Hi,
Recently moved into a 70's house (detached 4 bed 1700 sqft) and now winter is here the central heating system is struggling, it's fuelled by a Baxi Solo 2 60pf boiler supplying heating and vented HW using S plan plumbing.
I've pretty much come to the conclusion that the boiler is undersized, the system feeds 12 rads, these together place a 59000 BTU load on the boiler, the system takes over an hour to heat the flow output to 60 deg, and eventually gets to 68 deg but no higher (boiler set to max which is about 75 deg), subsequently the house takes a long time to heat, once the system is up to 68 deg flow temp (about 1 hr 40) the house temperature rises at a decent rate, just takes an age to get to 68 deg!
I have fully balanced the system, getting 10-11 deg drop across each rad, the boiler return temp is around 11-12 deg below flow. The lounge rads are furthest away and lockshields are fully open, pump is on speed 2. With 68 deg flow temp I have 57 deg return at the boiler.
TRV's are fitted to the upstairs rads, once the house is above 20 deg (after 2-3 hours) the upstairs rads start to shut down, then the system is able to reach 75 deg and the boiler shuts off and cycles every 3-4 mins supplying the down rads until the room stat temp is reached.
My confusion and question is if I replace the boiler for a larger BTU output this will surely increase the flow temp from the boiler? taking it away from the 11-12 differential, if I increase flow through the system to get the differential back down then the rads will be lower than 10-11 deg drop, struggling to understand what to do!
I really want the rads to get to temperature quicker, so the house warms quicker.
Any advice welcomed. Thanks
Recently moved into a 70's house (detached 4 bed 1700 sqft) and now winter is here the central heating system is struggling, it's fuelled by a Baxi Solo 2 60pf boiler supplying heating and vented HW using S plan plumbing.
I've pretty much come to the conclusion that the boiler is undersized, the system feeds 12 rads, these together place a 59000 BTU load on the boiler, the system takes over an hour to heat the flow output to 60 deg, and eventually gets to 68 deg but no higher (boiler set to max which is about 75 deg), subsequently the house takes a long time to heat, once the system is up to 68 deg flow temp (about 1 hr 40) the house temperature rises at a decent rate, just takes an age to get to 68 deg!
I have fully balanced the system, getting 10-11 deg drop across each rad, the boiler return temp is around 11-12 deg below flow. The lounge rads are furthest away and lockshields are fully open, pump is on speed 2. With 68 deg flow temp I have 57 deg return at the boiler.
TRV's are fitted to the upstairs rads, once the house is above 20 deg (after 2-3 hours) the upstairs rads start to shut down, then the system is able to reach 75 deg and the boiler shuts off and cycles every 3-4 mins supplying the down rads until the room stat temp is reached.
My confusion and question is if I replace the boiler for a larger BTU output this will surely increase the flow temp from the boiler? taking it away from the 11-12 differential, if I increase flow through the system to get the differential back down then the rads will be lower than 10-11 deg drop, struggling to understand what to do!
I really want the rads to get to temperature quicker, so the house warms quicker.
Any advice welcomed. Thanks
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