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Guide to Heating System Boiler Zone Valve Controls
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• Troubleshooting heating system boiler controls and switches
• What are the basic components of heating systems?
• How to inspect & repair central heating systems
• Cleaning & maintenance guide for heating systems

This website answers most questions about Heating System Boiler Controls on central heating systems to aid in troubleshooting, inspection, diagnosis, and repairs. The photo above shows a modern cad cell relay on an oil fired heating boiler - one of the safety controls which we discuss in this article. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Zone valves on heating boilers.

Our photo at left shows a Honeywell (TM) zone valve installation.

Heating water piping in a building, particularly where hot water baseboard heat is used, may be divided into separate heating zones (different floors, or different areas on a single floor) to permit more detailed control of heat distribution in a building.

The control of heating water through these different heating zones may be accomplished by use of zone valves (one per heating zone or area or "loop" of heating piping) which in turn are connected to individual thermostats. When the thermostat calls for heat in a particular building area, the thermostat switch causes the zone valve to open, to permit hot water to flow through that zone.

Other brands of zone valves such as those made by Flair (TM) (problem prone), and White Rodgers work similarly but their wiring may be slightly different.

In all cases, when the zone valve is fully open, an "end switch" inside the valve tells the heating system's circulator to begin operating, causing hot water to flow through the zone.

Typically heating systems using zone valves will have two or more zone valves (usually but not always located close to the heating boiler) and a single circulator pump (usually located on the return end of the hot water piping close to the heating boiler).

But if you see a zone valve with the cover off (photo at left) that may be a clue that the valve has been having problems with jamming or sticking - someone left the cover off to try to keep the valve a little cooler. Good installation details install a zone valve on the return side of the heating piping loop where it will be exposed to lower and thus less stressful temperatures.

Zone Valve Defects to Watch For

• Zone valve does not work - jammed, stuck, does not open in response to call for heat at that zone. Provided the wiring and thermostat are correct and operating, if no hot water flows past the valve on a call for heat (feel the pipes for heat) it may be jammed and need replacement
• Zone valve is leaking - leaky zone valves will stop working soon and need replacement
• Zone valves installed on the hot side or boiler-out side of the heating piping loop, exposing the valve to higher and more stressful temperatures
• Zone valve with covers off - may indicate overheating and jamming
• Zone valve with its manual lever left in the manual "on" position - may indicate that the valve does not work - this zone is forced into "always on" status

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

• Hot Air Heating Furnace Basic Operating Steps
• Guide to Heating System Components:
• Air Bleeder Valves for Hot Water Heating Systems: Radiators, Baseboards, Convectors
• Aquastats Heating Boiler Primary Controls: A guide to Aquastatus for control of hot water heating boilers and tankless coils
• Cad Cell Relays 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
• 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
• Gas Piping, Valves, Controls including gas regulator assembly and other controls
• Mixing 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
• 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 Valves: A guide to zone valves for heating zone control on hot water heating systems

While going through the detailed sequence in the operation of the heating boiler, watch for and inspect the condition of the heating boiler controls and safety devices (as required by ASHI 9.1.A.3 automatic safety controls).

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

HEATING SYSTEMS
BLUERAY Recall
BOILERS, HEATING
  BOILER OPERATION DETAILS
  BOILER PARTS LIST
  BOILER CONTROLS & SWITCHES
  BOILER LEAKS CORROSION STAINS
  BOILER OPERATING PROBLEMS
CARBON MONOXIDE/DIOXIDE
CARBON MONOXIDE WARNING
CHIMNEY INSPECTIONS
CHIMNEYS & Flues - Asbestos Transite Pipe
DUCT INSULATION - Asbestos Paper
DUCTS - Asbestos Transite Pipe
DUST FROM HVAC?
FURNACES, HEATING
  DUCT SYSTEM DEFECTS
  FURNACE CONTROLS & SWITCHES
  FURNACE OPERATION DETAILS
  HEAT EXCHANGER LEAKS
GAS PIPING, VALVES, CONTROLS
HEAT LOSS INDICATORS
HEATING COST SAVINGS
HEATING LOSS DIAGNOSIS-BOILERS
HEATING LOSS DIAGNOSIS-FURNACES
HEATING OIL CLOUD WAX GEL POINT
HEATING OIL SLUDGE
HEATING SYSTEM INSPECTION DIAGNOSIS REPAIR
  HEATING INSPECTION CONCEPTS
  HEATING INSPECTION PROCEDURE
HOT WATER HEATERS
HOT WATER IMPROVEMENT
INSULATION
NO HEAT - BOILER / FURNACE DIAGNOSIS
OIL BURNER NOISE SMOKE ODORS
OIL FUEL TYPES & CHARACTERISTICS
OIL TANK LEAKS
OIL TANK SLUDGE
OIL TANKS, BURIED
PLASTIC HEATER VENT
RADIANT HEAT Floor Mistakes to Avoid
Safety Recalls
  BLUERAY Recall
  CHIMNEYS & Flues - Asbestos Transite
  Goodman HTPV RECALL
  Lennox WARNING
  Weil McLain RECALL
SAFETY DURING HEATING INSPECTION
STEAM HEATING SYSTEMS
  Cad Cell Relay Switch Flame Sensors
  Low Water Cutoff Valves, Boilers
  Mixing Valves
  Relief Valves - TP Valves
  Sight Glass, Steam Boiler
  Pressure Switch, Steam Boiler
  Spill Switches
  Stack Relay Switch
  Steam Vents
  LOW WATER CUTOFF CONTROLS
  Water Feeder Valves, Steam
TANKLESS COILS
  Tankless Coil Leaks
THERMAL TRACKING
THERMOSTATS
Transite Pipe Chimneys & Flues

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - InspectAPedia.com ^TM Website Author/Editor
• Critique, contributions wanted: Contact Us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

More expert information on this topic

More Information on Inspecting and Repairing Heating Systems

• Carbon Dioxide Gas Toxicity
• Carbon Monoxide Gas Toxicity, exposure limits, poisoning symptoms, and inspecting buildings for CO hazards
• Dust from HVAC? An Investigation of Indoor Dust Debris Blamed on a Heating/Cooling System Reveals Carpet Dust
• 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.)

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