Sealing a System - Pre System

Bigben1357

Hi there. I was working on my furnace last year and noticed these two blue 1 1/2" pex pipes coming out of my concrete. My thought was that maybe they're for an old radiant floor heating system. (I know the original owner of the house had a wood boiler in the garage. I removed a copper tube and fin radiator type thing from the furnace stack). I'd guess they wanted to keep their boiler when they moved and just cut everything off.

I hooked up what you see in the picture to run a pressure test. It leaked pressure slowly. The test gauge I bought only goes to 30 psi so that's what I put in. When I woke up in the morning and checked, it was down to 15 (in probably 12 hours) and it's settled at about 10 psi and has held there for a week. I googled sealant and it looks like there's seal product that you can add to your water which can seal small leaks. I think I'd like to try that as I'd like to use the system if I could.

Any pointers on how to run a bottle of that sealant through without hooking up an entire system? I don't really want to invest in everything else if the piping is too far gone and it'll never work sort of thing.

I figured I'd need to get some sort of air purge valve so the additive would get to the entire pipe throughout.

Any advice or ideas would be welcome.

JUGHNE

Do you know where the other end of these tubes are?

Could they have been from the wood burning garage boiler to your furnace air handler coil?

What do you want to do with them?

Jamie Hall

Were you using air or water pressure? Air pressure can drop — sometimes dramatically — as the air temperature changes. Water, not so much. If it's holding at 10 psi, it may not actually be leaking.

Second, what is your plan for those pipes? Do you want to use them again for something? If so you can try a sealer. Otherwise, I'd leave them be. I'd never make a long term bet on a sealer, though…

Bigben1357

@Jamie Hall, I used my air compressor to put air pressure in to pressurize the system.

I would love to use them for a radiant heating system as that's my best guess as to what they're for. I just don't want to invest in a whole hydronic system and then find out there's a leak I can't fix and be out a couple $grand$.

Jamie Hall

I would suggest, then, that you take a nice length of stiff pipe. attach one of the stubs to that and tie it up against the wall. Fill it with your garden hose until you get a solid stream of water out the other stub. Record how long that takes so you have some vague clue as to how much pipe there is. Cap the free end while it's flowing, and then fill your stiff pipe to the top. Come back next day or a few days later and see how much water — if any — you've lost.

I might add that since you have only a guess as to what those pipes area/were, you might want to verify that they are, indeed, a radiant heat loop system…

Bigben1357

@jughne, I don't think they come out anywhere else... Or go to anything else. I think it's just one big loop. There's no radiator or anything anywhere else.

There were separate pipes that went from the copper/fin thing that was in the furnace out to the garage. I removed that from the furnace bc it wasn't being used and it was just creating unnecessary resistance in the air flow in the furnace.

The goal would be to use them to heat my slab.

EdTheHeaterMan

How can you be sure that those PEX pipes go to a radiant floor? is there a manifold somewhere in the home that the 1" or 1-1/4" PEX connects to elsewhere? No one uses 1-1/4" PEX as the floor tubing. they use 3/8" or 1/2" and tie it into a manifold where you can purge each separate loop of air as the water is fed into the system.

Where was the wood stove located in reference to the end of the blue PEX tubes in your photo? …a couple feet away or in another room, or was it an outside boiler?

GroundUp

Nobody used 1-1/4" PEX for a radiant floor heat emitter. Those are almost certainly an underground transfer route to/from a heat source outside the home such as a wood boiler. It's possible that the other end has been looped, but the chances of it being a radiant heating loop are one in a million. Find the other ends before sticking another penny into this.

hot_rod

With an air test, be sure to soap that gauge set up, all the threads and the schrader valve. All are prone to leaking.

Bigben1357

The only thing I can think of for why the 1 1/2" might've been used for a radiant floor system was the house was built in the late 70's. It seems like there wasn't much in the way of standards.

It also seems like something they (whoever built the house) would have done. Here's a picture of the radiator thing I removed from the furnace stack. The two copper pipes went through the wall and into the garage where they terminated. (Picture attached of the capped ends on the other side of the wall in the garage). This is where the wood boiler was at some point. So straight up from these giant blue, duck taped tubes coming out of the concrete, was this copper and aluminum fin heat exchanger they had built into the furnace.

There is nothing else these blue tubings would go to. I've been in the walls, ceilings, everywhere...and the only thing that makes sense is that it's a single zone radiant floor system. I'm not saying it COULDN'T be anything else. Just that I can't figure out what else it would be.

I may try and put a male thread on the capped end and hook up some hoses to see if it's an actual loop. I'd hooked up my shop vac to one end and sucked a bunch of water out right when I started investigating but I didn't feel suction on the other one.

hot_rod

PEX tube is usually CTS "copper tube size"

So 1" pex would be 1-1/8" OD (outside diameter)

1-1/4 pex would be 1-3/8 OD

1-1/2 pex would be 1-5/8" OD

What is the outside diameter of that tube?

That being said, there is some odd, metric sized tube around, it would have a mm (millimeter) number printed on it. Usually!

There may be some knock off, import tube in the market with no, or fake listing numbers printed on it.

Jamie Hall

The fact that those pipes are insulated the way they are makes me suspect that they had some other purpose than a radiant floor, and you really need to find out what…