OK, how do I use my domestic hot water tank and immersion heater to run the central heating over night?
Does your heating system run the pump when the boiler has reached flow temperature or does it stop? If the former you have a chance of making a go of it.
Over night you will need to turn the flow temperature to below the immersion heater temperature. The three way valves controlling flow to the cylinder will need to be overridden to ensure they remain open. Then when the pump runs water from the coil for DHW will pick up heat from the hot cylinder and pass it into the heating system.
Using portable electric radiators is far easier and avoids having a sequence of events that need to be run every night and reversed every morning. They also provide backup in the event that the central heating packs up.
Are the proposals really to pay us for using electricity at night? Are there then other options like charging batteries? Anyone know what limits there will be?
And the sequence you describe sounds like it can be automated
I haven’t seen the small print but I expect that the payments are to not use electricity at other times. The point being to load shift from peak to off peak demand.