Combi Boiler and Thermostatic Showers

[Willie120c]

Hi All
Can I have some advise please.
I have a Vokera Syntesi 29e Combi Boiler and I plan to install a Grohe 2000 Themostatic Shower with 3/4" connections. I'm worried that the either the flow rate or temperature won't live up to my wive's expectations. i.e. HOT and Fast.

My concern is the existing pipework. The cold mains supply to the bathroom is 22mm with individual 15mm tees to the existing Electric Shower, toilet & sink. The hot water supply from the boiler is 15mm however it changes to 22mm up to the bathroom with 22mm to the bath and 15mm to the sink.

I notice the Hot Water Pressure in the bathroom is not as good as the downstairs kitchen. Should I change the HW pipework to the bathroom to 15mm to make all HW from the boiler 15mm. (remember the CW would tee at 15mm from a 22mm pipe)
Should I connect CW & HW to the shower using 15mm Pipe with 3/4 connectors.?
Do I need to install a pressure equaliser?

regards
Willie

 

[Agile]

Why not look at the spec sheet for the shower and see what flow rate it requires.

Your boiler should give about 11 litres/minute of hot water.

In a normal situation all hot water pipework should be 15 mm. Mains fed cold can also be 15 mm but larger sizes dont cause any problem.

If you have a tank supply for your cold then the shower will not work!

Tony

 

[Willie120c]

Tony

Thanks, All tanks are gone since central heating system was converted to a Combi System. CW is off the rising main.
My Preference is to replace the 22mm HW part with 15mm but to leave the CW supply as is at 22 with 15mm tees. I was just a bit worried about inequal pressure between the HW and CW feeds to the shower. I see from other topics some have experienced issues with pressure differentials.

I'll check the flow requirements of the shower. I notice it says it operates with pressures of 0.1 bar to 5 Bar and a maximum pressure differential of 5:1. There is a flow pressure diagram which has pressure lost curve which is double dutch to me.
http://www.grohe.co.uk/m/25_852/pag...iew&action=product&article=34218&fragment=854

see the above URL. What does it mean?

regards

Willie

 

[Agile]

As you are fitting isolating valves in the shower feeds ( arn't you? ) then you could always balance the flow resistances if there was any problem.

However as both supplies are from mains pressure that will not be an issue.

You still need to check the flow rate required.

Tony

 

[Willie120c]

Tony

I've not been able to find any info on minimum flow rate only minimum pressure and the Grohe Pressure Lost diagram.
Yes there will be isolating valves. I need to get this right as they'll be behind my tiles once installed.
Looking at other routes for pipework so I can get to my valves but that involves work in the kitchen fitted last year. Not a popular choice with the other half.

Willie