Can I use existing hot water tank for radiant floor?
I'd like to install some radiant flooring at some point, using pex. I'm wondering if there are any issues if I tap into my main water heater? From my understanding, this is not permitted, but just want to confirm. What I'd do is T off the hot and cold line, and basically force the water back into the tank through the cold line. Since I'm not changing the volume of water, I don't think I'd be forcing against the municipal water pressure that is feeding the tank.
One issue I can see is that my water would not be hot enough, and if I raise the temp to compensate, then it would be dangerously hot when the radiant floor pump is not running. I could deal with that though, just need to be more careful at the faucet.
If this cannot be done then my alternate plan is to get a tankless water heater in the future, use that for my hot water, and then use the existing tank for radiant floor only. OR just get an electric heater for the radiant. Would that be ok?