Need to replace my WM MGB-6 (cracked casting)

Mike Valentine

My WM MGB-6 steam boiler developed a crack in the boiler casting and I am humidifying my neighborhood via the chimney! The leak is not bad enough to cripple the house heating; it can keep up down to zero Fahrenheit (tested in action).

My heating contractor wants to replace it. Its specs are 850 MBH in, 680 MBH out, 2125 ft^2 steam.

What are your suggestions for a replacement?

Many thanks in advance.

steve_6

boiler

How old is your boiler?

Earthfire

steamreplacement

have a correctly sized boiler installed by a knowledgable contractor who sizes it to your connected load not the building manual J load, or worse"that's whats here already". Also it should be installed with applicable codes and manufacturers instructions as the MINIMUM acceptable standard.The best boiler is one that is properly installed & serviced,& supported by a wholesaler that will be there to assist the contractor with parts and any possible service issues.

Ray M_2

Crack in casting

You could replace the section if the boiler is in otherwise good condition.A measurement of the rads are needed and piping pick up to size a new boiler.
lol Ray M

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Mike Valentine

How old is it?

I think it's only 25 to 30 years old.

Mike Valentine

Parts supply?

The MGB-6 is no longer listed as a current item on the WM web site. Are spares generally available for out of production designs?

Boilerpro_2

Follow Earthfire's Advice

Just was out recently on another Weil Mc Lain LGB about 750,000 input. Besides a welded header with no offsets and no Hartford Loop (Geee, guess what its leaking!), my immediate reaction was that the boiler was way too big. I disconnected the high fire wire on the gas valve and ran it on low fire only (50% fire). When I left the site it had already built a pound of pressure. Another cracked Weil MGB steamer I replaced about 4 years ago...my first steam boiler replacement...was 650,000 imput and I replaced it with a 200,000 input steamer. Fuel usage dropped about 40% and the comfort improved beyond belief. Definitely get it sized right..too big or too small will cost you a fortune in fuel and comfort.

Boilerpro

Steamhead

Perhaps just as important, Mike

is trying to ascertain why it cracked.

Was the low-water cutoff working?

Was the piping around the boiler done according to W-M's specs?

Was the boiler sized properly to the building's radiation?

Was the boiler firing at the proper rate?

Are all the system's air vents properly sized and working?

Are the return lines flowing freely?

Is the pressure set no higher than the system was designed for?

Is the water feed line piped into the wet return, so cold water will not shock the boiler?

Any time I assess a system with a cracked boiler, I look for things that could cause the crack. Often I find more than one of the above. I recently looked at a Hoffman Vapor system with a Columbia boiler that had cracked for the second time. The first time someone replaced the bad section and hoped for the best. This time it gets done right!

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Mike Reavis_2

MGB Sections and repair kits

are listed in the w/m discontinued boiler parts catalog. Your contractor can see his distributor for these parts if this is the way you would like to go. Mike

[Deleted User]

Hope you don't need

the right end section. I got the last one in November. The MGB was discontinued in the late 70's - early 80's.
Wasn't a real good steam boiler. Narrow sections, low water content, & a whole lot of fire.

Unless you have a Vanderbilt size mansion, the 6 sounds heavy. Choose your contractor and new boiler carefully. Right Mike?

Happy Steaming.

Boilerpro_2

Alittle more about sizing

Had that exact same boiler, except in water, at my former church. It heated 15,000 sq. ft. of 1850 and 1950 buildings, and was way oversized. Please get it sized right if replacing.

Boilerpro

Mark A. Custis

Dear BP

I wish to shout: DO THE HEAT LOSS.

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