clogged float in low water cutoff valve

HM

Looks as though the float in the McDonnell Miller 67 G low water cutoff valve on my steam boiler is clogged--when I open the blow-down valve no water comes out.  The water level in the guage glass is fine.  Can I take the McD-M valve apart to free the float or should I just replace it? 

Jamie Hall

This is a potentially

very very dangerous situation.  The low water cut off is a very important safety device; if you don't have a second low water cut off you really, in my humble opinion, shouldn't be running the boiler until you get this corrected.



Yes, in principle it is possible to take the thing apart and clean it.  You will need to be sure, though, that you have all the necessary gaskets and repair parts on hand.  I honestly wouldn't try it myself; I'd call a steam pro. to do it for me.

nicholas bonham-carter

LWCO repair/replace?

In the middle of winter, I would replace with a new unit. If it were summertime, you could take your time with the repair, but not now.--NBC

Pipedope_2

LWCO

It's important to note that McDonnell Miller recommends they be replaced every ten years.

EBEBRATT-Ed

M/M #67

These guys are correct. You really shouldn't be running the boiler the boiler without the LWCO. It would be best to replace it with a new one.

Hap_Hazzard

I have a good used one

I'd be willing to part with for the cost of shipping. I used it for two seasons before replacing it with a probe-type.



If you want to try and get yours working so you'll at least be able to run the boiler you can try opening the valve and sticking a screwdriver inside to loosen up the gunk that's obstructing it. If you can get the water flowing you might be able to free up the float by blowing it down repeatedly under pressure. When the float is freed up the burners will cut out when you open the valve.



Here are some manuals in case you need them.