steam boiler maintenance

jonny88

Hi, a question came up at work today as to how often you should take water out of a boiler to prevent sludge build up.There was two different opinions,one was that if you are using a probe type low water cutoff there is no need to drain boiler on a weekly basis and said that by adding fresh water all the time you are decreasing the life of the boiler.Another guy said you should take a gallon or two out every week.Whats the correct answer bearing in mind you are using a probe lwco.Thanks

nicholas bonham-carter

flushing the boiler, and the lwco

a float style LWCO should be flushed out once a month at a minimum, and preferably weekly, in view of its important job.

the boiler itself should be blown down through the main drain once a month as well, and will loose more water than the LWCO. this will hopefully remove any buildup of calcium in the bottom of the boiler.

when that water is replaced, do so at a time when the boiler can fire, and heat up, driving out the oxygen.--NBC

Fred

Probe type LWCO

The weekly blow-down on a float type LWCO is to ensure the float is able to bounce freely in its housing. Hence the recommended weekly blow-down. With a probe type LWCO, the concern for the float is no longer an issue and you should try to drain a couple or three gallons of water out of the boiler drain valve on a monthly basis during the heating season.

JStar

Maintenance

I recommend once a week at first. If the water is clean, go every two weeks, or 3 weeks, or 4. But, never less than once per month. The water should be tea-colored or slightly less than clear but never thick or gritty. You should drain the boiler as often as needed to keep it clean without having to add excessive fresh water.

BoBoBoB

Fresh water concerns?

I see recommendations here for draining and replacing several gallons of water per month here. Burnham says adding more than 1-4 gallons of fresh water PER YEAR results may result in scale, Cl-, and O2 problems.



How am I supposed to reconcile these recommendations?

JStar

Water

Don't drain the entire boiler, just a cup or two.

Fred

Water loss?

I'm not sure which Burnham manual you are referencing but I would suspect it may say no more than 1 - 4 gallons of make-up water (water lost to leaks, evaporation, etc). I have a 31 year old Burnham and I can tell you it takes more than 4 gallons of water, during the heating season to blow down the float type LWCO, weekly and to clean any gunk out of the boiler mud leg, monthly, not to mention flushing out the wet returns yearly (which is water that ends up in the boiler) After 31 years, mine is still going strong (knock on wood). The trick, I think is to run the boiler for about 15 minutes after adding water, blow downs and flushes to get as much excess oxygen out of the water as possible. 

jonny88

depends on what type of lwco

Fred,you are correct in what you say,as you probably have the float type lwco.I actually called Burnham and they said when using probe type there is no need to drain the boiler like you used to when using the float lwco.They said it will lessen efficiency and life span of boiler by adding fresh water on a regular basis.

SWEI

Even with a probe-type LWCO

you should drain a bit from the mud leg every so often.  Maybe once or twice per season?