PTC Heaters for Fresh Air Intake – GreenBuildingAdvisor

I posted a fair bit of the install here: https://www.garagejournal.com/forum/threads/super-efficient-hrv-retrofit-with-smoke-filter-for-300.505161/#post-9864530

The PTC heaters have worked flawlessly for a few years now. I do have some automation in play to control them using a Hubitat hub, temp sensors, and Zigbee dimming modules (one for each of 2 heaters) as I calculated I would need a max of about 150 watts to temper air after the HRV heater exchanger.

The automation looks at the stale air intake temp and the air temp leaving the HRv. That temp delta is used with CFM value at the moment to dial in wattage to the heaters. So if the system sees a 10F delta, and the CFM is currently at 90CFM, then the watts needed is pretty simple to calculate. This works surprisingly well to keep fresh air within a few F of target temps and varies wattage exactly to achieve the target delivery temp.

Note that I have five redundant safety strategies to manage the heaters in case temps in the heater housing go above 80F or so. Discussed in the thread link above 🙂

You can use an old school remote bulb (part number A19ABC-12C) line level thermostat to manage these, but it is an on/off solution with no ability to vary wattage. It is a very simple control solution though.