A friend is having 2 new combi boilers installed in a house which is setup as two dwellings. The combi's are replacing an existing gravity setup with two separate boilers. There are also 2 gas meters, if that matters. Both dwellings have their own CH flow/return and HW/CW pipes.
The owners of both dwellings would like the ability to use one boiler for both CH and HW if there should ever be a breakdown of the other boiler. My understanding is isolation valves on pipes joining CH Flow, CH Return and HW between the 2 setups should allow this. The caveats being:
1. The system would become unbalanced in this scenario.
2. The HW flow rate would be much reduced to serve both dwellings.
3. The iso valves should ALWAYS remain closed if both boilers are in operation (handles removed to prevent accidental opening).
4. There would be no zoning of the 2 CH circuits in this scenario, and both would be controlled through the one thermostat still in operation.
Is there anything else which needs to be considered? Non return valves to prevent circulation through the faulty boiler?
This scenario would hopefully never arise and would be temporary if it ever was used, until the faulty boiler could be fixed.
The owners of both dwellings would like the ability to use one boiler for both CH and HW if there should ever be a breakdown of the other boiler. My understanding is isolation valves on pipes joining CH Flow, CH Return and HW between the 2 setups should allow this. The caveats being:
1. The system would become unbalanced in this scenario.
2. The HW flow rate would be much reduced to serve both dwellings.
3. The iso valves should ALWAYS remain closed if both boilers are in operation (handles removed to prevent accidental opening).
4. There would be no zoning of the 2 CH circuits in this scenario, and both would be controlled through the one thermostat still in operation.
Is there anything else which needs to be considered? Non return valves to prevent circulation through the faulty boiler?
This scenario would hopefully never arise and would be temporary if it ever was used, until the faulty boiler could be fixed.
