testing of LWCO

Al Letellier_9

Just did an insurance inspection with this type of LWCO. The unit failed and the boiler cracked and cooked. The problem wasn't the control but clogged piping below the water line going back into the boiler. All changes in direction of control piping should be with a cross fitting and plugs in unused ports. These should be pulled annually and lines checked and cleaned if necessary. Very important maintenance step that gets overlooked a lot !!!

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targetman

testing of LWCO

Recently I went to work for a company that does commercial, industrial, and institutional HVAC/R. My experiance has all been residential HVAC. Last week I was sent to an assisted living home to do boiler PM's. I would like some explanation on the testing of LWCO's. I was dealing with McDonnell & Miller series 63 and 64.

tim smith

Testing of low waters

Was this steam or water? I water, we open the blow down valve during burn cycle and make sure that the low water cutoff shuts off when we drain out low water cutoff and if manual reset, make sure it trips. If steam, we pull apart low water cutoffs and cleaned float chamber and float ball and reassemble w/ new gasket. Also pressure switches, pig tails and handholes, manholes, mudlegs etc. Then when we bring up to pressure we blow down and make sure all lwco's are shutting off boiler during firing and pressure controls doing same.

John@Reliable_14

Todd, testing of ...........

any LWCO should be done like this, with system running drain water down with the boiler drain and not with the LWCO draw off. Once water is below float level unit should turn off, and restart once level returns.

targetman

The LWCO'S at this facility don't have blow down valves installed. McDonnell & Miller literature states that valves are required but not provided with series 63 and 64.
Also, the life expectancy of the controls is listed at 10 years.

Steamhead (in transit)

I'd replace them now

since without blow-down valves, they were never blown down!

If the boiler has the proper tappings and there are no Code issues to the contrary, I'd look into making at least one LWCO a probe-type unit. This gets around the blowdown issue.

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EBEBRATT-Ed

In MA.on commercial steam we are required to provide two lwco installed in seperate tappings. This is required if you have a boiler feed pump or condesate tank. Any time the condensate does not return to the boiler by gravity we must install two controls.


ED

Steamhead (in transit)

In Washington, DC

that LWCO piping has to be brass.

Expensive, but not as much as a new boiler would be.

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