Leaking McDonnell-Miller 47-2 Feedwater Controller/LWCO

John Carver

My son has a home built in 1921 equipped with a Warren-Webster Modulation System. Thanks to Steamhead and Pat for replies to my earlier questions. The boiler was replaced with a Weil-McLain EGH-95 boiler sometime in the late 1980's. At that time a McDonnell-Miller 47-2 mechanical feedwater controller was installed. If left to itself, the boiler will flood (over the top of the siteglass) in about half an hour. I've been able to confirm that the feedwater controller is leaking. It is installed with soldered copper piping so I couldn't conveniently run a broken elbow test. I did confirm that the LWCO is still working by opening the blowdown valve and making sure the burner shuts off as the level drops.

I had convinced myself that only the valve and strainer assembly needed to be replaced, but when I called State Supply, their tech suggested replacing the bellows & bracket assembly. Now I'm not so sure what to do, so I thought I'd ask the experts.

If there is a good chance that replacing the valve and strainer assembly won't fix the leaking problem and that replacing the float and bellows & bracket assembly would be required later, then we are probably better off just replacing the whole unit now. I find better pricing for the complete controller at www.controlsdepot.com and www.patriot-supply.com. Does anyone have experience, good or bad, with either of these suppliers? Would you like to recommend another supplier?

Thanks, John

[Deleted User]

The valve & strainer

assembly should correct the problem. However, that 47-2 is well past its recommended life.

Glenn Harrison_2

If you go by M&M standards...

that 47-2 should have been completely replaced at the 10 year mark. So in other words, protect your son and replace the whole thing.

Here's a link to the 47-2 manual, parts list, and M&M's service guidelines.

http://www.mcdonnellmiller.com/pdf/M&M/Product/Maint.pdf

http://www.mcdonnellmiller.com/pdf/install_instr/MM-316B.pdf

http://www.mcdonnellmiller.com/pdf/M&M/Product/47-47-2.pdf

EBEBRATT-Ed

Both of the above post's are solid advise.


Ed

Billy_4

Patriot Supply

I have used www.patriot-supply.com on many occasions. Their pricing is good but their claim to fame is their service. They are a great bunch of guys and truly go the extra mile for their customers.

Jimbo3000

Owner

I am currently installing a replacemnet Boiler in an old house. It is replacing a Burnham IN-5. I do not know how old it is. It has an Mcdonnell & Miller 47-2 water feeder. It seems that the switch is operable. the feeder itself needs at least a blow down valve. The unit has sat idle for 6 yrs. Is it worth putting money into parts for the water feeder? I do not want to open a can of worms and start dumping my clients money away with a failing product. Should I go new? Thoughts & comments

nicholas bonham-carter

New Auto-feeder or not?

These feeders are always over-feeding for various reasons. Their constant feeding can cover up various leaks in the system, which otherwise would be more apparent, and then repaired. My advice would be to have no feeder, or if one is requested, to make sure it can be valved off until the system has enough history to show no leaks, or over-pressure.

Later on, when the system may be unattended for a few weeks, it can be turned on.

I hope that you have chosen the replacement boiler after measuring the radiation, and not merely chosen the same size which had been in place before, which could well have been sized wrongly.--NBC