New Shower Install

[KonkyWonky]

We are getting a professional showeroom instal and are undecided as to what type of shower to put in. We have a Baxi 105e combi boiler which I'm sure is not the best out there as it was installed when the house was built. Mains water supply is good.

Originally we wanted to go with a mixer but we had doubts over whether the boiler would be able to supply it. We then decided on a 9.8kw Mira Sport electric but I would still prefer a mixer unless there is a reason not to install it.

The boiler is downstairs and would have to feed up one level (approx 10 - 12 foot?) to the mixer. Would this likely cause problems with water pressure/temperature?

In addition, there is a fair difference between the hot water pressure and cold water pressure as the cold water would be straight from mains. How would I reduce the cold water pressure to get an equal mix?

Thanks in advance guys

 

[bolshy]

Your boiler makes approximately 10 litres per minute of hot water @ 35 ° C rise, if working as it should be. This will run your thermostatic mixer shower (one spray head, I assume) with no problems if the mixer valve is installed according to the manufacturers instructions. Some mixer valves require restrictors to be fitted when used with combis, and these are provided with the thermostatic valve.
Your cold mains water is heated by your boiler to give mains pressure hot water. Pressure differential shouldn't be a problem.
I'm wondering why you mention that it is.........?

 

[KonkyWonky]

My main concern is that if i open my hot water tap fully it has less pressure than when I open my cold water tap fully, I thought this may cause issues when entering the mixer.

In addition, when I open the hot water tap half way the water is way hotter than if I open the tap fully. Would the water temperature entering the mixer be the same as the tap in the fully open position? If so I'm not sure it would be warm enough to shower in the winter.

 

[sooey]

Your 30 kw boiler will give you a far better shower than the 9.8 kw Mira.
While it's working that is.
Your 9.8kw Mira will give a far better shower than the boiler when the boiler breaks down.

 

[bolshy]

Your shower needs to have a thermostatic mixer valve. Not just a blending valve. Make sure it does. And it will provide a good shower in winter or summer, providing it's been set up correctly.
And providing no-one tries to run a bath at the same time as you're showering.

And as sooey posted, a lot of people like to have an electric shower as backup, in case their combi goes down. But it's personal preference, and electric showers aren't as good in winter.

 

[KonkyWonky]

I'm not concerned about going electric on the off chance the boiler breaks down, I can get a shower at work if/when that happens.

I checked flowrate at the bathroom supply and got:

14 lpm from the cold water tap
8 lpm from hot water tap fully opened
4.5 lpm from hot water with reduced flow rate to maximise temperature
3 lpm from 8.5 kw shower at our normal showering temp

I was worried that as the cold water flow rate is significantly higher it would prevent the hot water entering the mixer, resulting in a cold shower.

 

[sooey]

Worry ye not, that won't happen. Out of the two go for the thermostatic mixer off the combi if it's performance you want.