Can I have a powerful shower on Combi system??

[Neddy1984]

Hi there,

Just bought a first floor 1 bedroom flat which has an electric shower at the moment. The missus isn't at all happy with the power of water flow it produces and we want to improve this. We have a 24kw combi boiler system and plan to also build a 2nd bedroom with ensuite in the loft space in near future. I think I have heard you can't put a pumped shower on a combi system and im worried if I do away with the electric shower and put in hot and cold tails for a shower off the combi then when someone opens a hot tap it'll get cold.
There is no room for a megaflow system but I could spend more on a larger KW rating boiler.
Also, I used a flow cup earlier on the cold mains from kitchen and it said roughly 18-19 litres a minute.
Hope this is enough info for you guys to help me with. Really struggling so any useful information would be very much appreciated
Thanks in advance

 

[MP plumb]

do you think the hot and cold flow/ pressure to be good on the other taps? if so, the pressure should generally be the same on a combi if you install a normal mixer shower.

an electric shower is mains pressure but gets slowed down slightly as it goes through the electric heater.

 

[Neddy1984]

thanks Claire, would it improve further still if I were to install a more powerful Combi, say a 28kw, or is it still reliant on the mains pressure.

 

[Guest123]

If using supplies of a combi, get a thermostatic mixing shower as these are designed to work well with combis and regulate the temperature. You need about 2 bar minimum pressure.

Here's an absolute beauty which I recently fitted in a wetroom, it's an all over body shower and looks and works terrific:

http://www.plumbworld.co.uk/triton-unichrome-3240-13510

 

[Neddy1984]

Thanks alot for the input guys, any more info is always appreciated

 

[MP plumb]

guys....and girls regarding hot water pressure, the combi will only work with what you have, the mains pressure. combis wont boost the pressure/flow you have, so getting a bigger boiler prob wont help. the boiler chosen for a house is meant to be for the amount of BTU's/watts its going to heat quick enough and the amount of hot water needed.

i would also suggest a mixer shower valve. you can get mixers that are designed for the flow rate you have, check the spec on each shower you like, they will tell you the min flow rate or pressure you need, or the tap/ mixer wont operate properly.

 

[GQuigley67]

my mains pressure is 3.5bar with a 30kw Vaillant Combi and mixer shower, shower is great.

bigger boiler equals bigger flow rate, you would get around 11.5 L per minute from a 28kw nearer 13L for a 30kw, this does not effect pressure though flow rate and pressure are completely different things. A 30kw will be able to cope better with multiple outlets being used at one time i.e someone opens the tap while your in the shower, there will be a noticeable drop in flow rate but not as much as a lower output boiler.

 

[MP plumb]

so say a house has a 1 bar pressure, with a vaillant combi 824, in a 2-3 bedroom house, if i was to put a bigget boiler in, say, a 837, it would increase the flow rate?

 

[GQuigley67]

no all boilers reduce flow rate so they can heat water in time, my mains is 20+ litres a minute but my combi gives out around 13 per minute on the Hot water side.

 

[AWheating]

so say a house has a 1 bar pressure, with a vaillant combi 824, in a 2-3 bedroom house, if i was to put a bigget boiler in, say, a 837, it would increase the flow rate?

yes the hot water flow rate would increase if the cold main was sufficient. Pressure and flow are different, you could have a cold main at 1 bar with 10lpm flow and a main at 1bar with 20lpm and so on. So dependant on the figures yes a larger combi would mean better hot flow rate.

 

[fuzzy]

shouldnt need one