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Fresh Air Intake

2K views 8 replies 4 participants last post by  yuri 
#1 ·
Hi,

I am in Calgary Alberta, if that matters for the question.

I have to re-route my fresh air intake flex pipe from the end of a cold air plenum to somewhere closer to furnace. I am doing this because I am having issue where it is attached now with condensation in the winter and that area is going to be enclosed with drywall. I figure if I can get the connection into the mechanical room I can at least manage the moisture issues. This is house fresh air, not combustion fresh air as I have a high efficiency furnace with it's own feeds.

What are the things I have to look for on where to attach this tube? I am thinking of the code air plenum that is horizontal before it drops vertical down to the area where the filter is. Perhaps even one foot further down the plenum then this, but if it is there I would have to attach it to the bottom of the plenum.

Any ideas?

Thanks!
 
#2 · (Edited)
U want 2 keep that pipe as far away from the furnace as possible as the cold air can hit the heat exchanger and damage it. I had the same issue when I was in Calgary (Bridlewood). Have that in my house in Wpg now. I replaced that central exhaust fan with an HRV and that is a MUCH more NRG efficient system. If not I would get some foil backed insulation and try insulate the duct where it is sweating and make sure the flex pipe is insulated properly 2. HDepot may have it or you can carve pieces out of 1 of those foil insulated water htr blankets or get some from a sheet metal shop. If it fails then U may have 2 move it but I would try the insulating 1st. I would NEVER use drywall to close in a ceiling in a basement because if U ever need to access above it U are shot. Tbar and dropped ceiling is the best IMO.
 
#3 · (Edited)
To expand on what Yuri said.. we have a code requirement that will makes it mandatory that all fresh air intakes be taken off the CA trunk near the trunk end. You don't want a FA connection near or in the furnace room because if the connection come off you could suck flue gases from the water heater or from a 90% gas furnace if it is using indoor air for combustion.

Hope this helps.
 
#6 ·
Don't know if the code is the same in Calgary as B.C. doubt it as in my area it is considerably warmer in the winter than in Calgary. I know in northern B.C. they are making the hvac guys use an inline ductheater in the fresh air inlet to temper the air for the house. Guess drawing in -40 air tends to cool down the furnace somewhat. :)
As far from the furnace as possible is the best in my opinion you want to temper that air as much as possible before it hits your heat exchanger...
 
#7 ·
Building code(s) vary from Province to Province in Canada same as the code varies from State to State in the US. Does not fall under the gas code. If he eliminates the sweating at the source that is a lot easier than moving it and VERY soon they are going to start examining heat exchangers failures for overheating and cold cracking/corrosion which that can cause if it is too cold. May void the warranty.
 
#8 ·
I agree codes vary. But the idea i was trying to get across here is that the way I have always seen the code was that a extra margin of prevention is well worth it.

I have no disagreement that you can put the FA near the furnace, but the way I see it is why court a possible problem in the future?

Just my point of view. Yuri is a top notch tech I don't mean to infer any disrespect, but we each do what works for us.:yes:
 
#9 ·
No disrespect inferred. It takes a LOT to get me riled up. The construction code is changing here soon and all the seams on the return air duct will have to be sealed with mastic or tape and ALL the installers will have to have a basic sheet metal license and papers and be licensed. They are concerned with houses being too tight and being depressurized so yes you don't want to take any air from the furnace area.
 
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