Where does the return protection valve go on an Outdoor set-up with a standard 50 plate heat exchanger? My local dealers don't typically install them. I was thinking the point of return outdoors would make the most sense. However, I'd prefer the least amount of connections outdoors. How about adding one where the pex comes thru the foundation? I'm picturing a thermostatic valve on the return side , a short piece of ppie, and a tee to create a loop. Is that sufficient? Any specific valve models would be appreciated as well. I read up on Danfoss and it appears that there are several to choose from with the 140 degree protection.