Combi/shower

[henry smith]

I am having a new combi boiler fitted possibly an 30kw ideal and am considering feeding the shower from it. Is it just a case of plumbing the hot and cold into some kind of mixer valve ?

 

[kevplumb]

yup pref thermostatic

 

[StevieJB]

If your cold water pressure is too high (significantly higher than the hot water pressure delivered by your combi) you'll get temperature variations using a standard mixer. A thermostatic mixer will cost a fair bit more - but at least you won't swear in the morning. Alternatively, a flow rate regulator put into the shower cold water feed pipe should also work (I think)

 

[kevplumb]

or a pressure equilising valve

 

[ChrisR]

You'll need a pretty good mains supply to make a 30kW combi to work to its max in the first place. Have you had it checked for pressure and flow? Any competent installer should do that.
Thermostatic showers can give problems with combis sometimes - more suited is a pressure-balanced valve, such as one made by Mira.