Guide to Heating & Cooling Electrical Power Switches
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A guide to finding and using electrical power switches for heating and cooling systems
Where do we find the emergency-off switch for heating furnaces and boilers?
What are the basic components of hot air heating systems?
Troubleshooting heating system furnace controls
How to inspect & repair hot air heating systems - Furnaces
Questions & Answers about the emergency off switch on heating equipment

This article describes the usual location and function of electrical switches that control power to all types of heating equipment. We explain the purpose and use of heating system emergency "off" switches.

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A Guide to Finding & Using Electrical Power Switches to Turn On or Off Heaters for Furnaces & Boilers, Heat Pumps or Electric Furnaces or Air Conditioners

If your building has lost heat, checking that the heating equipment is actually turned "on" at all of these switches is a first step in diagnosing the problem. This website answers most questions about central heating system troubleshooting, inspection, diagnosis, and repairs. We describe how to inspect residential heating systems to inform home owners, buyers, and home inspectors of common heating system defects.

The articles at this website describe the basic components of a home heating system, how to find the rated heating capacity of an heating system by examining various data tags and components, how to recognize common heating system operating or safety defects, and how to save money on home heating costs. We include product safety recall and other heating system hazards.

Because some controls are used in common on hot water heat, hot air heat, and steam boilers, readers should see these other articles: see BOILER CONTROLS & SWITCHES, and also see BOILER COMPONENTS & PARTS for a detailed list of heating boiler controls, other heating system components, parts such as circulator pumps & draft regulators. If your building uses warm air heat, see FURNACE CONTROLS & SWITCHES. If your building uses steam heat see STEAM HEATING SYSTEMS. Also see Heat Won't Turn Off - Stop Unwanted Heat.

Readers needing to find and fix un-wanted air leaks, heat losses, or other energy wasters should see HEAT LOSS DETECTION TOOLS. Readers should see ENERGY SAVINGS RETROFIT CASE STUDY and also see HEAT LOSS DETECTION TOOLS and INSULATION INSPECTION & IMPROVEMENT for energy saving retrofit detailed guides. Also see GAS PIPING, VALVES, CONTROLS for more details on how to inspect and test LP and natural gas piping, controls, valves, and tanks.

Oil burner shutoff fuse switch (C) Daniiel Friedman

Electrical power switches on heating and cooling systems: where will the power switches be located, how do we know if we have turned on power to the heating or cooling system?

Our page top photo shows a typical emergency off switch for a heating system. Our photo at left shows a fuse box that is used to accomplish the same purpose, though this older switch is more likely to be found near the entry to a basement where heating equipment is located.

Electrical switches that turn off electric power that operates any type of heating system: furnace, boiler, steam boiler, heat pump, electric heat, are required for both safety and for service.

An emergency off switch for the building heating system should be found outside of the basement or other boiler or furnace room location and accessible so that an occupant can, in an emergency, turn off heat without having to enter a possibly smoky or dangerous area.

A second electrical "off" service switch should be found on or very close to the heating equipment itself. This second service switch is used by the heating service technician.

A third electrical switch or fuse turns off power to the heating equipment service at the building electrical panel. If a circuit breaker has tripped or a fuse has blown on the heating equipment's electrical circuit, you may be able to restore heat at the electrical panel.

But for safety reasons it is important to determine why the fuse blew or the circuit breaker tripped. If you replace a fuse or re-set a circuit breaker and the fuse blows or circuit breaker trips again, do not restore electrical power to that circuit - call a service technician to diagnose and repair the problem.

Questions & Answers about the emergency off switch on heating equipment

Question: My mom turns the boiler “service” red switch on and off all the time

My mom turns the boiler “service” red switch on and off all the time and I am worried that it is a danger. She has oil heat that primes a burner and I’m afraid that she is turning it off when the system is still on and demanding heat (programmed thermostat in other apt. units)and that this will create fumes, or some kind of buildup or off gassing. There is no need for her to do this. She is elderly and is not thinking rationally. Can you advise please? Thank you in advance, Her daughter, K.E.

Reply: What sort of problems may be caused by frequent turning of the oil heat switch "on" and "off"?

Heat off switch (C) D Friedman A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a problem or in this case that might indicate whether frequent "on-off" switching of the oil heater emergency off switch has caused an operating problem such as sooting-up of the combustion chamber or oil burner nozzle.

That said, here are some things to consider about using the emergency off switch on an oil fired heating system or oil fired water heater:

Infrequent (once a day or less often) turning on or off of an oil fired heating appliance (heating boiler or water heater, for example) at the service switch like the one you describe would not cause damage to the equipment though, of course, if someone leaves heat off in freezing weather a freeze-up in the building could lead to very costly damage.

Just turning off the oil burner, provided the system has reached full operating temperature, would not be expected to cause a problematic level of fumes or smells in the building.

Watch out: But frequent "on-off" switching of an oil fired appliance when it is in use (calling for heat or calling for hot water) could lead to a more subtle operating problem: it takes about five minutes for an oil fired heating appliance to reach full operating temperature.

Up until that time the system is not running as cleanly as it does at full temperature, it's a bit more smoky/sooty. So if someone keeps turning the system on and off frequently such that it does not sufficiently often reach full operating temperature, the result could be sooting and ultimately a clogged oil burner nozzle, leading to improper operation, inefficient operation, or even in the most extreme case, loss of heat.

Why don't you ask your mom why she's been turning the system on and off to see if you can find another way to ease her concerns.

How to Identify, Reset, or Adjust Heating or Air Conditioning System Controls and Switches

For details about the setting, re-setting, or function of the controls and switches commonly found on hot air heating systems see these articles:

A/C - HEAT PUMP CONTROLS & SWITCHES - list of controls and switches found on air conditioners and heat pumps
Air Bleeder Valves for Hot Water Heating Systems: Radiators, Baseboards, Convectors
Aquastats Heating Boiler Primary Controls: A guide to Aquastats for control of hot water heating boilers and tankless coils
BLUE vs YELLOW COMBUSTION FLAMES - the Blueray history and blue flame vs. yellow flame combustion, flame color & combustion efficiency, & how oil competes with gas as a heating fuel.
BOILER CONTROLS & SWITCHES - list of controls and switches found on hot water heating systems
CAD CELL RELAY SWITCH on oil fired furnaces or boilers as flame sensors & safety devices
Check Valves Guide to check valves and backflow preventers on hydronic hot water heating systems gas or oil fired
Draft Hoods on gas fired heating equipment, function and safety
Draft Regulators & barometric dampers on oil fired heating equipment
ELECTRICAL POWER SWITCH FOR HEAT - emergency heat on-off switches and equipment service switches
Expansion Tanks Guide to pressure control and expansion tanks on hydronic hot water heating systems gas or oil fired
Fan Limit Switch on hot air furnace heating systems gas or oil fired
Flue Gas Spill Switch on gas fired heating equipment sense combustion and protect from blocked flues
FURNACE CONTROLS & SWITCHES - list of the controls and switches found on hot air heating systems
Gas Piping, Valves, Controls including gas regulator assembly and other controls
Heat Won't Turn Off - Stop Unwanted Heat explanation of why heat may continue to come out of radiators or baseboards even though you have turned down the thermostat
Heating Boiler System Components - dictionary of heating boiler components
Hot Air Heating Furnace Basic Operating Steps
MIXING / ANTI-SCALD VALVES: Guide to mixing valves on hot water heating systems and radiant heat systems
Power Switches to turn on or off heaters for furnaces & boilers, oil & gas fired, heat pumps or electric furnaces or boilers
RELIEF VALVES - TP VALVES: A guide to temperature and pressure relief valves & safety controls on hot water and steam heating systems
Stack Relay Switches Explained on oil fired furnaces or boilers as flame sensors & safety devices
STEAM HEATING SYSTEMS - steam heating system components, switches, diagnosis & repair guides
Thermostats & Heat Controls for furnaces & boilers, oil & gas fired, heat pumps or electric furnaces or boilers
Water Feed Valves: A guide to water-feeding/pressure-reducing valves on hot water and steam heating systems
Zone Dampers: A guide to automatic or electrical zone dampers in heating or air conditioning ductwork
Zone Valves: A guide to zone valves for heating zone control on hot water heating systems

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ELECTRICAL POWER SWITCH FOR HEAT

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 2010, $69.00 U.S., is available from Carson Dunlop. The Home Reference Book is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. InspectAPedia.com ^® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.

Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
DUST CONTAMINATION FROM HVAC? An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
Fuel Oil & Oil Heating Magazine, 3621 Hill Rd., Parsippany, NJ 07054, 973-331-9545
Goodman Furnace High Temperature Plastic Vent HTPV safety recall US CPSC notice
Home Heating System Should Be Checked [for proper venting and for CO Carbon Monoxide Hazards - DJF]
Inspection Procedures for Oil-Fired Heating Systems Detailed step by step approaches for inspecting complex systems]
Lennox Pulse Furnace Safety Inspection/Warranty Program: Carbon Monoxide Warning
Oil Tanks - The Oil Storage Tank Information Website: Buried or Above Ground Oil Tank Inspection, Testing, Cleanup, Abandonment of Oil Tanks
Oil Tanks Above Ground, UL Standards, guidance for home owners, buyers, and inspectors
Plastic Heating Vent Pipe & Other Heating Safety Recall Notices
Weil McLain Model GV Gas Boiler/gas valve CPSC recall/repair
Domestic and Commercial Oil Burners, Charles H. Burkhardt, McGraw Hill Book Company, New York 3rd Ed 1969.
National Fuel Gas Code (Z223.1) $16.00 and National Fuel Gas Code Handbook (Z223.2) $47.00 American Gas Association (A.G.A.), 1515 Wilson Boulevard, Arlington, VA 22209 also available from National Fire Protection Association, Batterymarch Park, Quincy, MA 02269. Fundamentals of Gas Appliance Venting and Ventilation, 1985, American Gas Association Laboratories, Engineering Services Department. American Gas Association, 1515 Wilson Boulevard, Arlington, VA 22209. Catalog #XHO585. Reprinted 1989.
The Steam Book, 1984, Training and Education Department, Fluid Handling Division, ITT [probably out of print, possibly available from several home inspection supply companies] Fuel Oil and Oil Heat Magazine, October 1990, offers an update,
Principles of Steam Heating, $13.25 includes postage. Fuel oil & Oil Heat Magazine, 389 Passaic Ave., Fairfield, NJ 07004.
The Lost Art of Steam Heating, Dan Holohan, 516-579-3046 FAX
Principles of Steam Heating, Dan Holohan, technical editor of Fuel Oil and Oil Heat magazine, 389 Passaic Ave., Fairfield, NJ 07004 ($12.+1.25 postage/handling).
"Residential Steam Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Residential Hydronic (circulating hot water) Heating Systems", Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
"Warm Air Heating Systems". Instructional Technologies Institute, Inc., 145 "D" Grassy Plain St., Bethel, CT 06801 800/227-1663 [home inspection training material] 1987
Heating, Ventilating, and Air Conditioning Volume I, Heating Fundamentals,
Boilers, Boiler Conversions, James E. Brumbaugh, ISBN 0-672-23389-4 (v. 1) Volume II, Oil, Gas, and Coal Burners, Controls, Ducts, Piping, Valves, James E. Brumbaugh, ISBN 0-672-23390-7 (v. 2) Volume III, Radiant Heating, Water Heaters, Ventilation, Air Conditioning, Heat Pumps, Air Cleaners, James E. Brumbaugh, ISBN 0-672-23383-5 (v. 3) or ISBN 0-672-23380-0 (set) Special Sales Director, Macmillan Publishing Co., 866 Third Ave., New York, NY 10022. Macmillan Publishing Co., NY
Installation Guide for Residential Hydronic Heating Systems
Installation Guide #200, The Hydronics Institute, 35 Russo Place, Berkeley Heights, NJ 07922
The ABC's of Retention Head Oil Burners, National Association of Oil Heat Service Managers, TM 115, National Old Timers' Association of the Energy Industry, PO Box 168, Mineola, NY 11501. (Excellent tips on spotting problems on oil-fired heating equipment. Booklet.)
Links to our list of additional information on heating system inspection, repair, maintenance
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Guide to Heating & Cooling Electrical Power Switches InspectAPedia® -

A Guide to Finding & Using Electrical Power Switches to Turn On or Off Heaters for Furnaces & Boilers, Heat Pumps or Electric Furnaces or Air Conditioners

Questions & Answers about the emergency off switch on heating equipment

Question: My mom turns the boiler “service” red switch on and off all the time

Reply: What sort of problems may be caused by frequent turning of the oil heat switch "on" and "off"?

How to Identify, Reset, or Adjust Heating or Air Conditioning System Controls and Switches

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Guide to Heating & Cooling Electrical Power Switches
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