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  1. #1
    Join Date
    Jan 2014
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    3

    Default How to run my HVAC efficiently in the winter?

    Hope this is in the correct thread.

    I have noticed that my heater will run for an hour to an hour and a half while putting out very little heat. However, if I were to turn the thermostat up a few degrees more heat will start to come out of the vents and get to the desired temperature more quickly, in a about 10-15 minutes. I will then turn the thermostat back down to my desired temperature in my house, 70° and wait till the next time the heater turns on and repeat the process.

    Is it more economical to adjust the thermostat to have the heater run at “full strength” for a shorter amount of time or set the thermostat to a constant temperature where the heater runs for a much longer time while putting out less heat?

    Thank you, in advance, for your response.
    Stuart

  2. #2
    Join Date
    Aug 2008
    Posts
    86

    Default Re: How to run my HVAC efficiently in the winter?

    Stuart,

    There has to be some other factors occurring that is preventing you from getting a quicker heating response from your forced hot air system.

    Although it seems to you that turning the T-stat up higher gives you more heat more quickly, you have to realize that the T-stat is not like a "volume control" on an audio system, or TV-----the T-stat is simply an on/off switch that is programmed to stay on when turned up, & then go off (after a brief "override" of a few minutes) as soon as the temp in the room reaches the same temp as the set pointer on the T-stat-----or the T-stat pointer is manually turned back by the room occupant during the "call for heat" by the T-stat.

    Clearly, other factors can be at work here; perhaps the ducts inside the walls or in the basement are not insulated, & the duct metal is cold & is "stealing heat" from the forced hot air that the furnace is producing, until the inner duct surfaces are warmed up enough to transmit their heat to the living quarters; or you may have long runs of ducting in the basement that are also "stealing heat".

    Sometimes a simple mis-adjustment of the furnace blower motor fan (set too low/comes on too soon) causes the partially warm forced air to start blowing before the furnace gets a chance to heat the metal inside the furnace & plenum on a call for heat from the T-stat---why not call you heating service person in to show you how the furnace blower motor switch can be adjusted so that you can be more comfortable.

    I'm of the school of thought that says you should set the heating or AC system to whatever temp that makes you feel comfortable.
    Last edited by dodsworth; 01-23-2014 at 11:59 PM.

  3. #3
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,969

    Default Re: How to run my HVAC efficiently in the winter?

    Tell us more about your heater;

    Model, make, year, thermostat, fuel, and your geographic location

  4. #4
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    1,722

    Default Re: How to run my HVAC efficiently in the winter?

    You didn't say, but I assume you have a heat pump. The second stage heat, usually an electric resistance element at the air handler, is not coming on properly. By jacking up the thermostat you are making it come on. Either adjust the t-stat second stage bulb or get a new one made for a heat pump.
    If you don't understand get an HVAC tech to correct.
    Above about 32 degrees the heat pump should work ok, even if the air output isn't as hot as a gas or oil fired furnace. Could be a heat pump issue if it doesn't work properly when warmer outside.

  5. #5
    Join Date
    Jan 2008
    Posts
    2,203

    Default Re: How to run my HVAC efficiently in the winter?

    I think ed21 is on the right track, but it could also be a bad thermostat location. Where that part is placed can make a lot of difference in how well it is able to regulate things.

    Phil

  6. #6
    Join Date
    Jan 2014
    Posts
    3

    Default Re: How to run my HVAC efficiently in the winter?

    Thank you for everyone’s response, it is greatly appreciated.

    The manufacture of the heat pump is Goodman and I believe the model is CPJ18-1B and about 20 years old, if I am not mistaken. I do not know what kind of setup is in the crawl space. The fuel used is electric. I live in North Carolina. The thermostat is almost in the center of the house in a hallway between a bedroom and kitchen across from a bathroom with no apparent external forces affecting the thermostat’s operation. The thermostat is a digital Hunter model 44860.

    When the heater first turns on, we notice that initially the air is cool (almost cold, from the air in the insulated duct work in the crawl space) for two to three minutes then warms up quite a bit for a while then will become less warm for quite a long while. If I can catch it between when it goes from warmer to cooler I’ll turn up the thermostat a few degrees until the house has reached the desired temperature.

    Our HVAC was inspected the end of last year and I was not told of any issues. Maybe it is just this colder winter or I am getting to old with-stand it.

    Thanks again for all of your advices. I think I will call my HVAC guy and see what he thinks too.
    Stuart

  7. #7
    Join Date
    Aug 2007
    Location
    Maryland
    Posts
    1,722

    Default Re: How to run my HVAC efficiently in the winter?

    A 20 year old unit is due to be replaced soon. That's about the lifespan of a heat pump.

  8. #8
    Join Date
    Dec 2007
    Location
    Tennessee
    Posts
    1,791

    Default Re: How to run my HVAC efficiently in the winter?

    ed is onto something. The heat pump does put out cooler air and takes longer to heat the house, but it is more efficient than running the electrical resistance backup. Sometimes the "wind chill" from the ducts makes people uncomfortable though even when the house is actually being warmed up and I suspect that is the case with you.

    Do you have a split system, that is an outdoor unit with the compressor and condenser coil with two refrigerant lines to the indoor unit that has the evaporator and fan motor or is it a package unit with all the mechanicals outdoors and the ducts going through the foundation walls? The reason I ask is that it may have an affect on how the duct work is designed and the type of fan motor used.

    In a package system, the fan motor is usually correctly sized by engineers at the manufacturer. But sometimes the people who install the unit will feed it into a plenum that is too large. The ducts should be smaller so that less heat is lost in them.

    In a split system where the fan motor was supplied separately, not only may the ducts be too large, the fan motor may be too large.

    It may be time for a new HVAC technician to really look at the system and determine if the ducts are properly sized and the correct fan installed. One problem today is finding someone who will go into a crawl space of an older house to replace the ductwork. All they want to do today is new construction.

  9. #9
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,969

    Default Re: How to run my HVAC efficiently in the winter?

    Do I get any credit for hinting at the 2 stage heat pump ??

  10. #10
    Join Date
    Jan 2014
    Posts
    3

    Default Re: How to run my HVAC efficiently in the winter?

    My HVAC guy would agree that my heat pump needs to be replaced, after 20 years. He also thinks that I need to replace all of the duct system and the blower/”electric resistance backup” in the crawl space too, for a total of around 8k for a 900sqr foot home. I think I will wait till it all goes ka-poot at the same time until I pay that amount. Hopefully I can find someone who is willing to just replace the unit/part without wanting to sell me a whole new system.

    I’m not sure who should “get credit” though I would like to think of it as more of a group effort, and for that, I greatly appreciate everyone chiming-in on this issue and all should ‘get credit’ in my opinion.
    Again, thanks

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