Hi,
I’ve searched on the forum but I haven’t been able to fully answer my question. I understand it’s not a good idea to oversize a boiler, perhaps because of excessive cycling and it not running in condensing mode for long?
However I have bought a Vaillant system boiler 630 = 30kW output as it was the make I wanted and cheap! (person bought wrong one, left it for ages, company went bust, etc). It’s brand new boxed with all fittings and flue, etc.
The radiators need about 15kw and add a bit extra for a Megaflow indirect hot water tank and 30kw is still somewhat excessive. In reality when the house is warm, water hot and half the TRVs are shut the boiler won’t have much work to do at all.
Firstly is there any regulation that states the boiler can’t be oversized? Secondly do you think it will make much difference considering the boiler will modulate down to about 10kW or so and act like a smaller boiler anyway? Finally if it does make a difference, is it worth me selling this one and buying a lower powered one or should I stick with what I have. Changing it will cost me money, so I’m happy to put up with a slight loss in efficiency every year not to have to spend £500 now. What do you think?
I’ve searched on the forum but I haven’t been able to fully answer my question. I understand it’s not a good idea to oversize a boiler, perhaps because of excessive cycling and it not running in condensing mode for long?
However I have bought a Vaillant system boiler 630 = 30kW output as it was the make I wanted and cheap! (person bought wrong one, left it for ages, company went bust, etc). It’s brand new boxed with all fittings and flue, etc.
The radiators need about 15kw and add a bit extra for a Megaflow indirect hot water tank and 30kw is still somewhat excessive. In reality when the house is warm, water hot and half the TRVs are shut the boiler won’t have much work to do at all.
Firstly is there any regulation that states the boiler can’t be oversized? Secondly do you think it will make much difference considering the boiler will modulate down to about 10kW or so and act like a smaller boiler anyway? Finally if it does make a difference, is it worth me selling this one and buying a lower powered one or should I stick with what I have. Changing it will cost me money, so I’m happy to put up with a slight loss in efficiency every year not to have to spend £500 now. What do you think?