Combi boilers ans switched FCU

[andemz]

Hi all,

I've been looking around at combi boilers of late and have stumbked across something that i need answering.

for example a combi boiler on B&Q's web site states that it is 21KW. Now to me that seems quite high. I then thought that you would need to get power to this and that way could be by spuring off the ring main into a switched fused connection unit. That is when i frowned.

My calculations indicate you needing a high amp. it works at around 87.5 amps. Is this the correct way to do it as that seems rather high to me.

 

[ban-all-sheds]

Can I have some of what you're on, please....


PS - my boiler is 28kW - doesn't seem like too much to me.

 

[andemz]

Ban, c'mon that was only a point that you've made in relation to a point that i've made in my post. You haven't advised on the core of the thread which was the issue of the SFCU and the amp required.

Your 28kw 28,000/240 = 116 Amps. How is that wired up then, i am not aware that they do fuses with amp ratings that high. !!!

 

[Adam_151]

Think outside the box you have put yourself in, watts are a measure of energy transfer, not specifically a measure of electrical energy transfer

 

[andemz]

ok so can you teach me how to calculate this aspect?

 

[plugwash]

the electrical power draw is negligable (control systems only) and will be satisfied by a 3A fuse

the 21KW refers to the heat output of the boiler itself and is supplied by the boilers main power source (gas i presume in this case)

 

[ban-all-sheds]

Ban, c'mon that was only a point that you've made in relation to a point that i've made in my post. You haven't advised on the core of the thread which was the issue of the SFCU and the amp required.

Your 28kw 28,000/240 = 116 Amps. How is that wired up then, i am not aware that they do fuses with amp ratings that high. !!!

And I'm not aware that they do electric combi boilers.

Like yours, mine is a GAS boiler with an output of approx 28kW.

FFS....

PS - you're supposed to use 230V in calculations like that....

 

[kevplumb]

28 kw you need 28 mm t&e with a meter union on the end

 

[andemz]

Thanks gang, that's cleared things up for me....

 

[plugwash]

im not sure an electric comi boiler is paractical

afaict gas combi boulers have two seperate sets of pipes heated by the same flame system

 

[andemz]

No plug it's not an electric combi boiler. I was getting confused when it was stating large KW as energy transfer not thinking that this didn't mean electrical energy transfer.

It is a Gas bolier