# Sizing combustion air and ventilation air for boiler room



## katwalatapan (Nov 26, 2014)

Hello,

I have a query on the primary parameters required to size boiler room combustion air and ventilation air equipment.  Would you please provide comments/feedback if I would require to consider any additional parameters than the following to size combustion air and ventilation air equipment for a boiler room:

1. The boiler room has Oil-fired furnace, 6.4 GPH, 924,000 BTU.  The boiler has separate flue duct that exhausts to the building exterior.

2. The boiler room does not have direct access to the building exterior.  No louvered boiler room door.

3. The boiler room dimensions are 9.5' (W) x 20' (L) x 8' (H).

Would I also need to consider factors such as:

1. Ventilation equipment to maintain either balanced or slightly positive pressure in the boiler room.

2. Have separate fan to bring combustion air from building exterior into the boiler room and separate exhaust air fan to maintain temperature in the boiler room.

3. Any consideration for combustion air fan be linked to the boiler, so that it opens the damper only if the boiler is in operation.  Also thermostatically control the exhaust air fan.

I would appreciate your feedback and any special cases and formulas I should consider to size the combustion air and ventilation air system.

Thank you.


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## north star (Nov 26, 2014)

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Which codes and which edition are in effect ?



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## katwalatapan (Nov 26, 2014)

CSA B139-2009 is in effect for Oil Burning Equipment.  I am looking for sizing parameters that I should consider.


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## north star (Nov 26, 2014)

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Do you have any info \ specs on the particular boiler ?.......The manufacturer will usually have

installation requirements for their product.



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## north star (Nov 26, 2014)

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One document that I looked at online, referred the CAN\CSA B139-09 code to

comply with NFPA 31, ...the Standard for Installation of Oil Burning Equipment.

Is this a correct statement ?.......Can NFPA 31 be used to determine your

Combustion Air requirements ?



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## mtlogcabin (Nov 26, 2014)

IMC Chapter 7 2009

701.1 Scope.

Solid fuel-burning appliances shall be provided with combustion air in accordance with the appliance manufacturer's installation instructions. Oil-fired appliances shall be provided with combustion air in accordance with NFPA 31. The methods of providing combustion air in this chapter do not apply to fireplaces, fireplace stoves and direct-vent appliances. The requirements for combustion and dilution air for gas-fired appliances shall be in accordance with the International Fuel Gas Code.

NFPA 31 is where you need to go for the requirements.


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## tmurray (Dec 5, 2014)

Generally, the manufacturer of the equipment will give you the minimum dimensions in their installation instructions. If these are not available (this sounds like an existing problem) you could do a depressurization test to with a blower door to see how much air it is pulling. Then just use standard duct design to size the duct appropriately. You may need automatic louvers to comply with the National Energy Code for Buildings if it is adopted in Nova Scotia (last I heard they were ad doting it in December, but I can't remember the date.) You shouldn't need a fan as if there is no natural draft when the equipment kicks in there is no need to provide make up air (there is no air to make up for).

NFPA can vary significantly when compared to the Canadian counterparts, so I would refrain from using it. Also, IMC as referenced does not apply as we do not adopt ICC codes in Canada.


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