I have got a customer who has a netaheat mkII. The air pressure switch is on the way out and is getting stuck, I have freed it up twice now in the last 3 months. This part is now obsolete, but one parts supplier told me Honeywell have produced a pressure switch which can take its place. When I called potterton they made no mention that there was another pressure switch available. Surely I shouldn't be fitting it if it isn't manufacturer approved?