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Any advise would be appreciated.

We moved into a 30-year-old home and this is our first winter and we've noticed that some of the rooms are colder than the others but none of the rooms are actually at our set temperature.

We set our thermostat to 72 and I've attached a picture of the layout and temperatures in each room.

The room that has the thermostat in it faces east, but I've never seen direct sunlight hit the thermostat. And that room its self never seems to make it to the set point.

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We're worried that this could be an issue with our HVAC since no rooms in the house actually make it to 72, 68/70 is actually our preferred setting. Our realtor said that the HVAC was old and that we would likely need to replace it in a few years. But we're wondering if there could be another issue.

I've attempted to play around with the dampers and in doing so I can make all of the rooms upstairs warmer but the problem rooms still don't hit 68/70 and I had to set the thermostat at 74 to get most of the house around 68/70 and by doing that the master upstairs becomes horribly cold.

Could this be a damper issue and I'm just not setting them right? Or is it something else because there aren't actually any rooms that are hotter than I want them to be.

I was reading about boosters for specific rooms but I'm worried that adding them will make other rooms colder.

I was also wondering how complicated and expensive it is to move the thermostat to another colder room upstairs and if that would help.

Thank you for your time.

  • Are you saying that the thermostat deactivates the furnace at a temperature lower than it's set to? Does the thermostat read the set temp when it shuts off the furnace? What are you using to measure the air temps? Are you sure that it's more accurate than the thermostat? – isherwood Jan 31 '18 at 18:40
  • The thermostat thinks its deactivating at 72, at least it says its a 72. I've used both a heat gun (not pointed at the walls that face the outside) and I've used mercury thermometers placed in water that was allowed to sit in in the center of rooms for 24hrs to take on that rooms temperature. Both the heat gun and mercury thermometers agree. The colder rooms also feel a whole lot colder. – S Greenwald Jan 31 '18 at 18:53
  • Also, when measuring the temps, where in the room are you temping. Air or surface? High or low? If you have a way to confirm that the thermostat is correct, then make sure that it and you probe you are using are calibrated the same. If you have a thermostat that you can remove from the wall, and still show current temp, do so and place it and your probe together in the coldest room side by side, let them settle and check the temps on both from time to time. After an hour or so they should have settled enough to determine accuracy or a difference between the 2. – Jeff Cates Jan 31 '18 at 18:54
  • Hi Jeff - I've been pointing the heat run as center as I can and at the air. The thermometers in the water cup was placed as center as it could be in the room both in height and distance. – S Greenwald Jan 31 '18 at 18:59
  • My main concern isn't that I can't get the thermostat to match actual temperature in the house, if I have to set the thing at 76 and all of the rooms are then actually 68, I'm fine with that. I just need the bedrooms upstairs to be at a nice temperature without making the rest of the house cold. – S Greenwald Jan 31 '18 at 19:01
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I think two things will resolve 95% of your problem. Get a new thermostat (I like my Nest), and adjust your vent dampers seasonally and to suit your space usage.

Your thermostat apparently has issues with temperature, and a modern "smart" thermostat offers many benefits. One is the ability to run a fan outside of the normal heating/cooling cycles to equalize temperature in your rooms.

The variance between rooms isn't particularly concerning. Solar gain, airflow differences, human activity, and other factors can explain that. The highest temps are seen where cooking and bathing tend to introduce heat. Tweak your vents and see where that gets you. Be sure to look at the returns, too. They're critical to proper air movement.

Replacing your furnace won't do much unless you spring for multiple zones or automatic vent controls. That's probably not a practical approach for cost reasons.

  • Hi isherwood - we have a Nest, we installed it when we got the house but didn't upgrade anything else. But we have not tried to run a fan outside of when the heater is on. I can try to turn that on now. How do I check the air returns? – S Greenwald Jan 31 '18 at 19:08
  • Look to see that they're not obstructed by furniture. Feel to be sure they're flowing as expected. – isherwood Jan 31 '18 at 19:16
  • They're not obstructed by furniture and I know that some of them feel more powerful than others but air is moving out of all of them. Is this is a cause where a booster could help some of the rooms? – S Greenwald Jan 31 '18 at 19:18
  • Boosters are rarely needed. Pseudo-boosting occurs when you restrict other outlets. – isherwood Jan 31 '18 at 19:26
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The thermostat placement really won't help in this case because if you put it in a cold room all the rest will be warm. With a 2 story home there should be at least 2 dampers for a central forced air system. One damper for the up stairs and one for down stairs, if everything was perfect all you would need to do is adjust the 2 dampers 2x4 per year for the heating season the lower floor is opened further than the upper floor and for the cooling season the upper floor will me opened more, now since everything is not perfect each room may require some small adjustments to the vents in each room. This may take quite a few adjustment cycles to figure it out for the first season you do this but once all the rooms are balanced both upstairs and down mark the damper and vent position. If you think your thermostat is off 2 degrees calibrate it or just know it is different than other measurement methods but once all rooms are balanced they should stay that way until the change from heating to cooling, wilt my last home I was able to reverse the summer winter damper settings for example if winter the downstairs was 80% open and the upstairs 60% open for winter I adjusted downstairs at 60% open and upstairs at 80, after that I had 2 upstairs rooms that got hammered by sunshine so those vents needed to be opened , that's all I did and all the rooms in that house were balanced or at the same tempature when measured with a fine wire thermocouple probe & meter. Did I ever compare the reading on my probe and thermostat no it is not import and if the rooms are balanced and you are cold turn the temp up it really dosent matter what the display shows. With 2 possible main dampers and 6 smaller ones a hand held an annometer may be needed to see the pressure change effect of opening and closing a duct.

  • We found 8 dampers in our crawl space. Two of them have the handles and the rest are the screw type with the wings. We have no idea what damper controls which room(s). Last weekend we closed all of the dampers and opened them one at a time with the temp set at 85 and we tried to figure out which damper went where but it wasn't super clear. They seem to control blocks of rooms but one of the vents was on the entire time. Some barely seemed to have air flowing out of them. Is there a better way to figure out which damper controls what? Thank you for taking the time to help me – S Greenwald Jan 31 '18 at 22:53
  • I would just turn 1 off at a time , some dampers. In ducts are to adjust the flow not totally block it as totally blocking all of them could blow the ducts apart. I would have someone at the damper and open and close while a second person is checking the rooms to feel the difference in flow. I use cheap walkie talkie when we are troubleshooting out of site. I would expect half to go upstairs and half downstairs. There should be at least 1 large or several small return ducts on each floor these are not normally dampered but I have seen them. Check flow With fan running heat is not needed. – Ed Beal Jan 31 '18 at 23:09

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