Radiator question

NealJ

I working on getting a radiator with a long history of not providing heat to work. Looking at the piping, I find this third floor radiator is at the end of a “secondary” main coming directly from the boiler header. It has one first floor radiator that taps in, and is heating well. There is no main vent on this line, so the bulk of the piping must vent through the radiator. I replaced the radiator vent with a large variable vent and now can hear large volumes of air venting when the boiler starts operating. The steam got to the radiator inlet in

Long Beach Ed

You've got a two pipe vented system there, along with a Griffing Bundy radiator that goes back to just after Civil War days.

https://archive.org/details/bundyradiatorsfo00aagrrich/mode/2up

Do all the other radiators have two pipes and an air vent? Where does the return pipe from this radiator go? What is it connected into?

NealJ

My post got cropped by the photo. Here is my full post. House was built in 1887.

I’m working on getting a radiator with a long history of not providing heat to work. Looking at the piping, I find this third floor radiator is at the end of a “secondary” main coming directly from the boiler header. It has one first floor radiator that taps in, that is heating well. There is no main vent on this line, so the bulk of the piping (1.42 Ft3) must vent through the radiator. I replaced the radiator vent with a large variable vent and now can hear large volumes of air venting when the boiler starts operating. The steam got to the radiator inlet in <5 minutes, which is a huge improvement.

The problem is that it once the steam hits the first section of the radiator, the sound coming from the vent becomes a whisper and it takes 1/2 hour to get towards the last section of the radiator, with the last couple of sections never getting hot.

The radiator has no top connections between “risers”, only the bottom tank to move steam (and condensate). Each ‘riser’ of the radiator is screwed individually into the base. The radiator is dead level.

This is a vented two pipe system, with no traps and wet return. The outlet valve gets too hot to touch, but the drip return pipe where I can access it at the floor below does not get hot. I’m thinking there must be a section of horizontal return pipe under the floor under the radiator that may be plugged (I have other horizontal sections of return piping plugged that I need to replace) but think air should still vent out of the new vent. I have two other radiators just like this one that heat quickly at the inlet ends, but take forever to get to the outlet ends. Thoughts?

NealJ

Long Beach Ed said:

You've got a two pipe vented system there, along with a Griffing Bundy radiator that goes back to just after Civil War days.

https://archive.org/details/bundyradiatorsfo00aagrrich/mode/2up

Wow! Great to find a catalog cut! I’m always interested in the history of this stuff, Thanks!

Long Beach Ed

One pipe provides steam to the radiator, the other returns its condensate to the boiler. The supply pipe on a two-pipe radiator is too small to handle both the steam load and the returning condensate. The return line must route the condensate to the boiler. If it's obstructed, there's your problem.

That's a pretty big radiator which will produce lots of condensate. If it has to oppose the steam in the supply line, which may not even be pitched to handle the water, it's going to stop the steam flow.

The vent will remove the air from the line and the radiator, but once the condensate arrives and has nowhere to go, all your steam flow stops.

There are plenty of ways to clear the returns. You can use a hose, a snake, an air-ram...

NealJ

Long Beach Ed said:

. There are plenty of ways to clear the returns. You can use a hose, a snake, an air-ram...

Thanks Ed. I’m not sure if the return is blocked (or severely restricted) or not, but it seems to fit the evidence. I’m thinking I’ll rig up some adapters to attach a garden hose to the return pipe thread (remove the return valve) and see if I can blast some water down the line without making a mess. I don’t think I can get my snake around the 90 degree elbow.

I have an identical radiator (though a bit smaller) on the first floor with similar symptoms, that looks like it was added later. It’s piped up with a single pipe (no return). It has the same size steam inlet, so based on your previous comments, the steam line may be too small to support steam and condensate return. I think I can add a condensate return without a huge effort (first floor radiator, easy basement access below it and right above the return header).

Long Beach Ed

A hose would be an excellent place to start. Just follow the routing of the return and watch the water's not spraying out somewhere unexpected on your side of any clog.

GrafHeating

Have been able to inspect the bottom chamber? There is a possibility it is mostly full of crud.

AdmiralYoda

Those inlet/outlet valves look pretty old. Might not be a bad idea to disconnect the radiator from the valves and slide it aside for an inspection.

Make sure the valves are fully open and not obstructed and while your at it look inside the radiator to make sure it isn't full of crud blocking the flow of condensate as @GrafHeating mentioned.

DanHolohan

Get to know it better:
https://heatinghelp.com/heating-museum/bundy-radiators-for-steam-and-hot-water-also-heating-specialties-c-1894/

gerry gill

Question NealJ- If you measure from the floor to the very bottom of the inlet valves radiator stub pipe, (the part of the valve that goes to the radiator), how does it compare to the measurement on the return pipe side?

New England SteamWorks

With your type of system, every return needs to have a water seal before connecting together with any other return. Normally this was done by running a wet return around the perimeter of the basement, and every return was then individually piped in to it. There are other ways.

It is not uncommon that somewhere along the way, someone not familiar with this type of system, connected two or more returns together (usually in the basement) without a water seal. That is a likely cause.

You also could have a faulty valve.

It's not cheap, but we've made these systems perform much better by adding an additional vent on each return in the basement, ahead of the water seal. Usually a Gorton No.1.