Domestic coil tie in to tankless water heater

[Flem]

Is it possible to tie in an Ecosmart tankless water heater passed my boiler's domestic coil? I was thinking about shutting the oil boiler off during warm months and just use it to heat the domestic water when it is already fired up during colder months. Make any sense?

 

[mustash29]

I would plumb it in a series / parallel configuration with extra isolation valves so you can easily run it either way.

It would be ok to run the DHW through the furnace coil first, and then let it's output feed the Ecosmart (as a backup function) during heating season. I would not run it this way when the boilers is off line though, your cold incoming water will cause bad condensation in the oil boiler.

During oil boiler off periods, bypass the boilers coil and run your cold feed directly to the Ecosmart.