Steam radiator (C) Daniel Friedman Heating Radiator, Baseboard & Convector FAQs
Diagnostic questions help repair cold, leaky, noisy radiators & baseboards

  • RADIATOR REPAIR FAQs - CONTENTS: FAQs help diagnose & repair problems with hot water or steam radiators, baseboards, or heating convectors
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Radiator diagnosis & repair FAQs:

Diagnostic questions & answers help repair cold radiators, noisy radiators, leaky radiators, or other radiator or baseboard or convector problems in buildings.

This article series describes the types of all types of heating radiators: hot water, steam, cast iron, heat convectors, baseboard heat, electric heating convectors, and we explain the diagnosis and repair of no-heat or leaks or other problems with heating radiators.

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Radiator Diagnosis & Repair FAQs for Hot Water or Steam Radiators, Baseboards, or Convector Units

Steam convector heater (C) Daniel Friedman

Question: radiators recessed into wall cavity - asbestos?

I recently purchased a house built in 1960. It is a brick ranch. I have recessed radiators. I've never seen radiators like this. They are literally in the wall and do not look like your standard radiator. While trying to clean behind them, I noticed some type of foil which is stapled to some sort of insulating board that looks like card board on the bottom. Could this brown fiberboard contain asbestos? I've been worried sick over this. Any help or comment is appreciated. - A.S. 8/4/2014


The foil faced board behind the recessed radiator was added to help direct heat out into the room and is in a position where even if the board contained asbestos (which I doubt based on the ones I've seen) it is in a position where mechanical disturbance is very unlikely - making the risk very low.

If you want to send us some sharp photos of the whole radiator in-wall installation and closeups of the reflective board you have seen I will be glad to comment further.

A recessed heating convector (newer than your radiator most likely) is shown in the article above. And comments about improving the heat output of recessed radiators are at RADIATOR BASEBOARD or CONVECTOR COVERS

Question: replacing a cracked threaded nut on a steam radiator

(July 22, 2011) Daniel said:
I have an old trane steam baseboard convector radiator system in my office. The threaded nut cracked that seals it to the radiator. I am looking for a source just for the nut. It is a 3/4 inch nut and it is on a 1/2 inch pipe. It connects from the steam trap to the radiator.


Daniel, for old radiator parts you might still find an exact match or an equivalent if you can take the old cracked connecting nut to a large plumbing supplier - the pipe threads should be standard; Another source is folks who sell renovation hardware and heating radiators.

As a last resort, I've taken such parts to a machinist who could MAKE me a duplicate. You might pay more for the part but you're saving a much more costly replacement job.

Question: too much air in radiators

(Mar 29, 2012) Andrew Duncan said:
I have a Radiant heating system in my house and it work great in all the rooms but one. Of course it is my daughters room. I have to bleed the rad (a traditional wall-mounted heating convector unit) once or twice a week or it will not have much heat to it. It always seems to have a bunch of air in the rad. The boiler is a newer boiler and is in the basement with the bedroom on the main floor. Is there a valve that one can put into the rad that would allow the air to escape without me constantly having to bleed it? Any thoughts or help would be great. The valve on the floor is open fully, all other rads are working well.


Look for a leak in the system that's admitting air;


(Oct 12, 2012) jim said:
my baseboards are not emitting heat however i still have hot running water. i changed the thermostat with no luck. how do i get the baseboards to start letting out heat again?



Question: electrical stuff in contact with radiators

(Oct 18, 2012) Kelly said:
I recently moved into an apartment and the radiators had removable covers, I took them off and I noticed a lightbulb (was not dead) sitting on top of my radiator with the metal bottom portion touching the radiator which I removed. Then as I looked back behind the radiator I noticed a fluorescent light bulb stuck in between the radiators, could this be a fire hazard?



Question: leaky radiator vent

(Jan 25, 2013) Doug and Nancy Smith, Pinehurst, said:
Our steam heat system has a radiator that constantly spews mist when the furnace is running. Is there a part we can get to stop this annoying problem? Thank you very much!



Question: cracked blown radiators

(Feb 2, 2014) Lynda said:
Our old convector kitchen radiator 'blew' with water spewing from two areas. Had to be disconnected. It's been bitter cold, but heat was on and efficient, !2 hours later the living room radiator blew, same thing as kitchen. Heat was on, but window above radiator was open. Did the cold air seeping in get drawn down into the radiator and crack it? Kitchen radiator is positioned under window and next to a door, where door was left open and drafts came in while radiator was blasting heat and temps outside single digits.
We are ordering new radiators, but wondering if we did something wrong to end life of these two, since we have 5 more working and want to avoid them blowing.


I can't tell if you have steam or hot water radiators but I suspect they were left shut off and froze leading to cracks. A cold air leak could be at fault.


A radiator that "blew" and spewed water is indeed a worry - are these cast-iron radiators? Was the heating system pressure at normal levels (say under 30 psi for hot water heat and und er .5 psi for low pressure steam heat?)

Indeed if heat has been left off it is possible for a radiator to freeze and as ice expands, to crack - a problem that won't show up until things thaw out.

I would look for drafts, insulation voids, or a period when the home was left without heat. I'd also double check that the radiators were not turned off or air-bound. Normally an air-bound radiator is also not going to get hot and if it were really full of air it wouldn't freeze. But if that radiator also contained some water it could freeze as well.

Question: water temperature differences between convectors and baseboards

(Apr 15, 2014) wil said:
Could you say that a convector radiator works the same as a baseboard radiator, you would'nt have to set different temperatures



Yes. We do not set different water temperatures for convector heaters vs. their longer, lower sisters, baseboard heat. Using the same assumptions for building heat loss, the size, location, and number of convector heaters is chosen based on BTU requirements just as we do for baseboard heat.

If you look inside a convector heater you'll see a larger finned tubing segment, possibly with multiple bends of piping running through the tubing, and larger air intake and outlet openings than we see for the same *linear length* of heating baseboard. So we're getting more concentrated heat output from a convector in a shorter linear space than if we installed normal baseboard heaters.

It's worth noting however that there are also different models of baseboard heaters with varying levels of BTU output per linear foot. After a lazy and annoying Poughkeepsie plumber installed 1/2" PEX tubing to supply hot water heat to our InspectApedia office rather than the 3/4" tubing that we had specified we visited J.D. Johnson, our local plumbing supplier for help from their resident heating engineer. He explained that we had several choices of baseboard designs that, given the same incoming water temperature, could give different BTU heating output per linear foot. Choosing one of the higher output baseboard types could overcome our plumber's decision to install what was easy for him rather than good for us.

Question: adding antifreeze to a hot water heating system

(Oct 5, 2014) doug said:
We want to add proplyene glycol to our hot water heating system and are trying to calculate the amount of water in the system in order to calculate how much antifreeze is required. How do you calculate the amount of fluid a radiator holds. We have 28 radiators of varying sizes! Thanks for your help



In the More Reading links just above where you'll find a master Article Index for radiators please see the article titled

ANTIFREEZE for BOILERS for advice on how to add antifreeze - you don't really want to try calculating radiator volume.

I will include in that article a link to calculating radiator volumes - new material - later this morning.


Question: cold radiator diagnosis and repair

(Oct 6, 2014) kimmi said:
I have oil heat and old vintage radiators. I turned on the heat yesterday and again today because yesterday the heat comes on but the radiators are not heating up. They are still cold. I tried letting the air out of the radiators but the radiators still wont heat up. When I let the air out of the radiators, air and water comes out. How much water should come out? Should I let all of the water out or just a little just to get the air out? Please advise because my house is cold since my radiators wont heat up.



NO water should be coming out of the radiators - or that is, if you are bleeding out AIR, then STOP bleeding as soon as water starts squirting out of the air bleeder.

If no more air is coming out of your radiators (this is hot water heat not steam heat) then the radiators are not air-bound and the problem is elsewhere. Check that the boiler is coming on and that circulators (if any) are running and zone valves (if any) are opening. Feel pipes on the inlet and outlet side of a circulator or control to see if hot water is passing through (watch out for getting burned).

See the article series beginning at AIR BLEEDER VALVES

Question: safety of a chipped oil-filled electric radiator

(Nov 26, 2014) Robert said:
Hi, I have a question about my oil filled radiator heater, this is the closest sub-article I could find to post a question...please direct me to the proper page if you don't cover this here.

I have a Black and Decker heater (portable sealed oil radiator), I haven't used it in ten years. There are little chips in the outer enamel of the heater,along the outter edges along the top, revealing little specks of the metal radiator underneath. There are no actual holes in it, but I wondered how important that paint is on the outside and if it's really dangerous to use the heater if there are hole's in the would it create a pressure difference that could cause it to burst open or something....I guess those spots would be could be much hotter....I'm sure if I should use it or not.

Thanks for any feedback. rob.


Robert it doesn't sound dangers from your description; if you see heavy rust or perforation and leaks the radiator is shot and should be discarded. A minor paint chip won't affect its operation; If the radiator looks beaten-up I'd worry about the condition and safety of its wiring.

Question: noisy steam vents - rattles

(Nov 30, 2014) Erin said:
We have steam radiators in my building and the landlord and I are trying to figure out the problem behind a rattling vent. For about an hour every morning, a few of the radiators in our apartment hiss incredibly loudly non-stop; I'm pretty sure it's hot steam coming out. However, my radiator specifically may sometimes make a rattling noise. If I cover the vent hole with a piece of cloth, the rattling stops, which makes me think it's a problem in the vent. We've replaced the vent once already now, and my landlord thinks that it might be a pressure issue. However, he wants to avoid offsetting the balance of the entire apartment building and was wondering if putting a vent with a larger hole should fix the issue. I'm on the bottom floor so the vents have smaller holes than the ones above.



Noisy steam vents are usually caused by worn vent parts or excessive condensate in the radiator. If replacing the vent doesn't solve the problem your plumber will need to check for a blockage at the condensate return for the noisy rads.

See the articles beginning at RADIATOR STEAM VENTS - home

Heating Radiator Articles


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