Leaking gaskets on Low Water Cutoff

Seth Rothenberg

Dear Steam Team,
I am facing an issue with leaking gaskets on a Mcdonnell & Douglas 67G.
I am installing a new float, which definitely seemed due when I took out the old.

I tightened the bolts as much as I think is safe and still both gaskets
are leaking - both the square on the blow-down and the
circular on the side where the float is installed.

So far, I just filled to the LWCO, and not heated it yet, drained it lower to stop leak.

Thanks for any suggestions.

PS, I agree, this work should be done in the summer :-)

Steamhead

There is probably enough unevenness on the gasket sealing surfaces to cause the leak. Try coating the surfaces with high temp silicone caulk and see if that helps make the seal.

Seth Rothenberg

Thanks, Steamhead...That's something to try when Home Desperate opens :-) In the meantime, I re-examined and scraped both surfaces of the blow-down gasket and it seems sealed now. In the am, I can do the same for the Float gasket....that should be 1/2 as difficult, since the float bracket is new against the gasket, just need to scrape the side of the float chamber again.

Thanks, I will let y'all know...

Seth Rothenberg

I bought the high temperature silicone sealant, but first I tried scraping the float mounting surface again, and it seemed to work. I got steam. I'll be offline for a couple days, then will surely have a few more questions about the pressuretrol and gauges.

Thanks
Seth

Seth Rothenberg

First question....I have one pressure guage on a 1/4" pipe nipple near the front, a surface mount gauge....and I have one pigtail and pressuretrol on top of the LWCO. I would like more of each without having to do surgery with penetrating oil to open new taps.

The other tap that is available is the vertical-tap pressure relief valve. I could use a 3/4" tee on its side to add a tap there.

Should a pressure gauge be straight off the boiler, or through a pigtail?

Or I could use some tees where the pressuretrol is installed on top of the LWCO. I have some brass tees and nipples.

Also, since I started on the LWCO topic,
a) I noticed the LWCO has some kind of union on one connection (I think the steam part) and the other connection does not. Could I / should I add a union to simplify maintenance?
And, it would be helpful to have the sight glass and LWCO be mounted about 1/2 to 3/4" further out from the boiler.
What are the ramifications of changing those pipe nipples?

(Can they be changed? I think they can; Last year I advised my neighbor to have the plumber turn the sight glass right side up, to aid maintenance :-)

Thanks.
I hope these questions make sense, and maybe they
are helpful to others.

Abracadabra

Seth Rothenberg said:

First question....I have one pressure guage on a 1/4" pipe nipple near the front, a surface mount gauge....and I have one pigtail and pressuretrol on top of the LWCO. I would like more of each without having to do surgery with penetrating oil to open new taps.

The other tap that is available is the vertical-tap pressure relief valve. I could use a 3/4" tee on its side to add a tap there.

Should a pressure gauge be straight off the boiler, or through a pigtail?

gauge should be protected with steam with a pigtail. Some gauges have an internal syphon to protect it, so you don't need a pigtail.

Seth Rothenberg said:

Or I could use some tees where the pressuretrol is installed on top of the LWCO. I have some brass tees and nipples.

That's where I'd mount it.

Seth Rothenberg said:

Also, since I started on the LWCO topic,
a) I noticed the LWCO has some kind of union on one connection (I think the steam part) and the other connection does not. Could I / should I add a union to simplify maintenance?
And, it would be helpful to have the sight glass and LWCO be mounted about 1/2 to 3/4" further out from the boiler.

I always install LWCO with unions above and below for easier maintenance.

Seth Rothenberg said:

What are the ramifications of changing those pipe nipples?

(Can they be changed? I think they can; Last year I advised my neighbor to have the plumber turn the sight glass right side up, to aid maintenance :-)

Not sure what you mean... pictures would help.
With regards to the leaking LWCO, you need to make 100% sure both surfaces where the gasket sits are completely clean of the old gasket material. If not, you'll have leaks.

Hap_Hazzard

A new gasket for the float is only $3.59.
http://www.supplyhouse.com/Mcdonnell-Miller-318800-67-12-Sylphon-Gasket-for-67-80