How to choose a Combi Boiler for 4 Showers ONLY?

[rwang4]

MY house already has a conventional boiler (with tank) supplying Hotwater and Central Heating for the whole house (inc bathroom) - it works well. I'm now considering installing 4 ensuites to the 4 large bedrooms. We plan to install a seperate Hotwater system. I need your advice on choosing a Combi boiler which will only supply hot water for these 4 ensuites? What power/type/brand/model should I choose? Many thanks!

[acsimpson]

I'm no expert, but generally a domestic combi boiler is capable of supplying only 1 shower at a time. I guess if you are installing 4 showers then you plan for them to be usable at the same time.

I guess your choices would be to instal a large combi boiler capable of an exceptionally high flow rate, or installing a second system similar to what you already have.

Alternatively you could upgrade your current system so that it can handle the additional demand.

[Perry525]

It may be easier to instal electric showers.
I would suggest that you extend your current system to the new showers.
If you have a 28mm cold feed into the hot water tank and a 28mm supply from the tank you should not have a problem.
There is the possibility that the pipes may be overlong and the internal friction using 15mm pipes will result in unsatisfactory pressure, this can be solved by using 22 mm pipes to as close to the shower heads as possible.
Keeping in mind that the average shower time is six minutes, how likely is it that five people will choose exactly the same time to have a shower?