hot water radiator question

[JHZR2]

Question about a hot water radiator in my home. I believe it is at the absolute end of the run of pipe... The pipe in the basement is full hot all the way, but no heat to this second-story radiator.

The radiator is full. Ive opened the bleeder on the radiator, and water comes out at pressure - the system is good and full.

The pipes are only marginally warm, and the radiator shows onl the slightest bit of warmth over ambient.

Any ideas? Valve is absolutely open, and I have no reason to believe it is not functional. I get water out the bleeder, and I bled the radiators this fall as I had to take some water out of the upstairs system to remove a radiator - that one works really well...

Should I hit it with a rubber mallet? Let water bleed through it a while to try to displace air?

Thanks!

 

[Shannow]

Got a mate with a problematic upper floor radiator.

Looks like it's a venturi effect somewhere stopping it from flowing.

Dead head (bleeding wise), it's full.

 

[XCELERATIONRULES]

Look for your zone valves,they control flow to different sections of your home.
Probably the zone is getting partial flow and not complete circulation.

 

[Gary Allan]

Quote:
I believe it is at the absolute end of the run of pipe... The pipe in the basement is full hot all the way, but no heat to this second-story radiator.


Unless your return pipe is warmer than that rad, you're soaking up the heat somewhere. I agree that you may need to balance/reduce flow to some other zone.

Close off any other zones and see if it yields the performance you seek.

Some issue like Shannow describes will drive you nuts in finding the conceptual unicorn.

 

[AcuraTech]

Could be the lower floor is sucking off all of the heat before it returns to the boiler. Lots of variables here - system design, boiler operation, pipe condition, etc. This time of year you should be getting more than lukewarm though. Heat rises, so the upper floor should actually be warmer if the roof is well insulated.

Father in law has an old house with a boiler, second floor bedroom radiator gets so warm at times that windows need to be opened, even when its close to 0 degrees F, as ridiculous as it sounds.

 

[fdcg27]

In our house, only the upper floor convectors have bleed valves.
This makes some sense, in that air should rise through the water column.
I've only had to evacuate the system twice in the twenty three years we have lived here, once to replace the circulator, and once to replace the boiler.
Once the system is filled to correct static preassure, and then bled cold, with water added as needed to restore static preassure, I have found that it takes mulitple bleedings over several days when the system is running to get all of the air out.
I suspect you have some trapped air somewhere.
Keep bleeding the cold rad once a day or so, and I think you'll find that some air will work its way to the bleeder, where you can let it out.

 

[JHZR2]

Originally Posted By: XCELERATIONRULES
Look for your zone valves,they control flow to different sections of your home.
Probably the zone is getting partial flow and not complete circulation.


we dont have zone valves other than the shutoff valves at the radiators...

 

[JHZR2]

Originally Posted By: AcuraTech
Could be the lower floor is sucking off all of the heat before it returns to the boiler. Lots of variables here - system design, boiler operation, pipe condition, etc. This time of year you should be getting more than lukewarm though. Heat rises, so the upper floor should actually be warmer if the roof is well insulated.

Father in law has an old house with a boiler, second floor bedroom radiator gets so warm at times that windows need to be opened, even when its close to 0 degrees F, as ridiculous as it sounds.


Definitely not, earlier upstairs radiators are HOT.

We are pretty well insulated, especially in the attic.

 

[olddognewtrks]

Food for thought, if it's an air bubble: crack the water feed valve open, and crank up the thermostat so the water pump kicks on and begins to circulate the water mass in the system. Then, with a big bucket in hand, bleed the problem radiator a lot. Hopefully the water feed plus opening the bleeder will speed up the flow and 'dislodge' any bubbles.

Let us know what's up. I may be wrong, but I am morbidly curious. Good Luck.

 

[Gary Allan]

Originally Posted By: JHZR2
Originally Posted By: XCELERATIONRULES
Look for your zone valves,they control flow to different sections of your home.
Probably the zone is getting partial flow and not complete circulation.


we dont have zone valves other than the shutoff valves at the radiators...


Shut off the valves to all the other rads. The way you're describing it I have to wonder why you need a circulating pump at all ..or rather, without one the system would still work ..after a fashion.

 

[labman]

What sort of a system do you have? Hot water, steam, circulating pump, etc.?

 

[JHZR2]

hot water. We have a grundfoss circulator pump on the furnace, I pulled the small front cap, and the impeller wasnt spinning. The pump is so quiet even under operation that it is tough to tell. Once I gave the impeller a twist and a push, it seemed to engage again and start spinning.

Not sure if this means the bearings are shot or the thing is on its last legs...

I did re-bleed the radiator, but had a good 12psi stream of water coming through. I think without the circulator pump, that last radiator on the entire system just had too much resistance to moving the warem water in - so it took a real long time - longer than needed to warmn the house to 63-65, which is where we keep it.