Advice on boiler and rad size

KAT68_2

Hi

If anyone could help me please I would appreciate it. We are currently having a new conventional boiler system and rads fitted to a semi detached 1900's house. It has 4 bedrooms, 3 reception, 1 bathroom, 1 shower room and 1 kitchen. We may in many years time extend into the loft.

Our concerns are two fold. Our plumber has recommended a Worcester-Bosch 24KW boiler. According to the WB website we should be having a 30KW boiler but our plumber says this is over sized. Having researched this topic for months before hand, one thing I have discovered is everyone seems to have a different opinion with regards to what system etc to fit. I would have thought boiler size was a fairly scientific approach though.......

The other problem is he has recommended we buy a 1200 watt towel rail (one with a rad in the middle) for the downstairs shower room. When my husband went to buy one from a local bathroom room shop, they looked at him as if he was completely mad and said it was way too much. The shower room faces West so on a cold winters morning there will be no sun in there. It also has one outside wall and one window. As a rough idea on size I would say it is 2.25m x 2.25m, ceiling height 2.4m.

Does anyone have any comments or advice please?!

Thanks

justjohn

i always go for next size up for the boiler. (the plumbers always say its over size) i always say (ye but it will handle whatever i throw at it heat wise/water output). If its a combi hot water output is always on the top of my list.

As for the rad there is a chart for standard room size to kw needed.(google it).

gas4you

Assuming your sizes are correct and the outside wall is 9" solid, then you need 860 watts for that shower room.

Guessing rad or boiler sizes is a complete joke! Each room needs to be worked out for heat loss then all added up together with an allowance for the size of HW cylinder you will be having. In your case extra should be allowed for the possible loft conversion, if in the near future

KAT68_2

Thanks for your replies. I had total faith in our plumber until the trip to buy the rad!

ziggyman99

gas4you wrote: »

Assuming your sizes are correct and the outside wall is 9" solid, then you need 860 watts for that shower room.

Guessing rad or boiler sizes is a complete joke! Each room needs to be worked out for heat loss then all added up together with an allowance for the size of HW cylinder you will be having. In your case extra should be allowed for the possible loft conversion, if in the near future

I totally agree with gas4you but will add that 24kW to the rads would be large house. It may be big enough. Oversizing boilers is neither good for your gas bill or boiler. Condensing boilers work better when working hard.
Have a go at sizing you boiler here

http://www.energysavingtrust.org.uk/business/Business/Housing-professionals/Interactive-tools/Domestic-heating-sizing-wizard/Whole-house-boiler-sizing-Tool