Hi, thank you for your reply, to try and answer your questions, The problem I have got is the installer has left me with wiser controls and has told me that these controls will work when in ASHP mode or 3rd party boiler mode, but they don't, the wiser controls do switch the heat pump off and on but when in 3rd party mode do not switch off the oil boiler, so consequently the house gets too warm. Now I know wiser controls are not the best for ASHP but my problem at the moment is to get the 3rd party boiler working correctly and the reason to have a 3rd party boiler is heat pumps are less efficient at minus temperatures.