Heating system installation, repair, maintenance questions & answers set #2:

More frequently-asked questions & replies on how to troubleshoot & repair heating systems in buildings.

These heating system articles answer questions about all types of building heating systems and describe how to inspect, diagnose, and repair heating system problems, how to cut heating bills, and heating system safety, heating system efficiency and heating trouble-shooting advice.

Heating System Inspection Diagnosis & Repair FAQs #3

These questions & answers about troubleshooting heating systems in buildings were posted originally at HEATING SYSTEMS - home - that's a great place to start.

[Click to enlarge any image]

Photo: example data tag for a boiler. More examples of data tags and notes on finding them are at DATA TAG IDENTIFICATION & LOCATION

• What kind of heat have I got? If you don't know whether your heat is provided by a furnace (hot air) or boiler (hot water), or whether your fuel is oil, gas, or electric, and whether your heat is hot water, steam, or warm air, see HEATING SYSTEM TYPES.
• How to fix the heating system: If your heating system is not working properly choose one of the following diagnostic procedures:
• see DIAGNOSTIC GUIDE A/C or HEAT PUMP
• or DIAGNOSE & FIX HEATING PROBLEMS-BOILER
• or DIAGNOSE & FIX HEATING PROBLEMS-FURNACE

These Q&As were posted originally at HEATING SYSTEMS- home.

On 2017-12-10 by (mod) -

Chris

Often I see the pattern you describe when there is a lot of residual heat in the bottom of the furnace - the thermostat says "I'm satisfied turn off", the burner shuts down, the fan continues to run to extract the last heat out of the heat exchanger (and protect it from heat damage), then the fan shuts down. More heat from below warms the plenum and the fan limit control turns the blower back on.

Look first for a loose or corroded electrical connection, then a dirty air filter, and finally, possibly a defective fan limit switch or one whose sensor coil in the plenum is damaged.

On 2017-12-09 16:06:33.197268 by ChrisJ

Why would my oil burning furnace run for several minutes as normal, then shut off [the blower continueing to run as normal for a brief time] and then come back on for less than a minute and shut back off ?

On 2017-12-08 14:14:29.955643 by Kip

I saw a few sights that referenced that but I do not see a serial number on the furnace ID tag, just the model number and series number.

Any idea where the serial number might be hiding? Thanks for the reply.

On 2017-12-10 by (mod) - where to find basic zone valve wiring connections

Gene

On the page where we started this discussion - ZONE VALVE MANUALS & WIRING INDEX https://inspectapedia.com/heat/Zone_Valve_Wiring.php

you will find in that article on that page a section titled
Honeywell Zone Valve Wiring Wire Colors

where you will see details about connecting the red and yellow wires of the Honeywell zone valve

On 2017-12-10 by Gene 12/8/179

@Gene 12/9/17, I forgot to say my zone valve Honeywell V8043F yes I see where the wires go onto the valve but what to do on the other end the wire ?

On 2017-12-10 by Anonymous

In past I have seen where people has said some things about my problem but I cannot get to those pages from the past . I have saved I had to tell it where to do it I have never had to do that in past.

On 2017-12-10 by (mod) -

Gene,

Our discussion with you about zone valve wiring is at

inspectapedia.com/heat/Zone_Valve_Wiring.php

Print out that page and you will be able to read and go to it again.

On 2017-11-26 by (mod) - look for an electric motor that is seizing or a jammed

Warren,

I would look for an electric motor that is seizing or a jammed coupling or blower fan or a seized fuel unit any of those would easily cause a humming sound from the motor that might sound like it was the Transformer.

On 2017-11-20 by Warren Jones

One site said that I should call a heating or electrical contractor. Another, that I'd probably have to buy a new system. Then, there's this one, but the one that finally helped me in an instant was the one that said this: If the thermostat runs from the house's electrical system, check on the circuit breakers.

One of them might have tripped and cut off the power the thermostat. Reset the breaker. THAT DID IT. I NOW HAVE MY HEATING SYSTEM WORKING AGAIN. Now I only have to wonder if I should be worrying about why the circuit breaker tripped.

On 2017-11-16 by Phil

I have a Beckett afg model burner wasn't coming on intermirtingly and a humming noise was coming from the transformer. When I have it a whack it would start up. I replaced the transformer thinking that was the fix. No go next morning had same problem. Sound still sounds like it's coming from transformer.....help! Anyonne

On 2017-11-15 by (mod) -

Brian

If your building is in the U.S. the usual arrangement is such that the circulator should run when the thermostat is calling for heat. The boiler itself may be on or off depending on the water temperature. The thermostat turns on and off the circulator, and the water temperature, via the aquastat, turns the boiler's burner on and off as needed.

If your building is in Canada it's often the case that the circulator runs continuously during the heating season and the thermostat turns the heating boiler on and off as needed.


Catherine: the system you describe sounds unsafe to me, as if there is an electrical problem. Leave the heater OFF and turn off the circuit breaker or fuse that delivers power to it, then call your electrician to ask for repair help.

On 2017-11-14 by Brian Brownawell

When should my circulator pump be running on my smith boiler system ?

On 2017-11-08 by Catherine

My wall mounted electric heater are making pow noise even loud ones and even when I set them at 5 celcuis wich is off ..only time they stop is when I turn off the power Switch they also made a strange buzz in the corner of the cord

On 2017-10-30 by Lorna

Where is the pilot light?

On 2017-10-16 by Anonymous

if condensaate drain from ac coil and the air handler connect, you may need to install air gap or vent in hard piping. the air handler blower fan and or power vent will cause neg. air pressure in conensate plplng

On 2017-10-16 by Anonymous

you may too adjust rhe volume control valves or install these valve at every heating panel.

On 2017-10-16 by everett

@bill,
@barbq australia,

On 2017-10-10 by (mod) - circulator pumps and circulator control relay switches are usually generic

Krystyna

Both circulator pumps and circulator control relay switches are usually generic: you can replace the pump or its controller with any of a variety of brands

On 2017-10-09 by Krystyna

Noticed the water pump running when the heat is off. Have located the issue and in need of an obsolete part for a Hydrotherm Boiler. The part is: Hydrotherm Circulator Control LS50. This part came from a Hydrotherm Model HC-85B. How can I locate this part? Is there an alternate part I can use to fix this issue?

On 2017-10-09 by Anonymous

Do the radiant heat plates in a Williams vented room heater circa 1990 contain asbestos?

On 2017-09-01 by (mod) -

Should be easy to make 4th he system run long enough to check basic burner operation, blower fan, air delivery.

Measuring temperature rise would be more difficult if thst were to be included, ehich its not in a normal home inspection

On 2017-08-30 by bill

how effective is a furnace inspection with temperatures above 70 degrees

On 2017-06-27 by barbq australia

I have a hot water hydronic system using panel radiators. I am living in a 2 story house. 3 panels on the ground floor stopped working. They are on the same side of the house. Replaced the panels instead of trying to fix them but they were still cold.

Called in a repair tech who installed a brand new boiler/pump unit as the old one was faulty.

The repair tech then bled the entire system and put in anti corosion treatment. One of the previously cold panels got hot and then went cold again it is full of water and no airlock as there is water coming out under pressure from the bleed valve., the other 2 panels stayed cold.

When the air bleed valves on these 2 are opened no air or water comes out and when I apply some vaccum to the outlet it stays in the negative for a few minutes until it gets some water comes in. I know some water is coming in as a trickle comes out of the drain valve at the bottom of the panels and no air rushes back in when I open the air bleeder.

There is water to the inlet and outlet valves as I unscrewed the pipe couplings and the water sprayed out everywhere. Hope you can shed some light on this, thanks

On 2017-05-13 by (mod) -

Zoom

In my opinion you need to drain the condensate to a drain system or to the building exterior; you might need a condensate pump if you can't make the drain work by gravity.

Continuing to wet a crawl space invites wood destroying insect damage, mold, rot.

On 2017-05-13 by Zoom

Hi, I had a high-efficiency gas furnace installed last year and within just a couple days, it wouldn’t stay on. The owner of the company came out right away and told me it was because the drain pipe for the condensation had been installed in a way where a section was run up before back down again.

So, in this section, the water was getting trapped and was turning off the heater.

Anyway, they came out and cut the pipe at that section and left it where the condensation just drained directly below into the crawl space under the house. I have a raised foundation and he said letting the condensation drain into the dirt won’t be a problem short term and would get back to re-route the pipe as soon as he could.

He finally returned today to tell me the pipe can’t be re-routed to drain outside for some reason related to framing of the house and the only other thing he could do would be to put in a pump but he didn’t really explain how that would work because he was pushing me to just leave it forever to drain under the house.

He said the condensation only makes about 1/2 cup of water a day when running the heater all day and it will never cause any damage.

I live in Los Angeles and we do have mild winters but it still gets cold enough that we run the heater almost every day for a good 4 or 5 months.

I wanted to get professional opinions on this matter to either give me assurance that what he is telling me is correct or explain why I need to insist that he do what is needed to drain the water away from my house. Thanks!

On 2017-04-21 by (mod) - Venting a direct-vent furnace into an existing masonry

Venting a direct-vent furnace into an existing masonry chimney may

- violate the manufacturer's installation instructions
- be unsafe risking fatal carbon monoxide poisoning

And I am totally baffled by the second part of your question: combustion air from the return air plenum?

What? Perhaps I misunderstand, but if I don't, I have to ask

1. who's going to live in this house?

2. does someone want to kill them?

Not to be too silly about it, the situation you describe sounds unsafe and improper.

I suggest noting the brand and model of the furnace, giving the the manufacturer a call, and ask them for an opinion. Keep me posted.

No one should be sleeping in the home you describe without working smoke and CO detectors properly installed, located, tested, and resolution of the question you raise is so urgent and sounds so unsafe to me that I suggest that any occupants be informed immediately of the concerns you've raised.

On 2017-04-20 by Mike Hickens

A home that I'm considering buying here Michigan had a 96+ furnace installed on 2015. The PVC exhaust vent is venting into one of a two flue chimney. The PVC pipe for combustion air is routed directly from the furnace to the return air plenum. Is this correct?

Isn't the combustion air pipe usually routed to the outside of the home. Also, I don't see the exhaust vent pipe exiting through the top of the chimney. Won't the moist exhaust air rot the inside of the Chimney?

On 2017-04-08 by (mod) -

Pete, using the Search the InspectApedia website box just above I found

MANUALS & PARTS GUIDES - HVAC - https://inspectapedia.com/heat/HVAC_Manuals_Air_Conditioners_Boilers_Furnaces.php that has both links to direct PDF files of many manuals and also company contact information for manuals we don't already offer free to our readers.

On 2017-04-08 by Pete manual for a 1968 'american standard' gas forced air furnace

Need a manual for a 1968 'american standard' gas forced air furnace

On 2017-04-03 by (mod) - Amtrol Extrol heating boiler expansion tank

Anon

The Amtrol Extrol heating boiler expansion tank does not use a condensate drain.

I think you probably have an air conditioning/heat pump system - that does use a condensate drain.

For detailed help un-clogging that drain see CONDENSATE DRAIN CLEAN & DE-CLOG at https://inspectapedia.com/aircond/Condensate_Drain_Cleaner.php

(found by using the InspectApedia search box just above to look for "clogged condensate drain"

Or see our ARTICLE INDEX

On 2017-04-03 by Anonymous

I HAVE AN AMTROL EXTROL BOILER SYSTEM EXPANSION TANK THATS SHOWING ON THE SCREEN " BLOCKED CONDENSATE DRAIN." HOW DO I CLEAR THE DRAIN BECAUSE THERE IS NO HOT WATER

On 2017-03-26 by (mod) -

This sounds to me as if a safety control is not working properly, perhaps a gas spill switch or a burner control. I'd ask for repair from an experienced gas boiler service tech. Do keep me posted - as what you find will help other readers.

On 2017-03-26 by RG

I have a gas utica boiler that stopped working last week. The circulator kicks on but the furnace would not fire unless I shut off the electric for approximate 5 mins.

Once I turn electric on system fires up and baseboard heat up appropriately. Will continue to operate for like a week than stops firing up again.

On 2017-03-14 by (mod) - what are the procures and tools used by a service technician in determining what's the problem with a furnaces.

Myles you ask a perfectly wonderful question, but far more than would be appropriate to try typing in to an off-the-cuff reply window.

Since you mention furnaces specifically, I add that there is a series of detailed, step-by-step heating system diagnosis and repair articles here at InspectApedia.com, addressing various areas of problem and solution.

Start at NO HEAT - FURNACE - https://inspectapedia.com/heat/Furnace-Diagnosis-Repair.php

Techs start with the basics: is there power, is there fuel, does the burner run, does the fan run, does air come out of registers; each of those general areas becomes a focus for a more-detailed look depending on the yes or no answer.

Separately, depending on the fuel type, e.g. oil or gas, we have flowcharts showing what a tech considers, for example, if the oil burner doesn't run.

It sounds as if you are taking a test - I hope you're not cribbing.

On 2017-03-14 by myles J.

I would like to know what are the procures and tools used by a service technician in determining what's the problem with a furnaces.

On 2017-02-25 1 by (mod) -

Sorry Tom, I don't understand your text. From what I can make out it sounds as if condensate return to your boiler may be blocked; water logged radiators will block steam and won't heat. I'm totally baffled about what "walls" you would open.

Condensate from radiators has to return to the steam boiler.

It's time to call for help from an experienced steam heat technician.

On 2017-02-25 by tomcatcardona

2 Family 3 level home new gas boiler 1 yr.old. Old baseboards no cut off valves.

Top flr. start of heat run the last 3 baseboards 2 in livngroom. spray water from varivalve then it goes to Bthrm.

no heat I take off varivalve it sprays alot of water then steam. Some told me to open walls cause there is a low point where upon cooling the water sits until system starts up again. Please advise. tomcatcardona@gmail.com

On 2017-02-25 by (mod)

Sorry Tom, I don't understand your text. From what I can make out it sounds as if condensate return to your boiler may be blocked; water logged radiators will block steam and won't heat. I'm totally baffled about what "walls" you would open.

Condensate from radiators has to return to the steam boiler.

It's time to call for help from an experienced steam heat technician.

On 2017-02-25 by tomcatcardona

2 Family 3 level home new gas boiler 1 yr.old. Old baseboards no cut off valves.Top flr. start of heat run the last 3 baseboards 2 in livngroom. spray water from varivalve then it goes to Bthrm. no heat I take off varivalve it sprays alot of water then steam. Some told me to open walls cause there is a low point where upon cooling the water sits until system starts up again. Please advise. tomcatcardona@gmail.com

On 2017-02-18 17 by (mod) - heat won't turn off

Mr. Walker:

First confirm that nobody used a switch at the thermostat or at the air handler to put the fan into always FAN ON

Then
Check for shorted thermostat wires or a bad fan relay control.

Search InspectApedia for HEAT WON'T TURN OFF to see more detailed diagnosis and repair suggestions.

On 2017-02-18 by D Walker

Re-posting comment made on an obsolete version of the article above:

AUTHOR:D. Walker (no email)
COMMENT:Our fan has been running for 12+ hours. We tried turning the heat off and it continues to run.

On 2017-02-13 by (mod)

Jason,

Take a look at the ARTICLE INDEX at the bottom of this article and click on NO HEAT - FURNACE if your heat is by forced hot air, or NO HEAT - BOILER if your heat is by forced hot water or steam.

Each of those articles is a great starting point for step by step procedures to figure out why your heat is not working and to fix the trouble, or to recognize when it's time to call a trained repair person.

From your comment it sounds as if your boiler is working - the water is hot - but your radiator or baseboard is not heating enough.

That could be water not hot enough or a circulator not forcing water through the system, or a clogged or blocked readiator or, of course, something else that would be more obvious to an on-site expert.

On 2017-02-12 by Jason m

Lol.im not sure how i would check if u answered me.it didnt ask for an email but heres mine if u can help.musserjason2@gmail.com
Hi,just wondering if u could help?.

i live in an apartnent building.only my heat isnt working.thermostat is working.bled the lines and right when we do hot water comes up but then notbing after that.changed the curculater.theres hot water going up the line from the furnace and in the return.we dont understand why its not oushing hot water up.theres not a blockage cuz when u bleed it hot water comes up but yhats it,then it cools right back down.help!

On 2017-02-10 by Dave

I'm having a problem with our baseboard Heat system. We have a multiple zone set up and thermostats for both zones.

Each are set in the low 60's. Our downstairs zone reads 80 degrees on the thermostat yet it's set at 62. This zone will run at 80+ till I turn off the burner using the emergency switch.. .

I tried new thermostat, no luck.
My other zone is Upstairs and I have no problem..64 degrees. Rooms are at proper temp.. Can someone help me out and point me in the right direction as to what's causing the problem?

System:
Beckett oil burner
Newport Boiler

Honeywell electronic aquastat L7224/L7248
Honeywell Mercury thermostats

On 2017-02-07 by Paul

Infloor radiant heating:
I have 2 wall thermostats in a 1100 square foot house with infloor radiant heat. I normally leave one at 21 and the other at 18. The house to me feels cool but to the wife warm.

My question is is it better to have both thermostats close to or even at the same temp setting.

I am wondering if by having the two thermostats at a different temp setting if one side of the house is trying to fight with the other resulting in uneven temps. It is an open system and heated with a Nautral gas direct power vent hot water tank.

On 2017-01-09 by (mod)

Steve is it possible that the boiler sports an extra, obsolete hi-limit that's no longer needed? What does your heating service tech say?

I've seen extra limit controls on older heating boilers that made domestic hot water with a side-arm coil or a range boiler system.

I speculate that particularly with a cast-iron boiler residual heat in the combustion chamber and in the cast iron may heat the water a bit at the end of a burner on-cycle.

As long as the burner is off at the limit and as long as system pressure remains below the spill point of the relief valve (typically 30 psi on a residential hydronic boiler) you should be ok.

On 2017-01-09 by (mod)

RE-posting from old copy of this web page

AUTHOR:Steve S (no email)

COMMENT:Hi. I have a hydronic heating gas boiler. In addition to the combination aquastat, there is a high limit manual reset thermostat by Honeywell. The manual reset thermostat keeps tripping at 205 degrees which is what it's set at. On the combination aquastat, the high limit temperature is set for 190 degrees.

The low limit is set for 170.

It seems that after the burner goes off, the temperature still increases. Any idea if the setting is wrong, if I have a bad aquastat, or what else might be causing it to trip.

One thing to note, there are a few other boilers in this room that are set to very similar settings and they do not trip.

I appreciate all your help.

...

Continue reading at HEATING SYSTEMS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see HEATING SYSTEM FAQs-4 - more questions and answers about heating system installation, troubleshooting, repair.

HVAC SYSTEM TYPES for a more complete list of types of heating and cooling systems & equipment & diagnostic procedures

Or see these

Recommended Articles

• HEATING SYSTEMS - home
• AIR HANDLER / BLOWER UNITS - home
• BLOWER FAN OPERATION & TESTING
• BOILERS, HEATING - home
• COMBUSTION AIR REQUIREMENTS
• DUCT SYSTEM DESIGN SIZE & DEFECTS - home
• ELECTRIC HEAT - home
• FAN, AIR HANDLER BLOWER UNIT - home
• FURNACES, HEATING - home
• HEATING SYSTEM INSPECT DIAGNOSE REPAIR - home
• MANUALS & PARTS GUIDES - HVAC - home - Master Index to All Brand Names & HVAC manuals, wiring diagrams, installation and repair guides
• ODORS FROM HEATING SYSTEMS
• RADIANT HEAT - home
• SOLAR HEATING SYSTEM DESIGNS
• STEAM HEATING SYSTEMS & CONTROLS - home
• THERMOCOUPLE REPAIR / REPLACEMENT
• THERMOSTATS, HEATING / COOLING - home
• WOOD STOVE OPERATION & SAFETY

Suggested citation for this web page

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

Or see this

INDEX to RELATED ARTICLES: ARTICLE INDEX to HEATING SYSTEMS

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