Thread: Upside down condensate trap?

Came across this today. Condensate pump at furnace is connected to piping and looks to be upside down at the joist, then continues horizontal outside. This does not look like it would work to me. Any thoughts.......

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If we presume that the condensate pump is connected to the left riser of the pipe going vertical (under pressure when the pump is on), then across the top, then turns down and from there on it is gravity draining, then that configuration makes sense.

Of course, though, the condensate pump would need to be rated for that many feet of head, and the condensate pump will fill that rather large pipe, shut off, and the water in that pipe would then flow back down into the condensate pump reservoir (unless there was a backflow check-valve in that vertical pipe, and then these tend to go back and allow the water to leak back down).

Anyway, I believe that was the intent of the plan, just the execution and material selection to carry the plan out was lacking a bit.

My take is they simply brought the pipe up to the beam to put that nice bracket on it for support.

the best way to proof it is to test it by putting water in the line which goes to the pump or in the tray that collects the condensate. that way you will see it go on and what happens. but as a trap yes it would work but with a lot more water backing up into the pump. if the pump ever leaks you will have a lot more water to deal with. but the good news it is limited to what is in the trap. not like it is connected to the water supply side.

Sidney

This inverted trap is recommended by the condensation pump manufactures. This configuration creates a siphon that assists the pump in discharging the water. Provided you have sufficient drop and length of tubing or pipe after the inverted trap the system will be self draining. When installed correctly all the condensate pump has to do is get the water up and over the trap and gravity takes over and assists the pump until the reservoir is emptied.

See attached.

I never saw one of these inverted traps (only hoses around here).
But it;s good to know that they are recommended by the manufacturer.... I would have not thought it was correct.

It does not look correct, but can't see everything. Test it, as mentioned.

The issue with that setup and using a 3/4 PVC line is air would enter and break any suction effect. That's why Michael posted the inverted line info on here, which uses 3/8 flex tubing.

The county here created a nice PDF covering HVAC traps. They require a capped clean out access and air vent after the trap. Plus no 90's in the trap. Need to use 45's or the pre bent traps that most system have. picture below

Originally Posted by Binford Tools

the pre bent traps that most system have. picture below

Your photo shows: at the top- a running trap and running traps are not allowed; center and to the left - a shallow trap which does not meet the minimum 2" trap seal required by most manufacturers - some require 3" trap, and I've even seen a couple which required a 5" trap; at bottom right - put a left facing 90 on the left side and then extend the top up a bit higher and that might just about work for most manufacturers which require at least a 2" trap seal and then at 2" above the trap weir.

Thanks for the tip on the running trap not being legal. That was a pic I found, as it showed the normal condensate P traps that are manufactured. i.e pre bent pipe.

I dug through a couple documents, most show the 2" minimum which you mentioned, and did locate one that shows a 3"

Attached is one from Trane and one from a Carrier.

Locally here, the county requires a clean out access. The trane pic shows a clean out access.

Good review on this topic.