Heating baseboard (C) Daniel Friedman Heating Baseboard Diagnostic FAQs
Diagnose & fix heating baseboards #3

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Hot water baseboard heat repair tips & troubleshooting FAQs Set#2:

Frequently-asked "cold heating baseboard" questions and answers help diagnose and fix hot water heating baseboard troubles in your building.

This article series provides common hot water heating baseboard questions and answers that will help diagnose & repair most common heating baseboard troubles including no-heat or leaks or other problems.

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Baseboard Heat Diagnosis & Repair Questions & Answers #2

Dirt dust clogged heating baseboard (C) D Friedman

These questions & answers about troubleshooting and fixing problems with forced hot water baseboard heat were posted originally at BASEBOARD HEAT.

On 2017-11-29 by (mod) - can gases leak from a hot water baseboard system?


In a properly working forced hot water system the pipes and boiler are completely filled with water and you'd not expect a gas leak.

However in a system that is air-bound or that does not have adequate air venting, air can accumulate in radiators, baseboards, piping, eventually blocking the flow of hot water - the symptom will be cold baseboards even though the boiler is chugging away and the circulator is circulating like mad (or at least running like mad).

Now, in the unlikely event that you had BOTH an air-bound hot water heating system AND a leak out of that air at a bleeder valve or other point, that air is often smelly and might be, speaking loosely, referred to as a"gas" .

But a more general answer to your question is no.

On 2017-11-29 by Sally

Can gas leak from forced hot water baseboard heating system

On 2017-11-13 by (mod) - no way to turn off the furnace fan


If the problem you describe has always been present since the thermostat was installed, I suspect a wiring error. If that is not the case in the problem is new then there could be a control board failure or possibly a shorted thermostat wire.

On 2017-11-12 by Danny Wilson

We have hot water base board heating that is switched on by a digital thermostat. It also runs our air conditioner.

The problem is that when the heat is on, the fan comes on. All it does is blow cold air and it seems counter productive to me. There is no way to turn the fan off. It only has recirc, auto and on. What can we do?

On 2017-11-11 by Jamie Spencer

I have a hwbb system with 4 zones. All of a sudden one zone is not heating. The thermostat was older so I replaced it hoping it might do the trick, but it has not. Any ideas what it might be?

On 2017-11-03 by Janam

Hi there
I live in semi basement apt. Has two baseboard heaters (not water type).one heater in main area second is at corner of main area and bed room as bed room has no door this main room corner heater heat flows the bed room area.

Have a question. Even though heater is on heat is flowing out from heater but still I feel some cold. Heat flow is not effect to raise the room temp.can I do one thing can I able to change this heat regulator that regulate the heat like 25c°..does changing regulator can result in unread heat out flow? ??I spike with landlord but they said as far as heater are working they can't do anything. .. but at night when it's cold then room become cool. .

On 2017-09-26 by (mod) - do you need a new boiler to fix an air-bound heating system?


Well for heaven's sake don't get talked into a new boiler just because someone doesn't know how to find and get an air blockage out of the heat piping system. I suspect that air bleeding has been incomplete and that there is a partial air blockage along a horizontal heating pipe segment at the input side of the warm or cold radiators.

Sometimes we have to push the air out using the circulator pump. If your heating system truly has no pump, that is it's a gravity system, then yes adding a circulator can help push air out. But so can the one-time use of a pony pump or service pump used by the technician.

When the air blockage is fixed, also be sure that the air bleeders on your system are working. Often there are several in multiple locations including at the boiler.

Search for AIR BOUND RADIATORS to see details that work also for baseboard heat.

Only if someone showed me that the heating boiler is cracked or damaged beyond economical repair in a way that happens to let water leak out or air leak itno the system might I trust the boiler replacement suggestion right-off.

On 2017-09-26 by Caryn

Have a 2 bedroom condo with hot water baseboard heat. Liningroom gets warm but the 2 bedrooms are cold and the radiators are warm not hot when the heat is on. Bleeed the bedroom radiators but didn't make a difference.

Had people come to check it out all with different suggestions get a new boiler, add a pump to push the water through, move the thermostat and move the furniture. Want to get this issue fixed but noy sure which if any sollution is right.

On 2017-09-23 by (mod) - can air block radiant heat tubing?


If there is air in the radiant heat tubing that would prevent water flow. It's possible that the air bleeding procedure wasn't done correctly or wasn't done sufficiently. That's what I would check first.

On 2017-09-23 by Jack

We bought our how going on 3 years ago. We have never had a problem with our radiant heaters in the basement until last spring.

My brother in law came over and started to bleed the lines and now no heat comes out. I don't know much about the radiant heater since this is the first place with them in. Could he have done it wrong or shut it off by chance since all the others work just fine?

On 2017-04-21 by (mod) - trouble sorting out what's really wrong with the furnace


I understand the upset and aggravation, but this is a question for your lawyer not for us. You will perhaps need

- an inspection by a very qualified, independent, articulate onsite expert who inspects the system, diagnoses its condition, failure cause, failure effects, and notes evidence of proper or improper maintenance.

- a written report documenting and illustrating those findings

- a review of that along with service history and service contract with your attorney

On 2017-04-20 by JR

I'm wondering under what conditions would one take legal action against the oil/furnace company - only to pay for the cost of a new furnace, which looks to be well over $5,000, but complicated by the age of the house and grandfathering regulations, etc.

There was an overnight cascade of problems, ultimately resulting in the furnace being "condemned." When the annual cleaning was done, it was cursory at best. The same company has been attending this furnace for 10 years, although there has been a change in ownership and personnel, but they know the furnace.

They were called back to do the thorough cleaning, but still did not do the job. (There is a service contract). Oil ran out, and they were called but did not come for one week. company repairmen.

This week, the furnace would not shut off, and was sending hot water through the radiators even though the circulator was not on. (If only the baseboards had gotten this hot when the weather was frigid). So, they came back and decided the 3 year old aquistat was bad, and replaced it.

When the repairman turned the furnace on again, it started clanking and there was grey 'smoke' issuing from the back bottom of the furnace.

It hardly seemed to be coincidence. They take no responsibility, and maybe the furnace simply failed. They are happy to sell us a new furnace. Sorry, I'm not more specific than this.

On 2017-03-23 by (mod) - find the leak location in order to fix it


Anything's possible, but I'd want to know where the leak is, where work was done, and how they touch one another.

On 2017-03-23 by Dave

One of our pipes in our hot water heating system is leaking. We had a contractor doing wok in the upstairs bathroom. Is it possible that the contractor did something incorrectly when turning the system back on that would have caused the damaged pipe?

On 2017-03-04 by (mod) - If your apartment is too hot when the heat is on and cold at other times I suspect more than one issue is at hand:


If your apartment is too hot when the heat is on and cold at other times I suspect more than one issue is at hand:

1. the apartment is not well insulated or is drafty and losing heat unnecessarily rapidly. Start by looking for drafts or windows without storm window coverings, or for cold exterior walls that are not insulated.

2. The thermostat may not be located in the best position - that is if the apartment gets too cold before the thermostat calls for heat, the thermostat may be in a warm location such as in sunlight or on a warm wall.

On 2017-03-04 by Bruce bonkowski

I live in Westland Michigan our apt has gas waterbaseboard heat were cold most of time when the heat is on too hot

On 2017-01-31 by (mod) - noises caused by air in the heating pipes


Most likely the noise you hear is from air in the heating lines.

That air needs to be purged. If it doesn't happen automatically through anext automatically purging valve, then your heating service tech will have to do the job.

The risk is that enough air accumulates in the line somewhere that the heating water flow becomes blocked and you will have no heat.

On 2017-01-31 by dan garman

We recently had a new kitchen installed, the contractor had to relocate a section of our baseboard hot water heat run. He discovered a slight leak in the furnace room and made the repair now the sound of the water rushing through our pipes is much louder.

Is this normal or do we need to have someone check our system.
Email address is :, thank you

On 2017-01-19 by (mod) -


Plain copper pipes with no fins will still radiate heat but at a much lower rate.

The number of degrees of heat loss and the rate and how that loss extends across the length of a heating piping loop is going to depend on the piping lengths and location and the temperatures in the areas through which the pipes pass. So uninsulated heating pipes passing through a cold attic or crawl space lose heat faster.

While the absolute temperature reading would be incorrect (unless you mark the measurement area with flat black paint), making IR temperature measurements along a heating pipe will give reasonably accurate estimates of the temperature drop at various points along the loop.

Start right at the boiler: measure the temperature at the point where hot water leaves the boiler and measure it again where water is returning to the boiler.

On 2017-01-12 by Les: Solutions for Cold baseboards in Edmonton Alberga

Our building has a radiant baseboard heating system. I live in Edmonton, Alberta Canada, and we can have some pretty harsh winter nights. I own a suite in an 84 unit apartment. We went through a hyper freeze in early December, with wind chill factors on December 5th 2016 in the mid -30 degrees centigrade. My suite got to 18C degrees, which is 64F and would not go any higher.

Would it not be cheaper to turn up the boiler a bit to heat the building properly, so the zone valves are not constantly calling for heat, than it is to have it turned down too low, causing a constant call for heat? The boiler nor the circulation pump should not have to work anywhere near as hard?

Could a zone valve problem cause the heat pipes in one suite to be colder than others?

If a zone valve is stuck or acting sporadically, can it be reset somehow?

If the furniture is pushed against the baseboard for only about a four foot length of the line in the room, but the vent holes on the top are clear allowing the heat to rise, how much would it affect the air circulation, and heat efficiency of the suite?
Forgot to mention the boiler temp is set at about 170 degrees



I can but guess as I don't know anything about your building.

If a heating system is not able to maintain the building indoor temperature at the minimum required by law for rental properties where you live, it would make sense for the owners to have an experienced heating technician examine the system

. I would be very reluctant to propose a "fix" before I understand the "cause" of the problem. For example, if the aquastat controlling the boiler temperature is already set to 200 degF (93.3 C) at its high limit, then it cannot be set higher without making the system unsafe.

And there could be other problems: a bad circulator pump, a pump circulating at too slow a rate in lpm through the piping, building drafts and air leaks, improper zone piping, a zone valve that's not opening when it should, a thermostat that's not properly located. Or other problems such as those discussed at

A zone valve that is stuck closed MIGHT be able to be manually latched in the OPEN position as a temporary fix.

If furnishings are blocking much of the length of a baseboard you are significantly reducing the heat output from the baseboard. Blocking ari flow into the bottom of the baseboard is as much of a mistake as blocking the warm air exit from the baseboard at its top. Blocking air inflow stops air outflow.

You can guesstimate the impact of blocking air flow through a baseboard as a percentage. The percent of blockage of length of baseboard is probably equivalent to about 80% of that percent of blockage of the heat output. I'm taking less than100 % as there is some heat output even when there is no air input.

Eg. in a 100 ft. long run of baseboard in an apartment, ten feet is blocked by furniture, curtains, etc., reducing heat output in that apartment by (.8 x 10/100) or 8 percent.

On 2017-01-07 by Abby: ok to replace a rectangular thermostat with a programmable one?

I have baseboard heating in my home which is heated by a gas boiler. I am looking to replace my rectangular thermostat with a programmable one. Is this possible? I saw on the boiler that it has 115V electrical input. What sort of programmable thermostat would you recommend, and is this something that I could potentially replace on my own?



Most likely the 115 votes about which you speak is the electrical power to a circulator pump.

A boiler such as yours typically would use a low voltage wall thermostat. You can confirm that even by looking at the existing thermostat, or at the boiler control board. In that case any 24 volt programmable thermostat should work fine.

On 2016-12-22 by victor No heat in my baseboards

the pipes in the base board are warm but the heater is not getting hot i put the thermostat all the way up but it didnt help



Sounds to me as if the heater burner is not working.

On 2016-12-17 by Beth

Are baseboard water heaters connected to Gas or Electric? Our heaters do not seem to be turning on.

On 2016-12-13 by Chris: changed from radiators to baseboards, now no heat

We switched out cast iron rads for baseboard heaters.
The thermostat a Honeywell always reads a few degrees lower than what we want it to be. I set for 72 I only get 67 or 68.

We cant get it to come up at all. I read something about air trapped but all the lines going in and coming out are hot.Warm air is coming of the rads as well but the room just wont warm up.
We also have a gas fireplace in the living room and we use it as a last resort when its just too cold.

That thermostat reads the temp we want it to 72. The home is open concept from kitchen/dining /living rooms.
Do we need a new thermostat or more heaters?
Thanks for any tips.



Please search InspectApedia for AIRBOUND HEATING BASEBOARD to see how to diagnose and correct this problem.

If your boiler was originally properly-sized for the home and runs continuously but heat never is able to satisfy the thermostat there's either a problem with heat delivery or the home has an unexpected source of heat loss.

On 2016-12-08 by Deedee Lewis:

I didn't realize that you needed baseboard covers to assure proper heating of the room. I suppose this makes sense, you don't want warm air blowing somewhere it shouldn't go. My sister has been looking to buy her first home. She found a house that she loved. I'm not sure if it had baseboard heating or not. This would be a good thing to remember if she does buy the house.

On 2016-11-24 by Lana Kinzer: neighbor's airbound heat blocks mine

My landlord said the neighbouring (separated by elevator well) suite had to be bled out through my apartment. I found this strange, since each unit should be equipped with a valve if there was a bubble causing trouble for my neighbour. My heat is fine. Is this true?


Possibly, depending on the routing of the heat piping.

On 2016-10-19 by Sixpack Mitchell: propane line clearance to baseboard

Hi, I was installing baseboard heater in a workroom which really is an old garage. There is a propane water heater to the right about 4 ft from baseboard heater about 4 ft off the ground.

The propane supply line comes down and take a 90 degree turn, and end up being about 13 inches next to heater and goes up the wall and out. I didn't wire the heater in yet, cause i wasn't sure if it is safe. My question is whats is the distances need to be away from electric heater? I wold have put the heater some were else but the pot it is in, is the only place. Any Suggestions would be great, Thank you


Good question, I don't know the answer: we're researching it. Using PSEG's installation specs as an example ( ) I don't see this clearance specified.

On 2016-10-06 by Ron S: new tile will block baseboard

I have cast iron base board heat,and I want to install ceramic tile which come close to the bottom of the unit leaving no gap for circulation. Any suggestions?


Either move the baseboard up or stop the tile a few inches from the baseboard. Or accept that you'll have less heat.

Question: Pipes for baseboard too small; can I add a device to pull hot water into the baseboards?

(Nov 15, 2014) Gino said:
Hi - I moved into a home with a recent addition to the house. The original part of home has cast iron radiators and the addition has 2 floors with hot-water baseboards, all one zone. It looks like contractor did not size pipes properly because the baseboards never got warm even though the cast iron radiators get very hot thru rest of house.

Based on the piping I was able to have the 1st floor addition zoned and re-piped so that water flows to baseboards on first floor and it appears to work so far for 1st floor addition.

However the 2nd floor addition is still cold and based on piping in basement it looks like the original contractor may have tapped into a supply pipe that feeds a cast iron radiator in a 2nd floor room that is adjacent to the 2nd floor addition.

My new contractor and I think that water simply flows to that 2nd floor radiator but does not run thru baseboard on 2nd floor addition because radiator is the path of least resistance. Unfortunately if the original contractor did what we think he did then we can't really access the piping for the 2nd floor baseboards without opening up walls.

Question: is there a product (pump of some sort) that can be attached at the baseboard to "pull" hot water into the baseboard?

Reply: how to get more heat out of smaller-diameter or otherwise insufficient heating baseboard


My Poughkeepsie Plumber (the Disappointing Plumbing Company) did the same thing on an addition we built. He saved himself a few dollars by installing smaller diameter piping, not considering that we had already limited the number of feet of baseboard around the walls for aesthetic and other reasons. I was really disgusted but we didn't want to do the job over again. For this situation there are several things you can do:

1. Be sure that you've done the best possible job with stopping air leaks and adding insulation to the heated space. Minimizing heat loss from the heated space improves the satisfaction offered by the installed sytsem even with smaller piping.

2. If the heat is still inadequate, change out your circulator pump to a higher speed or variable speed unit to push more water through the baseboards. This should enable them to run hotter on a call for heat, increasing the rate of heat transfer into the room.

3. Increase the diameter of all accessible (not too costly) runs of heating baseboard piping. This will improve overall flow.

4. Increase the boiler temperature to 200 F. if you haven't already done so. Don't go over 200 F or you may spill the relief valve.

5. If necessary, add more linear feet of heating baseboard.

If heat is still inadquate one can (at greater cost) swap out all of the baseboard in an under-heated space, leaving the supply piping alone, but installing an alternative, higher output heating baseboard system. Heating baseboards for hot water heating systems are available in a variety of models that offer different BTU output per linear foot.

Question: are steel heating pipes bad?

(Nov 15, 2014) Jim Johnson said:
How problematic are steel pipes going to be in my hotwater baseboard heat system in a 1963 building? The pumps are burning out which makes me think the inside of the pipes may be corroded causing the pumps to strain.


Unless the steel heating pipes are blocked, causing inadequate heat flow and abnormal pressures in the system I suspect the problem is elsewhere. I'd look for a misaligned circulator pump mount - that mistake, particluarly on some older circulator pump assemblies using large motors - can ruin the bearing assembly in short order.

I went to a home where there was literally a pile of dead circulators on the floor by the boiler. The repairman kept changing the circulator pump motor and pump assembly but never noticed that the rear support for the motor had sagged enough to torture the motor shaft.

Question: my radiator sparked then smoked

(Nov 21, 2014) sparking radiotors said:
My radiator sparked and then smoked on one end. I am going to replace it, but wanted to know what caused this. I don't think it is dust.



Watch out: If you truly saw a spark at a radiator and it was not caused by static electricity, say from walking across a carpet, you need to call a licensed electrician. Improper electrical wiring or grounding in your building could be at fault and could be quite dangerous.

Details about electric baseboard heat given separately

Question: Huh?

(Nov 29, 2014) lawrence said:

Please I need help my wall above my radiant heat looks like suit but wont wash off my boiler is natural gas long away from the walls looks like alumium fin tube causing this can you please advice lawrence roessler ph 2172020824 or email l.Roessler@mchsi.Com


Sorry Lawrence but despite the shouting in capital letters I don't understand the question.


Continue reading at AIR-BOUND HEATING SYSTEMS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.

Or see AIR BLEEDER VALVES for how to find and operate those cute little controls on baseboards (or radiators)

Or see DIAGNOSE & FIX HEATING PROBLEMS-BOILER if the boiler is just not working like it should

Or see these

Baseboard heat repair articles

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BASEBOARD HEAT DIAGNOSTIC FAQs3 at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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