Frequently Asked Questions

Burner and Controls

Q1: Do I need a Barometric Damper?

A barometric damper is recommended for use when common venting multiple boilers and when using sealed combustion. Please contact Gasmaster Industries for further information on either scenario.

Q2: What type of signal does the boiler accept from BMS?

The standard controls can accept a standard DC signal, either 4-20mA, or 2-10V, or 0-10V signals.

Q3: What type of temperature controller is used in the boilers?

Gasmaster Industries uses both Omron and Siemens temperature controllers. For specific details on different models, contact your local Gasmaster Industries representative.

Q4: Is the blower speed constant or variable?

All GMI boilers have constant speed blowers. A variable speed option is available, contact a Gasmaster Industries sales representative for information regarding this option for different GMI units.

Q5: Can we use sealed combustion with Gasmaster units?

Yes, sealed combustion may be used with Gasmaster units. Please contact a Gasmaster Industries sales representative to discuss particulars.

Q6: Are Gasmaster boilers on/off or modulating?

Gasmaster boilers are all fully modulating. The on/off option is available if required.

Q7: Are the spark plug and ignition rod readily available?

Yes. All parts and components used in Gasmaster boilers are off-the-shelf and readily available from major suppliers.


Q1: What is the minimum gas pressure required?

Standard gas pressures are 8”-14” wc for low pressure and 1-2 psi for high pressure. Please consult a Gasmaster Industries sales representative for specific details.

Q2: Where do I measure the manifold pressure?

For the standard Riello burners used, please consult the Riello burner catalog. For all other burners contact a Gasmaster Industries sales representative.

Q3: What is the turn-down of a boiler?

Turn-down is the ratio of a boiler’s maximum fuel input as compared to its minimum fuel input. For example, a boiler with a maximum fuel input of 2,000,000 Btu/hr and a minimum fuel input of 400,000 Btu/hr would have turn-down ratio of 5:1 (2,000,000 divided by 400,000 is 5).

Q4: What material can you use for vent?

The vent material should be corrosion resistant, such as stainless steel, AL29-4C, for use with Class II, III and IV gas boilers. The vents should comply with UL 1738 and UL 636.

Q5: What is the vent size?

It depends on the boiler model. The outer diameter varies between 4″ – 24″ from GMI 200 to GMI 8M.

Q6: What is the maximum equivalent length that I can use, without using any exhaust fan?

It varies with each model. Detailed information is provided in the manufacturers catalogs. You may also contact a Gasmaster Industries sales representative for guidance and clarification.

Q7: What is the water pressure drop through the boiler?

The pressure drop will depend on the flow rate. In general, water tube boilers have higher pressure drops than fire tube models. You can significantly reduce the pressure drop by reducing the flow and increasing the ∆T. In fact we recommend this, because by reducing the return water temperature, you increase the efficiency of the boiler/water heater. We are also reducing the pressure drop in the GMI 1, 1.5 and 2M boilers with a new design that uses 1.5″ tube instead of 1″ and 1.25” tube. This new model has a much lower pressure drop.

Q8: What are the tube dimensions and materials of your coils?

Up to GMI 1M we use 1″ tube with 0.049″ thickness. Above GMI 1M we use 1.25″ and 1.5” tube with 0.065″ thickness. The material used is Stainless Steel 316/316L.


Q1: What flame safety features does Gasmaster Industries utilize?

All models are equipped with a flame sensor. If at any time during the operation a flame is not detected, the gas valve will be instantly shut-off.

Q2: What kind of flame safeguard does Gasmaster Industries use?

Gasmaster Industries uses Honeywell or Siemens burner controllers. Contact a Gasmaster Industries sales representative for details on the different options available.


Q1: When would condensing technology be discouraged?

Condensing technology is only discouraged when #2 Oil is used as a primary source of fuel. Condensing technology is discouraged by boilers that have copper or cast iron heat exchangers. While operating in condensing mode the flue gas condensate can corrode the heat exchanger. Gasmaster Industries boiler & water heater are manufactured from 316/316L stainless steel and can resist the corrosive action of the condensate.

Q2: Can I order a GMI 2M or GMI 4M with 460V or 600V supply?

Yes, both GMI 2M and GMI 4M units can run on both 460V and 600V supply.

Q3: What will my payback be and how can I calculate it?

The payback will be the number of years it takes for the condensing boiler installation to pay for itself. The cost of installation will be the additional cost incurred to replace an existing system with a condensing boiler system. Simple payback can be calculated as cost of installation/yearly savings. Yearly savings resulting from higher boiler and system efficiencies can be estimated with the help of the “Savings” tool on our website.

Q4: What makes condensing boilers more efficient than other technologies?

Condensing boilers can operate at low system-water temperatures and extract the latent heat from the products of combustion. When flue gasses condense, they release approximately 1000 Btu’s for every pound of condensate. This is called the latent heat of vapourization.In conventional boilers this energy is lost with the flue gas going up the stack. For example, a 8,000,000 Btu/hr input boiler operating at 87% efficiency will have an output of 6,960,000 Btu/hr.A condensing boiler operated for an hour will produce 687 pounds of condensate. The combustion efficiency being 89% the overall thermal efficiency of the condensing boiler will be 97.58%
(8,000,000 X .89) + (687 X 1000) = 7,807,000
7,807,000/8,000,000= 97.58%

Q5: Can your boiler be installed outdoor?

Yes. We do have installations where our boilers are installed outside. All we do is that we place the boiler inside a watertight box. We manufacture the box ourselves, and ship the whole pack on one skid, which can be easily placed on roof-top or any other location. Obviously the box has an access door, which allows for periodic inspection of the boiler and its components.

Q6: Do Gasmaster boilers require water storage tank?

Gasmaster water heaters have been certified as one pass, instantaneous heaters; therefore, they can be used in tank-less configuration. We have a number of applications, such as condominiums and office buildings where the water heaters are connected directly to the buildings hot water supply. All these buildings have a re-circulating loop, which hold 30 – 50 gallons of water, depending on the building’s size. This is more than sufficient to provide the hot water on demand before additional hot water is produced by the heater.

General Information

Q1: What do I need for start-up?

The following tools and instrumentation are necessary to perform start-up and combustion calibration of the unit:

  • Digital Combustion Analyzer
  • Digital Multi-meter
  • 20 inch W.C. manometer
  • ¼ inch NPT fittings for use with manometer
  • All size Phillips and flat blade screwdrivers

Q2: When does condensation occur?

Condensation occurs when a gas undergoes a phase change into a liquid. This is a natural process and occurs at the point at which the gas temperature begins to fall below its dew point. This dew point varies for different gases, and for natural gas fired boilers, condensation takes place at temperatures below 135F. With respect to condensing boilers, this phase change occurs when the temperature of the vapour produced from combustion fall below the dew point.

Q3: What is the principal of operation of Gasmaster units?

Very briefly, air/gas mixture enters the combustion chamber where it is combusted by a spark from the ignition rod. This combustion creates instantaneous high pressure inside the combustion chamber which in turn generates pressure waves. These pressure waves carry the products of combustion out towards the perimeter of the coils. Water enters the coils at the perimeter and exists close to the center. Rapid expansion of exhaust gases together with the cooling effect by the water flowing through the coils causes the pressure in the combustion chamber to drop below ambient. Some combustion products are returned to the combustion chamber; the new volume of air/gas mixture enters the chamber and is pre-compressed by the returning exhaust gases. The temperature in the chamber is still high, therefore, the second combustion takes place and the cycle is repeated. The process is known as radial pulsed combustion and is patented internationally.

Q4: What is a condensing boiler?

A condensing boiler is able to condense the water vapour in the flue gases and can withstand the corrosive and acidic qualities of the flue gas condensate. Although most boilers can condense the flue gasses but only boilers that have heat exchangers constructed from materials able to withstand the corrosion should be used in condensing application. The most common material used in 316L Stainless steel which had high resistance to corrosion. Other materials like copper, aluminum, cast iron etc are prone to heat exchanger failure from flue gas corrosion. Condensing boilers with primary and secondary heat exchanger do not work well as they are not able to fully condense and defeat the purpose of using a condensing boiler. Also boilers with this arrangement are prone to condensation in the primary heat exchanger at lower firing rate which can cause damage to the heat exchanger.

Q5: What is flue gas condensation?

Condensation is a phenomenon that can be observed in everyday life. A glass filled with cold water or cold beer at room temperature will form condensate on the outer surface of the glass. Flue gas condensation occurs when the combustion gas flows over the heat exchanger and is cooled below its dew point and so undergoes a phase gas from liquid.  When the water in the heat exchanger is below the dew point temperature of the flue gas condensation will occur.

Q6: Why 316/316L stainless steel?

300 series stainless steel (austenitic) has much higher chromium and nickel content than 400 series (ferritic) stainless steel in its material composition. Gasmaster Industries products uses ONLY 316/316L grades of stainless steel in its heat exchangers. 316/316L stainless steel is a product which has much higher resistance to corrosion than the 400 series of stainless steel. The ‘L’ designation means that the product has low carbon content which results in the continuity of its corrosion resistance properties after welding. The unstinting requirement for quality material comes with a heavy premium. 316/316L stainless steel is twice as expensive as 400 series material. With Gasmaster Industries products, owners get the peace of mind which only quality materials, unique designs and experienced personnel make possible.