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Thermostat keeps calling for heat even when turned off

Don't really know what kind of heating system is being used cause i rent, but im pretty sure its gas and i know there are only two wires behind the thermostat, my old honeywell mercury button unit blew out and the landlord put this new honeywell in and now the heat won't shut off unless i take the unit off the wall. he put one wire in the r, and the other in w.. what do to correct it so i can turn heat on and off when i want?

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  • rklemyk Dec 20, 2008

    I have a similar problem but with one variation.

    My thermostat is calling for the heat but the air handler isn't engaging all of the time unless I turn the thermostat on and off. It usually goes on then and heats fine. I notice that each time that I experience this problem, I can hear a gurgling or flowing water-like sound approximately below the thermostat. It's almost as if there is an air bubble or the like that needs to be burst before the air handler engages. Like I said, this isn't all of the time; but lately it's happening in the middle of the night. The temperature will drop 4 - 6 degrees and I'll awake to the gurgling sound as the thermostat is close to my bed. I will then have to get up, turn the thermostat off for a minute or so and the bubble (if that is what is is) clears and the handler kicks in. I notice that there is an audible popping sound that occurs above me where the air handler is located in the attic.

    I have a two-zone system, propane-fueled with two old, round thermostats controlling the temp in my house.

    Can anyone advise?

    Thank you in advance.


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  • 52 Answers

SOURCE: Need to know which terminals run what

Had similar problem, continuous fan, turn off power, then won't start up. Replaced thermostat, no change. The main controller board in the furnace went bad. What was weird was that it happened in the summer, while the heat was turned off. One day I noticed that the fan was running. The thermostat was in the off position, and I had to shut off power to the furnace to make it stop. I forgot about it till heating season came along and it wouldn't start up. The preliminary blower would start, the gas would click on, it would light, then quit. After tracing and checking the various safety switches, etc. it became apparrent the main board was bad. I found one on ebay, replaced it, [a simple job, unplug, a few screws, replug] and it's been working fine..good luck, John

Posted on Nov 07, 2008

  • 5 Answers

SOURCE: Replacing Round Honewell Mercury Thermostat

try to get one that is made for oil heat, the installation is easy only two wires, and the instructions make it easy.

Posted on Apr 26, 2009

  • 1420 Answers

SOURCE: Three wires not marked for new Thermostat!

You will need to go to the heating system and see what color wires are hooked to that. Typically the black and white wires will be used unless they used another color due to a bad wire. Hook the colored wires to the R or RH terminal on the thermostat and the other wire to the W terminal. You can also try taking the wires you have and one by one twisting them together and have a second person inform you when the heating system turns on. Take those two wires and hook them to the terminals I mentioned above.

Posted on Jan 14, 2010

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Honeywell Thermostat Heating Problem

there is definitely a cross connection problem there -- the issue could be any number of places besides the thermostat, but as the thermostat is 24 volts, I would urge you to start there, and call a service person to deal with any 240 volt issues (please!). to find out if the thermostat is the issue, remove the orange wire labelled heat -- if the coils stop glowing, make sure the wire is neat and not exposed outside the terminal screw (this goes far all wires in a thermostat) and re-install it. if the problem persists, and there is no cross-connection from wires touching at the terminals, the thermostat is bad. If you remove the orange wire and the coils continue to glow -- call a service person, as there is a problem in the high voltage circuit

Sep 30, 2012 | Honeywell Heaters


Boiler Aquastat - How to set it

It is the coldest day of the year and your boiler is chugging along. However you notice that your house is slowly cooling off even though the boiler is running. Then you notice that the boiler is shutting down even though your house is not up to the thermostat temperature setting.

You look into the situation farther and notice that you boiler temperature is below say 180F. What is shutting the boiler off? The device that controls the temperature of your boiler is called an aquastat. This device senses the temperature of the water in your boiler, and then fires the burners to keep the water at the temperature call for by the aquastat.


The other role that this device may play is to keep the boiler from getting too hot and making steam. However for this time we will concentrate on the lower side and the heat of the water. If you have a house that has barely enough baseboard or radiators for that really cold day then you need your water to be very hot or around 200F. This will give the water enough BTU's to carry around the piping to give off to keep your house warm. The downside is that it also makes your boiler less efficient when it needs to heat the water this hot.

So, now you know that if you need more heat you can turn the aquastat up higher to get more heat and turn it lower on the milder days to save energy. Another way to do this is to buy and install a smart control that will do that automatically for you. These are called an outdoor reset control and will vary your boiler temperature according to the outdoor temperature, saving you money and keeping you warm all at the same time.

Now, the one thing you need to know yet. The aquastat is usually a gray box with a screw driver slot in a little wheel that has numbers on it. It is often hidden pretty well and may take some looking to find it. Some of the newer boilers may have a digital one that is in a bigger gray box. Read the instructions to learn to change the temperatures.

Setting your aquastat correctly can save a lot of money and it can be the difference between keeping you warm or not.

on Dec 08, 2009 | Heaters


Becoming more efficient with your heating and cooling

Here are some ways to become more efficient with your heating and cooling. Obviously you do not have to do them in order but try to complete as many as you can! = )
· Buy a laser thermometer! You can use this to detect air leaks (or at least areas with “minor” temperature differences) so you know where to put seals
· Keep blinds shut on hot days and open on cold days----helps reduce temperature extremities
· If the temperature is can be negated by using a t-shirt or a jacket, use that clothing! You will save temperature control costs and still be able to keep warm or cool
· Do not use those old lightbulbs on hot days---they make extra heat increasing cooling bills (but you can use them on cold days to help warm your house)
· Utilize energy star products to increase efficiency comfortably
· Set your thermostat as low as is comfortable in the winter and as high as is comfortable in the summer.
· If you are on vacation, turn of that air conditioning/heating! No one will be in the house if everyone is away and it shouldn’t be too uncomfortable to wait like one hour for the house to cool/heat
· Don’t turn your thermostat up/down just to heat/cool faster---all temperature control changes the house temp at the same rate and if you forget to turn it off, you just wasted some energy there!
· Don’t block heating/cooling vents so that your rooms can be controlled quickly and so that your air actually gets controlled, not your furniture
· Check up your air conditioning and heating systems regularly (not once a month but maybe once every year) so that the systems stay running the best they can

on Dec 07, 2009 | Heaters

1 Answer

Have installed a new Honeywell thermostat. The fan does not turn off even when the room has reached the desired temperature. I originally replaced th ethermostat because the old one the fan ran forever and...

Most T-Stats have a On / Auto on a forced air system. On means the fan will run all the time even if it is not calling for heat. Auto only runs when calling for heat. Does the fan turn off in the auto mode at all? To test it...BE SURE THE FAN IS IN THE AUTO MODE ON THE T-STAT... Turn the thermostat all the way down and keep it there for appox 15 mins. If it is wired properly and the fan limit is set properly the fan should turn off. If it doesn't it is not the thermostat were the problem lies.

Most forced air units have a fan / high limit switch. There is a setting on the switch for the fan to turn on and a setting for the fan to turn off or it has a setting and a differental switch for it to turn off/on. Example - the fan comes on when the temp in the heat exchanger reaches 110 degrees F and will shut down at 95 degrees F after the thermostat is satified...this would hav a differental of 15 degrees F. It may be set to low and the fan continues to run long after all of the heat has been removed from the heat exchanger. This in turn will cause cool air to be coming out of the registers.

Mar 09, 2011 | Honeywell CT87B ROUND HEATING&COOLING...

1 Answer

Renting a house and there is a green flashing light on honewell furnace. Thermostat set at 70 but the temp is 54. Should I press the reset button or just call and bother the owners. Used to living in a...

Clean the flame sensor at the furance burner compartment. This is found left hand end farthest burner tube from ignitor, Make sure your filter is clean. Turn powwer off at furance and then turn back on to reset.

Jan 26, 2011 | Heaters

2 Answers

My Honeywell thermostat does not heat the house to the selected temperature. It will come on but not long enough to heat the house to the temp I selected.

Verify that you have heat coming from the vents.
Also do you use a heat pump system with electric emergency heat?
It may be that if it is to cold outside that the heat pump can not handle the load due to the cold outside and you will need to turn on the emergency heat.
Keep me posted.

Thank you for using FixYa!

Nov 17, 2009 | Honeywell Heaters

1 Answer

Most economical use of heating

There should be "how to"program instructions with the new thermostat. If you had this professionally installed... the tech should have set it for you. All T/stats are different. I suggest that you "do not" set the temperature up or down more than 4-5 degrees. If you go back more than this you are defeating the purpose of the program. Yes you will save $$$ when it is set down to a lower temp. BUT.... when you turn it "back up"... not only are you heating up the ambient air in the house that you lowered. You are also heating up the couch, the walls, the drapes, the table, ect . this can possibly use back up all that you saved and then some!
I am a retired heating contractor. I have been in the business since 1977. I now teach heating and cooling to high school students at a career center. I have experimented with most thermostats at my own home. I want to know them before I would sell them. From my own experience I found that the most economical savings is to find a comfortable temp and leave it alone. It is cheaper to maintain a constant temp then to keep playing with it.

Mar 08, 2009 | Honeywell CT87B ROUND HEATING&COOLING...

1 Answer

Inducer and ibm turns on and stays on no heat or cooling

Check to make sure you have 24-28 volts between R and C. If you do, you probably have a bad board but you also need to verify that you have the same voltage between W and C on a heat call if not then it could be something in the tstat ot he wires (jumping R and W pretty much rules this out).
The Kill switch may not reset the board, kill the power to the furnace itself.
Was the problem there before the new tstat was installed?
Also on some models continuous blower is initiated by a "kicked" roll out switch or and overtemp condition, Check for continuity on the whole safety circuit.

Nov 18, 2008 | Honeywell Electronic Programmable...

1 Answer

Honeywell Old T874D1512 dual heat/cool thermostat

I think I understand what you are saying....First, that switch marked On and Auto, is to control the blower fan only. So when you switch that to On, it turns on the blower, but not the actual heat. It sounds more like a problem at the furnace then at the thermostat.

Nov 17, 2008 | Honeywell Consumer Products Mechanical...

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