Fitting a thermostat shower to a combi boiler

[lbhomesolutions]

Hi all i have a 3 storey house which is fed from a combi boiler.
I am fitting a bathroom in the top of the house with just a bath and on the second floor i wanted to fit a thermostatic shower over the bath.
I have read that a combi boiler will not run a 2 bathroom property.

Question1, If only one bathroom was used at a time would this be a problem?

Question2, why does the pressure drop when both hot and cold water is turned on the in the bath and does this mean that if i run a thermostatic shower will the same thing happen?

I was just going to branch of the exsisting 15m pipe work.

Thank you in advance for your time and knowledge

 

[gas4you]

Most traditional combis will only efficiently supply one hot outlet at a time, so if you only use one bath or shower at a time you will be ok.

As a combi uses mains fed cold water to heat for hot water, if your incoming pressure/flow rate is low, then when you turn on the bath hot and cold you are asking 2 outlets to share the same pressure/flow.

A shower would not be affected by this phenonenom as the water flow through it is more restricted in the shower head than at the bath taps.

HTH

 

[lbhomesolutions]

Thanks for your help Dave that helps loads.

 

[Doctor Drivel]

Hi all i have a 3 storey house which is fed from a combi boiler.
I am fitting a bathroom in the top of the house with just a bath and on the second floor i wanted to fit a thermostatic shower over the bath.
I have read that a combi boiler will not run a 2 bathroom property.

There are many high flow two bathroom models around.

High flow models available:

Wall mounted:
Alpha CD 50
Glow Worm Extramax
Vaillant 937

Floor mounted:
Viessmann 333
Worcester Bosch 440 Highflow
Vokera
ACV HeatMaster
Atmos Multi
Gledhill Gulfstream
Ideal Istore
Potterton Powermax
..and so on...

Your mains must have enough pressure and flow. Test it.

Question1, If only one bathroom was used at a time would this be a problem?

see above

Question2, why does the pressure drop when both hot and cold water is turned on the in the bath and does this mean that if i run a thermostatic shower will the same thing happen?

I was just going to branch of the exsisting 15m pipe work.

Size the pipes to suit. Have a dedicated 22mm pipe from the stoptap to the combi. At the stoptap fit a tee and run a pipe for all the cold supplies, except the showers. Just before the combi have a tee and take the showers cold supplies off this.

Uprate the stoptap too. most are too small restricting flow.

Also have a shower mixer with an integral pressure equalizing valve inside. Some are termed "combi compatible" or "combi mixers". Having thermostat on the mixer is not enough, don't let sales people push you to anything else.