radiant floor heating

[mountain_momma_mustache]

House recently moved into had an addition added a few years back (master bathroom and walk in closet). This addition is the only part of the house that isn’t over the basement, and has PEX pipe ran under for radiant heating (looks to have never been used)
How easy of a DIY project is this? Can I use existing water heater? Should I get a separate water heater? Tankless?
Thanks in advance for any advice!

[J Boogie]

Not an easy DIY project.

Don't use your existing water heater.

I'd probably get a bid from a plumbing/heating/HVAC company, though admittedly this could be difficult since they want to control the entire installation so they don't charge you $10,000 to install a boiler/on demand heater and hook it up to a system with major issues and have an unhappy customer they can't please.

If the PEX is buried in cement or mortar, then it's really tough to inspect it.

Maybe there's a portable boiler/pump they can bring to test it, I don't know.

Good luck!

[robartsd]

MMM's radiant floor used the house water heater in an open loop. Some comments on that post indicated a risk of growing microbs in the pipes that circulated into the hot water supply (MMM brushed them off). I'd like to build a system modeled after this one: https://www.builditsolar.com/Projects/SpaceHeating/DHWplusSpace/Main.htm.