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I have a 6 unit 2 story apt bldg which has only one basement furnace controlled by one thermostat from the first floor apt #1. The duct work has dampers to each unit. the problem is that the temp in unit #1 dictates how hot or cold the rest of the apts are. Is there anything that can be done to even out the heating?

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    Have you though about a smart thermostat, like ecobee, that has sensors you could place in eac apt. Then you could see the temp in each apt and adjust te thermostat, and each can adjust their dampers. – Jeff Cates Mar 12 at 16:24
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    They make zone controllers that take inputs from multiple thermostats to control electric dampers and one main furnace/AC. Does that sound like something you could use? – JPhi1618 Mar 12 at 16:35
  • I have looked into the smart zone dampers by a few manufacturers. I think the easiest/cheapest solution is posted below as an answer, about the damper positions. My comment was to use the thermostat and adjust dampers until you can equal the units. You will still have some cooler units than others. The best way...install units in each apartment. Use a unit heat pump type system, then you have heat and cool together. Not cheap however. Or use a combination of these devices, smart thermostat, smart dampers, sensors..... – Jeff Cates Mar 12 at 18:44
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The simple answer is to set the fan to on instead of auto. This will help even out the temperature during off cycles. Using the dampers in the duct system close off the damper to the apartment with the thermostat 50% and make adjustments to all the other apartments accordingly. Keep notes on how the dampers are set because this will likely be a seasonal change that has to be done when switching from heating to cooling.

Adding a multi sensor thermostat like an ecobee as mentioned in the comments will also help. But it won't eliminate the problem. You need to balance the air flow into each apartment. If the apartments that are normally cold are suddenly the apartments that are comfortable then the ones that were comfortable will suddenly be too warm. Try getting it sorted out with dampers and possibly adding multi sensor thermostat. The downside of an ecobee is that you have to change the batteries periodically in the remote sensors tekmar makes some hardwire versions but then you need to run a wire to each sensor. Changing batteries in a single dwelling home isn't such a problem but in a rental it becomes problematic.

There isn't much else in the way of a simple fix you can do that I'm aware of.

Side note

In my region multiple-unit dwellings require fire separation in between every apartment. If one duct system is used then fire dampers need to be installed at all fire barriers. I don't know if this applies to you but be careful when dealing with multiple dwelling homes.

  • Batteries are a common consumable, maybe an annual change, similar to smoke or fire sensors. And yes, once a system is in place, the dampers would need to be separately controlled. As far as fan to on vs auto, the problem is that after awhile, the fan will blow cold air into the units. Perhaps, if allowed on the furnace or thermostat currently installed, there is a switch/jumper/setting, to extend the fan run time. – Jeff Cates Mar 12 at 18:37
  • Tricky problem no doubt. Factory selectable delay off is limited to minutes post cycle. Ecobee lets you run the fan in 5 or 10 minute increments per hour. I've got set at a minimum 45 minute per hour fan run time. Those smart zone dampers could work but with A/C or heat pump you've got to be careful sizing and balancing it properly to ensure adequate airflow. 400cfm/ton of cooling should be maintained for cooling, not sure about heat pump. I've never used dampers on a system in a retrofit application. On a designed system all the dampers work together to maintain proper cfm at the evap. – Joe Fala Mar 12 at 20:19
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    Not sure about heat pumps as in, due to my climate I don't use them and therefore don't know much about cfm. Actually the OP could install ductless splits equipped with heat pump in the problem apartments. – Joe Fala Mar 12 at 20:22
  • There are a few brands of DIY ductless splits that are basically a heat pump unit. I have looked into such devices to add heating and cooling to my garage. It would get little use, therefore I have not yet do one! – Jeff Cates Mar 12 at 22:33

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