No water when flushing

mattpaluszek

So when I went to flush the water from my oil furnace system last night, no water came out at all. There appears to be water filling the glass tube indicator. What do I do next? Coincidentally, or not, the furnace recently has started making a very loud ongoing noise. I turned the system off with the emergency switch, waited a few minutes, turned it back on and the noise went away. Any thoughts on what I should try next before calling for emergency service the next time the noise happens?

Jamie Hall

I would turn the emergency switch off again and call a service person, if you are not comfortable trouble shooting this. Do NOT run the boiler again until you figure out the problem.

Why? You may be seriously low on water in the boiler -- which could then dry fire and make very loud and expensive noises.

You may find that the connection at the bottom of the sight glass to the boiler is clogged. That wouldn't be that unusual. If you are handy, you can take that apart and make sure it is clear. Ditto the connection at the top.

Another, less likely possibility is that the valve you are using to "flush" the system is clogged -- but those valves are usually larger, and don't clog.

However. You need to find the problem and be sure you have water in that boiler to the level required.

Until you do, turn it off and leave it off.

mattpaluszek

I just looked at the glass tube water level indicator again and it has clear water in it almost to the top. The system is currently operating as normal. I've called and scheduled a tune up for next week.

Jamie Hall

Good luck.

mattpaluszek

Is there anything I can do myself to get the water flushing out of the system again?

Fred

A steam boiler, I assume? It sounds like your auto water feeder may be leaking water past the valve and over filling the boiler. It will make loud noises when it is trying to boil water all the way up into the risers. If you opened the drain valve on the bottom of the boiler and nothing came out, take a wire or a heavy cable tie and try to push it into the drain valve to try to unclog it. Let the boiler cool down first so you don't get scalded. Also, Make sure you shut the auto water feeder off if the water continues to over fill the boiler. If left unattended, it will fill up and flood things from the main vents and radiator vents. Have the tech check the feeder when he comes. It sounds like the solenoid valve is stuck partially open.

Abracadabra

Where are you flushing from? What valve are you opening?
Is it the LWCO blowdown valve? If so, your LWCO may need cleaning.

Jamie Hall

I probably sound like an old grouch, and I dare say I am. But... if I open what should be a drain valve on a boiler, and no water comes out, I would want to find out why. It could be that the valve is plugged, or the opening into the boiler is plugged. It could also be that there is no water in the boiler at that level.

It's that latter possibility that I want to absolutely positively eliminate before I turn the boiler back on.

Do I trust the sight glass? Usually, yes -- but if I have a drain at a level below the sight glass and it doesn't drain, then no. Sight glasses have been known to get plugged up.