One cold radiator

Keogh

I have a hot water system with cast iron radiators. I'm pretty sure its a one zone system for the entire two stories of the house. The problem I'm having is for the bedroom on the first floor, the radiator never heats up. The supply and return pipes from the radiator through the floor get hot, but the radiator doesn't. I tried opening the valve as far as it goes, but it just turns and turns. Is it likely that I have a blockage within the radiator itself (meaning I'll have to replace it), or should I be able to replace just the valve. I don't know if it matters, but the radiator runs parallel to the supply, ie the pipe has a T before the radiator and after, so not all the water flows through it. Also the radiators are probably original to the house, which was built in the 1950s, though we've only been in the house for a year.

Brad White_200

To everything, turn, turn, turn

I suspect that the valve stem is sheared off and the valve is in the closed position. You need to replace the valve.

mark ransley

Did you blead out the air at the top of the radiator

kpc_40

i agree

many of the hot water valves you decribe are only 1/4 turm valves.....I learned this w/ my parents home.

Keogh

One cold radiator

Yes, last winter was our first winter in the house and when we first noticed that radiator wasn't producing heat we tried to bleed the radiator, but if I recall correctly it only produced cold water, no air.

Is there a chance that the radiator is corroded on the inside? I expect if that's the case I'll have to replace it, how can I tell if its corroded? I expect I'll have to drain down the system and then disconnect the radiator from the supply and return. What can I do after that?

kpc_40

barking up the...

wrong tree. VERY rare that the rad is corroded to a point that it is blocked.

kevink1955

You may have a 1/4 turn valve and the stops are sheared off, I have several in my home.

Mark the top of the valve and try turning the valve 1/8 turn, wait 1/2 hour and see if you get heat. If not turn another 1/8 turn and wait again. If you get a full turn and still do not get heat you have other problems but it is worth a try.

The system must be calling for heat the entire time you are doing the turn and wait thing.

Eric_32

bad valve

change that valve and that rad will get nice and toasty

Keogh

Thanks

So it looks like I had a combination of problems that were covered by all the advice I got. The stops were broken off the valve, so I made small adjustments until I got the rad to produce heat. But I think the (stem?) that connects the knob to the valve itself is busted because I had to push down pretty hard while turning (I used a stethescope to listen for water gurgling in the radiator).

Based on the issue I had with this valve and a couple of the others I think I'll go around the house and replace the valves.

Thanks again for all the help!

Jim Erhardt_3

Maybe it's the valve...

...but there's another, perhaps more common cause to this problem - branch piping that no longer pitches up toward the radiator.

Your radiators are connected to either a 1-pipe (aka "mono-flo") or an older 2-pipe system. In either case, the branch piping that connects the radiators to the main(s) must pitch upwards from the mains(s) to the radiator in order to eliminate air in the branch piping. There are many reasons why the branch piping may have lost proper pitch:

1. The house has settled
2. A pipe hanger fell off
3. A renovation was done and someone disturbed the piping (I have seen this happen with electrical wire and the vent from a JennAire grill).

Since this is a first floor radiator, I would take a small level and trace out the branch piping that connects it to the mains. If you find any section of that piping that is not pitching up towards the radiator, you will have found a problem that needs to be corrected.

I hope this helps!