I have a job on a house where the shower cartridge is faulty (seized solid) however the basins and bath/shower filler in all 3 bathrooms are putting out hot water which goes cold then warm back to cold, the kitchen tap downstairs runs nice and hot and they have an outhouse close to the kitchen which has a sink in it which runs hot aswell, in said outhouse is a large biomass boiler, I'm not very clued up on these, theres an awful lot going on. I'm convinced there is a TMV tucked away somewhere in the house that's feeding the bathrooms. Currently to run a hot bath they are running the cold on the basin at the same time as filling up which is helping. Any thoughts would help out, the house is quite old (farm) and very large, it had an over haul at some point in the past on the bathrooms. Cheers.