Trouble Getting Temperatures Comfortable Upstairs and Downstairs


Old 05-19-15, 07:41 PM
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Trouble Getting Temperatures Comfortable Upstairs and Downstairs

My home was built in 2007 and the builder installed a Comfortmaker furnace and air conditioning unit (single unit). The house itself is 2452 sq ft with the upstairs having a little bit more square footage than downstairs due to a built-in garage. I'm having a lot of trouble trying to achieve comfortable temperatures for both upstairs and downstairs at the same time. The thermostat is located downstairs, near the center of the house, just below the downstairs air return (there is also an air return upstairs). Currently, the thermostat is set to 72 downstairs. And that feels perfectly fine. The problem is upstairs is always too warm.

I called up the company who originally installed the equipment in my house and asked them about the problem. Their solution was to either A. Adjust the 2 downstairs air ducts coming off of the furnace to about 50% to force more air upstairs than downstairs (There are 4 ducts coming off of the furnace - two for upstairs and two for downstairs.) or B. Pay them to zone the system upstairs and downstairs.

Even with their advice of backing off the downstairs baffles in summer to get more cold air upstairs, I'm still not able to regulate the temperature as much as I'd like. On the North end of the house where the Master bedroom is (upstairs), the temperature is around 73-74 - which I'm fine with. But on the South end of the house, the bedrooms are typically 75-77 degrees. There are computers in the bedrooms on the South end (one used as an office for me and one as a bedroom / office for a renter). When the computers get turned on the temperature generally stays at either 77 or 79 degrees in these rooms.

My concern about sticking with the baffles solution is whether this is good for the equipment given the increased duct back pressure and whether this increased pressure will wear out the equipment prematurely and / or increase utility bills. Conversely, I'm concerned about their suggestion of zoning the system given that it's single stage and I've heard that to zone a system properly you really need more than a single stage system.

I don't want to set the downstairs temp any colder as my guests complain about the temp being too cold and want blankets. But I want my renter to be able to fall asleep at night as well.

My questions are:
1. Are my concerns about increased utility bills / premature equipment failure by adjusting the downstairs air duct baffles well founded or needless worry?
2. Should I consider zoning the A/C system that I have? Or just save money for a new system?
3. Presuming the only solution is to pay for a complete gutting of my HVAC, please describe what the ideal setup should look like. Single outdoor A/C unit zoned, dual outdoor A/C units - one up one down, both, larger ducts to the South end bedrooms? or what?
NOTE: I have to reverse the baffles in winter or I have the opposite problem.
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Old 05-19-15, 08:09 PM
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I would get the motorized zone damper system.
This would be even more appealing if the original installing company did the installation of this zone control.

2 systems is better if it is done with the original build out but the zone damper system would be my choice at this point.
Old 05-20-15, 05:00 AM
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best way is to get a system just for your 2nd level and one for the first. I would not get the originally company to do it.
Old 05-20-15, 05:33 AM
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The other replies are good ideas...
I'd also check the temps from the diffusers downstairs & upstairs, plus see if airflow is less upstairs.
You need most of the 'Return-Air' coming from the upstairs.

Many valid performance tests have shown that air conditioning systems 'on the average' only deliver to the conditioned areas between 59 to 63% of their Nominal Rated Performance. It pays huge dividends to check performance as that also just might save the compressor from failing! Indoor airflow also needs to be STRONG; many techs don't even check it at all.

Simple easy anyone can do ways to check the performance of your central air conditioner so, if needed; you can call an Energy Efficiency HVAC Technician

If U want me to run a ballpark analysis of how your system is performing in respect to its ‘Nominal Rated Btuh’ we need at least the following numbers:

Performance Data Collection – Best Time to collect data is late afternoon around 4:30 pm, when attic is HOT; also when outdoor temps are around 85F to 95+

*All U need is a good thermometer (digital reading in tenths preferable) & and ia low cost indoor Humidity Gauge you can get at Walmart or z hardware store or the Internet.

1) Helpful: Tonnage & SEER of Unit &/or outdoor condenser model number: __________________

2) TXV or, orifice metering device? _______. Only if U know…

3) Outdoor condenser’s discharge-air-temperature ______-F

Subtract Outdoor air temperature: _______

Outdoor Condenser Air-Temp-Split _______

4) Need the ‘Indoor’ percent of relative humidity - in the middle of the rooms or, at Return-Air inlet grilles ___

5) Indoor Return-Air Temperature ______

Subtract Indoor Supply-Air Temperature ______ -F

Indoor temperature-split _______-F

Copy & paste in your post then highlight it & then Click Quote or, & also fill it out with some remarks outside the Quoted area; or, U don't have to Quote it.

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