30Kw v 35Kw running costs

[AJ16]

Will a 35Kw boiler use a lot more than a 30Kw? Only two bathrooms in 4 bed house but need a good hw flow to fill a bath each day.

 

[chris watkins]

Are you after a combi ??? because the heat load should be calculated & boiler selection based on that if not.

 

[TBServices]

You should leave sizing the boiler to your installer and listen to his recommendations

 

[doitmyself]

You should leave sizing the boiler to your installer

Assuming he knows how to size a boiler correctly.

 

[wheeto]

Will a 35Kw boiler use a lot more than a 30Kw? Only two bathrooms in 4 bed house but need a good hw flow to fill a bath each day.

Well I agree you should leave the sizing to your installer, but to A the Q...

If it's a combi then in theory, ceteris paribus, they will use exactly the same amount of gas to warm a given volume of water - your bath! - the same amount but the 35KW one will do it faster. In practice they will use roughly the same amount.

For heating, it will depend how well they modulate down to supply the steady-state few KW that you house will need. This will be far below the peak output of either the 35KW or the 30KW so, again, I'd say it will be about the same.

Anyone disagree strongly?

 

[chris watkins]

Well I agree you should leave the sizing to your installer, but to A the Q...

If it's a combi then in theory, ceteris paribus, they will use exactly the same amount of gas to warm a given volume of water - your bath! - the same amount but the 35KW one will do it faster. In practice they will use roughly the same amount.

For heating, it will depend how well they modulate down to supply the steady-state few KW that you house will need. This will be far below the peak output of either the 35KW or the 30KW so, again, I'd say it will be about the same.

Anyone disagree strongly?

Spot on !!
Just to add that we are finding a lot of people putting in these large (heating boilers) thinking that all will be alright because they will modulate down only to find that the control within the boiler mean it is shutting down & holding of firing (anti-cycling) because the system can not carry way the heat. There is no excuse not to select the correctly sized boiler for the job, apart from anything else they cost more !!!! Does anyone else see this problem with the larger boilers ???

 

[Kemble]

Firstly... I'm very impressed with the latin Wheeto !

Correct boiler sizing is important, and I think it's totally right for the OP to ask these questions and NOT blindly leave it to the installer... if the suggested sizing is correct the installer should have no problems in explaining it to the OP. That's what I would expect to do anyway...

 

[chris watkins]

Well I agree you should leave the sizing to your installer, but to A the Q...

If it's a combi then in theory, ceteris paribus, they will use exactly the same amount of gas to warm a given volume of water - your bath! - the same amount but the 35KW one will do it faster. In practice they will use roughly the same amount.

For heating, it will depend how well they modulate down to supply the steady-state few KW that you house will need. This will be far below the peak output of either the 35KW or the 30KW so, again, I'd say it will be about the same.

Anyone disagree strongly?

Oh, that's what it was !!!! I only just about managed English at my school, they wouldn't let us do foreign languages. LOL

 

[Kemble]

I've always wanted to use "obiter dicta" in a posting... but I never seem to get the chance !

 

[Ray Stafford]

My favourite is "quidquid Latine dictum sit altum videtur"

 

[Dotty]

My signature pretty much covers all occasions!

 

[kirkgas]

English is fast becoming the second language in our schools

 

[chris watkins]

English is fast becoming the second language in our schools

& even Scottish is reduced to third place. LOL

 

[AJ16]

Are you after a combi ??? because the heat load should be calculated & boiler selection based on that if not.

Yes it will be a wall mounted combi, I would hate to settle for the smaller output if at some stage later I found that it was a bit slow to fill the bath, that's why I asked the question really.
I was recommended a 30Kw some months ago but just want to be sure.

 

[AJ16]

You should leave sizing the boiler to your installer and listen to his recommendations

Thanks but it's good to know the reasoning, it's not a complex issue so it's seems reasonable to take an interest particularly as we will be the end users