Top Floor (Zone) not Heating

dc101

I am having a real hard time getting anything going on the top floor of a home heated with a boiler and four (4) zones.



All three zones work fine - water temp (180) and pressure (18) is fine. I simply can't get things going on the top floor. The system was working fine the first time we used it this winter. However, a few days ago it was too hot upstairs wile sleeping and I turned the thermostat down to 67 from 70. This killed the upstairs heat.



Please see the attached image. All air has been bled and all three other zones are working as expected. I also don't hear any water in the upstairs zone as I normally  would. - it is cold and quiet.



*See attached image. Should I turn these on in sequence to get water upstairs? Both outgoing pipe (seen here) and returning pipe for all zones is piping hot.  Should I turn all off and then bleed (I've done this already) should I turn upstairs zone on only and thermostat all the way up?



Any help would be greatly appreciated.

tim smith

Re: top floor not heating

Gauges are not accurate much of the time. We carry test gauges to verify against boiler gauge. 18 psi good to about 35 ft, is this enough to get to top of your system? Is the top of your piping at  the radiator height of top floor or is it an overhead feed and the water has to be all the way to the attic? Many old systems were attic fed overhead? All this needs to be known.

heatboy

Ya' know........

.....air will work it's way to the high point.

dc101

Re: Top Floor (Zone) not Heating

Thank you for the response, Tim.



"18 psi good to about 35 ft, is this enough to get to top of your system? Is the top of your piping at  the radiator height of top floor  or is it an overhead feed and the water has to be all the way to the  attic? "



While the boiler is in the basement, less than 35 ft is accurate. Also,  the top of the piping is at the radiator height - not the attic. The  outgoing pipes to the different zones (I believe this photo is the  returning water) pipe just out of the boiler is hot but the pipe is cold just two feet down the line.



Also, I do not have individual bleed valves on the radiators.

dc101

Re: Top Floor (Zone) not Heating

So having some air in the line is good?

NRT_Rob

air would seem the most likely culprit

though maybe your thermostat died or something. if you can verify the thermostat is calling for heat (maybe turn off other ones and turn this one on and see if the boiler fires, if it's a cold start model and not up to temperature), then it's probably air.



might need to purge this line.

dc101

Re: Top Floor (Zone) not Heating

after determining all included factors, that is exactly what I need to do. How exactly would I purge a single line of this system (#2) - there are no individual bleeders on the baseboards.



Thank you for the reply.

NRT_Rob

if

you have a pair of boiler drains on the system (or one and a fast fill valve), and appropriate ball valving that you could isolate flow from water in through this zone to the boiler drain out, you can power purge just this loop.



Sounds to me like you need a good air separator on this system too.. if this is air.



I would also want to know why air was coming in... not "pumping away" from the expansion tank, maybe?

Gordan

Not to be obtuse, but...

Is there a reason why the ball valve on the "problem" branch has the slot rotated 90 degrees relative to the others? Is that how it is currently?

Jean-David Beyer

I wondered about that.

Before I had my boiler and near-boiler piping replaced, there was a manifold soldered to the five 1/2 inch tubes coming out of the slab. It had 5 valves that looked a lot like those in the picture. Since the heat in the 5 rooms was not balanced as I wished, I thought to adjust those valves. They, too, had turned green all around. So I soaked them in WD-40 for a few days and loosened the nuts. It took more to loosen the shafts so I would not strip the slots. They were never as loose as I would have liked, but it was no good. I could turn the shafts as much as I liked, and never came to a stop at either end. And they never seemed to change the flow. I wondered if they were like an air damper in a hot air system, but never found out.



When the contractor replaced all that stuff, they fixed than manifold with the sawz-all treatment.

Gordan

Just ran into something similar myself

Had to drain the system in order to cut out a branch that was getting in the way of my new boiler install. The old system will be retired in its entirety fairly shortly. As I was bleeding the convectors, I noticed that one of them wasn't getting hot even though it wasn't air bound, and I thought to check the shut-off valve. It spins freely all the way around and, due to the plastic round knob being affixed to the stem by way of a stripped screw, I never even had the chance to take a peek at the stem position.



Interestingly, after the system had been running awhile, it is that side that was getting hotter (by convection) and the other side remained cold. Hmmm. I'd figure it out if I weren't ditching it wholesale in a coupla weeks.

Alan (California Radiant) Forbes

Top Floor (Zone) not Heating

Mr. dc101:



You may have to drain the system and replace the supply and return valves........replace them all with ball valves while you are at it.  I'd also check that old steel manifold for clogging. 



Before you put it all back together, stick a hose on the supply and see if you get water coming back on the return.



Other suggestions:

- Install a purge assembly on your system so you can power purge the piping and radiators.  It will save you a lot of time if this ever happens again.