What size combi boiler?

Postby GB » Wed Sep 10, 2008 10:52 am

Hi all, renovating an old house and putting an extension on at the same time, so was wondering what size combi boiler I would need (going to purchase myself as have a mate that works for Bosch so can get it cheap) when finished house will consist of a mix of underfloor heating and radiators, downstairs will consist of four separate underfloor heating areas and the rest of the house will consist of about 8 - 10 radiators. There is also going to be a family bathroom, an ensuite shower room and also a seperate toilet with wash hand basin.


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Simply Build It

Postby htg engineer » Fri Sep 12, 2008 1:37 pm

The majority of combi boiler will cope with 8 radiators, the consideration has to be given to the hot water flow rate. Get a boiler with a better flow rate and it should meet your needs.

Worcester Bosch Combi flow rates:
27CDI 11.1 l/min
30CDI 13.1 l/min
37CDI 15.2 l/min
42CDI 17.2 l/min

All decent flow rates, but the better flow rate will be best for a house with 2 or more showers/washrooms. The 30CDI will probablt be adequate.

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