Estimating the required boiler Kw

[platforminc]

Hi All.

I had a gas engineer come out to quote for a new piece of work.

The requirement is as follows.

6 showers
11 radiators
300L unvented cylinder
12sqm of single zone underfloor underfloor heating

The engineer estimated a 30kw system boiler, not sure if this is an overkill or about right. I was wondering if anyone has undertaken a similar sized requirement and could comment on the above.

 

[Mister Banks]

Looks way over sized to me, most uk properties have a heat loss under 10kw. I recommend you do a heat loss calculation on your property and ask the installer for a copy of theirs.

 

[Madrab]

The engineer estimated a 30kw system boiler

How did he arrive at the estimate?

Normal approach would be - Heat Loss calcs would be used to obtain the requirements for each room/space and then a suitable sized radiator could be installed. Once the radiators/UFH are known/fitted then their KW capacity is added up + 10% figure for pipework etc. The HW cylinder is also taken into consideration though the system is then considered with diversity in mind - or the system is setup as a DHWP system therefore the capacity of the boiler is directed exclusively to the cylinder until satisfied. Normally the CH system KW capacity is the figure that drives the boiler rating.

So there should be three things that are know and form part of the information the engineer supplied - total capacity of the CH system - capacity of the HW cylinder coil - and what type of system design it would be.

Did he suggest any reason as to why such a large capacity boiler?

 

[muggles]

What's the application? 6 showers seems like rather a lot in a property with only 11 radiators, and a 300L cylinder will run out quite quickly if all 6 showers are likely to be used at the same time. Is it in a house, or a sports hall?