One radiator is not getting hot

mholzap

Hi,

One of the radiators in my house is not getting hot.
-- I have a single pipe steam radiator system
-- I recently replaced the steam vent and the valve on the radiator that isn't working
-- The radiator that isn't working is on the first floor, and is the farthest away from the boiler
-- The pipe to the radiator isn't warming up. Could there be a blockage? I tried following the pipes backwards from the radiator to see where they stop heating up. One of the inlet pipes is very hot. It then connects with another inlet pipe at an elbow. This pipe does not get hot. There are two long pipes ahead of this (also connected at elbows), which also don't get hot (as you would expect..). Then finally, there is an elbow and a small pipe that goes up the floor to the radiator
-- The radiator worked ~1 year ago then we had to get the long inlet pipe closest to the radiator fixed because it was had a leak at one of the elbows. It stopped working shortly after that

Any ideas on how I can fix it?

acwagner

Got any photos? That might help.

Make sure the inlet valve is fully open.

Also, you can try taking the vent entirely off and see if the radiator heats up. Don't leave it that way, just do it as an experiment.

JUGHNE

Is the new repaired pipe sloping correctly back to the main, with no sags.
Pictures of the piping repair.

mholzap

The pipe on the left is hot. The pipe on the right is not.


This is where the pipe on the right leads to. It is also not hot.



Here is the repaired pipe (on the right)


And finally, the radiator

JUGHNE

Did he just fix the pipe under the rad, the one that is copper?
Are the lengths and pipe sizes as they were before the repair?
Looking at the first picture the hot pipe looks to be running uphill and the cold one looks sloping down away.

One pipe steam must be able to drain back from where it came from. Could the "hot" pipe have been pushed up and now the "cold" pipe is full of water?

mholzap

Yes it’s just the copper pipe under the radiator that was fixed

Lengths are the same. Might be a different diameter now though

It’s possible the heights were thrown off.. it took a lot of shaking to fix the bad pipe since it was really stuck in there

JUGHNE

Can you show where the hot pipe is connected into the main?

mattmia2

What happened to the old pipe? Did it collect water and freeze?

mholzap

First photo shows the hot pipe connecting to the main. Second photo shows the main

Replaced the pipe because it was leaking at the joint so it was spitting water on the wall. No freezing

mholzap

I just tried closing all of the valves except the one for the radiator that isn’t working. All of the pipes leading up to the radiator are warming up now but the radiator isn’t getting hot

acwagner

They drilled right through the main beam!

Did you try taking the vent off?

Jamie Hall

It may be just my eye, or the angle of the picture, but I'd check the slope on that pipe which is giving trouble.

mholzap

Should it slope up (or down) more? There is a nail in the wall that looks bent. Wondering if it got bent during the repair, making the pipe slope down more

Jamie Hall

It has to slope downwards to wherever it can drain... a wet return or back to the boiler.

mholzap

I got it working again! Looks like it was a pitch problem. I tried removing the air vent and that didn’t help. Then I tried holding the pipe up a little higher where the bent nail is. After doing that, water started flowing nicely and the radiator started to heat up

Thanks everyone for the help!!

JUGHNE

The pipe must slope from the radiator down to drain back to the main. No dips, sags or up and back down. Just like a plumbing drain but with 1" drop for every 10' of length.

When the system is off and cold that pipe should drain dry.
If there was water remaining in the old leaking pipe for years it probably rusted thru for that reason.

There could be sludge partially plugging the pipe now because of the work done on the leaker.

You could test for actual sludge plug by removing the stem and bonnet of the rad valve and dumping water down the opening.
It should all go away back to your boiler.
If you have a simple pooling of water issue the water will go away but will tell you the pipe is open of actual physical sludge plug.

neilc

is it just me,
or does that look like a real long run,
and rather small pipe,
for what looks to be a counterflow branch ?

JUGHNE

Neilc, yes I have been trying to follow it around the basement and get lost. Looks hard to get enough slope with the length involved.

neilc

may need to consider piping a wet return, from way over there,
maybe you found a sag, and it will keep working.