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I am about to buy my 5th condensate pump in 12 years. HE furnace or 2.5T A/C run 10-11 months out of the year here. Humidifier attached but not in use.

I have a 7.5' rise, 20' horizontal span, then 8' down into my drain from the pump.

Failure modes vary only slightly. For the most part, the pumps will start making noise (varies, but usually a noisy motor type of noise, usually the motor physically heats up until I smell hot electronics), and will eventually stop pumping if not replaced within a month or two. For this reason I keep a spare on hand, and just replace them when they quit entirely. The pumps I've been buying are the standard $60 $133 120V ones from Home Depot. The make/model varies every time I buy one.

To be clear, my question is on why the pumps might be failing so often. The only thing I can think is that the drain line might have become restricted (furnace installers tied it to rigid pipes with zip ties), making the pump work much harder. It looks relatively un-kinked, but the tubing is opaque. The drain line is exposed and easy to get at, so would be easy enough to replace I suppose, but I wanted to ask here first to see if there are other things I should be checking.

I could eliminate the 7.5' rise in theory, but it'd either be a trip hazard, or a 50' run along the outer perimeter of the house.

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  • "The pumps I've been buying are the standard ~$60 120V ones from Home Depot" <- have you considered that this may be the root cause of your trouble? – brhans Sep 28 '19 at 14:12
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    @brhans I had not considered that, mainly because as a consumer, I haven't really seen a demonstrably better option than the ones on offer at hardware stores, and they're extremely simple devices. I've also never seen the same make or model twice. I'd gladly buy a better one though! What would you suggest I look for? (Canada, but US sources are fine, too.) I think my $60 number was way off. The one I have is C$133 now! homedepot.ca/product/everbilt-condensate-pump-w-safety-switch/… – type_outcast Sep 28 '19 at 14:35
  • Interpretation: I self-identify as a consumer, and as such, I shop at places consumers shop, i.e. Strip malls and stores with big TV ad budgets. The government/system/”Man"/invisble hand is supposed to ensure this meets all my needs. – Harper - Reinstate Monica Sep 28 '19 at 15:44
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    I would strongly consider altering the plumbing to a properly sloped rigid pipe as early as possible in the run. i.e. 7.5 feet of hose up, then try to get 2-3 inches of drop in the 20 ft horizontal section, at a steady slope, with pipe to the drain, rather than running 36 feet of hose. – Ecnerwal Sep 28 '19 at 15:45
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    Interpretation: I self-identify as a consumer, and as such, I shop at places consumers shop Actually @Harper, I self-identify as a large waffle cone, and as such I am at constant risk for type 2 diabetes. It's a hard, crunchy life. – type_outcast Sep 28 '19 at 21:11
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There is a big range in quality for condensate pumps. Condensate is actually hard on pumps and most of them are plastic, plastic seals impeller sometimes even bearing surfaces and case. The more expensive ones have rubber seals or ceramic and better level switches , many of the plastic ones I have found that are bad were because the shaft seals melted (plastic) I believe that the cause in part is because of contacts sticking or the pump running dry from mold when the pump runs dry melting the seal.

The high end pumps I use in commercial systems cost much more but are metal, both brass and stainless models with much better seals and capacitive sensors to turn the pump on. The price difference if you are going through them this often the more expensive is worth it because you only mess with it every 15-20 years and the seals are replaceable ~20$ and the sensors can also be replaced ~34$ this with a new set of bearings ~10$ for both and the pump is like new and will last another 15-20 years . so yes it can be the pump. mold buildup can plug the inlet to the pump and run it dry causing failure quicker. I mentioned it but did not explain. Having some head pressure depending on where the check valve is if it has one can actually extend the life because there is water being pushed (as long the pump specs are not exceeded).

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  • Fortunately mold hasn't been much of a problem. At worst, I get a light buildup of scum on the bottom of the tank, which I clean. The water is clear. The head pressure tip is well taken! Sounds like leaving the 7.5' rise is a good plan, then? I might have a local wholesale contact I could buy a commercial grade pump from. Before I buy an expensive pump, I want to make sure nothing in the rest of my system is going to cause it to self-destruct like all the others. – type_outcast Sep 28 '19 at 21:22
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    All pumps can fail. But higher quality pumps last longer and can be rebuilt. Yes I have installed a few cheep plastic pumps, they fail . My last home I spent the $ to cut the slab and tie into the drain system with a trap. Cost of the drain was 600 or 700. This will last as long as this house ( I thought I would be there longer) . Even a drain with a trap can fail if the system is not cleaned (mold blocking the drain) So real drains or pumps can still have problems but cheaper plastic pumps regularly fail, it sounds like you are getting a fair life out of yours. – Ed Beal Sep 29 '19 at 0:00
  • @EdBeal: this is exactly the solution I used. No regrets. Although I could've probably did a better job in covering the pipe back up if I had not used Quik-crete but just a sand/cement mix instead (ie no gravel). – peinal Sep 30 '19 at 13:24
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When pumps fail, sometimes it's from the lack of a check valve/back flow preventer which depending on the drain pipe can overwork the pump's duty cycle rating.

Verify that when the pump shuts off, that no water flows back into the reservoir. If it does, then the pump has to repump the same water multiple times.

The fix is to change the drain pipe slope, and/or add a check valve at the pump. This isn't a common thing to do on a condensate pump though, not as common as putting one on a sump pump.

Furnace condensate can be acidic, so it's not the friendliest thing for a pump, but if you're smelling burning it's most likely from the pump being overworked, but like you said there could be restriction in the drain pipe too, so you obviously need to verify that your drain isn't plugged like you suggested first.

I suppose the condensate could be eroding the impeller and causing it to push less flow/pressure, but you'd have to list all of the failure modes from your previous pumps to know for sure.

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  • With no check valve the pump last longer because they don’t run dry as often, when the pump shuts off water flushes back and cools and lubricates the cheap pumps. If the duty cycle is a problem the pump is undersized again a problem with cheap pumps. Just my opinion. But I have been flinging electrical since the 70’s and hvac since licensing was required and currently have a universal 608 & 609 epa license. – Ed Beal Sep 29 '19 at 0:05

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