Hook-up Procedures for
Heating, Heat Pump, or Air Conditioning Thermostats
POST a QUESTION or COMMENT about heating, air conditioning, and heat pump thermostat installation and wiring
Thermostat wiring connections for the Azel i-Link multi-zone switching relay used to control HVAC equipment. This article gives a table showing the proper wire connections for the Azel i-Linkroom thermostat used to control heating or air conditioning equipment.
Room thermostat installation & wiring guides: this article series explains the basics of wiring connections at the thermostat for heating, heat pump, or air conditioning systems.
Our page top sketch, courtesy of Honeywell Controls, illustrates the wiring diagram for a traditional Honeywell T87F thermostat used for 2-wire single pole single throw control of heating only in a typical gas-fired heating system.
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In a radiant floor heating system that uses a controller, the additional thermostats must be wired to instruct that controller to send heat to their zones.
Azel Technologies, a Canadian heating controller manufacturer, provides installation instructions and wiring diagrams for their controllers, including
Reader Question: 3-zone radiant heat: Honeywell RHT2300B thermostat can't talk to Azel i-Link SP83 zone controller
I am installing a 3 zone in-floor radiant system in my home. Every thing is going well so far, except I am running into an issue where Honeywell (my T-Stat manufacture) is telling me my RHT2300B t-stat cannot be used with my in-floor zone controller (Azel i-Link sp-83) when I call their tech support hotline.
They cannot tell me why or what their letter designations mean.
I am an industrial controls electrician of 23 years, who I must confess, does not have much experience with HVAC.
All I need is a simple t-stat that sends voltage (24vac) when heat is called for to my controller and opens back up (back to zero volts) when the set-point is achieved. I am having a hard time believing that this t-stat is not capable of doing that. Can any one help? Eric - Eric 9/9/11
Reply: get the thermostat and controller product numbers correct and it's easy to find wiring instructions
Eric,
I found two important details in researching your question:
1. you gave me an in-valid Honeywell thermostat number, but I was able to guess at the correct one and easily obtain wiring instructions from Honeywell. Correctly your thermostat is the Honeywell 5-2 Day Programmable Thermostat - RTH2300B1012
2. For the Honeywell thermostat model that you mention, correctly named, Honeywell's instructions point out that
The [Honeywell 5-2 Day Programmable Thermostat - RTH2300B1012] thermostat cannot be used if your old thermostat had [and used]
any two of the following wires: R, RC, RH, 4 and V.[5]
Call back and ask for senior service tech or service manager. So if, when you spoke with the Honeywell service technician, and if your old thermostat included and used any two of the wire labels I quote above, then indeed, even if s/he couldn't explain why, indeed you cannot use this thermostat model for your application.
Wiring details for the Honeywell 5-2 Day Programmable thermostat are found
Question:
Replacing a round Honeywell T87 with a Digital Honeywell Thermostat
Hello - I am replacing a round Honeywell thermostat with a non-programmable digital Honeywell unit. I have a hot water system with multiple zones and with no air conditioning.
There are three wires at the thermostat. On the old round unit the red wire went to the R terminal, the white wire went to the w terminal and a green wire went to B terminal.
I hooked up the new stat the same way but it would not work. If I selected "fan on" instead of "fan auto" the zone would heat up but would not shut off (hot water kept flowing even if I selected a temp below room temp). Appreciate your help. - Patrick - 1/20/12
Reply:
Patrick, typically the three wire thermostat hookups would be exactly the same for the old and new thermostats.
For details of wiring a typical and simple digital Honeywell thermostat,
Question: Replacing a mercury thermostat with a digital unit
I am replacing an old mercury thermostat with a digital. my system is a heat pump. my neighbor gave me the digital, no instructions, no box.
I'm trying to decide if this is even a heat pump compatible thermostat. on the therm it has c, g, rc, rh (which are linked by a black wire.) w, y, b, and o. coming out of my wall is, white connected on old therm w2, yellow connected to y, green conn g, black conn e, red to r, blue to b and bro to x. any help would be great. - Kurt 6/4/12
Reply:
Kurt, as you see in the examples at For help in understanding the wiring of your old thermostat,
Many thermostat wiring setups are straightforward or "cookbook" but why not find the brand name on your thermostat and then you can obtain the installation instructions right from the manufacturer?
Also, Honeywell's thermostat replacement advice (and most likely that of all thermostat manufacturers) warns:
Watch out: MERCURY NOTICE: Do not put your old
thermostat in the trash if it contains mercury in a
sealed tube. Contact your local waste
management authority for instructions regarding
recycling and proper disposal.[5]
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Citations & References
In addition to any citations in the article above, a full list is available on request.
[2] Thanks to reader S.R. for discussing loss of heat due to a thermostat wiring mistake, October 2010
[3] Thank to Mr. Scott Meenen , G&S Mechanical Services , for providing some common thermostat wiring codes also found at Mr. Meenen's web page Malware Deleted 12/9/2014 . Mr. Meenan provides heating, heat pump, and air conditioning repair services in Maryland, Washington D.C., and northern Virginia. He can be contacted at 301-591-1646 or by Email to Malware Deleted 12/9/2014 - 10/2010. Quoting: We service American Standard, Amana, Arco, Arco-Air, Bryant, Carrier, Coleman Evcon, Comfortmaker, Day/Night/Payne, Dunham-Bush, Fedders, Fredrich, Goodman, General Electric, Heil, Intertherm, ICP, Janitrol, Lennox (Armstrong, Johnson Air-Ease), Miller, Modine, Nordyne, Rheem/Ruud/Weatherking, Sears, Stewart Warner, Trane, Weather King, Williams, White-Westinghouse, Whirlpool, Weil Mclain, York, (Frasier Johnson/Borg Warner) and others.
[5] Honeywell Controls, the company wants you to use their contact form at this web page: http://www51.honeywell.com/honeywell/contact-support/contact-us.html Honeywell Consumer Products,
39 Old Ridgebury Road Danbury, CT 06810-5110 - (203) 830-7800 World Headquarters, Honeywell International Inc.,
101 Columbia Road,
Morristown, NJ 07962,
Phone: (973) 455-2000,
Fax: (973) 455-4807 1-800-328-5111
Honeywell product model numbers & instruction Manuals: see http://yourhome.honeywell.com/home/Applications/FindYourModelNumber.aspx
[6] White Rodgers Thermostats and HVAC controls, Homeowner information: http://www.emersonclimate.com/en-US/brands/white_rodgers/Pages/wr-homeowner-info.aspx Contractor information: http://www.emersonclimate.com/en-US/brands/white_rodgers/wr_contractor_info/Pages/white-rodgers-contractor-info.aspx White Rodgers Product Catalog (don't misspell the company's name as White Rogers Thermostats) - http://www.emersonclimate.com/Documents/thermostats.pdf - Thermostat Catalog
[7] White Rodgers 1F90 Low Voltage Digital Comfort-Set thermostat Installation Instructions, PN 37-3654, White-Rodgers Division, Emerson Electric Co., 9797 Reavis Rd., St. Louis MO 63123
[8] "Automatic Oil Burner Controls - Thermostats", Domestic and Commercial Oil Burners, 3rd Ed., Charles H. Burkhardt, McGraw Hill, 1969 (and later editions), ASIN B0000EG4Y8
[9] Thermostat wiring color codes & conventions,
Thanks to reader "
Helpful Pointers" Regarding 24V T, 10/7/2012
[10] Domestic Central Heating Wiring Systems and Controls, 2d Ed., Raymond Ward, Newnes, ISBN-10: 0750664363, ISBN-13: 978-0750664363, Quoting from Amazon.com: This unique A-Z guide to central heating wiring systems provides a comprehensive reference manual for hundreds of items of heating and control equipment, making it an indispensable handbook for electricians and installers across the country. The book provides comprehensive coverage of wiring and technical specifications, and now includes increased coverage of combination boilers, recently developed control features and SEDBUK (Seasonal Efficiency of Domestic Boilers in the UK) boilers ratings, where known. In addition to providing concise details of nearly 500 different boilers fuelled by electric, gas, oil and solid fuel, and over 400 programmers and time switches, this invaluable resource also features numerous easy-to-understand wiring diagrams with notes on all definitive systems. Brief component descriptions are provided, along with updated contact and website details for most major manufacturers.
[11] Proliphix Corporate Headquarters [Website: proliphix.com] , 3 LAN Drive Suite #100, Westford, MA 01886 Phone: +1.978.692.3375 Toll Free (U.S.): 866-IP-LIVING (866.475.4846) Fax: +1.978.692.3378 - Sales: [email protected] Marketing: [email protected] Customer support: [email protected] http://www.proliphix.com/ - quoting from the company's website: All Proliphix Network Thermostats come with our free Uniphy Remote Management Service. This unique offering lets you monitor and control your HVAC systems by simply pointing your Browser to our secure Proliphix Web Site. Enjoy the convenience of programming a thermostat from any location, using a simple graphical interface. No computer equipment or software is required. And since Proliphix takes care of the network configuration for you, you’ll be up and running in no time. We’ll even proactively monitor your thermostats and send you an immediate email or SMS message when an HVAC problem is detected.
[12] "Heating Control Handbook for the Installer and Service Man,Oil Burner, Gas Burner and Stoker Controls", Honeywell Corporation, March 1949 [copy on file as HoneywellControlsHandbookSA1399-2-1949.pdf] . Some of the controls discussed in detail here include the
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
In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: [email protected]. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.