Thermostat Terminal Designations Explanations - You are wiring a new thermostat or about to wire a new thermostat and you want to understand what the terminal designations are on your old and your new thermostat. Why is it such a mystery with these terminal designations? Once you get into seeing how this works it all becomes common sense. This is as long as whoever wired the thermostat originally followed the common sense code of designations. A good example of this is I have opened thermostats and seen black used on the R terminal. Green used on the W terminal and red used on the Y terminal. Once you see the thermostat wire and the colors of thermostat wire that are available you will understand. As far as those unconventional wired thermostats I’ve seen, I can only think that the person was color blind. And that is giving them the benefit of the doubt. Now, on to the designations. (more…)
4 Wire or 5 Wire Thermostat Wiring Problem - Question: We have a 19-year-old condo with an old Carrier mercury thermostat. We have both a natural gas furnace and an AC unit. There are only four wires going into the existing thermostat - red, green, blue, white. On the back of the thermostat are a number of labeled contacts, only the following have wires connecting them:
W - white wire
Y - blue wire
R - red wire
G - green wire
Y is also jumpered to a contact labeled 1 (more…)
How Can I Tell 1 or 2 Transformers for Heating Cooling System? I get this question a lot and I also see this question used in my stats on how people find the site but I do not believe I have directly addressed or dedicated an article to this subject yet but there are residential HVAC systems out there that use 2 transformers and it befuddles some people.
Programmable Thermostat Wiring Diagrams - Installing a programmable thermostat is not unlike installing any other thermostat for your HVAC system. The key is to get the right thermostat for your HVAC system. And to make sure it is wired properly. (more…)
Heat Pump Thermostat Wiring Chart Diagram - HVAC - The following graphics are meant as a guide only. Always follow manufacturers instructions for both the thermostat and the HVAC system. Additional articles on this site concerning thermostats and wiring can help you solve your problem or correctly wire a new thermostat. (more…)
Honeywell VisionPro Heat Pump Thermostat - Programming and Settings Question: Richard, I have a Honeywell Vision Pro Programmable Thermostat. I was wondering how I can program the settings to save money? It was recently installed six months ago and I want to make sure it is programmed to get the best out of it for a heat pump. At this point I do not believe I have saved money and was told I could save 10% or more with a programmable thermostat. Please help me with the appropriate settings and give me some insight that would help me save money. Thank you and I look forward to your answer. (more…)
Thermostat Wiring Diagrams – Heat pumps are wired for HVAC control far differently than air conditioning systems so make sure you know the difference and correctly identify the type of HVAC system you have installed. (more…)
Basic Thermostat Wiring Colors - Air Conditioner Systems - Always remember when changing a thermostat for a new thermostat to take a photo of the colors and where they go on the old thermostat or get a pencil and paper and write it down. It is better to take a good up close photo of the old thermostat and what terminals the colored wiring are terminated. Nearly everyone has a camera on their cell phone. (more…)
- this article includes a comprehensive list showing thermostat wire terminations for an air conditioner and a source of heat that includes five wires.
- a detailed description of where each wire goes in the air handler and condenser and what it controls.
- a detailed diagram illustrating where the wires go for 5 wire air conditioner and heating system control.
- resource and related links to help you with wiring and installing a thermostat.
HVAC Products Containing Mercury and Proper Disposal – Mercury is extremely harmful to the environment and cause severe health problems in humans and animals. For many years HVAC and HVAC Controls manufacturers have used mercury in switches. Mercury is a liquid metal and provides a good source used in many switches because of its fluidity and conductivity. From thermostats to boiler controls the liquid metal provides a reliable and efficient switching mechanism to start and stop certain sequences in HVAC applications. (more…)