Home>Discussions>INSULATION & HVAC>Connecting High Efficiency Furnace Condensate Drain to Household Drain
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rhouse123
Connecting High Efficiency Furnace Condensate Drain to Household Drain

I recently installed a high efficiency furnace in my attic. Currently, the condensate drain runs out to the exterior and down to the ground level. On very cold days the condensate drain freezes and the backup drain kicks in until the sun can warm up the pvc again...

I would like to run the htr condensate drain to the 4" cast iron drain stack in the attic (eliminating the need to go outside). The instruction manual for the high eff htr states that the heater condensate drain water is slightly acidic. Is it ok to run the pvc condensate drain from the attic furnace to the 4" cast iron drain stack? Will the cast iron pipe be affected by the slightly acidic condensate?

Thanks, Tony

canuk
Re: Connecting High Efficiency Furnace Condensate Drain to Household Drain

I think you might check with your local building department on this one. I think they may tell you you can't drain into the main stack .... not because of any acidic water but because of safety from the methane gas potentionaly entering the furnace.
It's common for the condensate line to be also routed to a laundry sink or to a drain line protected by a "P" trap.

NashuaTech
Re: Connecting High Efficiency Furnace Condensate Drain to Household Drain

I agree with canuk---codes vary across the U.S. & Canada, but most municipal systems don't allow this for various reasons & require a separate plastic drain into a drywell, etc.

One major reason is many waste disposal plants across the U.S. are overloaded & will not allow any additional increase in volume if they can avoid it---most towns don't have the $$$ to put in a larger capacity waste treatment plant.

Google "condensate disposal" for sample codes in various towns & states. or "boiler condensate disposal".

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