Persistent problem with ONE radiator not heating

Leopold

OK, I know, check the vent. Everyone who has tried to help has done that. Here's a run down of everything we've done so far:

We have a steam heating system, single pipe. We have one radiator that does not heat. I replaced the vent with a new vent. Nothing.

So I called our heating company. They sent down a technician (or two) who also changed the vent and told my wife that the pipe was blocked, so we needed a plumber.

We have a friend who is a plumber who came over. We ran the boiler with the vent removed. Nothing. And nothing coming out of the vent. We then disconnected the radiator from the pipe, verified that the valve was in fact in the open position, and ran the boiler with the radiator disconnected from the pipe. Absolutely nothing comes out of the pipe. In the basement where the pipe for this radiator attaches to the main loop, the main loop is nice and warm, right up to the boiler return, but the pipe leading to the cold radiator is cold. Hmmm. Maybe the pipe is blocked? It seems like a really big pipe, and what could possibly be blocking it? He works at the shipyard and didn't have tools to proceed further. So he also tells us to call a plumber. LOL.

So, we call a plumber/heating company that he suggested. They send two technicians down. They replace the radiator vent. Nothing. The radiator is disconnected from the pipe again. Nothing coming out of the pipe. He replaces the main vent, and then lets the boiler run for a REALLY long time. At this point, there is a tiny wisp of steam that comes out of the pipe. He takes me downstairs to the basement, and shows me the two loops that the steam runs in. The radiator that is always cold is the last radiator on one of these loops. He explains that replacing the main vent may help this, but that since the radiator is on the end the loop and our old oil burner doesn't burn as hot as the new systems, it takes a really long time before it will heat up. I'm hopeful that maybe the new main vent will help.

Well, it doesn't. I have a wonderful piece of cold cast iron sitting in our room. In normal usage, it is ALWAYS cold.

Except, one day we ran out of oil and the house was really cold. When we ran the heat, it did in fact run for a REALLY long time. And eventually, that radiator did in fact get warm. But in normal usage, it is always cold. And I'm disappointed that we don't have heat there. I also don't want to have/pay a fourth person to look at it and not be able to help. Everyone has checked the pipe slope, and everyone agrees that it is sloped properly.

The steam pipe is warm all the way to the main vent.

Any ideas on how we can get heat out of this radiator in normal usage?

Abracadabra

What kind of vents for you have on the other radiators? Slow down the venting to all the other radiators. #5 gorton or smaller. Slow down the main venting to the other loop and and more main venting to the loop with the cold radiator. Check the runout for proper pitch. Check main that feeds the cold radiator for proper pitch and no sags. What is attached EDR? What is the EDR of the boiler? Pics of near boiler piping please.

Fred

A picture of the vent on that Main would also be helpful.

New England SteamWorks

Yes, pictures please, but sounds like venting. You've found the right place. For now stay here and let us help before you call anyone else. We'll straighten it out.

Jamie Hall

Has anyone carefully checked the pitch of all the pipes between the main and the offending radiator? Could there be a really low spot?

BobC

Does the boiler ever shut down on pressure Shuts down for a couple of minutes and then restarts)? If it never shuts down on anything but the thermostat there is a chance the boiler is not firing at the correct rate. If it's a gas boiler, clock the meter to make sure it's burning the right amount of gas.

If this radiator is on the second floor there may be a horizontal pipe you can't see that is pitched wrong. Check every inch of the pipe from the main to that radiator for pitch and dips.

Bob

Fizz

Check EDR capability of supply pipe vs EDR of attatched radiation. For example: if a lateral has EDR value of 100sf and supplies 3 rads with 140, one or more might not heat properly or at all in some instances.

Leopold

First of all, thank you all for helping. I have learned a LOT about steam heating over the past year, but I certainly don't have the training and experience that you have.

Fizz and Abracadabra, I have no idea what you are talking about when you mention EDR. Maybe the pictures I am going to upload will answer those questions. Otherwise, please tell me what I need to look for and I will get you the information.

Abracadabra: It looks like most of the radiators have "varivents" installed or some type of adjustable vent. Some of them were all the way "open" or dialed to the highest number. I have gone through the house and dialed everything back so it is no higher than half way (except for the offending radiator which I left at the highest setting).

There appears to be only one main vent for both loops? They are tied together at the bottom near the boiler. Hopefully, the pictures I will provide will clarify. The vent appears to be at the end of the loop that has the offending radiator, though. If it was the other way around, I'd say maybe I need another vent? But that doesn't seem to be the case here.

Jamie: Yes, everyone who has been out has checked the pitch of the pipes. At least everyone has done that. And everyone agrees that there is no problem there. The offending radiator is on the first floor, and the pipe leading to it and the entire first loop is entirely accessible from the basement.

Bob: I haven't really been paying attention, but I believe that the boiler never shuts down until the thermostat says "no more". It is an old oil burner. Old enough that when the oil pump burned out last year, our heating company wasn't immediately sure if they could get a replacement (they did).

Attached is picture of boiler and faceplates.

Leopold

Pictures of main venting arrangement. First picture is main vent, showing two pipes. The pipe the main vent is on is the loop with the offending radiator. The other loop does not have a vent. Instead, both pipes descend next to the radiator and are attached at the bottom where they go into the boiler. See picture 2 for that arrangement.

Leopold

Then we have the radiator vents. First pic is the vent on the offending radiator. The rest show the other main types of vents we have on the other radiators.

Also, a picture of burner showing how pipes come off it.

Leopold

And bonus material. Our home is old, so it had a coal furnace at one time. The picture below is of a wind-up mechanical thermostat for a coal furnace. Off in the shadow is an old dry cell battery. When you wind it (I have the key), it feels like winding a seven day clock (if you know what that feels like). There are two levers.

The way it worked is when the mercury actuator detected the room was too warm, it would activate the spring mechanism that would pull one of the levers. That lever was connected via pulley to the draft and would close it down so less heat was produced. When it detected that more heat was needed, it would pull the other lever, which would open the draft so more heat was produced. I have verified manually that it is still "operational".

Jamie Hall

Whatever else you do, don't scrap that mechanical draught regulator! If you don't want it, someone here will, for a museum piece!

dennis53

I am willing to bet the Varivalves are stealing the steam from the cold radiator. Change all your Varivalves to a much slower vent (#4 or #5 or the good adjustable Vent-Rite).

Also, change the main vent to a Gorton #2 if headroom allows, and add a main vent to the unvented loop you have now.

Dennis

Abracadabra

Leopold said:

Fizz and Abracadabra, I have no idea what you are talking about when you mention EDR.

http://www.columbiaheatingsupply.com/page_images/Sizing Cast Iron Radiator Heating Capacity Guide.pdf

Calculate EDR for each radiator and add them all up. What's that number.

Leopold said:

Abracadabra: It looks like most of the radiators have "varivents" installed or some type of adjustable vent. Some of them were all the way "open" or dialed to the highest number. I have gone through the house and dialed everything back so it is no higher than half way (except for the offending radiator which I left at the highest setting).

Turn down all the radiators that are getting hot to the lowest setting. Varivents tend to vent too fast. My guess is that possibly the radiators that are getting hot are stealing steam from the ones that aren't.

Leopold said:

There appears to be only one main vent for both loops?

You need more main venting. Vent mains fast, radiators slow.

BobC

Is that Heat timer on your problem radiator? i agree the Heat timer Varivalve can be a problem, the one in your picture looks like it's set all the way open and that means it's venting 6 or 7 times as fast as the VentRite radiator vents can. It's also venting much faster than your main vent (Ventrite 35?). How many radiators have the Heat timer Varivents on them?

I would turn any Varivalves down (except the one on that problem radiator) till they are almost off so they can't hog the steam. It looks like you have limited headroom for main vents so I'd try a Gorton #1 that has about 3X the venting as the one you have now, you may need more than one of those but this should tell us if we are on the right track.

Try to work up a list of radiators, their sizes, and the vents on each.

Bob

Fred

Also, let us know what diameter of the steam supply pipe to the problem radiator is. There have been cases where someone over the years moved or added a radiator and pipe the supply too small to both supply steam and carry condensate back to the boiler.
One other point, you say you have two Mains and one has that Ventrite on it, the other no vent at all. Both need adequate venting to get the steam to the ends of the mains and into the radiators. The fact that those two loops tie tother back at the wet return, near the boiler does not mean both mains can share that one vent, or any vent for that matter. Tell us how long each of those mains are and what diameter they are as well.

vaporvac

EDR refers to the square ft of steam capacity for each rad. The 588sq ft rating on your boiler plate is how much total edr the boiler will support. It already includes piping and pick-up losses. Use the instructions above to measure ALL your rads, add up the total and compare it to the 588 number. Ideally, they should be close. In reality, they're often way off resulting in so many of the problems one sees.

Steamhead

Another possibility here is that the burner is not set up correctly and/or there is a lot of soot inside the boiler. Both can cause the boiler to not make enough steam.

That boiler has the original American-Standard DH series burner on it. To say this burner was difficult to set up properly is an understatement, which raises the possibility that whoever did the maintenance on it simply didn't bother.

Most of these boilers that I encounter have been upgraded, usually with a Beckett AF burner which is light-years ahead of the DH. With a proper firebox, this upgrade will increase both the boiler's initial efficiency (at the moment it is tuned up) and its seasonal efficiency (over the course of a season, since the AF when set up properly will not produce smoke or soot over the course of a heating season). Note, however, that a burner upgrade would not make your boiler match the efficiency of a newer model.

My point here is that you have to look at the entire system. It is possible that there are several smaller issues that together add up to that cold radiator.

Where are you located?