Thread: Downward flue pipe

This is a standard 80% gas furnace installed 2003. As you can see the flue pipe is routed downward before it's routed up. Furnace has a draft inducer fan. Is there any type of exception that would allow this type of installation. Personally I don't feel that it will be a problem since it has a draft inducer fan.

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What does the manufacturer say?

I don't know what model you have, but Aire-Flo states the flue transition can't be installed at the 6 o'clock position, only 9,12, or 3.


http://www.aireflo-hvac.com/products...structions.pdf

Looks like an up-flow furnace mounted as down-flow. Condensate will collect in the flue trap, not good! With this wrong you need to look at the rest of the installation carefully. e.g. no condensate trap on the condenser.

Yes it appears to be an up-flow unit that's being used as down-flow. I agree that condenstion will likely accumualte in the lower elbow. Talked to an HVAC guy and described the condition, he thought it was strange but most likely acceptacle, however I have my doubts. I am wondering if the flue can be configured so that it vents out the side vs down. I will recommend further review by an HVAC contractor.

Under NO circumstances may a CAT I gas appliance vent downhill
Under NO circumstances may a CAT I gas appliance vent under positive flue gas pressure
Under NO circumstance may B-vent or single walled vent connector operate under positive flue gas pressure.

The rating plate should note if this furnace is approved for multi-poise installation but still the flue gas outlet must be side or top. If it is upside down, it must be replaced with the correct unit. Fireplaces don't vent upside down and neither do furnaces.

Originally Posted by Bob Harper

Under NO circumstances may a CAT I gas appliance vent downhill
Under NO circumstances may a CAT I gas appliance vent under positive flue gas pressure
Under NO circumstance may B-vent or single walled vent connector operate under positive flue gas pressure.

The rating plate should note if this furnace is approved for multi-poise installation but still the flue gas outlet must be side or top. If it is upside down, it must be replaced with the correct unit. Fireplaces don't vent upside down and neither do furnaces.

Thanks Bob,

That's pretty much what I thought after researching things. If the furnace is not designed to be placed in down-flow position it would need to be repalced with proper down-flow unit. If their lucky the flue pipe can just be routed out the side, other wise they will be looking a new furnace.

I went back to the property to take another look at the furance. Manufacture tag states that it's a muiti-position unit and can be installed in down-flow position. The repair will be make adjustments so that the flue pipe terminates out the side vs below furance.