Watter hammer from a single radiator.

Tolik

I'm currently fine tuning my home's steam system. This is our first heating season and this is all new to me but thus far I've;

a. Replaced three non-functioning air vents (They didn't close and hissed steam, even after cleaning)
b. Fixed a radiator which was dripping water from the valve stem. (The washer in the packing nut crumbled into 20 pieces when I took it off)
c. Fixed a leak in a copper convertor radiator. (It was dripping water, had to re-solider the joint)
d. Lowered steam pressure to .5 cut-in and 1 differential.

Now one radiator starts to hammer for about two minutes when things first fire-up. From what I read here "If you think the valve is fully opened and you're still getting water hammer, check to make sure parts of the valve haven't fallen off and lodged in the valve's seat.".

When I close the valve, tight, the radiator still gets partially hot. Short of replacing the valve, how do I going about checking the valve's seat or anything else I can try?

KC_Jones

Did you check the pitch of the radiator? It should be sloped slightly towards the valve, check it with a level. If it is sloped you could try checking the pipe leading up to it to make sure it has slope back towards the main. It sounds like water is laying somewhere then getting picked up by the steam and hammering, since you say it happens right at the beginning of the cycle.

Fred

After you check the pitch of everyting, if you still need to check the internal parts of the supply valve, you have two options. One is to disconnect the radiator at the coupling between the radiator and the valve and look inside to see if anything is loose or broken, the other option is to turn the square nut on top of the valve body (you may have to put an open end wrench on it and tap it with a hammer to get it loose). That will let you unscrew the valve cap off and see all the internal parts. In either case, make sure the boiler is shut down so that the boiler doesn't fire and make steam that you can't control.

Tolik

Thank you for the suggestions...

After I posted this question I noticed that the stem valve is leaking a bit so i tightened the packing nut. Also I removed the air vent which started, recently, not to close fully. It had enough water in it for me to notice. The boiler just ran for about 30 min. There is no longer banging near the radiator. There is now however some banging in the basement vicinity, there wasn't any before.

The radiator is pitched well from what I can tell.

What's going on? Is it still the valve not letting condensate to flow back down freely?

Thank you

BobC

That "new" banging might have been masked by the radiator hammer. What did you replace the air vent with?

I suspect the piping below may be pooling water, check all of it with a level and watch out for any dips in a pipe run.

Bob

Tolik

BobC said:

That "new" banging might have been masked by the radiator hammer. What did you replace the air vent with?
Bob

I put a vari-valve on it.

BobC said:

I suspect the piping below may be pooling water, check all of it with a level and watch out for any dips in a pipe run.

Bob

By that you mean a sudden drop in the pipe?

Thank you.

BobC

Even a small slight dip can pool water that will collapse steam as it travels down the pipe. You might want to stretch a strig along the pipe to see if that shows a dip.

If the varivent is open all the way it might be causing trouble, try throttling the valve way back to see if the hammer changes.

Bob

agurkas

I downfired my boiler by 35% (for the next 2 days still on oil, until I am converted to gas) and not only hammer disappeared from one radiator that was giving me grief, my house heats up literally in 12 minutes. That is down from half hour pre-downfiring. Or hour when I bought it (pressure was set too high, non of the vents were functional, and mains wish they had Gorton #2s on them).

Tolik

agurkas said:

I downfired my boiler by 35%

You mean you reduced the size of the flame?

agurkas

Yes. Heating guy today told me I actually downfired it closer to 50%, since I am running higher pressure gun. For my load though it is still too high. Doesn't matter anymore though. New gun is going in tomorrow and will be tuned based on load calculation.