Fresh Air Intake for Furnace Room. Help Needed

hvac benny · 10-16-2010, 11:04 AM

Quote:

Originally Posted by yuri

I wonder who supersedes who in the Great White North. Local building codes or gas code? I don't get involved in new home construction but know that in Calgary the furnace has to be interlocked by building code to run the fan with a fresh air intake if the kitchen exhuast fan is over 100 cfm or some such size. That may not be in the gas code?

Building codes as well as provincial acts and regulations supersede code, but not if the requirements aren't up to the standards of the gas code. Basically whomever has the tougher requirement (eg. code says that combustion air vents must be 12 inches from finished grade, but the BC and Alberta acts and regulations require 24 inches). In BC we've gotten rid of requiring a fresh air intake into the return, but some inspectors still ask for it, or just that the furnace fan runs on low 24/7, or is timed to run 8 hrs of everyday. Again, this all depends on what city it's in.

yuri · 10-16-2010, 11:52 AM

Yeah, and the climate. You probably have more humidity problems and mold issues than we do. We use a motorized Hoyme damper in our fresh air intakes as 95% of our sales are 2 or 3 stage units with continuos running ECM motors. Don't want to be sucking cold air in all the time or hot humid air in during the Summer.

**beenthere** · 10-16-2010, 12:10 PM

National/international code is min requirements. Local jurisdiction can make tougher guide lines, but not lessen national/international code.

samantha.77 · 10-20-2010, 09:43 AM

Thank you all for the information is it most appreciated. I just came across another decision I have to make. Another HVAC Technician told me that he wants to remove my fresh air intake which is hooked up directly to my cold air return (about 10' away from the furnace), he informed me that by bring the cold air from the outside directly into the cold air return is not a good idea since that cold air will be hitting the furnace fins and causing condensation. He told me to remove the fresh air from the cold air return and seal the hole in the cold air return and patch the concrete wall.

What do you think do I need to remove the fresh air duct from my cold air return I taught it was to provide fresh air to the furnace and duct work????? Now I am really confused...

yuri · 10-20-2010, 10:02 AM

Have a motorized Hoyme damper installed in the fresh air pipe. Have it wired in so that it gets energized by the W (heat) terminal on the circuit board. That way it opens and mixes fresh air with the return air and does not shock the heat exchanger or cause condensation on it when the heat is off.

http://www.hoyme.com/

SPS-1 · 10-20-2010, 10:25 AM

Quote:

Originally Posted by samantha.77

... he informed me that by bring the cold air from the outside directly into the cold air return is not a good idea since that cold air will be hitting the furnace fins and causing condensation. .....Now I am really confused...

Condensation is caused by warm, moist air hitting a cold surface.

samantha.77 · 10-20-2010, 10:44 AM

Thanks Yuri, I could mention the damper to the HVAC tech, but to my understanding he wants to remove it completely. What do you think do I need one or should I listen to him and have him remove it completely??

yuri · 10-20-2010, 11:18 AM

If he removes it and you have a humidity problem or stuffy feeling then you will have to pay him to re-install it. You could try it an find out. If you have a problem then I would get the Hoyme installed (5" and pipe upsized) and if he does not seem interested then call some other contractors and ask to have one installed and enlarge the hole and upsize the pipe. Ideally that pipe should be 5" to do any good. 3" is useless and 4" not recommended. Does not sound like this guy knows what he is doing IMO. Probably looking at $500-$750 to recore the hole larger and install the damper. Less expensive if we don't have to pay a diamond driller/corer and can just enlarge the hole if it is just a stucco wall.

silver_flash · 09-28-2012, 12:55 AM

I think the contractor is talking about makeup air. So when you turn your bathroom fan on. It pushes air outside and then air has to come into the house from some where. If the chimney is open the air will come from the chimney where your water heater co2 is vented. So new houses require a makeup air vent witch is a pipe that runs fresh air into the house. Newer houses need these because they are efficient. old windows and old houses have drafts and air can enter them easy. New houses are more air tight. Make up air vents are separate from air exchangers that you described on your furnace.

techpappy · 09-28-2012, 11:20 AM

b 149.1 IS THE CANADIAN GAS INSTALLATION CODE which is adopted in most Provinces. Sometimes local authorities will add extra provisions but usually follow the B149. But as per other comment from "Winter Peg" said NOT Required

AND YOU DO NOT REQUIRE SEPARATE COMBUSTION AIR FOR THE HW HEATER AS STATED. unless your tank ios in a virtually hermetically sealed room ..air infiltration from rest of house should be sufficient for combustion..Is the room tightly closed up. Is it open to basment? If not you can put an air grill in the door to be sure OR just undercut the door to allow indoor air into the room.

**beenthere** · 09-28-2012, 04:07 PM

This is a 2 year old thread.

silver_flash · 09-28-2012, 07:57 PM

Quote:

Originally Posted by beenthere

This is a 2 year old thread.

thank you. I'm new here.

**beenthere** · 09-28-2012, 08:19 PM

We wee all new here at one time.

Lot of people miss the date of the post.

samantha.77 · 10-09-2012, 10:53 AM

As a follow up.

I had the cold fresh air intake which hook up to my cold air return removed and sealed up the concrete wall. I had a 95% efficiency furnace installed which has it's own combustion air and there is enough air for the water tank.

so far I have no problem, I just air my house out everyday to get rid of humidity if needed.