They work fine here the only drawback is at the start/end of the cold weather when you are having to think ahead 24 hours about switching them on or off. The Warm Air is a good top up and handy for a blast of instant heat. House is cavity wall insulated, double glazed and loft insulated so retains warmth well.
I'm glad I left behind broken pumps, thermocouples, sludged up radiators to bleed.
Pikey 7 also means low dishwasher and washing machine running costs