Hi folks, my current CH system is quite old fashioned. 1977 House with microbore pipework, 'Potterton Profile 100e' type boiler (just cycles between on/off) and vented cylinder with main water tank and expansion tank in loft.
The system has been modified by previous owners mixing in some 15mm connections directly off the existing 10mm microbore. Some rads only get luke warm.
I want to upgrade the whole system to an unvented with a modern condensing boiler, and gradually replace the old radiators in rooms as I gradually decorate each room in the house, I cant currently afford to have everything done at the same time and want to use modern type vertical radiators (sized to suit) instead of the standard type 22s. So after the initial heating system itself has been replaced, and 22/15mm pipework used wherever possible but leaving the old microbore runs and old rads in place to start with, I will gradually go round each room and replace the radiator and microbore to modern stuff, eventually working my way around the whole house.
My question is with regards to sizing my new radiators to replace the old. I presume that I would calculate the required BTU/Wattage for each room based on T50 rating, as the new boiler will be condensing and therefore running a lower temperature throughout it's pipework. If that's true, then I also presume that when I get the new boiler installed my existing old rads might not get warm enough as they were presumably sized based on the original boiler(s) which I understand have a much higher working temperature?
Basically, I want to order a new radiator for a room I'm decorating knowing that I'll be replacing the boiler shortly afterwards.
Any help is much appreciated, and I acknowledge that I might talking total cr*p on my understanding of boiler temps and T ratings.
CheeRS
The system has been modified by previous owners mixing in some 15mm connections directly off the existing 10mm microbore. Some rads only get luke warm.
I want to upgrade the whole system to an unvented with a modern condensing boiler, and gradually replace the old radiators in rooms as I gradually decorate each room in the house, I cant currently afford to have everything done at the same time and want to use modern type vertical radiators (sized to suit) instead of the standard type 22s. So after the initial heating system itself has been replaced, and 22/15mm pipework used wherever possible but leaving the old microbore runs and old rads in place to start with, I will gradually go round each room and replace the radiator and microbore to modern stuff, eventually working my way around the whole house.
My question is with regards to sizing my new radiators to replace the old. I presume that I would calculate the required BTU/Wattage for each room based on T50 rating, as the new boiler will be condensing and therefore running a lower temperature throughout it's pipework. If that's true, then I also presume that when I get the new boiler installed my existing old rads might not get warm enough as they were presumably sized based on the original boiler(s) which I understand have a much higher working temperature?
Basically, I want to order a new radiator for a room I'm decorating knowing that I'll be replacing the boiler shortly afterwards.
Any help is much appreciated, and I acknowledge that I might talking total cr*p on my understanding of boiler temps and T ratings.
CheeRS
