plumber wrote:I know the perks of an indirect in a push button boiler, but I'm learning that solid fuel is a lesson in forgetting everything I know. What works better in a coal boiler?
Plumber, I have set up several OWB with heat exchangers to heat the DHW. I used the return water after the A-coil to supply the heat exchanger.
If you have a domestic coil in your boiler then run it, I have run several boilers that have a domestic coil. The system worked well.
I have installed full sized (200,000+ BTU) boilers to heat nothing but DHW. They were Direct systems, the boiler heated the water and sent it to a storage tank, than out to the system.
I have installed Indirect systems off of hot water and steam boilers also. Indirect systems are a little safer as they control the water temperature in the tank. I had to install a mixing valve on the DHW coil on a friends indoor wood boiler as the water coming out of the boiler was way too hot (180°F) going into the system.
I prefer indirect over a DHW Coil.