps, the factory’s overall fuel use will not go down. Once boiler monitoring is on track, extending it to the downstream steam system shows where steam is being lost. Steam trap monitoring is covered in our article on wireless steam trap monitoring.

Connection Methods: How to Get Data from the BMS and Boiler Controls

Do not touch the safety circuits

Boiler data can be obtained through 3 broad paths.

1. Read from the communication port of the boiler control unit or BMS: use the communication functions of display units or gateways provided by the manufacturer
2. Read from retrofitted sensors: add a flue gas O2 analyzer, flow meters, conductivity meters, etc., and wire them to monitoring I/O or a gateway
3. Read by branching existing signals: bring running/stopped and alarm contacts into monitoring inputs

Of these, the third requires the most care. Avoid adding wiring for monitoring to the combustion safety circuit or the BMS wiring. It may affect how the safety circuit operates, and it also has implications for the manufacturer’s warranty. If you really need to take a contact, use the output terminals the manufacturer has provided for monitoring, and confirm this with the manufacturer.

Examples of checking the manufacturer’s design

Manufacturer documentation for BMS shows designs that separate safety and monitoring systems. For example, the data sheet (2018) for Siemens’s LMV5 burner management system states that component devices such as the display unit, actuators and O2 module are connected via a dedicated safety-related bus and, for safety reasons, cannot be integrated into an external CAN bus. On the other hand, the display unit (AZL5) serves as the interface to higher-level systems such as building automation and to PC software, enabling settings and operating status to be read out and trends to be recorded. Parameters for the manufacturer and technicians are password protected.

A Bosch Industrial catalog (2020) states that the company’s boiler controls come with preconfigured data points for common protocols such as Modbus, Profibus and BACnet and can be connected to customers’ central monitoring or energy management systems.

In other words, the basic approach is to read from the communication functions of the display units or gateways provided by the manufacturer, without touching the safety bus. Which data can be read, and whether access can be made read-only, varies with the model and the generation of the control unit, so before the RFP, ask the manufacturer for “a list of readable data” and “how to disable writing.”

Connection architecture

The figure above shows the connection architecture this article recommends.

• Data from the boiler control unit and BMS is extracted read-only from the manufacturer’s gateway or display unit
• Retrofitted sensors (flue gas O2, flow, conductivity) are wired to monitoring inputs separate from the BMS
• Both are combined at a gateway on the factory OT network side and sent to a historian or dashboard
• Connections outside the factory pass through a buffer zone (DMZ) between OT and IT and can be physically cut at any time

With older boilers whose control units have no communication function, you will start with retrofitted sensors and contact inputs only. Even then, if you can retrofit the efficiency layer measurement points (flue gas O2, flue gas temperature, fuel and steam flow, conductivity), you can achieve the main purpose of remote monitoring, which is noticing declining efficiency early.

Remote Access and OT Security for Boiler Remote Monitoring

5 basics

Viewing boiler data from outside the factory means creating a path into the OT network from outside. A fact sheet issued jointly in May 2025 by the US CISA, FBI, EPA and DOE lists the following 5 basics for reducing OT cyber threats.

1. Remove OT connections to the public internet
2. Change default passwords immediately and use strong, unique passwords
3. Protect necessary remote access with private IP networks or VPNs, phishing-resistant multi-factor authentication and least privilege
4. Segment IT and OT networks and place a buffer zone (DMZ) between them
5. Maintain and practice the ability to operate OT manually

The fifth is especially important for boilers. It means keeping the on-site controller able to operate the boiler with the on-site instruments and control panel even if the monitoring system or network goes down. Remote monitoring needs to be designed as something “the plant can operate without.”

Applying this to boilers

The Bosch MEC Remote materials mentioned earlier state that the external data connection can be switched on/off at any time with a hardware key in the boiler room, and that login uses https encryption, a username and password, and a one-time code sent to a mobile phone. Whether manufacturer-provided or in-house platform, it is reassuring to put the following into the specification.

• There is a switch or key that can physically cut the external connection on site
• The monitoring path is read-only, with no path for remote writing (or it is opened only with on-site approval when used)
• When the manufacturer’s technicians connect for service, the date and time, person in charge and work performed are recorded
• Accounts are issued per individual and can be disabled when someone leaves or changes roles

The international standard for industrial control system security is ISA/IEC 62443. It consists of 4 parts, covering terminology and concepts, program requirements for asset owners and service providers, risk assessment and system requirements, and product development and component requirements, and it is aimed at asset owners, product suppliers, system integrators and service providers. When ordering, asking vendors about their status against this standard is one option.

How to build a safe path for equipment vendors’ remote maintenance is covered in our article on OT remote access for vendor maintenance, and how to turn OT security requirements into an RFP is covered in our article on implementing OT security. For the overall design when monitoring a Thai factory from head office in Japan, see also our article on how to monitor Thai factories from Japan.

Model Cost Calculation for Boiler Remote Monitoring (Hypothetical Figures)

Here we estimate the benefits and costs of introducing boiler remote monitoring using provisional figures. All the fuel costs, efficiencies, ratios, hours, unit prices and costs below are hypothetical figures for this article. Replace them with your own figures for actual decisions.

Model assumptions

• Food factory, 2 natural gas-fired shell (fire-tube) boilers (1 of them on duty)
• Annual fuel cost THB 24,300,000
• Currency is Thai baht (THB)
• Currently no continuous flue gas O2 monitoring and no O2 trim control; blowdown is manual

Benefit (1): Revising the excess air ratio

We assume that by noticing deterioration in combustion tuning early through continuous flue gas O2 monitoring and keeping the excess air ratio at an appropriate level, boiler efficiency rises from 80% to 81% (+1 point). This is a conservative assumption in light of the DOE rule of thumb of “about 1% for every 15% reduction in excess air.”

The fuel needed to produce the same amount of steam is inversely proportional to efficiency.

• Fuel cost after improvement: 24,300,000 x 80 / 81 = THB 24,000,000
• Fuel reduction: 24,300,000 – 24,000,000 = THB 300,000/year (the same as 24,300,000 x 1 / 81)

Benefit (2): Blowdown control

We assume that by continuously monitoring boiler water conductivity and matching blowdown to the amount needed, fuel can be reduced by the equivalent of 0.5%.

• 24,300,000 x 0.5% = THB 121,500/year

Benefit (3): Avoiding unplanned shutdowns through early signs

We assume that by noticing changes in the number of flame failures and the condition of auxiliary equipment early, 2 unplanned shutdowns a year (3 hours each) can be avoided. The loss per hour of shutdown is set at THB 30,000.

• 2 times x 3 hours x THB 30,000 = THB 180,000/year
• This benefit is realized only if signs of shutdown actually appear in the data and there is a setup in place to see them and take action

Total benefit and payback period

Costs are set as follows.

• Initial cost: THB 1,200,000 (adding a flue gas O2 analyzer, flow meters and conductivity meters, gateway, screen and notification setup, FAT/SAT)
• Annual cost: THB 180,000 (communications, cloud or server maintenance, sensor calibration)

The calculation is as follows.

• Annual net benefit: 601,500 – 180,000 = THB 421,500/year
• Payback period: 1,200,000 / 421,500 ≈ 2.847 → about 2.8 years

Sensitivity: when combustion is already optimized

Benefit (1) assumes that current combustion has room for improvement. At factories where O2 trim control is already installed and combustion is kept in an optimal state, benefit (1) is zero.

• Benefit: 121,500 + 180,000 = THB 301,500/year
• Annual net benefit: 301,500 – 180,000 = THB 121,500/year
• Payback period: 1,200,000 / 121,500 ≈ 9.88 → about 9.9 years

How to read the calculation

In this model, about half of the benefit (THB 300,000 out of THB 601,500, about 50%) comes from combustion, that is, from improving flue gas O2. In other words, before deciding on the investment, the first step is to measure current O2 and flue gas temperature with a portable flue gas analyzer. If O2 is high and flue gas temperature remains high as well, it is likely that, together with remote monitoring, combustion tuning has room for improvement, and payback will be faster. If O2 is already low and stable, the benefit will center on blowdown control and avoiding shutdowns, and the payback period will be longer. In that case, decisions such as narrowing the sensors you add to lower the initial cost are possible.

As a price reference, the DOE Steam Tip Sheets give USD 500-1,000 for a portable flue gas analyzer (recommended for boilers with annual fuel costs over USD 50,000) and USD 2,500-6,000 for an automatic blowdown control system (conductivity probe, temperature compensation and signal processing, and control valve), which in many cases has a simple payback of 1-3 years. These are all prices from US materials from 2012, not current prices in Thailand. Prices for gateways in Thailand and for manufacturers’ remote monitoring services are not published and require a quotation.

What this calculation does not include

• Reduced labor for regulatory compliance and record keeping
• Reduced CO2 emissions
• Reduced water treatment chemicals and makeup water
• Addressing difficulty in hiring staff
• Taxes and BOI incentives (not covered in this article)

Items to Check in the RFP and FAT/SAT

Checklist

The table below lists items you will especially want to confirm when putting boiler remote monitoring into an RFP.

How to divide FAT and SAT

In the FAT (factory acceptance test), use simulated signals at the vendor’s office or in a test environment to confirm screens, calculations, notifications, permissions and rejection of writes. In the SAT (site acceptance test), connect to the actual boiler and confirm that measured values match the on-site instruments, that trip notifications actually arrive, and that data is recorded as missing when communication is cut.

In the SAT, we recommend comparing against the on-site instruments at both low load and high load. This is because flow meters and flue gas O2 analyzers can show errors differently depending on load. Also, discuss with the manufacturer in advance whether the trip notification test can be performed with test signals without stopping the boiler.

How to Proceed: From Assessing the Current State to FAT/SAT in 90 Days

This is a guideline for what to do in the 90 days around choosing a product or service. The duration varies with the number of boilers and existing equipment.

Days 1-30: Measure the current state and inventory measurement points

• Measure flue gas O2 and flue gas temperature of the duty boiler at low load and high load with a portable flue gas analyzer
• Check whether fuel, steam and feedwater flow meters are present, and how blowdown is done (manual or automatic)
• Check the model and generation of the boiler control unit and BMS, and ask the manufacturer for “a list of readable data” and “how to connect read-only”
• List the placement of controllers, training deadlines, the schedule for the annual safety test and how the monthly report to the DIW is prepared
• Create the first version of the 3-layer measurement point list

Days 31-60: Run a PoC on 1 boiler

• On 1 duty boiler, add the missing efficiency layer sensors (flue gas O2, conductivity, etc.) and connect read-only via a gateway
• Using 1 month of data, calculate the blowdown rate and fuel intensity, and compare them with manual measurements and invoices
• Test notifications and measure the time until they reach the controller and shift supervisor
• Confirm that cutting the external connection has no impact on on-site operation

Days 61-90: FAT/SAT and operating rules

• Finalize the RFP based on the PoC results, and carry out FAT/SAT using the checklist in the previous chapter
• Decide who does what in an abnormality (who receives the notification, who checks on site, who contacts the manufacturer)
• Decide the forum and owner for the monthly efficiency review (trends in flue gas O2, flue gas temperature and blowdown rate)
• Decide in advance how benefits will be measured (which items in the calculation will be verified, and against what)

For how to proceed from PoC to full implementation and how to establish a baseline, our article on factory energy-saving measures is also a useful reference.

Points to Check Especially at Thai Factories

Controller shifts and notification recipients

At some factories in Thailand, boiler controllers work in shifts with only a few people at night. If remote monitoring notifications are sent only to head office in Japan or the regional headquarters in Thailand, time passes without the people who can act on site knowing. Always include the controller and shift supervisor for that time slot among notification recipients, and make sure notifications arrive in Thai. Placing the Japan side in the role of looking at trends and proposing improvements, rather than receiving notifications and giving instructions to the site, makes roles clear.

Avoid double entry with the DIW monthly report

As noted above, the DIW boiler management system has a function for uploading monthly boiler reports. Even after the monitoring system is introduced, if controllers still prepare the monthly report by hand from paper daily logs, the burden will not decrease. Benefits are easier to realize if you separate which items come out of the monitoring system and which items people fill in, and align the output format.

Guidelines change with fuel type

The DOE rules of thumb and efficiency table introduced in this article mainly assume natural gas firing. For fuel oil-fired and biomass-fired boilers, the appropriate level of flue gas O2 and the range by which flue gas temperature can be lowered differ. Stack emission standards also differ by fuel type (the Ministry of Industry notification mentioned above). Set target values for each fuel type with the boiler manufacturer and combustion specialists.

Availability of manufacturer-provided services in Thailand

Much of the published information about the manufacturers’ remote monitoring services cited as examples in this article comes from US or European websites, and we could not confirm the terms of provision, communication methods or prices in Thailand. If you are considering a manufacturer-provided service, check with the sales and service contact in Thailand whether it is available, the communication method (including the cellular network generation), where data is stored, and whether support is available in Thai.

Frequently Asked Questions

What is boiler remote monitoring?

It is a system that reads boiler operating data (running/stopped, steam pressure, flue gas O2, flue gas temperature, fuel and steam flow, boiler water conductivity, trips, etc.) from a remote location, records it and gives notice of abnormalities. This article does not include remote starting/stopping or changing settings, and recommends designing it read-only. You can either use a service provided by the manufacturer or bring the data into the same in-house monitoring platform as electricity, air and water.

Does boiler remote monitoring remove the need for a boiler controller?

That cannot be concluded. The Thai Ministry of Labour Ministerial Regulation B.E.2564 requires employers to place a boiler controller, to have the controller attend training at least once every 2 years, and to carry out a safety test at least once a year and report within 30 days. As for whether remote monitoring can replace the on-site controller, the regulation has no explicit provision, and it is not clear under the law. Design remote monitoring as a tool that supports the on-site controller, and if you change staffing, check with the DIW and the Department of Labour Protection and Welfare beforehand.

What should a boiler monitoring system measure?

It is easier to organize if you think of measurement points in 3 layers: “regulation and records,” “efficiency” and “early signs of shutdown.” To see efficiency, you need flue gas O2, flue gas temperature, fuel and steam flow, feedwater volume, blowdown volume and boiler water conductivity. Existing boilers often have no flue gas O2 analyzer or steam flow meter, so count what you will retrofit at the start.

Why does flue gas O2 matter for boiler efficiency?

Because flue gas O2 shows how much excess combustion air is going in (the excess air ratio). With too much air, the excess air is heated and thrown away up the stack. US DOE materials, mainly assuming natural gas firing, give the rule of thumb that boiler efficiency rises by about 1% for every 15% reduction in excess air, and recommend online monitoring of flue gas O2 as an early warning of control failures.

What does boiler blowdown control change?

The boiler water drained by blowdown is at the same temperature as the steam generated, so too much blowdown wastes fuel, makeup water and chemicals. In US DOE materials, the guideline for the blowdown rate is 4-8% of feedwater in Steam Tip Sheet #9 (up to 10% when solids are high) and 1-8% in #23 (which can likewise reach 20%). By measuring conductivity continuously and matching blowdown to the amount needed, you can reduce the excess blowdown typical of manual blowdown.

How much does boiler remote monitoring cost?

It varies widely with the range of sensors added, the amount of data that can be read from the control unit, and whether you go manufacturer-provided or in-house platform. Prices for gateways in Thailand and for manufacturers’ remote monitoring services are not published and require a quotation. In this article’s hypothetical calculation, with an initial cost of THB 1,200,000 and an annual cost of THB 180,000, payback came to about 2.8 years when combustion has room for improvement and about 9.9 years when it does not.

Can boiler remote monitoring be retrofitted to old existing boilers?

In many cases, yes. Even if the control unit has no communication function, there is the option of retrofitting a flue gas O2 analyzer, flow meters and conductivity meters, and taking running/stopped status and alarms from output terminals the manufacturer has provided for monitoring. However, avoid adding monitoring wiring to the combustion safety circuit or BMS wiring, and check with the manufacturer whether the installation affects the boiler’s warranty.

Summary

• The success of boiler remote monitoring is decided not by how easy the screens are to read, but by whether 3 points were decided first: (1) the boundary between people and the law, (2) the 3 efficiency indicators, and (3) a connection that does not touch the safety circuits
• The Thai Ministry of Labour Ministerial Regulation B.E.2564 requires placement of a controller, training at least once every 2 years, and a safety test at least once a year with reporting within 30 days. Whether remote monitoring can replace the controller is not clear under the law, so design remote monitoring as a tool that supports the on-site controller
• To see efficiency, capture flue gas O2, flue gas temperature and blowdown rate continuously. The DOE rules of thumb are guidelines mainly for natural gas firing in the US, and the blowdown rate guideline differs by sheet
• Split measurement points into 3 layers, “regulation and records,” “efficiency” and “early signs of shutdown,” and count up front which layers existing sensors do not cover
• Do not add wiring to the BMS or combustion safety circuits; read data read-only from the manufacturer’s display units or gateways. Make it possible to physically cut the external connection on site
• In the hypothetical calculation, about half of the benefit came from improving combustion (flue gas O2). If combustion is already optimized, the payback period extends from about 2.8 years to about 9.9 years. Before investing, measure current O2 and flue gas temperature with a portable flue gas analyzer
• In the RFP and FAT/SAT, confirm the guarantee of read-only access, notification delay on trips, handling of missing data, time synchronization, output for monthly reports and the impact on the manufacturer’s warranty

TOMAS TECH helps factories in Thailand with utility monitoring by organizing measurement points, reviewing connection methods and planning RFPs and FAT/SAT. You can also consult us before choosing a product or service, for example at the stage of measuring current combustion with a portable analyzer or creating a 3-layer measurement point list. Please contact us through this form.

References

• The Star (Reuters): Thai August factory output rises 4.44% y/y, beats forecast (September 30, 2026)
• Trading Economics: Thailand Industrial Output Growth Beats Forecasts (September 30, 2026)
• Trading Economics: Thailand Manufacturing Sector Hits 9-Month High (October 1, 2026)
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• InfoQuest: National Energy Policy Council approves Energy Conservation Fund guidelines for 2026-2028 (in Thai) (October 27, 2025)
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