Hi All,
My home is 2 storey - split into 2no zones. 14 rads downstairs and 7 upstairs. Open vent system standard boiler. Hot water is immersion heater.
The old boiler was a worchester bosch dansmoor rated at 26-32kw. Nozzle spec was 1.0 gph. However the enginer had 0.85gph nozzle in it. It always heated the rads pretty quickly. Say within 30 mins the downstairs rads would be hot.
Just fitted a new Firebird Condensing oil boiler. It is currently fitted with a 0.5gph nozzle. That is 20kw output rating but depending on nozzle spec and fuel pressure the same burner can put out 26 or 35kw.
I note that with the 0.5gph nozzle the boiler appears to take well over an hour to heat the radiators up on one zone. Downstairs in particular suffers. Now I know a condensing boiler is more efficient when worked hard but perhaps this is too much of a downsize.
So next step will be to fit a 0.65gph nozzle and get it set by engineer at 26kw output. I hope then it will heat the house faster and get up to temp to cycle on and off with stat quicker. Would you guys agree with the principle of what I am saying here?
In summary drop one nozzle size when upgrading to a more efficient condensing boiler. (Don't drop too far like I did at the start)
Also - I notice since the new boiler is installed the radiator balancing is out of whack. Is this something that can happen when a boiler is replaced? In any case that is something I can address myself I understand the principle of 11 degree target drop across each rad and start with the closest rad and work outwards.
I think first step is to get the engineer back to up the nozzle size on the new boiler from 0.5gpg /20kw to 0.65gph / 26kw and after that then I will re-balance the radiators on both zones and hopefully the house will heat up as quickly as it did on the original boiler but should in theory still be more efficient.
My home is 2 storey - split into 2no zones. 14 rads downstairs and 7 upstairs. Open vent system standard boiler. Hot water is immersion heater.
The old boiler was a worchester bosch dansmoor rated at 26-32kw. Nozzle spec was 1.0 gph. However the enginer had 0.85gph nozzle in it. It always heated the rads pretty quickly. Say within 30 mins the downstairs rads would be hot.
Just fitted a new Firebird Condensing oil boiler. It is currently fitted with a 0.5gph nozzle. That is 20kw output rating but depending on nozzle spec and fuel pressure the same burner can put out 26 or 35kw.
I note that with the 0.5gph nozzle the boiler appears to take well over an hour to heat the radiators up on one zone. Downstairs in particular suffers. Now I know a condensing boiler is more efficient when worked hard but perhaps this is too much of a downsize.
So next step will be to fit a 0.65gph nozzle and get it set by engineer at 26kw output. I hope then it will heat the house faster and get up to temp to cycle on and off with stat quicker. Would you guys agree with the principle of what I am saying here?
In summary drop one nozzle size when upgrading to a more efficient condensing boiler. (Don't drop too far like I did at the start)
Also - I notice since the new boiler is installed the radiator balancing is out of whack. Is this something that can happen when a boiler is replaced? In any case that is something I can address myself I understand the principle of 11 degree target drop across each rad and start with the closest rad and work outwards.
I think first step is to get the engineer back to up the nozzle size on the new boiler from 0.5gpg /20kw to 0.65gph / 26kw and after that then I will re-balance the radiators on both zones and hopefully the house will heat up as quickly as it did on the original boiler but should in theory still be more efficient.
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