Advice on adding a LPG Gas Boiler on Central Heating System with a Hot Water Storage Tank heated with Solar Panels
I have no experience working with your type heating system but worked in the boiler business, heating and process applications, for 40+ years. My recommendation would be something like this; install the boiler into the hot water system using 3 way zone valves for connection and isolation, or 2 way zone valves for isolation, and a primary/secondary loop arrangement, and a 2 stage thermostat or 2 thermostats if you prefer. The first stage would control the solar system and the second stage would open the zone valves, and power the boiler's circulating pump through a relay, allowing the boiler to add heat to the circulating water as needed. The boiler would only add as much temperature to the water as needed, while still allowing the storage water to produce some of the heating. An outdoor reset control could be utilized to keep the boiler from overheating the water in the loop. Control of the whole system would be of your own choosing. Hope this helps