Radiator Below Mono-flow line

Neil_5

I have a hot water mono-flow heating system. I was replacing the valve on one of the convectors. This convector is below the mono-flow main line. I replaced the valve, and now when I fill the system (bleed etc) there is no circulation in this one convector. There is a bleed valve that I opened, no air, seems like air is trapped on the return leg going back up to the main line.

Any suggestions?

Thanks,
Neil

Mike T., Swampeast MO

Is there perhaps a valve in the main between the radiator connections? If so, close and purge the radiator--may run water for quite a while before you get any air--possible you'll never get air. Run circulator and purge all radiators (especially the one immediately after this radiator). Then re-open the valve, run circulator, purge again and you should have circulation everywhere.

A valve installed that way will force the entire flow through the radiator and its piping when closed. When you run the circulator, you'll force any bubble in the supply side into that radiator; any air bubble in the return side will go somewhere else. When you re-open the valve and circulate there will probably be some air trapped in the pipe between the connections. It will wind up somewhere but at least not in that radiator or its piping.

Neil_5

No Valve

No valve in between the radiator, so cant close this off and force the water thru the radiator. I can add a valve, but I am sure over the last 50 yrs of this house, at sometime this was done and the air went away eventually? I am running the circ on/off over the next few days, will see if I get rid of the air, if not, cut the main line and install a valve.

Neil

Neil_5

Any Suggestion?

Just bumping this up for any last resort suggestions.

Thanks,
Neil

bob young

monoflow mania

over the years i have had similiar situations where rather waste a thousand hours trying to bleed a line ,i have cut in an isolation valve & hose cock & bleed the culprit and moved on never looking back. monoflow can be murderous.

Neil_5

Bleed ....

Bob:

I was thinking of installing a valve between the riser and thus forcing the water to move thru the radiator, then re-open. Is this what you have in mind?

Neil

bob young

bleed tee

if you put valve on branch you might still be air locked. i would cut in valve and tee w/ hose cock in trunk line after return tee. it is probably locked at tee mono flow junction. you don't wanna do it twice.

Neil_5

Valve and T

Bob:

So between the 2 risers/mono-T install a valve(thus forcing the water thru the radiator) and then install a T with a bleed valve where?

Neil

bob young

bleeding

cut trunk line after return tee & install tee with hose cock & ball valve. this will force water thru branch line & radiator & into trunk. then open ball valve to restore circulation. hope you are not pulling my leg because this is pretty elementary stuff. in any case , best of luck.

Neil_5

Bob:

How in the world did the original fill of this system took place with this radiator below the line and no valve/bleeder in line? How come it was done back then and have to be modified to work now?

Bob, I cant see how the water will flow thru the radiator with the valve closed off (located after the return T as you suggested) and no where to go or vent, if you do open the bleeder, the circulation will take the path of least resistance and go thru the trunk.

Am I missing something, thanks for your all your help, much appreciated.

Neil