Using Tankless water heater for floor heat?
I have run into a strange one. Long story short the neighbor has offered to pay me to finish a job someone else started and bailed out on. It amounts to finishing out a bathroom and office in a rural machine shed. Most things look decently done and no big deal, except for floor heat which, according to the owner, was to be run through a tankless water heater. Has anyone familiar with a way to do this? The domestic water is already plumbed to the water heater and to various outlets for a shower, clothes washer supply, sink and scrub sink. The PEX tubing is sticking out of the floor near the mounted tankless heater. I am trying to figure out if there is a way to install a circulating pump and use the tankless heater without some kind of heat exchanger and not polute the domestic water. I am open to ideas and suggestions as this is a new one on me.