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Running 2 showers at the same time

Hi Have recently moved into a 3 bedroom flat. Two of the bedrooms are very large and have handbasins in them. We plan to build 2 shower ensuites. The current CH / HW system is vented, cold water tank in the loft etc. Both the boiler and hot water tank (if we keep one) are to be replaced and moved to a new location.

The problem is how to run 2 showers simultaneously with a reasonable flow.
The cold water feed into the flat is 2 bar and with one cold water tap on delivers about 12 litres / min. On the CH side need a 24kw boiler. It just my wife and myself living in the flat with the occasional visit from family etc . So with just one shower in use we would like a "deluge" and with 2 showers on the go a "reasonable" flow of water,

There are various solutions -
1 - system boiler with unvented 160 / 80 litre cylinder
2 - normal boiler, vented cylinder and 60 gallon cold tank in the loft with a 3 bar pump
The disadvantage is the cost of heating a tank of water

The alternative is a combi boiler with just one of the showers in use at any one time. Don't particularly want to go down the electric shower route for the 2nd shower, However I was wondering whether either the combis that have an uprated DHW supply would be the answer such as either the Valliant ecoTEC 937 or the Wocester Greenstar Highflow 440CDi ,

Thnaks for any advice

2 Answers from MyBuilder Plumbers

Best Answer

Hi Martin,
from your description of your water supply/boiler/tank options. if you only have 12l/min incoming, I am afraid you won't really be able to supply 2 showers at the same time with adequate flow, and I am not sure that 12l/min would be adequate to supply either of the boilers you have flagged up.
At our own property, 5 years ago we had a similar issue, as we were installing a Triton 300si electric shower, and when the water board checked our supply we were at a disappointing 14 l/min, and after it was discovered the existing lead supply had been bent by tree roots they replaced the supply increasing us to 24l/min, which meant we could have the electric shower as this required min 16l/min.
I believe the water authorities regulated min supply pressure is 20l/min, but may be mistaken on this figure, but 12l/min is very poor and needs rectifying.

Have you considered a mains pressure hot water tank, I appreciate the cost will increase with this option, but from the figures you are giving for incoming supply even this may be a problem.
I hate to say it, but you do need to address the incoming pressure first, then you can figure out the best option for your requirements, but I wouldn't rule out modern 13.5kw electric showers on a 45A supply, as you would be surprised at their output, once you have increased your incoming supply.
Ours really does blast us out of the shower if that helps your decision.
kindest regards


Answered 23rd Jul 2012

You say you have a loft with water tanks. In which case i would fit a Stuart Turner 3 bar twin shower pump to come off of the vented cylinder. I get 30 litres a minute out of mine and there is still room for more improved flow. Fit a real drench head and this flow rate is quite within reach. A vented cylinder will only give you 2 bar. P.S Stuart Turner do a bigger pump if pockets allow.



Answered 25th Jul 2012

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