combi boiler - powerful shower - mixer or electric?

[tanya01]

Hi,

I have a combi boiler and would like to have a powerful shower in my bathroom. What is the best solution? I'm worried the pressure from the boiler won't be enough and I'll have a weak mixer shower. How can I find out my hot water pressure? What is the rule of thumb for sufficient pressure to have a powerful mixer shower?

Thanks for your advice!

Tanya

 

[chrishutt]

If only the answer were as simple as your question.....

Basically, your combi boiler will only supply so much hot water - typically around 10 litres/minute, depending on model. this will be adequate for a good shower unless somebody else opens a hot tap and "robs" the shower of hot water.

You might also have a problem when somebody else opens a cold tap, if your cold mains flow is poor. Exact figures depend on all sorts of variables, but roughly speaking I would say you need a cold mains flow of at least 20 litres/minute.

You will see from the above that pressure is not so important as flow rate. There are lots of threads discussing this in more detail which you should be able to find if you do a search.

 

[Paul Barker]

Never bother with a combi less than 28kw

I haven't come a across a house yet where I wouldn't be satisfied with a thermostatic mixer shower off a combi

Never expect a combi to supply more than one tap, bar one with large storage (direct or indirect).

If you want a shower when your combi is broken down get an electric shower.

Don't be so optomistic, one of the few certainties in life is that your combi will break down.

If you have an electric shower, make sure your main supply can handle it, get it wired in 10mm cable, 45 amp isolation, 30mA rcd.

 

[CockStop]

Look into pressure balanced valves, these help with keeping a constant feed to a mixer shower in a combi boiler setup