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Guide to Heating, Heat Pump, or Air Conditioning Thermostats - how to find, use, adjust, repair thermostats
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• Guide to Thermostats for Heating and Air Conditioning Systems - how to Find, Adjust, or Repair Thermostats - Troubleshooting & Repair Guide
• Traditional wall thermostats and how they work
• Detailed Guide to Round Honeywell Room Thermostats
• How to Set the Honeywell Room Thermostat To the Desired Temperature
• How the Honeywell Room Thermostat Senses & Responds to Temperature Changes
• How & Why to Adjust the Heat Anticipator on a Room Thermostat
• How to Use a Mini Ammeter to Check Heat Anticipators and Thermostats for Proper Adjustment
• What are the Other Little Switches For on a Room Thermostat: Heat, Air Conditioning, Off, & Fan ON OFF MAN positions
• How Do I Install & Wire Up a Room Thermostat like the Honeywell Round Wall Thermostat?

This article explains the basics of heating or cooling system thermostats, their use, setting, and adjustment. here we provide A Guide to Finding, Using, and Adjusting Thermostats for Heating & Air Conditioning Furnaces & Boilers, Heat Pumps or Electric Furnaces or Boilers. 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.

Also see GAS PIPING, VALVES, CONTROLS for more details on how to inspect and test LP and natural gas piping, controls, valves, and tanks. We continue to add to and update this text as new details are provided. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. © Copyright 2009 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.

Types of Thermostats Used to Control Air Conditioning & Heating Systems

Traditional Round Wall Thermostats & How They are Set

Heating & Air Conditioning Thermostats where are thermostats usually located, what types of thermostatic controls are used on various heating and cooling systems, how do we find all of the thermostats, how do we set, adjust, and use thermostats The round Honeywell (R) wall thermostat shown in this photo has been locked in a plastic enclosure to prevent people from changing its set temperature. Set temperature and how the thermostat works are described in excruciating detail below. Room thermostats for air conditioning work and are set the same as when these devices are used for controlling heating systems. We provide lots of detail about how these devices work - see Detailed Guide to Room Thermostats below.

Traditional Rectangular Wall Thermostats and how they are set

On this wall thermostat the red pointer shows the current room temperature.

The black pointer at the center of the scale at the bottom of the little window shows the temperature that the thermostat has been "set" to.

The "Set Temperature" is the temperature that the room occupant is requesting.

Moving the thermostat adjustment lever (located at the top, side, or bottom of the thermostat depending on the model) will change the set temperature up or down, causing the heating or air conditioning system to turn on or off as needed.

See Detailed Guide to Room Thermostats below.

Remote control thermostats such as the unit shown at left are usually used with air conditioning or heating split systems using an outside compressor/condenser unit and one or more indoor wall-mounted cooling or heating units..

The thermostat controls in the hand-held remote control communicates with a wall-mounted air conditioner or heater using infra red signals. The open finned area at the bottom of this Sanyo control permit ambient air to enter the control for purpose of sensing the air temperature.

A control such as this Sanyo (TM) unit can be quite sophisticated and include automatic set back temperatures, timers, etc.

A Guide to Using Wall-Mounted Room Thermostats - How to Set the Thermostat

Here is our photo of a traditional round Honeywell (R) round room thermostat. Detailed photos of the major components of this thermostat and a description of how they work are provided below.

How to Set a Room Thermostat To the Desired Temperature

Heating thermostats: Here we use a traditional, and very simple dial-type round wall-mounted thermostat as an example. Notice that the thermostat face has two temperature scales and two pointers.

The top scale on the thermostat and the red arrow shows the "set" temperature that the thermostat is asking for.

The bottom scale shows the actual room temperature.

Rotating the thermostat dial to the right (clockwise) will increase the "set" temperature. Rotating the dial to the left will decrease the "set" temperature.

Heating thermostats are a simple switch to turn on a heating furnace, boiler, or other heat source. As we explain again below about cooling, for a heating thermostat to actually cause the heating system to turn on, the ambient temperature at the thermostat must be below the set point or temperature to which the thermostat has been set.

Make sure that your thermostat has been set to the proper position for the season: cooling or heating. The air conditioner will not run with the switch set to "heating" and conversely the heating system won't run if the thermostat has been set to "cooling."

An air conditioning system thermostat is a switch to turn on or off the A/C equipment as indoor air temperature varies around the thermostat's set point. Air conditioning thermostats are typically wall mounted in the living area. The thermostat, if it's a combination unit, may have both a temperature setting switch and a switch that can be moved from "cool" to "off", or "heat" positions.

For the thermostat to call for cooling it must be in the "cool" position and the temperature set to a level below the ambient air temperature at the thermostat location. Thermostats contain an internal temperature sensor which compares the air temperature at the thermostat to the temperature called-for by the user, turning the cooling (or heating) equipment on or off as appropriate.

How to Save Heating Cost & Air Conditioning Costs by Thermostat Adjustments

Substantial heating or air conditioning cost savings can be achieved by manually setting back your thermostat when the building is unoccupied or when occupants are asleep. The thermostat is set several degrees (or more) cooler during heating season or warmer during cooling season.

The settings of thermostat "mode" switches into "heating" or "cooling" and the use of other thermostat switches to control an air conditioning blower fan or heating system blower fan are discussed in detail at Other Switches on a Room Thermostat.

Lots of websites offer calculators that will tell you how much you'll probably save in energy costs for every degree you set back your heating or cooling thermostat. Just don't set the thermostat down so low that you suffer costly damage from freezing pipes in winter or mold from high humidity in summer.

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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.

THERMOSTATS
  Types of Building & Room Thermostats
  How Thermostats Work
  Detailed Guide to Room Thermostats
  How to Set the Thermostat
  COOL OFF HEAT Thermostat Switch
  FAN ON AUTO Thermostat Switch
  HEAT ANTICIPATOR Adjustment
  HEAT ANTICIPATOR Mini Ammeter to Check
  HEAT PUMP Thermostats - Outdoors
  INSTALL & WIRE Thermostats
  TEMPERATURE RESPONSE of Room Thermostats
  SWITCH FUNCTIONS on a Room Thermostat

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

• Our recommended books about building design, inspection, and repair, and about indoor environment testing, diagnosis, and cleanup are at the InspectAPedia Bookstore.
• ...

More Information on Building Diagnostic Inspections and Repairs

• Carbon Dioxide Gas Toxicity
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• 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
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• 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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