Condensation pump runs but does not pump water out


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Old 01-23-13, 08:16 AM
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Condensation pump runs but does not pump water out

I have a furnace/AC combination where the condensation lines for both units meet at a condensation pump next to the furnace in the basement. The pump is an old one, but it has worked consistently since I bought the house about 18 months ago.

The pump receives both condensation drain lines, and pumps the received water through a plastic tube that runs straight up about 8 feet, then horizontally about 12-15 feet until it feeds into a short copper tube that exits the house and deposits the water outside.

As I said, it has worked fine for over a year, and for however long before that (the unit itself looks to be at least five years old).

Yesterday morning I came down to hear the pump running while the heat was off. I examined the pump and found the reservoir was full. I looked at the plastic drainage tube and could see the water level, maybe about 5 feet up the tube, hovering there, as if the unit was unable to push it past that level.

I went outside and examined the copper end of the drainage tube, and it was clear. I used my mouth to create suction at that end, and there appeared to be no obstruction. Once I started the siphon action, all the water drained out. When I went back down, the reservoir was empty and the pump was off.

A few hours later, I saw the same thing was happening. I figured the pump was finally dead, so I went out and bought a replacement. Hooked the new one up, and left it alone. After a few hours, noticed it had collected water and was running, didn't see any water in the drainage tube, thought that was odd. After another few hours, I noticed water had filled up the reservoir. The pump was running, but it wasn't pumping out the water.

I went back outside, examined the copper end of the drainage tube, and it was clear. I again created a siphon with mouth suction, and the entire tube drained out. I went back downstairs. The reservoir of the pump was empty and the pump was off. That evening, the reservoir filled up again, the pump was running, yet it was not pushing any water up the tube.

So, the pump itself doesn't seem to be the problem. Confused as to why all of a sudden it stopped working when nothing has changed with the drainage line. The only real change is the weather is colder than it has been all winter (around 18 degrees this week), however I've been checking the outside and have not seen any frozen water blocking up the exit pipe.

Anyone have any suggestions?
 
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Old 01-23-13, 12:31 PM
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I would suppose that something is frozen up, preventing the pump from emptying the reservoir.


You might try temporarily emtying the tubing into a five gallon bucket near the furnace to see if that causes reliable operation to return.

When the weather warms up, try reconnecting the pump to the outdoor line again.


Or check out the line in more detail for an obstruction of some kind.

You could also try to see if the pump will discharge water above the five foot level you observed when the end is not obstructed.
 
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Old 01-23-13, 06:29 PM
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Try disassembling the pump and give it a good cleaning. I've seen some disgusting looking slime/snot grow and coat everything. Gradually the impeller looses efficiency until it can not longer generate enough pressure to get the water up and out.
 
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Old 01-24-13, 12:20 PM
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Thanks for the advice. Last night I was testing it again, and found the line was completely blocked. I think it was a mixture of ice and crud. Cleaned everything out and connected it all back up.

This morning, it was blocked again. I pushed through the external tube with a coathanger, and a chunk of ice came out.

I think the temperature is causing water to freeze in the spout, blocking it up.

How can I solve that? Would wrapping the pipe prevent it from freezing? Right now I am alternating between the original copper fitting and a 2 foot length of 1/4" PEX pipe.

I had this outrageous idea of drilling a hole in the external vent pipe that takes hot air from the furnace and sends it outside, right next to where the condensation pipe drains, and threading the drain pipe through the same air pipe, thereby thawing the pipe every time the heater runs. I'm sure that would violate code, though.
 
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Old 01-24-13, 12:51 PM
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In the exhaust is a No No, but you could tie the condensate line to the outside of the exhaust. That would pick up some warmth. Drill a drain hole for the condensate near the furnace exhaust. Just set it up so the final run has a downhill pitch and it should be "frost free".
 
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Old 01-24-13, 12:55 PM
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Here the inspectors required the condensate line to exit on it's own outside which promptly froze. I re-routed mine to empty in a floor drain and have had no trouble for 11 years.
 
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Old 01-24-13, 12:58 PM
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Sorry, I would advise against Goldstars suggestion. You don't want to poke holes in the line that vents the combustion gasses.


Insulating the condensate pipe discharge might be worth trying. Running larger diameter pipe might be worth a try.

Discharging the pump into a basement sink or drain might avoid the outdoor issue.


Warmer temperatures would be good...
 
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Old 01-24-13, 04:03 PM
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I had the same problem and finally tied it into the house plumbing drains inside my basement. Has caused no problems in two years now. I do clean pump and reservour each year.
 
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Old 01-24-13, 09:12 PM
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Thanks for all the suggestions. I came to the conclusion that avoiding the outside altogether is good for now. At least until we sell the house and find out what they make me do. I'm leaving the old exit pipe in place, so if I sell in the summer, I'll route it back and be fine. Ha!

I added 20 feet to the existing 17 or so to make a pretty long length of vinyl tubing to reach the floor drain, but the pump has no trouble pushing the water through. No more risk of freezing.
 
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Old 01-24-13, 09:50 PM
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Usually extra distance doesn't have a noticeable effect on pumping.....it's raising the line higher that causes more issues.
Make sure line is pitched down slightly or you'll get a lot of water back into pump (unless it has a check valve in it)
 
 

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