In chasing a mole out of our basement, I moved a weird little black-box pump that seems to be connected to our furnace–and now it’s seeping water all over the floor. I’m not sure what it is, or what to do about it.
Basically, it’s a little black box plugged into the wall. There’s a tube of what looks like medical tubing, about 1" in diameter, leading from the side of the furnace down to the box on the floor. A smaller tube, maybe 3/4", leads from the box up to our washing-machine drainpipe.
The tube that goes into the box isn’t firmly attached: it just rests in a larger (maybe 2" diameter) hole in the top of the box. When water leaks, it seeps out of this large hole and out of the seam to the box, running around the upper edge.
I have no idea what this thing is, whether I can fix it, whether I can replace it myself, whether I need to call a plumber, whether I need to call an electrician, etc. Does this description make sense, and does anyone have any advice they can offer?
What kind of furnace is it? Oil? Gas? Does it have a humidifier attachment? Does this look like an official piece of kit, or some previous homeowner’s patched together solution to some problem?
It’s a gas furnace; I don’t think there’s a humidifier attachment although I’m not sure (my wife thinks this may be some sort of dehumidifier to extract condensation from within the furnace); I highly suspect it’s a kluged solution, given the other atrocities we’ve found in the house. If it helps, the pump has a little label on it saying something like “Not for use with swimming pools.” And there’s another wire attached from the pump to the furnace, I think–I have no idea what purpose it serves.
There’s no air-conditioning unit attached; just heat. I don’t know that my moving it broke it, but we only noticed the problem after I moved it. Should the tube bringing water into the pump be attached to it, or is its lack of attachment normal?
I’m far from an expert (just a veteran of various home improvement disasters), but I’d say that if this is a pump, the tube should be attached. Is it possible that there was some grommet or other fixture that has detached and receded into the body of the pump?
It may be that it’s just fed by gravity, though, seeing as it’s leaking water. The water has to be getting there somehow. The real problem is that it doesn’t seem to be pumping it away. Did you break any of the leads on the wires when you moved the pump?
I don’t think there was such a grommet, but I’ll check that when I get home.
The water is pretty definitely coming in through that tube; the only reason why I think it might need to be attached is because maybe it needs a tight seal to work properly. I don’t think I broke any of the wire leads, but I’ll check that when I get home.
Thanks for the advice–and if anyone has any more, I’m very open to it! At the very least, now i know what it’s called if I need to call a professional (and speaking of which, what kind of professional would I call?)
Daniel
There should be a float switch inside the pump that controls the pump. The wire from the pump to the furnace is probably the high level alarm limit switch. If for some reason the level of the condensate gets too high due to the pump failing, this limit switch should turn off the furnace and thus the condensate source. That switch should work even if there is no power to the pump. Since it isn’t working, I’d guess that the float inside the pump isn’t operating for some reason.
When you say it’s a little black box plugged into the wall, do you mean plugged into an electrical outlet? If so, then the pump works on 120V power and I’m probably right about the cut off switch. If it’s not plugged into a wall outlet, then I’m probably wrong about the cut off switch and I’d guess that the wires are either 120V or 24V power from the furnace to the pump.
I’d check power first, and then the operation of the float switch inside the pump.
If you could get a pump, you could replace it yourself. If you are not comfortable (or entirely sure about the function of the wires from the pump to the furnace), you could call a plumber or HVAC company to do it for you.
The only reason it would be a condensate pump would be if the OP had central air, which he said he doesn’t. Furnaces don’t have a need for condensate pumps-I’ve been servicing and installing HVAC equipment for a number of years and never saw a pump on any unit that didn’t have an cased coil evaporator, and only then if gravity drainage to a sump hole wasn’t available. Units with humidifiers are typically fed with a length of 1/4" copper similar to what supplies an icemaker. That said, it’s supply only-there is no return or discharge side to the plumbing circuit.
High-efficiency condensing furnaces do indeed produce condensate. The units extract so much heat out of the fuel that the water in the flue gas condenses.
In my poking around the Net, it appears that the high efficiency gas furnaces produce some sort of acidic condensation. Makes sense to me – one of the byproducts of combustion is water.
Dag Otto: Would they really put a float in the pump that would turn off the furnace if the pump stopped working? That sounds like an infinitely bad idea. I’d much rather have a damp cellar floor than a cold house and frozen pipes.
It’s possible. I know that condensate float switches on fan coil units can be configured to shut off the fan and turn off the flow of chilled water if the pan overfills. I was trying to figure out what the wires from the pump to the furnace were for and could only come up with power or a cut off circuit. Maybe a pump enable signal, though I don’t see the need for one.
Quite true. When a high-efficiency furnace is vented using an older masonry chimney, flue gases will condense, form an acidic precipitate, and over time destroy the chimney. A pump isn’t curative. Proper sizing of the chimney, including installation of a liner per the installation manuals shipped with every modern furnace, is.
Your statement applies to commercial chillers, not a residential air conditioning system, which the OP says he doesn’t have.
Which is all besides the point. A high-efficiency furnace usually vents via a PVC pipe, the heat exchanger is designed to withstand the acidic environment, and the condensate is drained via a floor drain or a condensate pump. The OP did mention that he was evicting a mole for a basement, so a condensate pump makes sense for a furnace located there.
First, my statement appies to fan coil units, not chillers. Second, I was making a point about the operation of the condensate float switch. You may not believe it, but I’m pretty sure the little black box that the OP is concerned about is a condensate pump. Thus my statement about condensate float switches is applicable.
Interesting. Obviously the float inside isn’t working–at least, it’s not turning off the furnace. I checked when I got home, and while there’s a cord plugged into an electrical outlet, there are also two blue wires with stripped ends that aren’t connected to anything, and that I can’t see where they’d connect to. Perhaps these should connect somewhere to the furnace?
The closest i can imagine them connecting is to a wire that runs underneath a piece of duct tape along the side of the furnace near the pump (I told you it was DIY hell–it’s just I wasn’t the DIYer). It may be that when I moved the pump, these wires came loose.
That said, the pump does seem to run when it’s turned on: at least, it vibrates, although no water goes up the tube. Maybe it’s just that the motor conked out when it was moved, as (for example) water sloshed into the inner workings?
If it was working, would the outflow tube need to be securely fastened to the pump?
The pipe or tube from the furnace to the pump is probably doesn’t have to be fastened securely (condensate is only draing by gravity), though it probably could and should be. The pipe or tube from the pump to the washing machine drain box should be securely fastened to the pump since the water will be under pressure in this line.
But face it, I’m only guessing on what those wires are for. You could open up the furnace and try to figure out from the schematic (if there is one on or inside the furnace) what those wires do, but you have to be fairly confident in your ability to do that.
I think you are much better off getting a professional to make the repair.
An update: based on the ideas in this thread, I figured out how to open up the pump (really easy once I realized it could be done). It basically consists of three components, near as I can tell:
A collection tray for water;
A flotation device attached to a switch; and
A motorized pump that turns on once the flotation device gets too high, draining the water.
I have no idea what those stripped wires are for.
I emptied the collection tray out and filled it with blue-dyed water (so I could watch its progress through the tube); I also worked the many air-pockets out of the outflow tube. I then plugged the pump back in.
It’s down there, diligently pumping away, but the water level is moving at a dreadfully slow pace–maybe an inch a minute. Before when the furnace was turned on, it was giving out condensate at a steady trickle.
I’m wondering if the pump is just mostly broken: should it be pushing the water up the outflow tube at a brisk pace? Or is this snail’s pace normal for a device like this, and maybe I just needed to empty it in order for it to “reset” itself?
If it’s broken, and if the two wires are extraneous (designed, for example, to turn off my furnace–yeesh!), I might just buy a new pump and see if it works: installation looks like it consists of fitting the tube onto the pump and plugging it in. Otherwise, if the furnace has gone into condensate overdrive, maybe I need to get a pro in to take a look at it.
I just wanted to mention we have a pump exactly like described in the OP. It was installed to handle the condensation when we (finally!) added central air conditioning to our forced hot air heating system a couple years back.
Last year we also had a whole house humidifier added to our system (for use in the winter when the air is dry). The type we have I have never seen before but apparently it is designed to have water trickling through it whenever the furnace is on, the water wets a filter thingy and an auxillary fan blows air over the filter. When the furnace turns off the water flow and the auxillary fan also shut off.
Anyway the system was set up so that any water that makes it through the filter thingy without evaporating ends up in the condensate pump. We had a minor flood earlier this winter when the drain hose which goes outside the house apparently froze up and the pump started overflowing on the basement floor.
Any chance your system has or had something like this?
