HVAC: 1 system, 2 floors, 2 thermostats?
Does anyone have any first hand experience with or know how to hook up the following configuration?
for a 2 floor house approx 1600 or 1700 sq ft….
Mixed heating and cooling climate –
per year usage guestimates: 5 months AC, 5 months heat, 2 months free
Split system, forced air, air handler in attic, heat pump or AC unit outside (could be gas heat or just the heat pump).
2 thermostats –
downstairs stat is the primary and controls the HVAC system as normal
Upstairs stat only controls the blower only.
There are no automatic dampers (electronically controlled dampers)
Background: 2 story houses of this size with only 1 system and 1 thermostat typically has problems with being warmer upstairs than down. One solution is to seasonally adjust the manual duct dampers so that more air goes downstairs during the heating season (winter) and more air goes upstairs during the cooling season (summer).
I’m looking for a better method than the seasonal adjustments of manual dampers, but a less expensive system than having automatic dampers and 2 thermostats (zoned system), which adds about $1k to the cost of the system, or 2 separate systems which adds even more expense.
Someone was telling me about this alternate set up. Basically the way it works is the downstairs stat and system work as normal. The upstairs stat just causes the fan (blower) to run longer so as to more evenly distribute (circulate) the air thorough out the house depending on what this upstairs stat is set at.
Anyone have experience with this? Apparently it’s pretty unusual, but we do know of an HVAC company that does it… He guarantees more even temperatures between the 1st and 2nd floors with only a very moderate price increase.
Replies
I have here at the house, and had installed some zoned systems on other projects. They use motorized dampers controlled by 2 or more normal thermostats. Up to six zones, I think.
Four zones on the back furnace here, all individually 7-day programmable.
Forrest
I'm not talking about a sytem with motorized dampers. BTW - that's what I have at my house.
I have done this on a home we lived in previously. That house had two floors, only one "zone" in the heating and AC. It was a older system that had been modified as additions and changes were done on the house.
A second thermostat added upstairs turned on only the Fan in either heat or cool mode.
It did help even out very uneven temperatures between floors, and was low cost modification. It still required me to tweak the manual damper settings between cooling and heating seasons.
It is not nearly as effective as adding a true second zone.
Thanks much - valuable input...
Anyone know of a good HVAC forum?
Isn't too much different from just running the fan all the time. Sometimes that works, sometimes not.
Shouldn't cost more than about $150 to set up, so long as chasing the wire isn't too bad. It's basically running two wires to the new t-stat location, and wiring that stat with the heating and cooling sides tied together. The other end of the two wires goes to the fan circuit.