Minisplits and thermostat: replacing the remote controls
I’ve recently built my house in Delaware. It is a 2 story 1300sf, better than code insulation hose, but nothing extreme, except it has a lots of glass ( 800 sf, u 0.24). It house is in a forest between mature trees. It is completely shaded in the summer, but lots of solar gain in the winter.
Heating and coling is with 2 ducted mini split units with very short ducts.
They work very well, but as others noted regarding mini splits they need constant fiddling with the controls to get the best result.
The bundled IR remotes/wired remote units are units are not really up to their task, not to mention they have confusing user interfaces and they are unsightly. Currently I use the wired remotes with the remote temp sensor, but still to keep the house comfortable it needs more manual intervention than I prefer.
Mostly it means I have to manually turn the units on/off via the remote.
In the summer, when I mostly need to control the humidity I use the dry mode for this, but if I don’t watch the unit and turn off in time it will undershoot the temperature and turns the house into a freezer. The cool mode does not have the necessary humidity removal capacity, it reaches the set temp quickly, then just blows the air around as the humidity rises.
In the winter, the heat with auto fan mode is mostly working fine, except when the sun comes out during the day and the unit is not able to adjust quickly. It reduces the compressor load, and the fan switches to high when you just want the whole thing to turn off. Also if the unit is around the set temp and the fan is blowing at auto setting (while you would want the unit off at this stage), at sunset it does not start to ramp up the heat until the inside temp drops several degrees. If I turn the unit off/on, it immediately starts the heat.
I’d like to have a just set and forget thermostat, which only shows the actual temp/humidity, the set temp and have up/down controls only for the set temp. I’d like to hide everything else. I know about the Cielo Breeze and similar, just I heard contrary opinions about the built in sensors, I don’t need the complexity and I don’t want to include the “cloud”.
So here is my thought: Most of the mini split units have an extra remote on/off wire connection somewhere on the main board. What if I connect a simple relay type thermostat/humidistat ( programmable or not) to this terminal to turn the unit on/off according to the actual temp/humidity at the thermostat. The mini split then does the heating/cooling according to the season.
Twice a year, when I would adjust my regular thermostat from heat to cool or vice versa, I also set the working mode of the mini split. I mean in the winter if my preferred indoor temp is arouns 70deg, I set the mini split to 75 deg, heating, auto fan. In the summer I set the target temp 76deg, the mini split to 70deg, dry, low fan, and hide all the mini split controllers, remotes until winter.
I know it sounds like I want to introduce cycling to the system, but it seems with the proper selection of the mini split set temp and the hysteresis of the regular thermostat, the setup will just turn the split units on/off when they are outside of their comfort zone anyway.
I think it can resolve a lots of comfort and conveninece issues.
Any thought about viability, efficiency hit, durability problems?
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