Radiators not heating up

mcp1

I recently took out 2 cast iron radiators from the 2nd floor bedrooms of my house and got them refinished. As I took them out, the risers dropped down a little bit. When I reinstalled them I had to raise the pipe at the bottom of the risers in the basement in order for valve to reconnect to the radiators. Now, some of the other radiators in my house are not heating up. This is a single loop system. I feel heat on parts of the pipe in the basement off the loop, but after it elbows up, the pipe is not hot. Could this be a pitch issue. Any suggestions on how to solve this would be greatly appreciated.

Jamie Hall

I hate to ask the obvious -- but did you purge all the air out of the system after it was put back together? Sometimes just bleeding the radiators is enough -- but usually not.

mattmia2

Is this monoflow where each emitter is connected to a single loop with branches connected with diverter tees or are the emitters piped one to the other in series?

mcp1

Thanks for the quick response Jamie. I am a complete novice when it comes to this. I did not purge the air out of the system nor do i know how. the radiators that i reinstalled are actually heating up well. Radiators in some of my other rooms are not. I'll post a picture of the pipes

mcp1

These are pictures of the pipes that are going to the radiators, which are not heating up. The pipe toward the end of the run before the risers are cold to the touch

neilc

show a picture of a cold radiator, of each end, top of radiator to the pipe to the floor

kcopp

I have a feeling this is a steam system. I think there is a droop in the line and it is trapping the steam from getting through.

neilc

let's add a picture of the boiler, floor to ceiling

ethicalpaul

Strictly Steam?

mcp1

This is a steam system on a single loop. Here are some pictures of the boiler & the radiators which aren’t heating up.

mcp1

mattmia2

How is the end of that main vented? Is there a return at the end of the main?

Chris_L

mattmia2 said:

How is the end of that main vented? Is there a return at the end of the main?

Looks like the steam main is just one continuous loop and the return is the pipe next to the copper fill line. I see at least 3 vents on this line. But I don't see a Hartford Loop anywhere.

As for the OP's problem of the radiators not heating, were all of them working ok before the two were refinished? If so, did the pipes that got lifted in the basement to reconnect those two radiators get put back in their original positions after the two radiators were connected.

By lifting the riser in the basement the pitch of other pipes may have been affected leading to poor heating in the other radiators.

mcp1

Chris, that’s exactly what happened. How do I find out what the right pitch should be? Previously the radiators were all heating up. As for main vents I have 1 Hoffman #75 & x3 Gorton #2 main vents at the end of the loop.

mattmia2

Make sure the end of the main keeps sloping toward the boiler so the condensate can get back to the return at the boiler and doesn't block air or steam.

Chris_L

Yes, you have to make sure the steam main is sloped toward the return for its entire length. And you have to make sure all the branches off the main are sloped back towards it.

I presume you've removed whatever you used to prop up the risers when you reattached the radiators. In addition to checking the pitch of the main, check the pitch of the runouts to the problem radiators in the basement.

You might also try lifting the problem radiators by placing something under their legs to see if that helps.

pedmec

listen to the radiator vent to see if it is letting air out. If not, then remove the air vent and listen for air. if you get air out with the radiator air vent removed then you need to make sure your radiator is pitched toward the the radiator valve so any condensate formed in the air vent is allowed to drain out of the air vent. You don't want the condensate keeping the vent closed. If its pitched correctly then replace the air vent. If no air comes out of the radiator with the air vent removed make sure the radiator valve is opened. if if all that checks out then start checking the pitch on the pipes in the basement.

neilc

so these are the rads that are not heating ?

I'm not so sure anything to do with having to raise supply riser pipes back up to the refinished rads would have anything to do with this, unless shims, or 4 inches of old paint were under the rad feet, blah blah,
and It's not like you added pipe nipples, you just raised existing pipe back to where it was,
now if when risers slid down, other laterals and elbows also fell or their hangers loosened , , , ,
and did not get back to their good elevation, well that's something to check, that the pitch from the main, all the way to where laterals turn up is even and consistently pitching to drain condensate,
again, I think you say the rads you refinished, and had to reset their risers, are working, cold issues are on other rads, confirm?

what I do see, or not see, is,
the white painted rad, its vent is at its top, and that vent should be down lower, 1/2 to bottom third, of far end from supply valve,
and I can't see that there is a boss there to accept a vent,

and on the silver rad, I don't see a vent at all,

I could have been a bit clearer on asking for the rad pics,
can we see both ends, from the top of the rad to the floor,

are the supply valves all the way open?

mcp1

Here are those pictures neil. 

mcp1

All the valves are open. The pipe that branches off the main loop is hot until it passes an elbow, then it gets cooler & cooler as the pipe goes towards the riser

Danny Scully

You had vari-vents before? You never know, maybe they just failed. 

BobC

In general we like to vent the mains fast which you seem to be doing, but vent the radiators slower. Those heat Timer vents are very fast, how open are they? maybe slowing the ones that are heating up fast will encourage the steam to head for the ones that aren't heating.

It sounds like things were fine till you had those radiators taken out for refinishing, maybe something changed furing that process. You might want to stretch a string along horizontal piping in the cellar ta make sure you don't have any sags in the piping.

Bob

Jamie Hall

mcp1 said:

All the valves are open. The pipe that branches off the main loop is hot until it passes an elbow, then it gets cooler & cooler as the pipe goes towards the riser

Steam is not getting past that elbow. The question is -- why? I'd start at that elbow, and check the pitch of everything very suspiciously, thinking like water: how would water in this pipe at this location get back to the main?

Is there any possibility that something got into the pipe during the work? A shop towel (it's happened)?

If worst comes to worst, try disconnecting one of the problem children and pouring water down the supply line -- it should run back, completely freely, to the boiler. Then try blowing on the line (boiler off please!!) -- it should be easy to blow through the line.