HVAC #2 is shut down and red-tagged

The unit’s condensate drain clogged and it has been overflowing into the catch pan. There’s a lot of water up there that needs to be drained ASAP. I’m not sure where the siphon hose for that is now, though. The drain needs to be cleared (or else it will overflow in hours), and that’s more difficult than it should be with the drains configured like they are.

We need to do meaningful servicing on these units and get them into a working configuration. This is going to reoccur and it can be expensive until the drains are re-run. The replumbing isn’t that hard and this doesn’t have to be done by an AC contractor.

Tagging @Jon as he’s been most involved with the HVAC lately

Do we know why the drains are getting clogged? I wouldn’t think condensate would be too grotty. I agree rebuilding with larger PVC and cleanouts wouldn’t be a major undertaking, but I’d be annoyed to do it and still get clogs.

Do you know if the prior clogs have been more organic or inorganic? It could be the shop dust clogging up the drains. OTOH, if you start getting something like an algae growing, it’ll clog more frequently until you run some bleach water thru the line to kill off the algae.

Any condensate drain can clog. Happens on residential too. Has happened with the Lounge unit. Dust is part of it, but you’ll never stop dust completely. The important part is being able to vacuum out the condensate lines and clear them. This won’t drain any condensate that has already overflowed a stuck drain, draining the overflow pan is a separate step.

Vacuuming the lines clean is not possible with the “common rail” where all 4 port onto a single line that passes each unit, that crap drain was here when we moved in. If you put a vacuum on the common drain tube, it’s going to pull air through the other 3 drains that are clear and will never draw enough vacuum to suck the muck past the p-trap on the clogged line.

Each unit must have its own line, and not meet up until at person-height with ports you can disconnect and hook up a shop vac to. Then you can suction individual lines clean any time you need. Ultimately these lines all just go to the building sewer. Thus the need for a p-trap on each unit. Note vacuuming will deprime the p-traps, so that’s a thing.

Algae is a part of it too, it’s supposed to be algae growing on dust making it clump together more. Typically we throw anti-algae tablets inside the units. Trying to bleach out the lines isn’t all that helpful by itself, though. Also, the way the drains are ported right now, it doesn’t have access to do that. We need to replumb it so we can keep the drains clean.

Plus, the rise/run of the current drain is far below guidelines. Needs more slope. But that’s not where our clogs actually occur.

Better filtering is good for other reasons, but this drain setup just has to be fixed. Even if we had the best filters possible, you can still have a mess of problems with that common drain.

The units DO have a low voltage float switch that shuts off the compressor (not the fan) if the overflow pan is full of water. The pan should never see any water under normal conditions, it only overflows once the condensate drain is already clogged, and will stay clogged if you just drain the pan, and will immediately start to overflow again. Don’t try to add a second drain to the overflow pan or anything, that’s just not a solution.

would it be reasonable to run separate drain lines that discharge into the sink? that’d leave the ends at a convenient height to vacuum…

Running them into the sink is one option. It’s quick and easy, but does limit what you can do with the sink. Not hard to change to a connection to the PVC drainage later though.

The way the drain rail is right now- sitting at the end of the units several feet from the wall- needs to change. It’s hard to the the orange ladder around in when we need it, and because the slope needs to increase, it would be lower near the sink.

There’s a bit of a question how to go around the columns jutting out of the wall on that side. We could make the pipes do a “U” around the supports with 4x 90 deg fittings, or just go straight pipe offset from the wall. Remember, the point is the drains have to be separate, so Front and #3 will have to run past columns as separate pipes.

Front could also be routed to the lounge bathroom or bar sink drain. The bar sink already has the drain for the lounge AC on it.

I think I’d do unistrut and pipe straps on the wall, and use 45º elbows to do saddle bends around the columns. We wouldn’t necessarily have to run all four pipes all the way down to the sink - we could do something like run all four drain lines to an air gap arrangement (eg APOLLO ABS Plastic Air Gap Drain Kit, For Use With: 4A RPZ 1-1/4 in to 1-1/2 in - 40D972|AGD4A112 - Grainger) that’s low enough to reach with a vacuum but not directly in the way of the sink, then run a common drain from that to wherever (the sink for now). In the future if we want to plumb it properly, only the common drain needs a trap.

Is the existing pipe an OK diameter? If so, we can salvage it.

HVAC 2 is functional again. I siphoned out the overflow drain tray, and cleaned the drain pipe from the unit out as well. I verified the drain is currently working. I’ve turned the unit back on, sounds like its running again.

I agree the overflow tray shouldn’t have a constant drain on it, but to help clean it out in the future. Perhaps a ball valve with a hose fitting on it, that way a hose can simply be screwed on and the tray can manually be gravity drained, instead of having to siphon it.

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Thanks!

@Jon we don’t need to salvage the existing PVC, it’s super cheap. We’re not talking lumber here.

I did collect a lot of fittings for the job, including the p-traps which are a little hard to find. I don’t know if it’s enough for everything. The couple of sticks of PVC beside the dust collector are for the drain


Ok now I remember, the drains pretty much have to go in front of the columns. They don’t stand off that much anyways and the conduits often keep it from being possible to put flush against the wall
The PVC parts are in a Home Depot bag by the dust collector

Well, that pic is from under unit 3. 3 and 4 (3d printer area) should probably unite with the drain for the lounge unit at the drain under the bar sink, so it won’t even go to the right where I took a pic. 1 and 2 can meet at the woodworking sink.

Airgapping would be ok. It does need a u-bend between the pipe and the sewer to stop sewer gases from escaping. The units will each have their own p-trap

hey @jamesmcnees , when you say you cleaned out the drain, how did you do that? They’re pretty difficult to access like that

That unit (2) is still off btw

I drained the overflow with the hose on the ground, siphoning out the pan as much as I could. I uscrewed the overflow pipe, vacuumed the pipe from the unit, vacuumed from the p trap, then reverse blew through both pipes. I let the main pipe drain as much water as I could before I re secured the screw joint. After I put the joint back together, I verified the pipe was dripping into the joint for the main drain line.
By turning the unit back on, I mean I just re set the thermostat. Not sure if there was more to it than that.

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OK thanks, I asked because clearing the drain is not very straightforward with the way the condensate drains are run. The unit was shut off at the service shutoff, not the thermostat.

Unfortunately, it is flooding again and I shut it back down at the service shutoff. This might be partly due to the filter needing changing