Question about whether a basement heat pump and furnace need a drainpan

[ideagarden]

Hello HVAC experts:
We recently purchased a home and in the process had it inspected. Later when we went to have the HVAC maintenanced, the rep looked at our systems and immediately said: "Who inspected this?"  We have a gas furnace and an electric heat pump in the basement. The furnace drains to the outside. But the HVAC guy is concerned because neither has a drain pan under it. He explained that if either system backed up or broke it would flood our finished basement.

I think this makes sense, and we will be installing the pans.

My question is: Is this something the inspector should have noted? We've gone back to him and said we think it is, and he says drain pans are only common in attics, not basements.I'm looking for an expert opinion on whether or not this was an obvious oversight on the inspector's part.

many thanks.
Trish

[Admin]

How does the furnace drain to the outside?  Does that drain line not freeze when it's below 32F outside?

I'm not sure what local codes might exist in your state, but I've never seen a furnace manufacturer require a drain pan be used in a basement installation.  It would take a long time for a furnace to produce enough condensation to flood a basement.  I'm sure you would notice water before it became a serious problem.

As far as the heat pump goes, in heating mode there shouldn't be any condensation being produced as the inside coil now becomes the condenser.  In the cooling mode the indoor coil is the evaporator and will produce a good amount of condensation, but again not enough to flood an entire basement before you noticed the leak.  The evaporator should already sit on a drain pan.  Usually the evaporator and drain pan are built as one and are concealed inside the duct work.  The indoor coil also has multiple drain ports, so you could have another drain line added in the event the primary drain line became plugged.

I agree with your inspector.  There should be no need for drain pans in a basement installation.  If you post the furnace and heat pump model numbers I can tell you for sure.

[Rustymike]

As an HVAC/R mechanic, registered in Ontario with a Metro Masters htg license, plus being a certified home inspector, if a furnace is installed in a basement with a water heater near by, as is most common, a floor drain must be present (within 8 ft) under the Toronto plumbing by law and it used to be a requirement in the gas code.
Now with hi eff furnaces and water heaters being installed, and relocated usually from the mid point of the house to an outside wall, a condensate pump is usually installed with the float switch wired to shut down the furnace and/or water heater.
I usually install a relay to shut down the furnace and water heater if they're both draining into a common condensate pump, to shut them down in the event of a failure and also sound an irritating  pizo alarm to provide audio notification to the homeowners.
To date, I haven't been rejected on this type of installation process.