I gave this thread a fairly general title but for now at least there is only one thing that I am looking for and that is a wet duct heater.
I have a duct heater that used to be connected to my central heating system and slightly warmed the air in my MVHR. The boiler ran at a maximum of 50°C so it was really a warmer rather than a heater. Now the central heating runs at up to 35°C and there is negligible heat transfer in the short coil and water is being returned to the heat pump at close to leaving temperature (but blended with cooler water from my radiators). Either I need a replacement much longer coil or several short ones. One longer one would be preferable.
So to my question.
Does anyone know where to find one? Preferably 160mm diameter but I could go for slightly larger with adapters to allow for the flow restrictions caused by the coils.