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1 unit or 2 on New Construction?

Good morning all,

My wife and I are building a two story 2800 sq ft colonial. Originally, the house was spec'd with 2 heat pumps and 2 air handlers. Due to budgetary constraints, it looks like we will only be installing 1 zone for the whole house. What we are wondering is how much more energy will be used to heat and cool with only 1 zone? How much merit is there to using automated louvers to do the zoning on the single unit?

I'm thinking this may be more of a summer issue than in the winter - we will have a relatively powerful wood stove in the family room which will keep the downstairs relatively warm in the winters.

Suggestions? Comments?




  • John Mills_5
    John Mills_5 Member Posts: 946

    Shouldn't affect utility costs much but can have some issues cooling the upstairs in the summer. That can be helped by automatic dampers, 2 thermostats and a zone panel. It also can be helped by a GOOD contractor who knows how to design a duct system. Most homes are uncomfortable upstairs due to insufficient ductwork to the 2nd floor, with or without zoning. So research the quality of the dealer/installer very carefully that he is there to do the best possible job and that he didn't get the work from the general due to low bid.

    My cousin is building a new home and has control of the subs. We chose the HVAC dealer based on recommendations from a trusted local contractor and an industry expert who lives in the area. So far we are pleased with his plans and progress. Too many doing new home work do it very poorly.
  • Techman
    Techman Member Posts: 2,144
    Which way to go?

    I find ( over years) that zoned compressors fail pretty consistantly. This is due to ,say, a 5ton single speed compressor, trying to cool the 1st floor (which is 35% - 50% of the total BTU load) w/ the 2nd floor satisfied.Then, in the reverse order the 5ton comp is still being damage while it is running. This may take a week or a decade,my heart is with the comp that lasts 20 or more years.Now,adays, there are 2 stage compressors that operate at 66% or 100% so the odds improve. And kinda new on the market is a Variable Frequency Drive( Speed ) compressor. Single speed indoor blower motors are subjected to the same % of duct .But no damaged,but costing more to run with any one  zone calling for cooling. Variable speed blowers ( ECM )  are good. NOT EVERY MFRG  ALLOWES THEIR EQUIPMENT TO BE HOOKED UP TO  ZONED DUCT SYSTEMS . And hardly any, of residential ducted zoned  systems have a "pressure relief bypass damper". Most ducted zoned dampered ducting is NOT sized properly according to the "Zoned Duct Sizing Rules" But, I have serviced alot of ducted zoned systems that made me say WOW! WHAT A NICE JOB ! 
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