Condensate lines 1 & 2 share TPR discharge

Seems all wrong to me. The secondary condensate line from a hi efficiency furnace drops into the condensate pump. The primary runs around the back of the water heater and drops into a laundry drain stack (yes the vent is plugged). The flexible condensate pump discharge line is direct plumbed into the same PVC line as the primary condensate that directly connects to the copper TPR discharge line (water heater is to the right in the pic, the flex connects behind the unit and I do not have a pic of this). The TPR discharge sits above a laundry stand pipe, in another room to the right of the pic.

Issue or no? I say yes! If the TPR line gets plugged, nothing drains. If the TPR blows, water is going to make it back into the condensate pump and possibly the furnace.

Code reference anybody???


****be constructed of an approved material, such as CPVC, copper, polyethylene, galvanized steel, polypropylene, or stainless steel. PVC and other non-approved plastics should not be used since they can easily melt.
not be smaller than the diameter of the outlet of the valve it serves (usually no smaller than 3/4").
not reduce in size from the valve to the air gap (point of discharge).
be as short and as straight as possible so as to avoid undue stress on the valve.
be installed so as to drain by flow of gravity.
not be trapped, since standing water may become contaminated and backflow into the potable water.
discharge to a floor drain, to an indirect waste receptor, or to the outdoors.
not be directly connected to the drainage system to prevent backflow of potentially contaminating the potable water.
discharge through a visible air gap in the same room as the water-heating appliance.
be first piped to an indirect waste receptor such as a bucket through an air gap located in a heated area when discharging to the outdoors in areas subject to freezing, since freezing water could block the pipe.
not terminate more than 6 inches (152 mm) above the floor or waste receptor.
discharge in a manner that could not cause scalding.
discharge in a manner that could not cause structural or property damage.
discharge to a termination point that is readily observable by occupants, because discharge indicates that something is wrong, and to prevent unobserved termination capping.
**be piped independently of other equipment drains, water heater pans, or relief valve discharge piping to the point of discharge. **
not have valves anywhere.
**not have tee fittings. **
not have a threaded connection at the end of the pipe so as to avoid capping.

I can’t copy the actual code because its pdf form but it says the same thing as the NACHI article.

TPR should discharge in the same room as the water heater to an indirect waste receptor.

In San Diego it is allowed to discharge a t&p line into the laundry drain

True. We see that all the time. But not configured as described.

Thanks Joe, Juan and Barry (for the PM). All of your information was helpful.

The secondary should drop where it can be readily seen if the primary gets plugged, not into a condensate pump, unless that condensate pump discharges to where it can readily be seen. It should not connect to the primary.

My opinion is there should be no connection to the TPR valve drain from the water heater to anything else, the TPR drain line should be stand alone so that something else can not interfere if the TPR valve releases.

Good points Ron. Thanks.


Here in the south west I see auxiliary condensate drain pan overflow shut-off switches installed onto the secondary. If the primary becomes clogged and condensate goes into the secondary, the switch shuts the system down.

Here’s a web site with more info about AC units:

Want code?

Get those damn shelves away from the HVAC equipment…

And while your at it, hook up the combustion air intake…

You got more issues than condensate.