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AIR CONDITIONING & HEAT PUMP SYSTEMS
BACKDRAFTING HEATING EQUIPMENT
BACKUP HEAT for HEAT PUMPS
BANGING HEATING PIPES RADIATORS
BLOWER FAN OPERATION & TESTING
BOOKSTORE - InspectAPedia
BTU USAGE MONITORS
CARBON MONOXIDE - CO
CIRCULATOR PUMPS & RELAYS
DIAGNOSTIC GUIDES A/C / HEAT PUMP
DIAGNOSE & FIX HEATING PROBLEMS-BOILER
DIAGNOSE & FIX HEATING PROBLEMS-FURNACE
DIRECT VENTS / SIDE WALL VENTS
DRAFT REGULATORS, DAMPERS, BOOSTERS
DUCT SYSTEM & DUCT DEFECTS
ELECTRIC MOTOR DIAGNOSTIC GUIDE
FAN, AIR HANDLER BLOWER UNIT
FLOODED HEATING EQUIPMENT REPAIR
FLUE SIZE SPECIFICATIONS
GAS BURNER Flame & Noise Defects
GAS PIPING, VALVES, CONTROLS
GEOTHERMAL HEATING SYSTEMS
HEAT PUMPS, DIAGNOSIS, REPAIR
HEATING COST SAVINGS METHODS
HEATING OIL PIPING TROUBLES
HEATING OIL TANKS
HEATING SYSTEM NOISES
HEATING SYSTEM TYPES
GAS LP & NATURAL GAS SAFETY HAZARDS
MANUALS & PARTS GUIDES - HVAC
MIXING / ANTI-SCALD VALVES
MOTOR OVERLOAD RESET SWITCH
NOISE, HEATING SYSTEMS
ODORS FROM HEATING SYSTEMS
OIL FILTERS on HEATING EQUIPMENT
OIL FILL PIPE LEAKS
OIL SPILL CLEANUP / PREVENTION
PLASTIC Plexvent / Ultravent RECALL
PUFFBACKS, OIL BURNER
RELIEF VALVE LEAKS
Reset Switch - Heater Primary Control
RESET SWITCH - ELECTRIC MOTOR
Reset Switch - Stack Relays
SAFETY, HEATING INSPECTION
SAFETY RECALLS CHIMNEYS VENTS HEATERS
SOLAR HEATING SYSTEM DESIGNS
SOOT on OIL FIRED HEATING EQUIPMENT
STEAM HEATING SYSTEMS
THERMOSTATS, HEATING / COOLING
VIDEO GUIDES: Heating System Videos
WINTERIZE A BUILDING
WOOD, COAL STOVES & FIREPLACES
WOOD STOVE SAFETY
ZONE VALVES, HEATING
Heating boiler problem diagnosis and repair guide - no heat or loss of heat calls: Here we explain how to recognize & diagnose no-heat problems with residential heating boilers, including loss of heat, heating boiler noises, leaks, odors, or smoke, and high heating costs. This article explains the diagnosis and correction of no heat conditions for water or hydronic or hot water or radiator or baseboard hot water heating systems.
This website answers questions about all types of heating systems, advising on troubleshooting, inspection, diagnosis, and repairs. 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.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
How to To Diagnose a "no heat" call: the Homeowner or Heating System Inspector Must Know the Equipment
If you don't know whether your heat is provided by a furnace (hot air) or boiler (hot water), or steam boiler (steam heat) or whether your fuel is oil, gas, or electric, and whether your heat is hot water, steam, or warm air, see HEATING SYSTEM TYPES.
If your heat is produced by a warm air furnace and you have no heat, instead of the article found here you should see HEATING LOSS DIAGNOSIS-FURNACES.
Hot Water Heating System: Once you confirm that your heat is made by hot water (a heating boiler) you might want to review hot water or "hydronic" heating systems at BOILER COMPONENTS & PARTS and BOILER OPERATING STEPS where we describe the parts and operating sequence of hot water heating systems.
Note: some hybrid or mixed heating systems combine both hot water and hot air to heat a building, such as water to air systems which use a heating boiler (oil, gas, or electric) to heat water which circulates through (and inside of) a heat exchanger (that looks like a car radiator) - described at HEATING SYSTEM TYPES.
Types of Defects and Problems with Hot Water Heating Boilers - Hydronic Heating Systems, Loss of Heat, Noises, Leaks
How to Diagnose Loss of Heat With Oil-Fired or Gas-Fired Hot Water Heating Systems - hydronic heating system troubleshooting
If the heating boiler oil burner is not turning on at all check the causes listed on this page. We'll take you through photo-illustrated step by step things to do when you have no heat and you need to determine what's wrong. First let's review these simple "no heat" concepts .
NO HEAT: BURNER OFF, SAFETY NOT TRIPPED: - Oil or gas burner has stopped, no safety switch is tripped
1. Is the thermostat calling for heat? check that the room thermostat setting is at least 5 degrees above the actual room temperature. See THERMOSTATS.
2. No electrical power: check that all of the switches that power on the oil or gas burner are in the "on" position. Check heating circuit fuses & circuit breakers, not just the wall switch. We discuss this in detail just below.
3. Is there fuel in the oil tank or LP gas tank? Check your oil tank or LP gas tank tank gauge.
4. Electric motor problem at the burner or blower fan: Check that an electric motor (for the oil burner, gas burner, or blower assembly) reset switch may have tripped. See our notes above about electric motors, and see RESET SWITCH - ELECTRIC MOTOR.
5. Aquastat or cad cell control or relay trouble: if you hear or have ever heard buzzing from any heating system control that includes a relay switch, watch out for a control cover that is in contact with a relay switch in the unit.
NO HEAT: BURNER HAS TURNED OFF ON SAFETY: Oil or gas burner has stopped, the safety switch is "off" or "tripped"
If you are not sure how to find and check the safety control reset buttons on your heating system, we describe these controls in more detail just a bit further on in this article.
The burner on your heating boiler, furnace, or water heater has shut down, if a red "reset button" has popped up on the burner primary control or on an electric motor that operates the system. This condition is called "Safety Off".
Watch out: Before re-setting the safety switch or button, it's a good idea check the following five common causes of loss of heat leading to a Safety Off condition. Photos and details follow these short paragraphs.
How to press the heating system reset button: If you do not see anything wrong, you can try re-setting the heating system: press and hold the red reset button down for 3 seconds and release it. If the heating system has electricity it will try to re-start.
Watch out: If the system does not keep running smoothly don't keep pressing the reset button - that could flood the combustion chamber with unburned fuel, causing a dangerous puff-back. Just press the reset button once. If the heating system starts and runs ok, you still should request a service call, but you can have heat while you're waiting.
1. Heating fuel failures - out of oil in the oil tank, clogged oil filter, clogged oil nozzle, oil line has been bent, crimped, clogged, clogged oil pump strainer (fuel unit strainer), or inability of the fuel unit to pump oil (broken motor shaft, missing internal bypass plug on a two line oil tank system, an air leak in the oil inlet line, or a leaky foot valve in the oil tank causing loss of oil prime). if the oil tank is outdoors in freezing weather the oil in the tank or in an oil line may have become waxy or jelled.
2. Oil burner motor failure: the electric motor that runs the oil burner may itself have gone off on reset. Some causes of electric motor failure: one pipe oil system with the bypass plug installed in the fuel unit (oil pump) causing excessive pressure and stalling the motor; centrifugal motor switch sticking (try banging on the motor once); motor condenser burned out; motor stator or internal windings burned or shorted; motor bearing failure. Try re-starting the motor - see RESET SWITCH - ELECTRIC MOTOR
3. Oil burner ignition failure: the oil burner's ignition transformer terminals are loose; the electrodes on the burner nozzle are dirty or not set to the proper gap; the oil is contaminated and is hard to ignite; the ignition transformer has become weak or has burned out (look for tar oozing out of the ignition transformer container); the oil burner nozzle is clogged preventing oil from contacting the ignition spark arc; the ignition electrode(s) are grounded on the air tube of the burner;
4. Faulty heating system control operation: the safety sensor that checks that a good oil burner flame has been established is not working; a stack relay spring or cad cell eye may be dirty with soot; the stack temperature may be too low for the stack relay (boiler is under-fired); the oil burner has been cycling on and off to frequently (a problem with the thermostat).
5. Irregular stack temperatures: in the flue can cause oil burner draft and temperature or control problems. Downdrafts (missing chimney cap), insufficient draft due to chimney problems, or fluctuating oil burner flame may be at fault. Also see CHIMNEY INSPECTION DIAGNOSIS REPAIR.
-- some of this material is paraphrased from Audel.
Oil Burner Operating Problems: Oil or Gas Burner rough, noisy, smoky, smelly
The heating burner operates but not properly. See OIL BURNER NOISE SMOKE ODORS
Next let's check each cause of no heat in detail; if your system uses warm air heat instead of water or steam, review the check-items just below before going to HEATING LOSS DIAGNOSIS-FURNACES.
SAFETY WARNING: If a heating system oil burner has been deliberately "shut down" and you don't know when or by whom this step was taken, beware of turning the heating system back on without an inspection and safety check by an expert technician.
Is the heating boiler turned on? Is there electric power to all of the heating system components such as an oil burner at the boiler and power to the circulator pumps?
Where are all the heating system reset buttons? If you are looking for the main reset button on heating equipment you'll want to see: AQUASTAT CONTROL Functions and CAD CELL RELAY SWITCH (hot water boilers and some water heaters), Stack Relay Switch on older oil fired boilers and furnaces, SPILL SWITCHES (gas fired equipment), and also Low Water Cutoff Controls on steam heating systems.
A Stack relay switch may be installed on the flue vent connector and may be in the "safety - off" position. To identify and reset this control see Stack Relay Switch. Stack relays are found on older oil fired furnaces and boilers.
Still no heat? Once you have assured that you have heating fuel and that electrical power is turned on to the heating unit, if you still don't have heat check these controls:
For full details of this topic be sure to see OIL BURNER NOISE SMOKE ODORS.
For full details of this topic see BOILER LEAKS CORROSION STAINS
When observing evidence of leaks on a heating boiler, keep these points in mind:
For full details of this topic see Inadequate Combustion Air
Lack of adequate combustion air can result in improper system operation, sooting, increased heating cost, damage to oil burner components (back pressure heat can destroy an ignition transformer), higher and more frequent heating service costs, loss of heat, noises, smoke, and potentially, the production of carbon monoxide or other flue or combustion gases which escape into the building - potentially dangerous
Safety warning: The sketch shown here, courtesy of Carson Dunlop, explains how dangerous furnace back-drafting can occur when there is insufficient combustion air.
These conditions can not only release flue gases into the occupied space, but they are likely to cause the production of potentially fatal carbon monoxide.
We've seen heating equipment that seemed to work just fine during its adjustment because the service technician was working with the door to the furnace or boiler room open. But when she left the system and closed the furnace room door, suddenly there was insufficient combustion air.
Unsafe Air Conditioning or Heating Duct Openings which describes the risks of
reduced combustion air on hot air heating systems when certain return air duct defects are present, and also see
CARBON MONOXIDE - CO and CHIMNEY INSPECTION DIAGNOSIS REPAIR
Green link shows where you are in this article series.
Frequently Asked Questions (FAQs)
Question: our heating boiler won't heat our hot water
Hi. our problem is that while our central heating is fine,our oil boiler will not heat our hot water. A local plumber has replaced all relevent parts,apparently, but still no hot water until the water has been running from the tap for around 25 minutes. - KennyBrown999@hotmail.co.uk - 9/9/2011
Kenny: sorry I couldn't even guess at what's wrong with so little information. "all relevant parts" - may not have really been "ALL" since you still have the problem. How is your hot water made - by tankless coil? If so the coil may be blocked with mineral deposits.
Question: oil fired heat not working
My oil heating is not working. the thermometer symbol is lit up on the boiler - Margaret 10.21.11
Margaret, it sounds as if a diagnostic light is lit on the primary control of your heater - it's time to call a service technician. Unfortunately hou didn't give me any other info; though you might get some help by following the basics at the top of this article - making sure you have electrical power & fuel and that the thermostat is calling for heat.
Question: oil burner 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. - email@example.com 11/12/11
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. 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 sensor.
Question: gas fired warm air furnace - gas boiler - huh?
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
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.
OK....so 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
Jason, flying somewhat blind with so little understanding of just exactly what you've got installed, but
Question: when I bleed the heating radiator black water comes out
when i bleed the radiator. black water is coming out. the system has only recently been installed - William Hanna 11/27/11
William, at RADIATORS (article links listed at Related Topics or top ) you will find details about using the air bleeder valves on radiators. In general, you should be bleeding AIR out of the radiator, not water. If you open the valve and allow air to escape, as SOON as you see water coming out of the valve you should close it.
Question: why does one of our rooms get no heat?
Hi, we have a forced hot water system. I'm wondering why,if all of our rooms are in the same zone, one room cannot seem to be heated? - JL 12/26/11
Question: heating system makes noise at startup
system starts up makes grinding noise and shuts off - Jim 12/26/11
is it easy to change bearing - Jim
Question: oil fired boiler turns on but no hot water leaves the boiler - and steam is coming out of the pressure-temperature relief valve
I have a warmflow bluebird oil fire boiler, where the boiler is firing but no hot water is exiting the boiler, and there is steam coming from the overflow pipe. Does this imply a problem with the internal pump ? - Jason 5/22/12
Reply: shut off the unsafe boiler immediately and call an expert
Watch out: I would SHUT OFF THE BOILER IMMEDIATELY
Question: boiler will start and run 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
Check for a circulator that is not running or zone valves not opening.
Question: one pipe steam system not working
I have a Burnham boiler (actually two) with a single pipe steam system. We shut the gas off to the boilers during the summer and restart them each fall. The startup sequence is
1. turn on thermostat and turn temp up (they are upstairs)
2. turn on gas valve on gas line.
3. turn on safety shutoff switch on boiler.
4. turn pilot gas valve from off to pilot, depress, and light pilot. Wait for pilot to heat millivolt sender.
5. Turn pilot valve to ON.
Furnace will usually fire up. This time, the pilot will light and stay lit, but no action from the boiler. I have checked the voltage at the thermostat and it is .25 V.
Closing that circuit does not fire the boiler. There is water in the boiler. It looks like there are two pressure safety switches and the low water cutoff. How do I check them? what else should I look at?
Richard, steam heating system diagnostics are over at STEAM HEATING SYSTEMS
Question: smoke pours out when our oil fired boiler starts up
I HAVE A HOME HEAT BY A OIL SISTEM BOILER ,AND IS MAKING A LOT SMOCK WHEN IT GOES ON W. - Anon 10/28/12
Reply: shut off the boiler - beware of a puffback explosion
Question: when I tap on the transformer on our Beckett oil burner it will run - else not. Can it be fixed?
I HAVE TO TAP ON BECKETT TRANSFORMER FOR IT TO COME ON DOES IT NEED REPLACED OR CAN IT BE FIXED - Dave 10/29/12
If that doesn't do the trick it's time to replace the transformer.
[People who type in all types get their text made teensy.]
Question: My heater stopped working - I like this heating company ...
Question: I get 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
Anon, if the heating boiler is running enough to heat the tankless coil to give you domestic hot water but no heat comes out of heating baseboards or radiators, check that the thermostat is calling for heat, that the circulator pump runs, and if there are zone valves, that they are opening.
Question: I keep draining water from my steam boiler but the water level in the glass tube never drops - what's wrong?
i have opened up the water (with a sump pump in a 5 gallon bucket) for some time, yet my glass tube never goes down? any ideas? - Damian 11/16/12
Question: my water heater has a damper, it's open, but the heater won't come on
i have universal water heter that one has damper on it but damper open but heter did not fire get on - Anonymous 12/5/12
Perhaps, Anon, you are referring to an electric or power damper in the flue vent connecot of your heater. For safety, on a call for heat the damper is supposed to open (to let combustion gases flow up the chimney) but if it doesn't the heater won't turn on. Of course there could be any of a number of other reasons for no heat. Check the items suggested in the article above.
the thermostat signals but the furnace will not turn on - Tom 12/10/2012
Tom there could be any of many reasons that you don't get heat when the thermostat calls for it. Your best bet is to start at the top of this article and run through the checklist.
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