Navian Tankless as Heat Source for Radiant

virtualplumber

I have inherited a new 199,000 Tankless Water Heater. It is new and it is free. I have two electric water heaters. Our electric bill is high.



I can replace the electric Domestic Heaters with the Tankless unit. I currently heat the house with a standard electric element inserted into a Brass Tube. See image. (R 40 walls R50 ceiling, Tight Construction and yes I have an HRV.)



Should I keep the Thermatube Electric Element for the radiant heat? Or should I attempt a primary secondary radiant loop off the Navian?



NOTE: The heating load

Not a typical load. The Heat Source is a 4500 watt element or 15,300 BTU's. So heating demand is much less than a standard Boiler.

NRT_Rob

I believe

you'll find that load below the min modulation of that heater.



If you don't want to kill it, you would probably need to at least keep one of the electric tanks as a buffer tank.



And you definitely want a heat exchanger at the very least.

virtualplumber

Buffer Tank

The navien has a pump built in for circulation. Could I run that through a heat exchanger as a primary pump and then add a secondary pump for the radiant loops?

NRT_Rob

I don't know

if it's just a DHW recirc pump it probably isn't strong enough, but you'd need to know its rating and the pressure drop/flow you're trying to hit.