Boiler power

Just been adding up the BTU's for the rads I need to fit a CH system into a 3-bed terraced house. The total is approx 40,000 BTU's.

I asked about boiler choice on here some time ago and was recommended a Vokera. Thanks to all that advised on that.

The retailer has 3 available - all Syntesi condensing SEDBUK A rated.

25e (80,000 BTU),
29e (100,000 BTU)
35 (120,000 BTU)

Hot water requirements will be washing, showering, baths, washing up etc.

The question is which boiler output will be most suitable? I have assumed that the highest output will be best (partly due to the endhanced HW flow rate). Do I need this high power output? And will 22mm pipework carry the heat away from the boiler sufficiently quickly to be efficient?

Thanks for any advice
Anderson

I dont recall any general recommendation for any particular make of boiler. I think that you were hoping that someone would recommend what you had already picked. If you ask enough people then someone will recommend anything.

You are confusing many different aspects and possibly even causing yourself more problems. The boiler size with a combi is determined by the hot water output required, 9 li/min for 24 kW and 14 li/m for 35 kW.

Gas supply is relevant and different power boilers may need an upgraded gas supply to the boiler. You CORGI registered installer can advise.

Be aware that buying the boiler yourself will generally mean that you will be on your own if anything should go wrong during the warranty period. Whereas most, but not all, installers will come out first if there is any problem.

Tony

Thanks for the information Tony. From what you said I therefore assume that the central heating BTU requirement could be considered irrelevant? Thus if I want to fill a bath fast I should get the highest power and that's it?

Thanks also for the point about warranty. I will be getting a CORGI engineer out to do everything associated with the boiler. I will enquire about post-installation support with him/her.

I will also require the current old 15mm gas supply pipe to be replaced so that should take care of any enhanced gas supply requirements if they are required.

You are right about confusion of aspects. The problem is that there is one hell of a lot of information available these days, and people like myself like to consider as much of it as possible. This does inevitably cause confusion but thanks to this website a lot of myths can be expelled.

The boiler should usually be set to provide the CH output required by the radiators.

Unfortunately over 90% of installers dont bother.

Some dont think its necessary even though they have been told to do it on their energy efficiency course.

Some manufacturers dont even advise it because a significant number of installers manage to mess it up when they try to set it.

Tony