Overfilled steam boiler

Cato

Hi everyone,



I've had a bit of a mishap with my steam boiler (single pipe system, boiler about ten years old) and I have a few questions I was hoping someone here could answer. The questions arise because I accidentally overfilled the thing while dealing with a different problem in the basement. The water was flowing in for probably about two hours, albeit at a trickle. Upon discovering what I'd done I immediately switched off the boiler and the fill valve and proceeded to drain the boiler to an acceptable level (sight glass about half full).



Should I do anything else before turning it back on? Should it be looked at by a professional first? Also, what are the chances I've done some permanent damage?



Any advice would be greatly appreciated!

Double D

Should be ok.

You're lucky you caught it but mainly before it did any damage to the house. You may get some hammering when you start it up if water is laying in the piping but you should be OK to start it up.

ALIGA

you may also have to drain the radiators

if they are not pitched properly.

bwoodard

When is best time to drain an overfilled boiler. After water returns and cools or anytime????

EzzyT

Anytime

bwoodard

Thanks a lot--another ?. I drained the boiler to lower the water level and at first the water was a very deep rust color and eventually it became clear. What is a possible cause or is this normal??

EzzyT

The rust color is rust, mud and sludge in the system which is normal in a open system just like a steam system.

j a_2

Agree with all....it should have all drained back,providing the system is pitched correctly.....An overfilled boiler should not turn on due to pressuretrol sensing if it was overfilled as much as you said....look at this way if there was no water under the boiler pretty much you can be assured your boiler block is intact....

EBEBRATT-Ed

Start it up and you will be fine. You don't have to drain any piping or radiators those that say you do don't understand steam...all water in a steam system flows back to the boiler by gravity.

You can drain a steam system when hot or cold.

Refilling is another story you don't want to add a large quantity of cod water to a ripping hot steam boiler..use common sense.

If you drain a hot boiler completely you should not refill it with cold water until the boiler has cooled enough so you can hold your hand on the boiler.

adding small amount of cold water to a hot boiler is ok the cold water shouldn't be piped directly to the boiler but should be piped into the returns so the return water will mix with and preheat the cold water

bwoodard

Thanks--had a big problem trying to read the water gauge and think I drained off too much water. Is there an easy way to read the gauge when it is filled to the top???? Also, my boiler automatically feeds the water in so if I drained off too much will it refill automatically once it hits the low water level????

Jamie Hall

bwoodard said:

Thanks--had a big problem trying to read the water gauge and think I drained off too much water. Is there an easy way to read the gauge when it is filled to the top???? Also, my boiler automatically feeds the water in so if I drained off too much will it refill automatically once it hits the low water level????

Read the water gauge when it is full? It can be surprisingly hard to determine from looking whether the glass is overfull or empty, if the water is clean. However, most systems have try cocks at the top and bottom of the glass, which can be opened to see if there is water there. Try them, if you have them.

And yes, with an automatic feed the boiler should refill automatically if you drained off too much. More to the point, the boiler shouldn't turn on at all if the water level is too low -- that's what the low water cutoff (LWCO) is supposed to do!

bwoodard

Again, thank you so much for all your help. I had to leave this afternoon and fretted the whole afternoon worrying about what I would find when I returned home. Well you are absolutely right the boiler refilled itself and started up on its own. It is working fine but the water level is still way up to the top with real rusty looking water. Will watch it carefully and try again to drain some of the water off.

BobC

The auto fill valve may have a slight leak. Try draining it down till the glass is is half full and valve the aouto fill off to see if the stops the overfilling.

If the boiler has a coil in it to heat domestic hot water that could also have a small leak that is overfilling the boiler.

Bob