Need a quick response here as I'm having plumber hook up water heaters today.
My initial plan was to have an electric tank water heater to pre-heat my water using excess solar (I have a 16kw system). My plan was to then have the output of the electric WH to go to the inlet of a propane on demand heater which will then be used as a back up, or if the solar just cant heat the water enough.
When I mentioned this to my plumber, he insisted that this won't reduce my propane cost because the propane on demand will fire up the moment water goes through it regardless if it's pre-heated or not (yet it has a thermostat on the output which regulates the temperature, so where would all the extra heat go if my water was going in at 120F and coming out at 120F?)
Anyone have any experience with this?
My initial plan was to have an electric tank water heater to pre-heat my water using excess solar (I have a 16kw system). My plan was to then have the output of the electric WH to go to the inlet of a propane on demand heater which will then be used as a back up, or if the solar just cant heat the water enough.
When I mentioned this to my plumber, he insisted that this won't reduce my propane cost because the propane on demand will fire up the moment water goes through it regardless if it's pre-heated or not (yet it has a thermostat on the output which regulates the temperature, so where would all the extra heat go if my water was going in at 120F and coming out at 120F?)
Anyone have any experience with this?