Y'all are a bunch of wankers!

Why does my furnace have a pump?


I have a gas powered furnace.  It produces condensation.  There's a condensation line out, in the top right.  It apparently fills a reservoir, which, when it fills, gets pumped out up, into that transparent hose, up and over and down to the drain pipe on the left.

Why?  Why doesn't it just use gravity?
Permalink Wabi-sabi 
October 10th, 2017 12:58pm
You need to call the manufacture of that furnace to ask this question. Unless it was jury-rigged by some bastards, they should have a logical question.
Permalink Done That 
October 10th, 2017 1:01pm
sorry, I meant to say logical answer.
Permalink Done That 
October 10th, 2017 1:01pm
Michael, this house is so fucked up. Why did you buy it?
Permalink Done That 
October 10th, 2017 1:02pm
Next thing you are going to tell me that they had a zoo in the basement where they kept a camel.
Permalink Done That 
October 10th, 2017 1:03pm
Weird. My high efficiency furnace has no such pump.  Gravity works for me.
Permalink Legion 
October 10th, 2017 1:12pm
Maybe in the event that it produces a lot of water the pipe backs up? A sort of storage tank for to-be-pumped water?

I think by code sewage should have enough grade to drain by gravity.
Permalink Nz 
October 10th, 2017 2:25pm
Cool post.

So yeah, gas furnaces do produce H2O as a byproduct of combustion!

Where does the H2O go? I never thought of it before since I've had several places with gas furnaces and I never saw a drain for water. But now that you mention it, hmmmm....

So yeah it looks like there that it could just drain into the pipe via gravity.

But there's no P-trap visible. Is it in the wall? Don't want sewage gasses (methane) coming into a room with a pilot light!

What is the pipe that goes up? What is it going to?
Permalink Reality Check 
October 10th, 2017 2:37pm
Calling EPA to report on RC's negligent discharge of toxic waste.
Permalink Done That 
October 10th, 2017 2:56pm
I'm assuming his furnace has A/C built in.

A/C generates more condensation water than heating does.

And probably it has a condensation pump, for simplicity.  Without a condensation pump, you need 1/4 inch  to 1/2 inch PVC pipe routed along the floor of your basement, to get to a sump-pump somewhere, whereupon it will get pumped out of your basement when it builds up enough.

With a local condensation pump, they can simply run 1/4 plastic hose up and out the nearest wall to the outside.

Gosh, a condensation pump costs about $50 to buy, and 10 cents a day to run.  And they're very reliable, and easily replaced.

That's why.
Permalink SaveTheHubble 
October 10th, 2017 3:02pm
Oh, wait, they DID run PVC pipe all over your basement already.

So why use the condensation pump just to cross 2 feet?

I don't know.  Perhaps the PVC was already installed, and when they installed the furnace, they had no extra PVC to extend the line, but they DID have a condensation pump.
Permalink SaveTheHubble 
October 10th, 2017 3:05pm
"Calling EPA to report on RC's negligent discharge of toxic waste."

Is H2O toxic waste?

My houses have had the furnace in a closet. Apparently there must be a drain in the back. Or maybe a humidifier that just evaporates the water.

Beyond closet and basement, there's natural gas wall, floor and space heaters. I really don't think these have drains.
Permalink Reality Check 
October 10th, 2017 3:06pm
"A/C generates more condensation water than heating does."

AH - HA!

Now we are on to something.

OP, please confirm if this is a combination unit that heats AND cools.
Permalink Reality Check 
October 10th, 2017 3:07pm
It's a gas furnace.  It expels condensation when I run the heat.  It's very humid in the winters where I live.

I'm 80% sure that drain pipe drops over the sump pump.

The best explanation I've received for this spurious pump here is that perhaps the previous owner installed the pump because it was phase one of sending it to a garden watering system?

And then they sold it before they could move onto phase two?

Now I want to probe that drain pipe to see if it actually drains, or if it's emptying into some hidden basin somewhere that will eventually back up and leak all over my floor.

Home ownership, lulz.
Permalink Wabi-sabi 
October 10th, 2017 5:17pm
"or if it's emptying into some hidden basin somewhere"

Older shit with a lot of owners can have some WEIRD ass shit in there.

Maybe you find a 1" steel plate behind which is the killing chamber where the victims were deposited via a system of chutes. If you find one of these, even god can't help you if there are thirsty vampires in there, ravished from a century without fresh blood.
Permalink Reality Check 
October 10th, 2017 5:25pm
So you're saying I should get one of those sewer scopes to explore the territory, rather than going myself?  Like that one made out of water that those aliens in The Abyss used?
Permalink Wabi-sabi 
October 10th, 2017 5:37pm
Dude, obviously I didn't say that.

However, if as a separate issue you're asking me if you should get a sewer scope the answer is why the fuck not!

I have a HD resolution USB sewer scope with a 30 foot long snake to it that I bought off Aliexpress for $6 including shipping. Works great, and has been tons of fun. You never know when you need a sewer scope, but you definitely will find lots of opportunities to use it.
Permalink Reality Check 
October 10th, 2017 6:31pm
I think my super hummer high efficiency furnace has a drain from the furnace part. But I might be remembering the A/C drain.

If you can get rid of that pump, do so!

It is a point of failure. If it fails, water probably won't flow through it. It works or you have a mess.

Gravity never fails, but you do have to check the drains periodically.  I've had blockage and a minor mess.
Permalink Legion 
October 10th, 2017 6:54pm
I know man.  It's so obviously wrong to put that pump in that I can't believe someone did it on purpose.

I feel like I'm missing something.

Probably going to cut that fucker out and splice in some PEX tubing.  Who needs this ticking time bomb in their lives.
Permalink Wabi-sabi 
October 10th, 2017 7:14pm
I've got a pump on my high efficency gas furnace.

The pump moves the water to the sink on the other side of the room. I would guess that gravity feed would work if the water has somewhere to go.

The water tends to be slightly acidic so the outlet ought to have a limestone filter or something like that to reduce the acidity to protect your pipes.
Permalink John 
October 10th, 2017 8:00pm
No worries if all your pipes are plastic.

I don't think I'd worry much if they weren't.  But I might research what John the plumber said.
Permalink Legion 
October 10th, 2017 8:04pm
I'll go with it being a standard install where everybody gets a pump willy-nilly at no extra charge.
Permalink trollop 
October 10th, 2017 8:10pm
It's an old house. The pipes are not plastic. Probably lead.
Permalink X 
October 11th, 2017 10:33am
The Romans used lead pipes, as did parts of their empire they colonized. After introducing lead pipes to Britain, the numbers of violent murders went way up, and we now know why. In general much Roman psychosis and extreme violence is likely due not to their being a superior race bringing civilization but they were an empire of serial killers driven mad by lead.

In any case, I've never seen lead pipes in any US house, no matter how old.

Houses from 1930 will have galvanized steel pipes, that was the cheap and standard option then. However leaded solder was used to join them and this is why older homes have trace amounts of lead in the water.

So why are there so many articles about lead pipes? Well, the service line going from the mains to your house is often made of pure lead. It was flexible like PEX and easy and cheap to install because it bent. No need to spend a lot of time with complicated bends and joins, the city or developer could just run a line easy. And yeah, shitloads of lead can leech into your system, make your kids retarded, and make you more likely to be a violent criminal.

These pipes are unheard of in wealthy white neighborhoods where they were all replaced decades ago but very common in minority neighborhoods where the city doesn't consider the cost worth it to fix, or simply says it is the homeowner/landlord's responsibility.

A convenient side effect is that it enables the story line that blacks are inherently violent, enabling tough on crime measures that destroy black families. Just don't mention that this is all because of lead pipes and toxins in poor neighborhoods. No, that's a conspiracy theory. Shut up!
Permalink Reality Check 
October 11th, 2017 11:07am
If your house is in a nice neighborhood you hopefully have copper lines. Those are great since they are antibacterial.

When you go in the crawlspace, take a screwdriver. Find the entry point of the service line. If it's dull grey, and you scratch it with the screwdriver and it is silver, then your service line is lead. If that's the case, you should immediately switch to bottled water for all drinking and cooking, and find a professional who can excavate the entire line to the service box and replace it.
Permalink Reality Check 
October 11th, 2017 11:11am
Great info RC

What's the status of plastic pipes?
Permalink X 
October 11th, 2017 12:08pm
Plastic messes with your hormones. It leches estrogen-like chemicals.

But that is no problem if you don't mind men with breasts.
Permalink Legion 
October 11th, 2017 2:30pm
Tiny possibly carcinogen or hormonal disruption risk. Don't run hot water in PVC, use CPVC to reduce the leeching chances.

Polybutylene is now banned because chlorine causes it to have small holes that will create the mother of all mold problems in the walls.

Its replacement PEX seems ok, but that's what they said about poly.

PEX being flexy and coming in big spools is easy and fast to run.

PVC gets quite brittle after 10 years.
Permalink Reality Check 
October 11th, 2017 2:38pm
If cost is no issue, copper is really great due to the antimicrobial properties.

Copper requires a blowtorch though for soldering and I get really scared using a blowtorch in a tiny enclosed space filled with wood.
Permalink Reality Check 
October 11th, 2017 2:40pm
Fortunately Wabi was on drain pipes, not supply pipes.

Nothing to worry about there.
Permalink Legion 
October 11th, 2017 3:19pm
I think Wabi and Mike are the same guy and these are two concurrent problems he's having, but who knows.
Permalink Reality Check 
October 11th, 2017 3:37pm
I had assumed they were.
Permalink , Cup 
October 11th, 2017 4:03pm
Hey while you're here, take a look a the wall behind his heater below the pipe. See how the floor is sagging there and there's a gap under the wall? And the black discolorations? That is pretty clearly water damage, going through the floor, and is extensive enough that the floor joists underneath are partially rotting too.

Needs to be looked at in the crawlspace for sure. Might need to rebuild the floor?

Also the matter of the purple towel meaning that he is aware there's a problem because he's apparently using it to absorb water. Towel isn't the right solution, isolating and stopping the leak is. Presumably that's what he was looking into and why he was asking about the pump.

Is the water coming from inside the wall, or spillover from the furnace? The stain pattern suggests inside the wall. There's a problem there.
Permalink Reality Check 
October 11th, 2017 4:08pm
Finally found the answer to the original question.

> Some *high-efficiency furnaces* may use a condensate pump to push condensation toward the proper draining area. A condensate pump is a small white box connected to the PVC drain pipe and pumps water toward drain. It basically acts like a small sump pump.

Issue is this is a newfangled "condensing gas furnace". More efficient than the furnaces I've had, but there's a small matter of the water.



> High-efficiency boilers, furnaces, and water heaters produce *acidic water* that can pose a disposal problem no matter how you handle it.

That article points out that during very cold weather, your condensate drain freezes and then the whole system backs up, floods, and shuts down!

His water damage there happened during a freeze.
Permalink Reality Check 
October 11th, 2017 4:13pm

> A high efficiency condensing gas furnaces is a category four vented appliance. Because they operate with a vent motor that pushes the gas through the pipe creating a positive vent static pressure, *the pipe must be airtight* so the products of combustion will not leak out of the vent.

See the problem? His pipe isn't airtight at all, he's got a tube going into an open pipe. 100% bad improper install, causing property damage.

That pdf talks about how the whole drain system has to be really special and properly done with these things or it will cause serious problems.
Permalink Reality Check 
October 11th, 2017 4:16pm
Leakage probably comes from the top of the pipe and the floor is not level so the water then heads to the wall and pools up there. I thought at first the water was coming from under the wall, and maybe it does depending on that pipe - if it froze it has cracks in it now that can cause leaking. But also could be overflow from the pipe when the system freezes downpipe.
Permalink Reality Check 
October 11th, 2017 4:20pm
Finally found the manual for the gas furnace.  It says to simply connect the condensate catch (which is open at the top) to drainage with PVC piping.
Permalink Wabi-sabi 
October 11th, 2017 6:08pm

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