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Posted on Jan 10, 2009
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Forced Hot Air Heating system doesn't maintain thermostat setting

I just bought a house and replaced an old, non-programmable thermostat with a Honeywell RTH2310 5-2 day programmable. For about 2 months, everything worked perfectly (thru, say, October & November). In December and now in January, something isn't right with the system. FYI: The house has an older ducted forced hot air system. Even if I set the thermostat to a steady temp (and forego the program bit altogether) the system can't maintain that setting. For instance, heat set to 62 this past night, woke up and it's 57 in the house. Went on vacation last week and turned the heat to 60, came back, set it to 68 and it took nearly 5 hours for the heat to even come on. The heat works, and occasionaly the thermostat seems to maintain a temperature, but only after a LONG lag time. It also seems to maintain temperature, just not at what I have the themostat set to...say, maintain about 60 if I have it set at 68.

I have no idea what's going on. I think it might be an electrical issue with lack of communication between thermostat / heating system. The thermostat typically says that it's heating (noted by a fire icon for this model) even if it's not. There is also no 'on-demand' way to make the system work, ie: if I manually turn the heat up, the heat doesn't kick in. Please help.

  • alihereatnu Jan 10, 2009

    Thing is...sometimes the furnace works great. It will kick in, but only on it's own time.

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  • Posted on Jan 10, 2009
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It sounds like you may have issues with the furnace. A qualified professional can go over the system and the house to let you know if the system and unit are properly sized. The poor performance of a furnace can be a sign of carbon buildup in the furnace.
Good luck, hope this helps.
Matt

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If you look closely at the installation manual page 6&7 it tells you settings to use for your type of system. If I'm not mistaken you will need to back out screw "b" 360°. Hope this helps!

If you need further help, reach me via phone at https://www.6ya.com/expert/thomas_092728000e6acb79

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Air Conditioning Programmable Thermostats - Great for Heating and Cooling

Programmable thermostats contribute to overall system performance, maximizing energy savings while providing complete comfort control. They also allow flexibility to homeowners because they can be programmed to match their lifestyle. Programmable thermostats save energy by turning down the cooling and heating system at night or at times when your home is typically unoccupied.


Did you know that properly using a programmable thermostat in your home is one of the easiest ways you can save energy, money. Homeowners can save about $180 a year by properly setting their programmable thermostats and maintaining those settings. They can achieve significant energy and money savings that are possible through the proper use of your programmable thermostat. Programmable thermostats do two things:
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Your savings will largely depend on the length of your energy saving program periods and the temperatures set. For example, an energy saving period of 10 hours with the temperature set back 10° will save more than a 5 hour energy saving period with the temperature set back 5°. By maintaining the highest or lowest required temperatures for four or five hours a day instead of 24 hours, a programmable thermostat can pay for itself in energy saved within four years.

A programmable thermostat will keep you and your home comfortable while you are there to enjoy it, and will change the set point at programmed times to an energy savings level when you are not home. The precise temperature control of a programmable, energy-saving thermostat saves wear and tear on high-efficiency heating and cooling equipment by properly cycling the equipment. A programmable thermostat will keep you and your home comfortable while you are there to enjoy it, and will change the set point at programmed times to an energy savings level when you are not home.


Controlling your heating more effectively could save you up to 17% on your heating costs. In fact, during the winter you can save about 3 percent of your heating costs for every degree you lower your thermostat. Begin lowering your heating bill immediately with the pre-programmed 7-day schedule, or modify the programming to suit your lifestyle. By delivering the heating or cooling when you need it, and optimizing temperature for activity, sleep and times you are away you can maximize your comfort level and save energy.

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on Dec 06, 2009 • Heating & Cooling
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I moved into an apartment in a very old house; 2 floors, each floor has it's own oil tank and furnace. Problem: I bought a programmable thermostat, removed the old one, hooked up the new one, and now the...

Most programmable thermostats have a configuration setting for the type of system you are using. They also normally have a configuration setting for the Heating Cycle Rate, Assuming it is wired correctly, I suspect the problem might be somewhere in one or both of those two configuration settings. Let me know what you find or if you have any further questions. :-)
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More information would help but I believe that you are trying to hook up a programmable thermostat to your old heating system which is what? Oil forced air, heat pump, gas? Give me more info and I think that I can help you.

hardrocko
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sounds like you have a heat pump the w2 on old thermostat is for a second stage heat. If you can give me a little more information on type of system you have (forced air furnace with heat/cool, Heat pump or boiler)? How many wires are on old thermostat? Is it a no programmable or programmable? How old is the furnace?
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There fore maybe one is still coming on. Do you have more than one heating zone? IF so see below

I guess the main question is why manually turn it off? why not use the program.

I will assume your heat is know as forced hot water heating. My house is multizoned however when the zone calling for heat turns off (zone valve closes) I installed a bypass valve in the lowest zone in the house, and reduced the circulator low shut off temp to 130 F which means even though the heat isn't on my circulator will continue to run dumping this excess heat in the lowest part of house to rise through house. (the spring loaded water valve allows the heated water to flow into this zone )We do have two thermistats. And even though the lowest one is not calling for heat the radiators are hot when the excess is dumped into this zone. So investigate and see if your system might be similar. (multizone).

Investigate your wiring, reprogram, replace any battery backup.

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