At present, the towel rail is electrically powered for a few hours per evening via an Eddi Relay Board and ‘Boost; settings as there is no heat pump input. I have closed one valve on the towel rail pipework as I think this will reduce heat flow away from the towel heating area. I have deliberately not shut off both valve as I suspect that this would be a very bad idea due to changes in pressure at different temperatures and I don’t want a big puddle on the floor! When we get to the time of year when the heat pump will start switching on in the evenings, I could just leave one valve closed and let the element provide the heat - rather than open the valve and possibly upset the ASHP settings due to the element-heated water return via the LLH and throwing the primary water circuit into confusion. Once the ASHP is in regular heating mode, I can turn off the electrical element and then leave both valves open all the time. Has any other reader experience of this type of setup and, if so, what do you do please? Regards, Toodles.