Guide to Heating Radiators, Baseboards & Convectors: Inspection, Repair, Maintenance
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How to identify, inspect, diagnose, and repair problems with hot water or steam radiators, baseboards, or heating convectors
How to inspect, diagnose, and repair problems with steam radiators
If your radiator or baseboard is cold and the heating system is "on" - here we diagnose the problem
Where leaks occur on hot water and steam radiators, convectors, and baseboards
Guide to unusual radiators, baseboards, and heating convectors in buildings
Questions & answers about troubleshooting heating system radiators, baseboards, convectors - hot water heating systems and steam heating systems

This article describes the types of heating radiators: hot water, steam, cast iron, heat convectors, baseboard heat, electric heating convectors, and we explain the diagnosis and repair of no-heat or leaks or other problems with heating radiators.

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How to Identify and Diagnose Problems With Hot Water or Steam Radiators, Baseboards, or Convector Units

In addition to cast iron radiators using hot water or steam as a heat source, we describe two other very common hot water heat distribution methods below. Our photo above (at page top) shows a typical "one pipe system" steam cast-iron heating radiator. A single pipe delivers steam to the radiator and condensate from the cooling steam returns to the heating boiler via that same pipe.

This website answers most questions about all types of heating systems and gives important inspection, safety, and repair advice.

Below we describe the identification and function of different types of heating output devices in hot water or steam heated buildings. First, here is a quick no-heat diagnostic guide for radiators & baseboards. Detailed diagnostics are in the articles we cite.

Radiators or baseboards do not get hot? - Quick Troubleshooting

Is the heat on? Make sure that your room thermostat is set to a temperature higher than the temperature in the room - so that it is calling for heat.

Is the heater working? Make sure that your heating boiler is working, that is that the heating boiler turns on and off normally. A hot water heating boiler may not turn on immediately when you turn up the room thermostat: if the water temperature in the boiler is already above the aquastat's cut-in temperature the circulators will send hot water to the radiator and the boiler will turn on later when its temperature is dropped by returning water from the cooler radiators in the building. Don't forget to check for having run out of heating fuel. If your heating system is not working properly, see NO HEAT - BOILER.

Are the radiators turned on? Make sure that the control valve at the heating radiator is "open" or "on". See RADIATOR VALVES & HEAT CONTROLS.

Are your radiators heated by hot water or steam?

The heating system troubleshooting articles listed just below address nearly all problems with hot water or steam radiators.

If you don't know what kind of heat your building uses, we explain how to figure out the answer at HEATING SYSTEM TYPES.

If your system uses steam heat and a steam radiator is not getting hot, see COLD STEAM HEAT RADIATORS and see Steam Vents.
If your system uses hot water heat and a hot water radiator is not getting hot,see COLD HOT WATER BASEBOARD / RADIATOR and see Air Bleeder Valves
Noisy radiators or heating pipes? See BANGING HEATING PIPES RADIATORS

How Does Heating Baseboard Work?

Hot water heating baseboard is warmed by hot water circulating through either finned copper tubing or through cast iron baseboard sections. Carson Dunlop's sketch (below left) and our photo of a heating baseboard (below-right) show a typical modern hot water heating baseboard system installation.

Heating baseboard warms the room by a combination of radiation (the hot baseboard radiates heat onto surfaces in the room) and convection (cool air enters at the baseboard bottom, is warmed, and exits at the baseboard top - see Carson Dunlop's baseboard sketch above left). Electric heating baseboard also warms by radiation and convection but the baseboard itself is heated by an electric element rather than hot water.

Details about inspecting, installing, diagnosing, or repairing baseboard heat are at BASEBOARD HEAT. Details about electric baseboard heat are at ELECTRIC HEAT.

If your heating baseboards are not in fact getting warm when your thermostat is calling for heat and the boiler is indeed running, see AIRBOUND HEAT SYSTEM REPAIRS. You may also need to see Air Bleeder Valves.

What is a Heating Convector or Wall Convector? & How Do Heating Convectors Work?

Heating convector unit (C) Daniel Friedman

Heating convector wall recessed (C) Daniel Friedman

Sketch of a wall convector (above left) courtesy of Carson Dunlop and our photo (above right) show a traditional wall-mounted heating convector unit.

Our photo was taken in a 1920's home in New York. A heating convector unit operates much like a radiator (page top photo) but instead of thick cast iron used to radiate heat, the convector is made of copper tubing covered with metal fins, or of cast iron with cast-in fins.

Our photo (left) shows a leaky heating convector that was recessed into the wall. While recessed heating convectors were popular for aesthetic reasons (no radiator projects into the room), often a high percentage of the heat is flowing through the exterior wall to outside.

We discuss this problem in more detail at RADIATOR or CONVECTOR COVERS.

Steam convector heater (C) Daniel Friedman

The heat source in a wall-convector may be forced hot water, gravity hot water, steam, or the unit may be heated by electricity. Electric-heated wall convectors and some other convector units may incorporate a blower fan to increase the heat output from the device. Our photographs of a wall-mounted heating convector (above) show a wall unit that is heated by steam.

Conventional wall-mounted heating convectors (units that do not include a fan or blower) rely on natural movement of warm-air upwards to draw cooler air in from the floor level. You'll notice that there is a very generous air intake space along the bottom of the convector - it is designed to move plenty of air across its heating coil.

As the convector gets hot, cool air is drawn up from floor level, is heated by the fins on the convector, and warm air is supplied out of the convector's front grille.

Below we provide articles that help in diagnosing and repairing no-heat problems with each of these types of heat delivery systems.

Fan-Driven Heating Convector Units

Electrically-heated, steam heated, or hot water heated fan convector heating units similar to what you see in our photo here but boosted by a fan that blows room air across the heater are discussed at FAN CONVECTOR HEATERS - HYDRONIC COILS. Also see RADIANT HEAT.

Wall Heating Convector Heater Maintenance

Once every year or so, we like to take the covers off of heating convectors to inspect the unit for leaks.

While we're at it, we make certain that the heat exchanging fins on the heating convector are not dust-clogged (photo at left). If your building is occupied by pets who shed much hair this step can be very important.

Getting good air flow through the heat exchanging fins of all finned heat exchanging devices such as heating convectors or finned copper tubing heating baseboards can make a significant difference in liberating the heat output from the device.

Just gently vacuum off the convector using a brush attachment and your vacuum cleaner - take care not to bend the fins. A heating service contractor can provide more aggressive cleaning using special products, but on residential heating equipment that has not been exposed to some unusual problem we usually don't find it necessary.

Also see FAN CONVECTOR HEATERS - HYDRONIC COILS for additional details.

What are These Unfamiliar, Weird-Shaped or Oddly-Located Heating Radiators?

Ceiling mounted heating radiator (C) Carson Dunlop

Plate warming home heating radiator (C) Daniel Friedman

If you are wondering why a cast iron radiator is found mounted high on a building wall or even on a ceiling, the explanation may be found in the sketch (above left) from Carson Dunlop.

For buildings in which hot water circulated through the heating distribution system by gravity - that is, without using the forced hot water provided by a circulator pump - the only way we could get hot water to rise into a heating radiator was to be certain that the radiator was physically located higher than the top of the heating boiler.

If you find a shelf-like cast iron radiator like the one shown in our photo (above right) where it is being admired by a red-jacketed realtor the radiator will probably located in the kitchen or pantry of an older home where it performed double duty as a plate warmer. The cast iron radiator in our photo, with its three flat shelves, was serving dual-duty as a both a heat source and as a plate warmer for plates coming out of a chilly pantry or dish closet.

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Questions & answers about troubleshooting heating system radiators, baseboards, convectors - hot water heating systems and steam heating systems.

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RADIATORS
  BANGING HEATING PIPES RADIATORS
  BASEBOARD, CONVECTOR, RADIATOR TYPES
  COLD HOT WATER BASEBOARD / RADIATOR
  COLD STEAM HEAT RADIATORS
  LEAKS at BASEBOARD, CONVECTOR, RADIATOR
  RADIATOR or CONVECTOR COVERS
  RADIATOR or CONVECTOR INSULATION
  RADIATOR STEAM VENTS
  RADIATOR STEAM VENTS, AUTOMATIC
    Install Steam Vents to Control Heat
  RADIATOR VALVES & HEAT CONTROLS
    Radiator Control Valves & Vents
    Manual Radiator Valves
    Hot Water vs Steam Radiator Valves
    Adjust Level of Heat
    Automatic Radiator Valves
  STEAM TRAPS
  UNEVEN HEAT DIAGNOSIS

Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Eric Galow, Galow Homes, Lagrangeville, NY. Mr. Galow can be reached by email: ericgalow@gmail.com or by telephone: 914-474-6613. Mr. Galow specializes in residential construction including both new homes and repairs, renovations, and additions.
Steam Boiler Inspection, Diagnosis, Repair books at the InspectAPedia bookstore - Amazon.com
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, (see next item in this list). ITT Fluid Technology, 1133 Westchester Avenue
White Plains, NY 10604, tel +1 914 304 1700 fax +1 914 696 2950 www.ittfluidbusiness.com
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
The Heat Efficiency of Steam Boilers, Bryan Donkin
Steam Boiler Operation, Principles & Practice, James J. Jackson

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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How to Identify and Diagnose Problems With Hot Water or Steam Radiators, Baseboards, or Convector Units

Radiators or baseboards do not get hot? - Quick Troubleshooting

Are your radiators heated by hot water or steam?

How Does Heating Baseboard Work?

What is a Heating Convector or Wall Convector? & How Do Heating Convectors Work?

Fan-Driven Heating Convector Units

Wall Heating Convector Heater Maintenance

What are These Unfamiliar, Weird-Shaped or Oddly-Located Heating Radiators?

Questions & Answers regarding this article

Ask a Question or Search InspectAPedia

Technical Reviewers & References

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