DHW Coil Mystery

Back in January, I filled my Yellow Flame boiler with water for the first time. The DHW coil inlet and outlet had no piping or plugs attached. Once the boiler was nearing full, water started running out of the DHW coil connections. At that point I assumed the coil was broken and installed two plugs.
Yesterday I was doing some replumbing and decided to check the coil again. It didn't seem to be leaking. Today I hooked a garden hose and a pressure gage to it. It seems to be loosing about a pound per hour. That could be because I am not using any valves to seal off the garden hose good.
At any rate, the DHW coil water is not running into the boiler like the boiler water was running out of the DHW coil!

I guess the next thing to do would be to pressure test the boiler leaving the DHW coil unplugged.

Anyone have thoughts about how a DHW coil can repair itself?

And I thought it was going to be a boring summer!

-Don

when I unhooked the hose this morning, the gage was reading 16 psi. That was about 18 hours after I charged it too 25 psi. The boiler return was open the whole time, no sign of DHW water coming out the return.

I removed the hose from the inlet first, leaving the inlet opened. Then I unscrewed the gage from the outlet. Water came spurting out as if it was under pressure!!!??? Inlet still opened.

I don't understand this thing. I thought that it's just a tube that's coiled up with fins on it. Do they have check valves or something in there?

-Don

Hmmm yes that is quite a mystery.. I don't think it fixed itself though.. Were missing some puzzle pieces here.. Sorry I couldn't be more help.

Where is the pressure going? you started at 25 psi and it fell to 16 right?

I wasn't realy planning on doing a pressure test when I hooked it up. I fully expected to hear and see water, dripping or running into the boiler. I hooked up the hose and the gage, went over to the laundry, crouched down behind the washer, turned the valve on for 2 or 3 seconds. I went back out to the boiler and the DHW coil was at 25 psi.

The whole garden hose was in the circuit so, the pressure could have leaked out anywhere. But, the water did not leak into the boiler.

-Don

Blow the coil out with compressed air and then charge the boiler with water.

Ok so hose expansion would explain the pressure drop. Yeah like Rob said, blow out that line and fill er up and see what happens..

I'm currently in the middle of re-plumbing the boiler so, I can't do a pressure test yet. May be next weekend I will seal up the boiler and pressurize it with water to about 30 psi or so and see if anything comes out of the coil.

If not, I will run water through the coil and see what happens?

I can kind of see the coil through the small hole in the front of the boiler, where I had the gage installed. While the coil was pressurized, I put a screwdriver in the hole. I found that I could move the coil around very easy. I didn't imagin at it would be that flexable.

Thank you,

-Don

I'd be careful of poking that coil with a screwdriver...you might find the "leak" after all.

Back to what started this whole thing. I have seen water drip out of coils when the boiler is first filled & heated. The water in the coil expands, and sometimes drips out the uncapped inlet/outlet.

While you have everything apart, why not put in a new coil. Then your good to go for years.

might have to cut it out.

Don are you using the two remote plugs to test? That is the correct plumbing, and the center plug is a direct opening to the boiler water supply. It should have boiler pressure at all times. The two outside plugs removed should have no water, however as the guys mentioned, residual water sometimes steams out of the coil for a while. If you have water pressure on the outside plugs, then the coil may be bad. I'd still check the two others with nothing connected but a hose into a bucket. from each. Remember that the water pressure in the coil will be domestic pressure and not boiler. Before you think you can remove that coil with ease, recall that a 4 or 6' pipe wrench will be required....or cut slots in the fitting after you break or cut off the exposed cap. safety glasses ALWAYS......try it and let us know. You may be OK.

tsb wrote:While you have everything apart, why not put in a new coil. Then your good to go for years.

tsb,

I ran a thread earlier this year about replacing the DHW coil. No one thought it was available. I don't think I can get that 4.5" pipe threaded coil out, that has been in there for 40, 50, 60? years. At that time it was decided to forget about the coil and just hook up the Amtrlo Boilermate. And maybe that's what I'll do. It just bugs me that the coil doesn't seem to be broken now.

-Don

Don, there is a radiator shop that makes custom coils for a reasonable price...I have posted their number before, but can't find it right now.

The old ones always come out, but sometimes it takes fire, big wrenches, a reciprocating saw, and a big guy to sit on the boiler.

Don, did you check with AHS. That coil looks (outwardly at least) suspiciously like the one in my AHS S130 Coal Gun.

Rob R. wrote:Don, there is a radiator shop that makes custom coils for a reasonable price...I have posted their number before, but can't find it right now.

Tunnessen Radiator. They are located in Hazelton, Pa. Telephone : 570-454-1161