Question for A/C guys

[mmike87]

I did a quick google for this topic, and just found 100's of sites trying to sell units.

I recently purchased a new house and it has dual-zone heat pumps (upstairs and downstairs.) I installed some cool (no pun intended) touch-screen programmable thermostats and they work great.

However, I am unfamiliar with dual-zone heating and cooling. Should I set both the upstairs and downstairs to the same temperature? I had been running the upstairs a couple of degrees higher since it's normally hotter up there anyway and I didn't want the system to run 12 hours a day. I currently have the D/S set at 76 with a 1 degree spread and the upstairs at 78 with a 1 degreee spread.

Also, the upstairs thermostat is in my son's bedroom. We have a large (watsed) loft area upstairs, and I closed the vent there to direct more flow to the two upstairs bedrooms, again since the loft is wasted space. His room also has a return and two vents, plus there is an additonal return in the loft. My daughters room has a single, larger vent. Not sure who thought this up ...

Any advice appreciated. Thanks.

[perna]

Im not an A/C guy, and do not have dual units in my house. If those bedrooms are not used all day you can program it so the upstairs doesnt even run during the day. Same with the downstairs if you are not home all day, just set it to turn on like an hour before you usually get home. You should be able to program it for different times on the weekends.

In the house you describe a dual zone was installed so that you dont end up with a comfortable upstairs and a freezing cold downstairs. If you set them for the same temp, in the summer the upstairs will run more, winter the downstairs runs more so it evens out I guess but doesnt really save anything. If you program them right you can make them both run as little as they need to to keep everything comfortable.

[mmike87]

Im not an A/C guy, and do not have dual units in my house. If those bedrooms are not used all day you can program it so the upstairs doesnt even run during the day. Same with the downstairs if you are not home all day, just set it to turn on like an hour before you usually get home. You should be able to program it for different times on the weekends.

In the house you describe a dual zone was installed so that you dont end up with a comfortable upstairs and a freezing cold downstairs. If you set them for the same temp, in the summer the upstairs will run more, winter the downstairs runs more so it evens out I guess but doesnt really save anything. If you program them right you can make them both run as little as they need to to keep everything comfortable.

Actually, I did find something in Google and it's not "dual zone" - it's dual units. I guess "dual zone" has motorized ductwork and diverts air from a single unit to multiple zones.

Pretty much all rooms are used throughout the day, my wife and daughter are home all day and my son during the summer. The kids bedrooms are upstairs, so people are up there during the day.

[Honu]

we have the same setup ? one for the upstairs and one for down

we set them different I asked the guy about it when we got new ones two years ago ? he said it wont matter at all how they are set compared with each other

I can say here in AZ its hot in the summer so they are working constant

I have noticed if the house heats up to much from turning down the upstairs it takes a while to cool ? so not sure it helps out in the long run to turn it down a bit in the day at least here our house ? sure each house is dif ? and with our floor plan layout half the lower is super tall ceilings so the heat goes up their quite a bit so we have to run them about 2-3 degrees cooler to get a even feel in the house with the heat from the roof and the heat from the house rising up inside

one thing I wish I did when I upgraded to the nice touch screen is get the one that switches from hot to cold as needed cause those inbetween months here when its hot in the day cool at night you go to bed warm wake up cold

[mmike87]

The touch screens are neat - they light up red for heat and blue for cooling. They were $68 each at Lowes. They were very easy to install.

[Honu]

do your thermostats kick the thing to heat or cool ?

sounds cool with the blue red thing :)


mine I have to set it one way or the other then program it ?

so in those months when the temp goes above 78 and below 78 I have to manually change it and its a pain

the guy who installed ours does not like the auto type but had no valid reason why and said they dont even carry them ?

[Irish]

Im not an A/C guy, and do not have dual units in my house. If those bedrooms are not used all day you can program it so the upstairs doesnt even run during the day. Same with the downstairs if you are not home all day, just set it to turn on like an hour before you usually get home.

All depending on location. I'm not sure how the weather is in VA this time of year, I imagine hot & sticky, but out in Vegas you can't afford to turn your A/C off at all during this time of year. It takes a lot longer to try to "cool it off" than it does to keep it cool all day. The house walls, insulation and everything in it is also at that temperature and makes it very difficult to cool with heat radiating out of all your belongings as well.

I'll be moving into a larger house with dual units here in the near future and will be running into some similar issues. My first thought is to have the downstairs slightly higher in temp than the upstairs due to hot air rising and this might equalize the temps... not sure if this theory really holds or not though.

[perna]

Yeah turning your AC off totally doesnt make much sense. But turning it down does, I think it saves something like 3% for every 1 degree. Like I said you have to figure out what works for your house.

[Honu]

My first thought is to have the downstairs slightly higher in temp than the upstairs due to hot air rising and this might equalize the temps... not sure if this theory really holds or not though.

posted above in my house layout this has proven true :)

I find 3 degrees cooler upstairs here in AZ makes the up and down equal ?
when it kicks on of course it feels cooler for a short bit but once its off and air is moving all feels about the same

[chadbag]

I am not a A/C guy or a heat pump guy, but after some reading when I was looking at home automation stuff, it seems heat pumps need to be set and used differently than a standard heater/A-C setup. Talk to an expert!

[Preferred User]

^^^And not only are they different they require different controllers so the external unit knows when to switch over to the gas forced air or whatever your auxiliary heat source is in the winter. When the thermostat is just calling for cooling or just heat from the furnace there is little difference in how it is controlled, it is the heat pump to furnace setting that is important.

Heat pumps are more efficient (higher seer rating) and should not be programmed for the turn on an hour before you get home scenario, they require more time to make major temp changes.

I have a Trane heat pump and it requires a specific Honeywell thermostat to run correctly.