Mouat Traps

Terry_10

steve_6

what do you want to know

mouat made water seal traps and thermostatic traps. We work on these all the time.

Terry_10

Re-Mouat Traps

Mine are marked Clev'd "O" and I was wanting to know with no moving parts can they also pass steam such as those with moving parts. If so, can they be cleaned or should they be replaced. If the later, where would I find replacements. I'm getting some very warm and noisy returns.

Thanks,
Terry

Fred Harwood

Warm and noisy

returns means that steam is getting past the radiators. How much pressure are you building? Tell us a bit about your system.

Terry_10

The system is an early 20's vapor with Mouat return traps on all the radiators. The inlet valves have been replaced with newer valves prior to our purchase of the home last year. The boiler is a Weil-McLain EGH-85-PIN replaced in 2000. I've been told the system is twice (350,000 BTU for 2800 sq ft) the size needed for the home.
There are three 2" supply mains coming off an 8" header, but one was to supply the garage and has been closed off for some time. The system has one large main vent (I belive a Gorton, but would have to double check) at the end of the mains. As best I can tell the system does not have any other vents or an F&T Trap. There is only a pressuretrol set as close to .5psi, best I can tell.
I'm in Northern Indiana where steam is truely a lost art, but I have been using a company with a long history of working with what steam there is in our area, buy mainly hot water. They have made some near boiler plumbing changes to the hartford loop and added some clean outs that were needed and should have been done when the boiler was replaced.
I've been reading Dan's books and am feeling more informed, but with the issue of hot and noisy return pipes, plus my heating company not truely sure of what to do next, it leaves me looking for further advice. I appreciate any help that you can give.

Many Thanks!
Terry

gerry gill

Hi Terry

greetings from Tom Mouat's home town..I had no idea that he had systems out of state..Steve Pajek and myself work on lots of these as they were local, so there are more of his systems here than anyone else's...okay- first mouat boilers simmered..they also ran at only around 4 ounces at the boiler..you should have a vaporstat instead of a pressuretrol..we like to put our vaporstats at the end of the main instead of at the boiler..use the existing pressuretrol as a high limit backup..also and very important here...you cannot use a regular radiator valve in place of a mouat valve...you can however use a marsh company R-105..very pricey..but its the only suitable alternative..you could use orifice plates in the valves and experiment with the size of drill hole in it..or you would have to replace the waterseal traps with thermostatic traps...Steve- are you out there,,,did I leave out anything?

steve_6

mouat systems

Terry , The radiator valves are key to making a mouat system work with water seal traps. As a matter of fact in their sales literature Mouat designed their trap and valve to work together as a unit and advise you not to substitute either piece.If your traps are water seal you need to replace those valves with Marsh R-105 or add properly sized orafice plates to the existing valves. We prefer the Marsh valves because the orafice is adjustable. If you have thermastatic traps your valves wont make much difference. Should these traps need reparing, Barnes& Jones makes replacement cage units for them.

Your system needs more venting than 1 gorton Even if its a #2 vent.

Do you know how many square feet of radiation you have? This is the only way to tell if your boiler was sized properly.

Mouat systems didn't use F&T traps.

As Gerry Gill said you Need a vaporstat. Your system was designed to run @ 3 ounces or Less, at the boiler. The only way to accomplish this is to downfire and this must be done with combustion testing only!!!

Post some pictures of your system. the more the merrier.

Here are some pictures of both types of Mouat traps and valves.

Terry_10

Steve and Gerry thanks so much, for the information. This helps to make things alot clearer. I was wrong about the way my system is vented though. I removed a temporary wall last evening to uncover the main vent and learned that there are two. One on the main and one on the return. I was unable to see any markings to confirm the type, best description is looks to be about the size of a small soup can, they are about 3.5" wide by 4.5" tall with a 1" dia. raised vent area on top. Sorry I will post some photos of the system as quick as I can. I also looked at the garage radiator last evening to find it still has the original Mouat valve. The newer valves are Hoffman and my Mouat traps are the water seal type. I will report back with the square feet of radiation and photos. Thanks again for your help. Terry

gerry gill

does your main vent

look like this..

Terry_10

Simular, only the top looks to be more squared off in lieu of rounded.

gerry gill

would love to see it.

please post pictures, most definatly..

t. tekushan

inlet orifices

Speaking of inlet orifices, many years ago standard inlet orifices were available both predrilled and blank. Are such universal radiator inlet orifices still available?

One of my ancient steam books has a chart that gives the orifice sizes based on pressure drop across mains and risers and EDR. I think that the ratios would remain the same but some adjustment for the Mouat system would have to be made so that you are at the right "base line."

(My desire for inlet orifices is merely for balancing a standard 2-pipe system).

PS I saw an out of service Mouat system just yesterday here in Cleveland. The mansion had been expanded many years ago and the whole thing converted to hot water. The original coal fired (never converted!) American Radiator CI "firetube" boiler and the Mouat components are still down there. Fascinating stuff.

Terry_10

Terry_10

Terry_10

Here are the photos you requested.
Terry

Mad Dog

Man!!!!! I'm gettin me an edumacation here too

Thanks guys. Mad Dog

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Boiler Guy

COOL Stuff huh MD

I'm getting smarter by the minute too!
Tim

gerry gill

Thanks for the pic's Terry

yup those look like cast iron mouat vents..sweet huh? dont drop it on your foot..if you judge quality by weight these win hands down...definitly install the vaporstat..take the boilers gas firing rate down as low as you can without the stack temperature dropping below say 415 degrees..the mouat system if properly running will NEVER cycle on pressure switch..least thats the goal your shooting for..got to remember, mouat designed his systems for a coal boiler run of 8 hours straight..and something will have to be done about those valves...orifices may be the quickest and easiest approach..marsh r-105 valves would be your best approach..here is what the insides of those vents look like..inlet pipe, volitile liquid cylinder, castiron houseing, the cylinder rests on and pushed against a diffuser plate..not much different than the insides of a hoffman 75 except the mouat has a prong attached to the cylinder and the hoffman has a seperate ball that sits on top the cylinder.