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Heaing system emergency switch (C) Daniel FriedmanRecent Heating Boiler Repair FAQs #4
Q&A on how to diagnose & fix heating boilers

Recent heating boiler repair questions & answers for no heat or loss of heat or boiler won't run, etc.

These frequently asked questions (FAQs) about how to diagnose & repair a heating boiler (hot water heat) that is not working can help find and fix the trouble or can help you understand what your heating service tech intended to explain.

This article series explains the diagnosis and correction of no heat conditions for water or hydronic or hot water or radiator or baseboard hot water heating systems. We describe how to inspect, troubleshoot and repair heating and air conditioning systems to inform home owners, buyers, and home inspectors of common heating system defects.

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

- Daniel Friedman, Publisher/Editor/Author - See WHO ARE WE?

Heating boiler troubleshooting FAQs

Photograph of a modern oil-fired heating boiler

These Questions & answers about troubleshooting and fixing heating boilers were posted originally at BOILERS, HEATING - home - be sure to see the repair and diagnostic procedures given there.

On 2019-12-19 by (mod) - our heat isn't hot enough; are we using too much LP gas?

Jimmy

I can't guess how much LP gas use is normal for your home because the amount of fuel needed and heat output needed to warm a home varies significantly by the home's rate of heat loss (how well a home is insulated, how much air leakage there is, how much glass there is, how much opening and closing of windows and doors occurs, etc).

But there are some sanity checks that one can make.

1. Look at the heating boiler's data tag

where you'll see the input BTUh consumption rate of your boiler. At GAS BTUH, CUBIC FEET & ENERGY https://inspectapedia.com/plumbing/Gas_BTUs_Volumes.php we give all of the ways to convert between cubic feet or other measures of LPG and btus. You can thus start by seeing the rate per hour (of "on" time) at which your boiler consumes fuel.

You'll need to watch or measure or count hours-on for your boiler.

2. Have your heating service tech be sure that the boiler is properly tuned and adjusted

. If your boiler's HI limit is set to 180degF that does NOT mean that the baseboard pipes will ever see that temperature; there is heat loss enroute; However your tech might agree to push up the HI to 190 or closer to 200F (not above that or the TPR valve will open); the thermal conductivity of baseboard is exponentially greater at higher temperatures so you'll see a bit more efficient heat transfer into the occupied space.

3. InspectApedia offers a number of articles on cutting heating cost

by finding where the waste or leaks are.

Two articles I like are

ENERGY SAVINGS PRIORITIES

and

HEATING COST SAVINGS METHODS

On 2019-12-19 by jimmy45

Thank you for taking the time

Our home is a late 60's pre-built with 1150 square feet. We have a weil-mclain CG 11 hot water boiler, Taco sentry zone valve on the supply side, and I think the issue is with the zone valve. We use 10% LP on a 500 gal. tank a week. When the thermostat calls, the zone valve closes, the boiler fires, as does the circulator.

The baseboards get warm to the touch, but not 180 degree hot. Once the heat is reached, the boiler stops as does the circulator, and the zone valve opens. We have our thermo set at 65, it turns out around 63 degrees, and shuts of around 66. It takes close to an hour to raise 3 degrees.

Is this much LP normal?

How has no damage occurred with the circulator running and the zone valve closed?

Thank you for your time.

On 2019-11-25 by (mod) - Weak Heating Air Flow

Lou

Using the InspectApedia.com on page search box just above to look for "Weak Heating Air Flow"

finds our diagnosis and repair procedure titledAIR FLOW TOO WEAK https://inspectapedia.com/aircond/Weak_Air_Flow.php

Take a look and let me know what you find.

On 2019-11-22 by Lou

Air flow from vents is very weak

On 2019-11-09 by (mod) - troubleshooting a Myson Zone Valve

Noel

It looks to me as if the "Operating" light on your Myson zone valve is off - that means the valve is closed, OR the valve is not getting power.

It's also possible that simply moving the manual level on some zone valves can get a stuck valve un-stuck so that it will work again - for a little while.

I can't tell if your valve is now in the manually OPEN position or not. But if it was closed and you opened it manually here is what could have happened:

I suspect that your zone valve relay or valve motor is not working so even though the thermostat called for heat and turned on the circulator, hot water didn't enter this heating zone -the valve remained shut.

If just that zone was calling for heat it'd turn the boiler ONLY when the boiler temperature drops below the limit set on the aquastat on the boiler.

So if no water was circulating, the boiler might run to heat up but then it would shut off on its high limit.

When you flipped the manual over-ride over to MAN (Manual) you forced the valve open, permitting hot water to flow out of the boiler through the heating zone.

Cooling water returning to the boiler then dropped its temperature there, so the boiler turned on again.

This Myson zone valve manual may help you out:

On 2019-11-08 by Noel Sheerin

My oil boiler stopped working this morning but I notice after I changed the setting on the attached image from auto to manual I could hear water moving in the pipe and the boiler started gain itself. What is my problem?

On 2019-11-04 by (mod) - bad thermocouple

Yes, a bad thermocouple or thermocouple that's not adequately connected at the gas valve and confirm it the pilot to continue to burn but think that there is no pilot because it's not properly sensing the flame. That case it will prevent the gas valve from opening.

On 2019-11-04 by Bob M

My gas fired boiler will not fire up. It was working fine for a month since starting it up for the season. Burner motor will start, pilot is lit and stays lit but burner does not ignite. Thermocouple is 2 years old and so is the gas control valve and burner relay. The burner transformer is putting out 24V but the is no 24V across the control valve terminals. Would bad thermocouple allow the pilot to stay on while keeping 24V from the control valve? Thanks.

On 2019-10-10 by (mod) - Boiler and pump working but no heat from the baseboards

Anon

See AIR-BOUND HEATING SYSTEMS as a reasonable place to start.

By feeling the hot water heat supply pipes you can follow the hot piping out of the boiler: where the piping turns cool or cold there is perhaps an air blockage (or a zone valve that's not opening)

On 2019-10-10 by Anonymous

Boiler and pump working but no heat from the baseboards

On 2019-10-05 by (mod) - Pilot light wont light

Check power, then gas supply, then the thermocouple

On 2019-10-05 by Bob

Pilot light wont light seems like no gas coming to pilot light

On 2019-03-11 by (mod) - have heat for my house but no hot water

I would look for a clogged tankless coil, or a closed valve, or a scale clogged tempering or mixing or anti scald valve

On 2019-03-10 by Matt

I have an oil operated boiler the runs both my hot water and heat to my house. I have heat for my house but no hot water what could be the problem?

On 2019-11-01 by (mod) - I have no hot water but I have heat

John and Brandi

Please check out the articles in the ARTICLE INDEX just above where you will find a discussion of

Airbound heating systems

Keep me posted on how that works for you and don't hesitate to ask follow-up questions

On 2019-10-31 by John

We have a boiler system hooked up to a hot water tank which usual has worked in the past but the hot water does not seem to make it through the pipes in our Florida room. The top outlet pipes on the tank are hot but it does not circulate beyond a few feet?

On 2019-03-10 by Brandi

I have no hot water but I have heat

On 2019-02-27 by (mod) - do I have to add water to my boiler

It's certainly not a silly question it's absolutely correct. When a new boiler is installed the entire system needs to be filled with water and all of the air in the piping and boiler needs to be purged. That would be the normal tasks of the installer.

On 2019-02-26 by Melissa

Silly? But i need to know this to diagnose a problem I am having with a new oil boiler i had installed . When a new oil boiler is installed do you have to add water to the the boiler to flow up through pipes and the flow to heating baseboards

On 2019-02-1 by (mod) -

That's a job for a trained gas heat service technician

On 2019-02-14 by Mo

Do you have any advice about how to check that the boiler doesn't have a problem with irregular ignition of gas, or what I should ask of someone who comes out to inspect it? As I said, I already mentioned this issue to the technician during our inspection and maintenance appointment (~1 week ago) and he didn't know what could be causing the problem.

A little more information... The boiler is from Burnham and was likely built around 1978.

One year ago, the boiler’s gas valve was replaced with a Honeywell V800A1070, and a new thermocouple was installed at the same time.

According to the technician who just did our inspection, we likely had a gas valve that opened slowly at first, and then eventually opened to full, whereas our new gas valve opens fully right away (My guess is he is referring to the step-wise vs. standard-opening pressure regulator options). Could the booming be caused by this change? Thank you again for your advice.

On 2019-02-13 by (mod) - dangers of flexing boiler parts

Let's talk about flexing metal and damage risks associated with that after you first assure yourself that the booming sound is not an irregular ignition of gas or oil.

those would be dangerous conditions.

On 2019-02-13 by Mo

We have an older boiler. Several times a day we hear a boom coming from the unit. It sounds like the metal casing around the boiler is flexing. I compare the sound to a piece of sheet metal being popped back in place. We recently had a company come in to inspect and perform maintenance on the boiler.

When we told the technician about the issue, he said he wasn't concerned, but also didn't know what could be causing it.

The noise didn't happen while he was there working. A couple side notes, in case they are important, one of the zone control valves is malfunctioning and we are planning on replacing it soon, and either the air vent or the pressure relief valve (not sure which one it is) leaks a little bit of water out of the top. Thank you for any help/advice you can give.

On 2018-12-19 by Kevin

I have a hot water heating boiler that feeds four apartments on two floors above the basement. The radiators in the front of one side of the house don't get warm/hot. I've bled them, so it's not an air issue. The pipe in the basement feeding the vertical pipes to those radiators also feeds other radiators which work fine.

But the pipe in the basement is cold where the vertical pipes to these radiators goes up. Seems the water in the end of the supply and return are blocked. What can I do?

On 2018-11-12 by (mod) - boiler makes moaning noise

Let's start by isolating the sound to a source such as an oil burner motor, an unsafe chimney venting problem, a noisy circulator pump, a combustion issue, or perhaps pipe vibration from water velocity. Buy your husband a mechanic's stethoscope. Let me know what you hear.

On 2018-11-12 by verna

we have a 2 year old boiler and it makes a loud moaning sound my husband has drained it several times and put new antifreeze / water mix it works for awhile then starts to moan again . any answers we would appreciate thank u

On 2018-11-12 by (mod) - moaning heating boiler cause & cure

Let's start by isolating the sound to a source such as an oil burner motor, an unsafe chimney venting problem, a noisy circulator pump, a combustion issue, or perhaps pipe vibration from water velocity.

Watch out: if you hear a moaning that's more like a roaring freight train you may have a dangerous chimney fire. If that's the case get everyone out of the building immediately and call your fire department from a safe location.

Also see CHIMNEY NOISE DIAGNOSIS

Assuming it's not a chimney noise, buy your husband a mechanic's stethoscope. Let me know what you hear after checking these heating boiler noise articles:

See this section: DIAGNOSE OIL HEAT NOISES - assuming you're asking about an oil fired heating boiler.

If your heating boiler uses gas fuel (LP or propane or natural gas) see

Also see OIL BURNER CLANKING RATTLING NOISE

Also see HVAC NOISE-2 CHATTER CLANK FAN GROAN - chattering, clanks, clunks, cyclical, fan, groans, growls, honking, where some of those moaning noise clues might be of use.

On 2018-11-12 by verna

we have a 2 year old boiler and it makes a loud moaning sound my husband has drained it several times and put new antifreeze / water mix it works for awhile then starts to moan again .

any answers we would appreciate thank u

On 2018-05-01 by (mod) - If the boiler is not heating up

Ramesh

If the boiler is not heating up one wonders if
- there is heavy soot insulating the boiler heat exchanger interior

But a poor nozzle spray suggests

- wrong nozzle, damaged or clogged nozzle, dirty strainer in the fuel unit, or a problem with the fuel unit or with its connector through the blower fan to the electric motor driving the burner

- a problem with oil flow such as dirty oil filter, clogged oil line - check oil pressure and flow on the outlet and oil vacuum on the inlet side

- improper burner adjustment - this would be suggested too by a smoky or poor flame but must be confirmed by actual measurements made by the tech such as CO2, smoke, temperature, and draft over the fire and in the breech

- the tech might also check the transformer spark

A tech seeing poor flame might must confirm that the oil flow is adequate, both rate and pressure.

To be clear you cannot properly adjust and set up a modern high speed oil burner "by eye" (as we used to do in the old days) - measurements are needed.

On 2018-05-01 by RAMESH CHANDRA

I agree with you and i have done total cleaning of stack, chimney, burner & oil filter and i have replace a new chimney but the problems has not been rectify .

There is same issue, its take too long time to heat @ 95 deg cent ( more than 2 hrs) and smoke is also there. So, is there any issue with fuel nozel which has not been spraying properly. How can i detect route cause. Please can you help & suggestion for above issues.

On 2018-04-29 by (mod) -

Ramesh

See BOILER OPERATING PROBLEMS

For a detailed sequence of Diagnostic and repair steps for your smoking oil burner. Be aware that that condition is unsafe and risks a puff back explosion.

Almost certainly you need a trained heating professional to clean and adjust the burner and to inspect to be sure that the chimney and draft are correct, or to look for other operating problems that would cause the conditions you described.

On 2018-04-29 by RAMESH CHANDRA

I have a small diesel fired water heating boiler (1000 lt capacity). There is problem of too much smoking (chimny or stack) and it take to long time period(2 hours) for heating water at 95 degree centigrade. When i start pasteurization at 95 deg cent, the temperature is droping down very fast ( within 10 minute) @ 60 deg cent. So please let me know how can i troubleshoot of this issues?

On 2018-01-25 by (mod) - water running and gurgling thru the pipes

Larry

If you hear water running in the heating pipes there is air in the system that needs to be purged. The risk is loss of heat from an air-bound system.

When you pay your guy $90. to bleed the air you might want to also ask that the automatic air bleeders be left in working condition or that if they are not working they be replaced.

On 2018-01-24 by larry

just purchsed this home.hydroponic with cast iron boiler (oil fired) seems to heat o k

,but always here water running and gurgling thru the pipes,( this is unsettling at night,for my little girl,,. Is this normal to here these noises? house was made in 1960.. hvac guy wants 90$ an hour to come and bleed it..

On 2018-01-02 by (mod) -

Gold

You dont want your floor temperature any hotter than it is.

You can use the search box at the top or bottom of this page to find our article on RADIANT HEAT FLOOR TEMPERATURE

On 2018-01-02 by Gil corey

How to adjust ball valve to boiler on slab heating. The in gage reads 120 degrees. The boiler gage reads 140 degrees.
Thank you

On 2017-12-30 by (mod) -

William,

Please Use the on-page search box at the top or bottom of this page to find our article series on

BANGING PIOE NOISES

if the noise is coming from the piping system.

if the banging noise is coming from an oil burner turning on or off, that's dangerous, you should turn off the system, and call for emergency heat repair. The risk is a puff back explosion

On 2017-12-29 by WILLIAM j WHITE

I am getting a banging noise

On 2017-12-04 by (mod) -

Cindy

Lead poisoning of building occupants from heating distribution pipes is rather unlikely since it's not carrying water that people drink. If the heating baseboards smell when the heat is on it may be possible for them to be carefully cleaned by an expert.

Don't try any heavy-duty banging or scrubbing or even smashing with a home vacuum cleaner as you may damage the fins and reduce the heat output.

Of course if the heating pipes are actually leaking than they need to be repaired promptly.

On 2017-12-03 by Cindy

40 year old slant fin cooper pipe with fins and solder smells bad, soldering breaking off and causing smell. What to do. Lead poisoning?

On 2017-10-30 0 by Glenn

Have1932 oil boiler converted to gas. The allitidude gauge goes past red line 30 when turned on. How do fix the problem of pressure build up?

On 2017-10-28 by (mod) -

Joe,

If previously you had heat on the Upper Floor then unless something has happened to the circulator pump I wouldn't suspect that it's a circulator capacity. More likely you haven't been able to successfully bleed the air out of an air bound system.

On 2017-10-27 by Joe

my boiler heat works fine on my first floor but I have no heat on my second floor. If I continue to bleed the farthest line it gots hot but as soon as I shut the bleeder off it gets cold again. Could it be that my pump is not large enough to push the water thru to the second floor? Any comments are appreciated

On 2017-10-25 by (mod) -

If the boiler pressure is under 30 PSI and the temperature is under 200 degrees Fahrenheit then it's within normal operating range. If the pressure is over that amount you should turn the system off immediately as there is danger of a boiling liquid Vapor explosion or bleve

Also if the pressure is over 30 PSI I would expect the relief valve to be spilling so if it's not the situation is as I said, dangerous.

If temperature is below 200 and
If an independent measurement of pressure shows that truly the pressure is abnormally High, the system is still unsafe and should be shut off.

There are several causes of abnormal boiler pressure including leaks into the boiler from a tankless coil or improper water feeder. But it's also possible that the gauge of Simply defective.

On 2017-10-25 by Alex

Pressure gauge on my boiler is way beyond 20 psi. What would cause this?

On 2017-09-25 by (mod) -

If the boiler starts and runs normally with just a rap on the control box I'd suspect a loose or bad wire connection.

On 2017-09-25 by Marilyn

My hot water boiler is not starting on its own, we installed a new 30 second relay box but we still need to tap on the box to get furnace to start? Can someone help me please?

On 2017-08-23 by JJ

On the boiler stamp, does " CAP 124 Lbs/HR" describe the DOE rating of the unit or the AGA (input) rating of the unit or none of the above?

On 2017-05-19 by (mod) -

Phil,

This is a pretty common problem, so you're not alone. See STEAM BOILER FLOODING REPAIR at https://inspectapedia.com/heat/Steam-Boiler-Flooding.php and let me know how well that works for you.

On 2017-05-18 by Phil

I am SO disappointed. After removing so many parts on my boiler, the water is still creeping up in the sight glass, so that means it is my tankless hot water heater. which will now need to be removed. Is that a complicated job?

Expensive? I have all new valves and piping and now am faced with this project. How involved s it. Do you have an article on your website I can read?

I'm discouraged.

On 2017-05-17 by Philomena

It's a cast iron boiler but it a case of replacing very rusted pipes, flanges,maybe the tankless water heater IF the water continues to rise after these repairs. I'm thinking I will get it all fixed up and there will not be anyone to repair it and any prospective buyer will be too scared to buy it.

IF after all this, if it is the tankless heater, I think I need to replace the entire system.

It's the lack of qualified HvAC people that is the major problem now and people are afraid of these boilers. Maybe I need to begin getting estimates but Ed reassures me it's going to be fine.

Thanks, Daniel, for being there every time I become a nervous Nellie.

On 2017-05-16 by (mod) -

I agree that it makes sense to compare total repair cost to boiler replacement cost. If a boiler is an old steel unit that's rust damaged, I lean towards replacement. For a cast iron boiler in good condition and that needs a control repaired or replaced, often that's a sensible approach.

On 2017-05-16 by Phil

Well, my plumber returned from vacation. He came to check out the boiler; he is coming tomorrow to remove the 4" diameter pipe on the return line; there is a very small leak right there. It looks like a tough piece to remove. He said it would be too difficult for him to unscrew so he is going to cut it out with his Sawzall.

He is also going to replace the steam vent that hisses and shoots steam up to the ceiling. Then he is going to replace the water feed valve with a newer style. IF the water continues to creep up in the sight glass, he said it would have to be the tankless hot water heater, which would need to be replaced.

Oh boy, I hope I am making the right decision to keep this old boiler going. I dread the thought of removing it; I have no hatchway. I think Ed is one of the last repair men who is willing to work on a boiler this age in this area. I'm hoping that after all of these repairs ($1,500 so far), I am doing the right thing.

I had the boiler off for most of last week when our temperatures dropped all week long. I blocked off my kitchen, hanging blanket on two doorways and using my gas stove for heat. If this had been the middle of winter, I don't know what I would have done. I'm in Massachusetts.

I'll let you know if it turns out to be my tankless water heater. Poor boiler. Poor me. I live alone in this old house.

On 2017-05-08 by (mod) - water creeps up in the steam boiler sight glass

Phil

there are several causes of steam boiler water creep up or overfilling ranging from a leak in a tankless coil leaking into the boiler to a water feed valve problem.,

See STEAM BOILER FLOODING / SURGING REPAIR at https://inspectapedia.com/heat/Steam-Boiler-Flooding.php for details.

On 2017-05-08 by Phil

Sorry Daniel, to be back again. Still waiting for HVAC man to call me. I have been co concerned about what is going on with my old National boiler, and you have been very helpful. (I cannot locate our earlier exchanges). I continue to have problems with sight glass, creeping up. I have noticed a new small drop of water coming from the pipe at the bottom of my boiler which I THINK is called an out take. It is in the area where the plumber removed a pipe a few weeks ago and had a lot of trouble with the connections.

When the water in the sight glass creeps up, I release some of it to get the level down. It seems to me that the boiler has been going on for just a short while. My thermostat is set at 62 in the house; the current temperature outdoors is about 50.

I decided to remove water and the furnace turned off! I was told by HVAC Plumber #1 that I should always remove water when the boiler is running and listen for the furnace to go off. He said that proves that the relief valve is working. Others say you shoulod reduce the water when the furnace is not working.

But now the furnace is completely off.

I am worried because I had the problem on Saturday of my National Radiator original pressure going from 1 to 4 and a vent emitting a LOT of steam.

I have left two messages for the plumber. I have even left a message for Plumber #1. I called the Gas Company this morning, but they are useless. They just advised me to call a plumber. Not easy to do with a vintage boiler.

I am sorry to bother you once again.

I have no one to help me; no one understands this system. And I am elderly and live alone.
Do you have any ideas - once again.
Thank you so much!!!!

On 2017-05-07 1 by (mod) -

Phil,
I answer as many questions as I can, sometimes getting behind, and on occasion taking time off for a wedding.

Your questions help us see where we need to add information, clarify text, or do more research.
Daniel

On 2017-05-07 by Phil

Once again, Dan, thanks for your continued help. I will certainly read all of the information you provided.

And good to hear you confirm that even though my old "scary" boiler is ancient, it's "good enough" to keep around. I feel that way, too. It has been dependable for the 50 years I have lived in this house. And it was old even then.

Do you answer questions every day of the week?

You do such a thorough job. I don't know how you keep up with all the questions people ask you.

You offer such a great service and I'm very grateful.
Thanks once again.
Have a good day.

On 2017-05-07 by (mod) - Everhot Tankless Water Heaters

Phil,

I've made good use of old cast-iron coal-fired boilers converted to gas or oil, properly fired and tuned and cleaned and running at about 79% efficiency - good enough to defer moving to a newer high-efficiency heating boiler in many cases.

Everhot tankless water heaters are still sold, as Everhot, now in Waterville MA, is a division of Therma-Flow - s

ee EVERHOT WATER HEATERS

Also see this article

INDIRECT FIRED WATER HEATERS https://inspectapedia.com/plumbing/Indirect-Water-Heaters.php


...

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BOILER REPAIR FAQs-3 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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