New two-pipe steam radiator not heating but trap is hot

Jamiedle

After a year, I was finally able to get someone to install this small Runtal radiator in our half bath. The technician said it was heating before he left last Wednesday, but now that it got cold outside and we've built up full steam in our system (two-pipe vapor), it's clear that the radiator is not heating at all. However, the trap (on the left side) is very hot to the touch.

Tracing the pipes from the boiler, our suspicion is that the trap is on the steam supply pipe side rather than the return side. Does this make sense? Is there any other reason this could happen? I just want to know what I'm talking about when (if?) we can get them back out here.

Also, is there any danger here? Could this situation cause damage? Should we turn down the thermostat until this gets fixed?

Thanks very much in advance.

Steamhead

If the trap is getting hot but the other pipe is not, I'd say it's reversed. Call the guy back and have him fix it.

Pumpguy

What's the temperature of the bottom square part of the radiator? Is that cold too, or is it hot?

JUGHNE

I wonder if the installer will try to just flip the rad around?? 😉

mattmia2

looking at their other posts, this is a broomel system. steam getting in to the returns because the pressure is too high or there are missing or incorrectly set vapor valves is also a possibility.

EBEBRATT-Ed

Could have a bad trap elsewhere back feeding into the rad so it can't vent. Have to get him back as @Steamhead says.

Jamiedle

https://forum.heatinghelp.com/discussion/comment/1906832#Comment_1906832

We also just switched to a vapor stat (from pressuretrol) and have it set at a cutout of 10 oz and a differential of 6 oz. So I think we should be OK there?

Jamiedle

https://forum.heatinghelp.com/discussion/comment/1906823#Comment_1906823

Bottom part is cold, other than slight warmth at the half inch adjacent to the fittings connected to the trap.

mattmia2

https://forum.heatinghelp.com/discussion/comment/1906844#Comment_1906844

that is the first step but there could be many other reasons that steam is getting in to the returns. it may just be at the place where the steam is and it is the only emitter that is affected or the vapor return fittings might be more tolerant of a little steam in the return. the trap will close when it gets hot from the steam, the vapor return fitting doesn't have a hard close off.

or it could be piped backward. if you crack the union on the supply side, do you get steam?

are any of the returns steam hot if you feel them?

ScottSecor

Are those heat emitters rated for steam? Obviously there is a thermostatic trap to "trap" the steam. Is there a method to get the air out of the radiator, return pipes, etc? Does the radiator start to warm if you crack the union on the trap? Did the installer pitch the supply upwards to the inlet?

mattmia2

with the small cross section of that bottom tank the reducers in the horizontal could be a problem, but i don't think that is your main problem here.

Jamie Hall

There should be no warmth at all in the bottom of the radiator near the outlet until the rest of the radiator is pretty warm, and the inlet is steam hot.

Start at the return, and trace it back in both directions — assuming it isn't the last one on a particular return — and see if there is anywhere where it gets warmer — or even steam hot. Whatever else is wrong, and there may be other problems, we're not going to get much of anywhere until we find out why that return is warm or hot — and fix that

Simply put, in most vaprou systems — and the Broomell is no exception — indeed in most two pipe systems of any kind, the returns may be (and often are) warm, but by the passage of condensate. Steam must never get into a dry return.