Home thermostats

My Honeywell thermostat has on/off and circulate. I also have electrostatic filters that the manual says they are only operable after 10-15 minutes of the fan running.
Is the circulate mode compatible with the circulate mode?

I think that the circulate mode will also activate the fan on signal that the filters are activated by. It would likely be more complex and expensive for the system to do it another way. So the manufacturer would go simpler route.

Are you wondering if your filters work for the few minutes your HVAC system is running?

I am not sure when your electrostatic filters are “on” in your HVACX cycle but it seems a super minor concern. Even if they turn off during the circulate cycle, so what? A tiny bit more dust gets blown around? I wouldn’t worry.

But, if you are really worried, then get physical air filters that work passively and replace them every few months.

Are they actual powered electrostatic filters with wires and metal plates, or plastic mesh filters? I think some of the plastic ones rely on the movement of the air to create the charge necessary to separate the particles out of the air. So I could see them needing time to build up enough static. The powered ones just use electricity to charge the dust particles, with oppositely charged plates to collect them. I wouldn’t think they’d need time to properly charge up though.

Not sure what you are asking by “Is the circulate mode compatible with the circulate mode?”

I am assuming you are meaning the stat has a switch for the fan labeled “on/off/circulate.” And I am assuming that the circulate mode would be the fan on continuously even if the stat is not calling for heating or cooling.

I would put the switch in the circulate mode so the fan could run continuously that way the filters will work.

No that would be just “on.” Thermostats with a circulate mode run the fan for roughly 1/3 of the time when there’s no call for heating or cooling. That keeps the air mixed and filtered without running the fan constantly, which can use a surprising amount of electricity.

My Nest thermostat has an option for this. The idea being if you just turn off the fans you are leaving hot/cold air in the air ducts and it goes to waste. So, it turns off the heat/AC but keeps the fans running a bit to push out the already heated/cooled air into the home so it does not go to waste.

Well, most relatively modern furnaces do that anyway. How much depends, but It’s been a long time since I’ve seen one completely shut down the second the gas/compressor turns off. They also usually don’t turn the fan on immediately on startup either, to give the heat exchanger time to warm up, or for the evaporator coil to cool down more quickly. The thermostat circulate mode starts and stops the fan almost randomly just to keep the air from getting stale during off periods.

I like that Idea. Could have used that in the house I just moved out of. A added a lot of insulation to the attic, beyond what was necessary for R30. On hot days if I put the fan on I could actually get the upstairs 2 degrees lower than downstairs. I also modified the return air to help with this. But Ihad to leave the fan rlunning at all times.

When I get a new stat for our new house, I will look for that feature. Thank you


Ceiling fans are an option too.

If the goal is just to circulate air a bit I think they are far more efficient. Can look cool too.

Just my $0.02

Ceiling fans only circulate the air in the room where the fan is located. Running the ventilation fan can make it easier to keep the temperature near the same throughout the house.

so the answer is NO. Circulate turns the fan on for only five minutes and leaves it off for ten minutes.
They put some randomness to it , but its about that. its never for more than 10 minutes at a time,
and so your electrostatic filters would never operate when in Circulate mode.

To be clear, you want to use " ON" and not Auto or Circulate.