QuietCool 2 speed Whole House Fan Automation using an Enerwave dual relay ZWN-RMS2 PLUS

I have seen many posts on integrating a 2 speed Whole House Fan in SmartThings but have not seen it integrated like this. The tough part is you need 2 zwave switches but there needs to be safeguards so that they are not on at once or it will fry the Fan. Here is how I will be implementing it, all the while keeping the dumb toggle switch on the wall which in my home is important.

This incorporates a 30A DPDT relay. Since Hi speed is through the NO and low is through the NC it is a safe way to make sure both speeds are not on at the same time. I will be writing simple WebCore Pistons as well with maybe virtual switches that say something like ‘If Hi Speed switch is on and Low Switch turns on, turn Hi switch off’ and vice-versa. Not 100% on that yet.

A large 30A relay ($18 on Amazon) is used ensure even turning on the fan at high speed (5.1 A continuous, more on startup) wont burn out the zwave relay. Low speed just goes directly from the Enerwave zwave relay directly through the other relay but low only pulls 1.1 amps so even at startup should be well less than 10A which the Enerwave dual relay switch is rated for. Keeps the manual Hi/Off/Low Toggle switch on the wall which is important for the wife who hates SmartThings LOL. And only one gang is required which is nice as the zwave dual zwave relay and additional 30A relay will be in a box in the attic.
Please excuse the chicken scratch below. Hope this helps people and if anyone see’s a better way to do this, please feel free to add comments!

Products Used:
QuietCool QC-ES4700 2 speed Whole House Fan Hi: 4195 CFM (5.1amps), Low: 2304 CFM (1.1 Amps)
Enerwave Dual Relay Zwave switch Model: SWN-RSM2-PLUS
Schnieder Electric 30A DPDT relay w/120v coil Model: 92S11A22D-120
Air Vent HI/OFF/LOW #58030 2SPD Wall Toggle Switch