Hi @Peter_X welcome to the community!
Your u3a group sounds great. :blush: Thank you for sharing!

From what I understand (which I admit is limited!) you could get a system which is compatible with your old gas boiler. By doing this rather than replacing the whole system with an air source heat pump, you can “top up” the temperature with gas to ensure you get consistent heating and hotter water. This is called a bivalent system as they won’t run at the same time, but if the temperature drops the heat pump stops and instead, you would use your old boiler.

But you’d have to take into account the impact this would have on costs as well and it might not be as efficient. In winter, when it gets really cold, you’d be getting a lot of heat from the gas boiler.

A properly hybrid system would mean fitting a new gas boiler from the same manufacturer as the air source heat pump, and having them integrated into a system so they can work together. Then your heat pump would run most, if not all of the time, and when it’s cold the gas boiler would fire for small intervals to maintain a consistent temperature. This would likely be more expensive to install though!

If your property isn’t very well insulated, a hybrid system is probably your best bet as even modern air source heat pumps can struggle in leaky homes. - Miriam :bulb: