Banging in relation to Pressure

Clank Clank

Have a radiator that bangs tremendously at the beginning, as the steam tries to get to the radiator. Tried everything and will have to resort to opening up the walls and fixing the pitch of the pipe.



Until then, i shut the supply valve and turned the air vent upside down. Now, some knocking occurs but this time, it is not as loud and occurs at the end of the cycle at about 1.5 psi (my current max).



I thought the supply valve possibly wasn't closing tight enough so i changed that out. That effort didn't make a difference.



Since all my radiators fill up with steam around 1 psi, i decided to lower my max pressure to that, thinking i would then be skipping the entire part of the cycle where the banging occurred. It now has the same banging it did at 1.5 psi, at 1 psi!! Once again, my experiment failed.



any ideas on what might be causing the banging and remedies?

- tempted to cap the pipe instead of closing the supply valve but cant logically see why that would create a difference.



- lowing the max pressure to 1 psi does create more short cycling but i don't need more than 1psi. What should be my low pressure point. I read that you typically want to keep it at .5psi. Should i lower it to .25psi? would this play any role?



thanks

nicholas bonham-carter

Lowering the pressure

You can do all your heating at well under a pound, even at 4 ounces.

There is probably a horizontal section supplying the radiator which is pitched backwards. Did you try raising up the radiator an inch or so? This will sometime correct a sagged horizontal which is halfway up the riser.

Don't rely on the settings of the pressuretrol without verifying the pressure with an accurate 0-3 psi gauge. When you adjust a pressuretrol down below its minimum, the linkage can disconnect, and allow the pressure to rise up too high. Those devices are works of the Devil! --NBC

Clank Clank

warning followed ...

Based on the books and everything read here, I've installed the low pressure gauge and a vaporstat so i'm covered there.



In regard to the sagging pipe, i've lifted the radiator but it didn't alleviate the problem. Pitch is probably too much to overcome. that said, if i shut the supply valve, shouldn't the trapped air prevent any steam from entering that runout and therefore no longer bang?



Second question in regard to pressure, I notice steam gets to all the radiators around .25psi with them being filled shortly after. I have room to lower the max pressure but what is the rule of thumb in setting the differential?



I thought fine tuning the pressure would help with the banging in this case but so far hasn't done the trick...

Clank Clank

Capped the pipe instead

Shutting the brand new supply valve didn't do the trick so I capped the pipe and removed the radiator completely. No heat in the bathroom but at least the banging stopped.