Do NOT attempt to use a "On-Demand" water heater. They do not work in this
application without extensive extra plumbing!
Instant hot water heaters (gas units) require a minimum BTU request to turn
on (smallest burner section available) . When your water is warm they will
not top up the temperature unless you draw a lot of volume!
"Tom Kessler" wrote in message
I'd like an expert opinion on the best plumbing and control scheme for the
following solar hot water system.
1 - Two story home in a sub-tropical climate (20 N Lat) - never freezes, no
2- Evacuated tube collector with 25 gallon tank on the roof.
3 - LP gas water heater on 1st floor.
4 - House is plumbed with hot water recirculation line to boiler from
Would like suggestions a completly automatic control and plumbing scheme
between solar only, boiler assisted, and boiler only modes. I can retrofit
the boiler to electronic pilot ignition.
Has anyone tried to implement this and optimize number of valves,
Or refer me to someone who has... thanks