Mouat Vapor System Balancing Valve?

offdutytech · 4:15PM

Yesterday while doing an emergency hot water tank replacement I stumbled on a Mouat Vapor system in Detroit. This particular neighborhood usually has two pipe Dunham Bush or one pipe systems. So the Mouat system was a cool find. In talking with the homeowner they had a previous contractor boiler replace the boiler a few years ago. I kept noticing the boiler had a lot of short cycling while I was there. Poking around I did find a steam leak and some radiators with leaking valves that the customer will have me back out to take a further dive into. Pressuretrol was set low, but already had talked to the customer about putting a vapor stat on.

The radiators still all have Mouat water seals on them. What I'm trying to dig into a few abandoned pipes close to the boiler. It looks like it used to be a Mouat balancing valve location based or air vent into the chimney. I found G.W. Gill Moaut PDF, but can't get the detail clear enough on the PDF when I blow it up.

The pics are next to the boiler. I did find the dirt pocket pipe on the wet return in the opposite corner of the basement where the boiler is. drywall might be covering where the vent might be. This is actually where I am hearing a steam leak.

Does anyone have a better drawing on the system? I attached a few pics and a drawing of what I found. Unfortunately there's drywall covering up 90% of the basement right now to fully trace out the pipes. I will be going back in the near future to address the customer issues. At any rate this was a cool find and made working Saturday a fun service call.

EBEBRATT-Ed · 5:33PM

Looks like the other guy didn't read the manual on the header piping.

Guess he flunked reading in school. looks like opposing risers.

Don't know anything about Mouat so I will clam up.

Cool find though. I am sure you can fix it up.

Steamhead · 5:40PM

@offdutytech , those drop pipes are where the Mouat Air vent would have been. At least one of them is draining the dry return, right? If it's the one with the plugged tee, you can put one or two Gorton #2 vents there.

The lack of a vent may be why someone jacked the pressure up. Not the first time I've seen that. It might also explain the steam leaks.

Hopefully @gerry gill will chime in, he's our resident Mouat expert.

offdutytech · 6:05PM

@Steamhead that was my initial thought until I found the mud leg in the opposite corner of the basement and heard the steam leak. In that area where the drywall needs to be ripped out I found a decorative bushing sticking out. The kind you find a a radiator, which makes me thing the air vent was over there and the pipes I found might have been a balancing valve. It's just based on the Moaut pdf I found. It appears to be a wet return because part of that line is buried in concrete near the mandoor from the basement to outside. Of course I'm dealing with pipes behind finished drywall too. So it's hard to get the full picture unless we start to rip it out.

@EBEBRATT-Ed For sure not crazy about the header at all. At least the Ptrol was set down low and the water level stayed stead ish in the boiler. I re set the VTX feeder to zero to see how much water we are making up until I can get back. Trying to focus on outside the near boiler piping for now. I did find a 3/4 copper riser taken from the steam main for a bathroom radiator that the customer showed me was leaking. Lord only knows what someone did there.. lol

mattmia2 · 6:30PM

https://forum.heatinghelp.com/discussion/comment/1874591#Comment_1874591

I can't tell 100% from that picture but it looks like the riser to the main is between the equalizer and second boiler riser so I think that is ok. Not sure that there aren't mains teed together in the old header at the ceiling that we can't see.

Is there a bunch of stuff in the corner attached to the return with 2 open tee connections at the top?

It is very likely that basement had a dirt floor when that stuff was installed.

A thermal camera may tell you where stuff is in the walls and ceiling.

Steamhead · 7:28PM

@offdutytech , perhaps there were two vent locations………….

offdutytech · 8:03PM

@Steamhead That could be as well. I talked to Gerry today it's possible that it was vented to the chimney. I'll have to go back with my FLIR and poke around some more when the drywall can be ripped out so hopefully see a vent in that area.

Mouat Vapor System Balancing Valve?

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