Yea I never really thought of that ( the cold water ) . Guess I learn something new everyday . I see , makes everything a little more tricky . Regardless of that blog I'd try and find a different way . HWH are full of scale , unless you have a water softener . Maybe you can rig an inline filter somehow ....... That's what I do for my well water to reduce scale in my tank . But of course it's easy to push water through an inline filter when you have about 30 psi . Good luck .