Is dumping condensate into a sump pump basin really a good idea?
Hello all,
My 1966 home’s crawlspace (CZ2) was encapsulated and a dehumidifier was installed just prior to my ownership in 2015. Two weeks ago I replaced the dehumidifier which was originally installed with the condensate drain dumping into a sump pump basin. Google tells me that this is a common way to take care of condensate water. But is it really a good idea?
My experience is that dumping water into a sump pump basin allows the water to flow through the drainage holes in the basin and into the soil surrounding the basin. This means that the basin never actually fills with water, and the water is never actually pumped out of the crawlspace. I assume this results in permanently damp soil surrounding the basin which is nearby the foundation. Although the encapsulation should prevent this water from evaporating up into the crawlspace, it seems counterproductive and sloppy to just dump condensate water underneath the crawlspace and hope it goes somewhere harmless.
Why not purposefully direct the condensate water away from the crawlspace and foundation? Can I get some opinions on best practices on condensate drain locations? Am I overthinking this?
I’m considering re-routing and combining all of my condensate lines (crawlspace DeHu, whole house DeHu, and AC) into a single line that terminates above a shower trap in the crawlspace.
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Replies
If you want to dump the condenstate into a drain somewhere, you just have to "air gap" the line so that you can't have any siphon action. There are fittings made for this purpose, or you can get one of the little "bowl" fittings for the PVC drain line and direct all the condensate lines there.
My own sump pump's sump doesn't have any drain holes, so it holds water until the pump pumps it out. You might be able to adjust your own sump pump so that it pumps out sooner (adjust the pump to come on at a lower water level), which might be another option for you.
Bill
Thanks for your reply, Bill.
If possible, could you describe in more detail (or provide a link) the two different PVC drain fittings that you are referring to? I have done lots of my own plumbing, but can't picture the particular fittings you are referring to.
Although I could try to make adjustments to the sump pump, I'd prefer to avoid using it for condensate if possible. Aside from the noise (directly below the master bedroom), I'd like to avoid a mechanical solution if I can use a simple gravity drain instead.
A quickly found example of a basic air gap fitting is here:
https://www.supplyhouse.com/Air-Gap-ET115-002-Multi-Purpose-Air-Gap-For-Water-Filter-and-Softener-3-4-NPT-Schedule-40-Inlet?utm_source=google_ad&utm_medium=Shopping_tm&utm_campaign=Shopping_TM_Returning_users&gclid=EAIaIQobChMIi5yssrKg_QIVZRCzAB1V7AEdEAQYASABEgJlDfD_BwE
The bowl-type fittings look a little like a funnel, bu they have a slip (or threaded) fitting on the bottom. The smaller air gap fittings are probably better if you just have one small line to drain into the drain pipe though.
BTW, if your sump pump is noisy, try one of the "quiet" check valves, which can help. Another trick is to run the pipe from the pipe to a masonry wall and not along the joists. Joists will tend to resonate and amplify the sound from the pump, but if you take the pipe from the pump and clamp it to a concrete or block wall, that will greatly reduce the conducted sound coming from the pipe. The way I like to do this is to make a wood block from a piece of 2x4 that has a round notch (cut with a hole saw) that the pipe fits in, then I clamp the pipe in place. The other way I like to do it is to use an uncut piece of 2x4, then I wrap the PVC with 1/8" neoprene sheet and clamp that with a two hole conduit strap for a size or two larger pipe so that it tightly clamps the pipe with the neoprene wrap. Either way, I drill a single hole through the middle of the 2x4 block and mount it to the masonry wall with a large 5/16" or 3/8" tapcon with the head recessed below the pipe (and make sure the head is well recessed so that it doesn't contact the pipe, otherwise it will tend to wear through the pipe over time). The rigid attachment to a masonry wall really helps to cut down on sound from sump pump lines, and also from water lines from a well pump.
Bill
Unless you can get it really far away from the house -- like ten or more feet, downhill -- I'd say the sump is a better place than dumping it outside.
DC: would you mind explaining why you think that? I agree that the condensate should ideally be dumped far away from the crawlspace and foundation, without the possibility of flowing back toward the home. But why is the sump basin OK? The sump basin is inside the crawlspace and near the foundation. Seems like outside the crawlspace and near the foundation (and exposed to sunlight) would be better, although still not ideal.
I still think that ideally the condensate should be dumped into a drain, but this is admittedly a bit tricky to do because of slope issues.
As Bill noted in #1, the sump basin normally doesn't have holes, so the only way water gets out of it is by being pumped out by the sump pump. If the sump pump does have holes, any water going out those holes is going out well below the foundation footings. If the perimeter drains were properly installed they should be below the footings, to protect the footings from the soil below them liquefying. Moisture below the level of the perimeter drains is normal and not a threat.
Pumping it out, your pumping it up to ground level. It can do a lot of mischief before getting back down to a level where it's harmless.
The whole goal of water management is to get it below your footings and out of the way. Pumping it up is the opposite of what you want to do.
Thanks for your thorough explanation. Routing condensate lines to the sump basin would definitely be the easiest solution.
However, my home was built in 1966 and does not have perimeter drains. With that in mind, does your opinion about dumping water into the sump basin change?
PS: I am planning on installing yard drainage (french and surface drains) this year. I already have gutters that route water far away from the house via PVC and corrugated pipe.
You'll be much better off using smooth wall pipe for drain lines than corrugated pipe. This is due to much less flow restriction with smooth wall pipe. The tradeoff is slightly more difficulty of installation.
I had a thought regarding your sump pump too. In a typical sump pump, the perimeter drain lines come into the sump on the sides, somewhere in the upper part of the sump. Those lines drain into the sump which gets periodically pumped out by the sump pump. If you find the water level is getting up above the low level of those incoming drainage pipes, then the water "backs up" into those drain lines and WILL saturate the ground until the pump pumps the water out. If this is what's going on in your sump pump, then the that is an incorrect installation BUT it's easy and cheap to fix! Adjust the float switch so that the pump comes on sooner. The ideal "on" location is when the water level is just BELOW the lowest point on those drain lines so that the pump will trigger before there is any chance of water backing up into ANY of the drainage lines.
With a stand type pump, you adjust the on/off settings with metal stops on the float rod. Usually you squeeze these together and then slide them on the rod to change the on and off setpoints. It usually takes some fiddling to get it where you want. I find that a hose to fill the sump is very helpful here to do a few test runs while making adjustments. Make sure that the pump shuts off BEFORE it cavitates -- that means the pump should make a smooth "wrrr" pumping sound. If the pump sounds "angry" like bubbling whitewater rapids, then it's cavitating and you need to adjust the "off" setpoint slightly higher so that the pump turns off at a slightly higher "low" water level.
If you have a float switch on a cord, you need to shorten the length of the cord to make it come on sooner. If you have a float on a short arm, you need to check what kind of mechanism you have. Shortening the arm will make for a shorter cycle (on AND off sooner), but if you have some adjustment screws you may have more flexibility. Either way, you don't want this pump cavitating either, so be sure it shuts off before the water level drops so low that the pump cavitates.
Note that putting a precast paver in the bottom of the sump for the pump to sit on can help minimize the chances of chunks of sediment getting into the pump and damaging it.
Bill