Boiler Repair FAQs #4

No Heat, boiler runs
No heat, boiler won't run
No heat downstairs
No heat, zone valve stuck

No Heat, but Boiler Runs FAQs

Tip: see our diagnosis and repair details at BURNER RUNS but NO HEAT is DELIVERED

Boiler runs but some or all areas get no heat.

I get domestic hot water but no heat from our heating boiler

I have a Burnham hot water boiler that I get both heat and hot water from, my problem is I'm getting hot water but no heat can you tell me what to do or try.

So far I've tryed bleeding the boiler and some oof the baseboards. - Anon 11/16/12

Reply: key things to check in 1-2-3 order

Anon, if the heating boiler is running enough to heat the tankless coil to give you domestic hot water in an indirect fired water heater, but no heat comes out of heating baseboards or radiators,

then check:

1. that the room thermostat is calling for heat,
2. that the circulator pump runs (or pumps if there's a circulator pumps for each heating zone)
3. and if there are zone valves, that they are opening.

If all three of those steps (Step 3 won't apply if you don't have zone valves) check out OK, then

4. I suspect that the system is airbound. Most homeowners need help from a trained service tech to fix this problem, but it's possible to do some simple diagnostics and some homeowners are up to trying a repair - those are described at
   
   AIRBOUND HEAT SYSTEM REPAIR 

What about the "reset button"? Some readers may ask. But notice that since the boiler is making domestic hot water, we don't think that the boiler is off on safety reset. It runs, it just doesn't provide heat to the occupied space.

Boiler will start & heats up to the HI limit, but no heat enters the house

I have a Burnham boiler with three zone valves (garage, house, hot water). There is fuel in the tank.

The boiler will start and run fine however it does not distribute any heat throughout any of the zones.

It shuts off when it reaches its temperature. I have had this happen once before and it lasted for a couple days and then started working again.

What could be causing this? What should I do? I live in Alaska, please help - Heather 9/28/12

Reply: most likely a circulator pump or circulator relay has failed

Check for a circulator that is not running or zone valves not opening.

Detailed diagnostic and repair steps are at

• CIRCULATOR PUMPS & RELAYS - home
• CIRCULATOR DIAGNOSTICS

In our water-to-air heating system one zone gets airbound

I have a very strange issue with my brand new boiler/heating system and I'm pulling my hair out trying to solve it.

I have a Forced air, gas boiler heating system. The boiler has one pipe that feeds 3 pumps; zone 2 heating, zone 1 heating, and Hot Water.

I have never had a problem with Zone 2 or Hot water but Zone 1 is another story.

Every 2-3 weeks my 1st floor heating blows cold air from the vents.

The problem is fixed when I bleed Zone 1. But it keeps happening. I have replaced the copper piping that leads to the blower and I have replaced the pump. An electrician has also assured me that it is not an electrical problem.

But it happnened again this past week. Any suggestions as to what might be causing this? Any help is greatly appreciated. - Jason 11/15/11

Reply:

Jason, If I've got it right you are describing a mixed hydronic and water-to-air heating system with at least one zone that uses a heating convector and air blower to deliver warm air to part of the building. If the blower fan runs but the air is cold, then your convector is not heating up.

When that zone is calling for heat, feel the pipes leading to and from the convector - I'll bet they're staying cold.

That suggests that a zone valve is not opening to circulate hot water to that piping loop, or the piping or convector itself have become blocked. Keep us posted - what you learn will help other readers.

Details of how to fix that problem are at AIR-BOUND HEATING SYSTEMS - home

Reader follow-up: replaced a check valve, system worked for a while and now is cold again

I have now replaced the check valve that sits above the circulator pump. It worked last night and then the system was off until the morning. In the morning, system was blowing cold air again.

I bled the system (which normally gets heat to work) and it did NOT work. I then banged on the check valve once with my wrench and it started to work. What is going on? Brand new system. I am losing my mind. Thanks - Jason

Reply:

Jason, flying somewhat blind with so little understanding of just exactly what you've got installed, but

- why are you repeatedly bleeding the system (presumably of air) ? E

ither you're missing a working automatic air purge vent or there is a system leak that's admitting air into the hydronic piping or boiler, right?

- check valves or flow control valves are normally there just as an anti-siphon device to keep hot water from circulating by convection when the circulator is not running. I don't see them clogging often but if there were an unusual amount of debris in the system that could be occurring.

But usually I don't expect a double fault - that is, typically just one of the explanations is likely to be the root cause.

Feel the piping leaving the boiler and enroute where you can access it; the point at which piping is cold is the beginning of a blockage, perhaps by air or even by a piping error (a solder blob?).

For a brand new heating system, I'm surprised that you're not able to get the installer back to diagnose and repair it. Is the work not guaranteed?

We don't get heat unless our hot water heater is turned on - what's wrong?

Our heating- (gas fired boiler with hot water radiators) won't come on unless the hot water is on as well. Thermastat is above room temp. can you help please? On 2012-11-19 by Jane

Reply by (mod) - check for a bad thermostat or aquastat control

Jane,

Sounds as if you have an indirect fired water heater that is heated by your boiler. As the hot water heater can turn on the heating boiler, that suggests the problem is with your room thermostat, thermostat wiring, or primary control.

I'd try disconnecting the thermostat wires and jumping the thermostat terminals at the control.

If the heater runs then the issue is at your thermostat or its wires.

If that sounds too complicated for you to do safely and comfortably, it's time to call a trained heating service technician.

What cauuses low heat in hotwater baseboards?

Lots of sites cover no heat or heat in some zones and no heat in other zones.

But what if low heat in all baseboard heaters?

Furnace is hot and pipes going up and down are hot. But the rooms dont heat up enough. On 2019-01-23 by Jay

by (mod) - why are all of the baseboards warm instead of hot? Diagnostic suggestions.

Jay

Excellent question.

There are a number of things to check when he does inadequate throughout the building and your report of low temperature at the baseboards are radiators is consistent.

But let's start with a report from you on what are the aquastat settings at your boiler and what is the actual temperature that you see on the pressure in the temperature gauge there.

See AQUASTAT HI LO DIFF SETTINGS

and GAUGES ON HEATING EQUIPMENT

With those question answered we will address the other common causes of inadequate heat throughout the system such as a

circulator that's not working, see CIRCULATOR DIAGNOSTICS and you might discover that your heat is circulating only by convection - without help from the circulator! Or wrong circulator velocity - on a variable speed circulator pump.

or a blocked line, a control valve or zone valve that's partly closed,

or partial air blockage in the system.

Really? Yep. I've sometimes found that air in hot water heating pipes can form just a partial blockage, so that the flow of hot water isn't stopped completely but its flow is drastically reduced.

See AIR-BOUND HEATING SYSTEMS - home

Also relevant, is this an oil or gas fuel heater and when's the last time it was cleaned?

If the boiler is very dirty soot can act as insulator to reduce heat transfer from the combustion chamber into the water itself.

My oil burner runs but the radiators don't get hot or even warm: why?

Hi I have oil heating which isn't working.

There is oil in tank, the burner is firing up but my radiators will not heat!

I think my problem is in my hotpress, either the valves or pump but I don't know how to check, it's an old system I believe On 2018-12-01 by Patricia

by (mod) - signs of air bound heating pipes, baseboards, or radiators

Patricia

If your system uses zone valves it's possible that a zone valve isn't opening.

See ZONE VALVES, HEATING 

If your system does not use zone valves, it's possible that the circulator isn't running.

See CIRCULATOR DIAGNOSTICS

If the circulator pump is running and the boiler is hot and radiators or baseboards are cold then most likely the system is airbound.

See details at AIR-BOUND HEATING SYSTEMS - home

No Heat, Boiler Won't Run FAQs

Burnam oil furnace (boiler) won't fire up regardless of thermostat setting

I have a Burnham oil furnace that worked perfectly till mid April. now it will not fire up irregardless of which thermostat I turn up to try to get it to go on.

The water circulation pump also runs constantly so I have the furnace turned off at the breaker box.

Is it correct to assume that this is a problem with the aquastat and the repair is better left to a trained person.

The furnace will be 24 years old this summer so would I be better of looking for a new furnace or just trying to get this fixed? (Apr 22, 2015) Dennis

Dennis says: should be called a Burnham oil boiler, not a furnace - furnaces are forced warm air heating systemns - (Apr 22, 2015) Dennis

Reply: you need help from a heating boiler service tech but first check the reset button

Dennis, at AQUASTAT RESET BUTTON - we explain "How to Find and Use the Reset Button on the Aquastat Combination Control on a Boiler". Start there. That article also lists the location of all of the reset switches and buttons found on heating and water heater systems.

Or start at DIAGNOSE & FIX HEATING PROBLEMS-BOILER  - no heat?

Our gas boiler won't fire up

I have an issue with my boiler with the burners not firing. When the water temperature gets down to 180 degrees it goes into heat mode as it should.

The electronic damper opens and the pilot begins to click. I am getting spark at the pilot but no flame.

If I turn the gas control valve to off and wait until I hear a "puff" sound, which is the pilot actually lighting, and quickly turn it to the on position it will fire and heat the water to 200 degrees then shut off as it should.

I am thinking it is an adjustment to the gas flow on the gas valve or a faulty valve but I am not sure at this point. - kwoyach@frontier.com 11/12/11

Reply: key things to check when a gas boiler's gas burner won't ignite

Kwoyach, I don't have a clear understanding of your heating system but indeed, "I am getting spark at the pilot but no flame" points to a problem with the gas valve or burners.

When I'm sure we have an adequate gas fuel supply (piped in natural gas or an LP or propane tank that's not close to empty) then my first suspect is usually a

faulty pilot light - see GAS PILOT WON'T STAY LIT for details

or

a faulty thermocouple - see THERMOCOUPLE REPAIR / REPLACEMENT for details.

I'd call a service tech for some diagnosis before replacing the gas valve.

There could be a gas pressure or regulator problem or even a problem with a safety device or CO gas spillage sensor.

For a gas boiler and where we are dead sure that it's not a pilot light or thermocouple problem, be sure to also

see FLUE GAS SPILL SWITCH TRIPPING & RESET for details about where to look for this control that will indeed shut off your gas boiler.

Basic step by step diagnosis and repair in what I think are the most helpful order are listed at

at NO HEAT - BOILER

No Heat Downstairs FAQs

First Floor Gets No Heat - Gas boiler - others are OK

We have a triplex with a gas fired hot water boiler heating system. There are 3 different zones.

The rads are fin type baseboard rads and all are 50 years old.

The upstairs and the downstairs apartments are no problem but the main floor apartment loses heat about once a month this year! My husband has bled the rads, and this doesn't help.

Each time he has gone over and added a bit of water to the system, then it kicks in for 3 or 4 weeks. There is no real evidence of water leakage anywhere.

Any idea what will cause the main floor rads to suddenly stop heating up?

Like I said the other 2 zones are fine. The basement apt keeps their heat pretty high, and the upstairs apt is normal temp with no problem.

We've had it looked at by the guy who installed the boiler and the heat zone valves and he can't see any problems and has no idea what is causing them to lose heat. Can you help? (Feb 8, 2016) Lesley said:

Reply:

If you're sure the zone valve for that bad zone is opening in response to the thermostat, then it might help to read the InspectApedia.com article

AIRBOUND HEAT SYSTEM REPAIR - you may be getting airbound baseboards that are not being fully purged.

No Heat from Stuck Zone Valve FAQs

No Heat from Stuck Myson Zone Valve

My oil boiler stopped working this morning but I noticed 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 2019-11-08 by Noel Sheerin

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.

For example some Honeywell zone valves that I will show below have a lever on one end that can be latched into the "OPEN" position so that the zone can get heat even if the zone valve motor is no longer working - you'll have heat until you can get the zone valve repaired or replaced.

But your Myson zone valve lacks that feature.

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:

• MYSON POWER EXTRA SPRING RETURN ZONE VALVE MPE 222 / MPE 2 3/4 “- 2 PORT 22mm VALVE [PDF] Myson Controls, Myson Ltd., Eastern Avenue, Team Valley, Gateshead, Tyne & Wear, Ne11 OPG Sales Office No.: 0845-402-3434, retrieved 2019/12/19 original source: https://www.myson.co.uk/static_files/my/media/downloads/MPE222_Installation_sheet_Sept_2009.pdf
  
  Excerps from Myson: The MPE 222 is designed to control water circulation in primary hot water or central heating circuits. The motor is powered to open the valve with a spring return to the closed position. The valve is not directionally sensitive and may be fitted with flow through either Port A or Port B.

Above: A Honewell zone valve manual switch or override lever that can be used to latch the valve into the "open" position by sliding the lever to the left and pushing it "down" to latch.

Also see these zone valve troubleshooting and repair or replacement procedures:

• ZONE VALVES, HEATING - home - describes types of zone valves and basic zone valve repairs
• ZONE VALVE DEFECTS or FAILURES - and links to diagnosis & repair detailed procedures
• ZONE VALVE MANUALS & WIRING INDEX