two bar stuart turner monsoon

[nickdesign]

Hi Guys,

I have bought the bristan prism shower in this link -

http://www.bristan.com/epages/Bristan.sf/en_GB/?ObjectPath=/Shops/Bristan/Products/"PM VSHXSPDIV C"

and am now in the process of buying a single pump to boost the hot water supply, if I buy a 2bar pump for the hot and the cold is a similar pressure do you think this will give a good strong shower through the showerhead above?

Only asking because I have no idea what that pressure would equate to through a showerhead like this?

Thanks!!

 

[nickdesign]

anyone?

 

[Agile]

If you are mixing hot and cold then you need to boost BOTH as otherwise you will never get any cold to mix and will drive hot water up the cold supply!

Tony

 

[TicklyT]

To get an idea of the flow rate you may achieve, have a look at the flow rates in the manufacturer's data for both the pump and the shower.

If you use the data to plot both lines on a graph of flow rate Vs pressure, you should get one line rising, and one falling. The point at which they cross represents the flow rate for the shower and pump combination.

Note the line in the specification:-

Supply: Suitable for all plumbing systems, preferably balanced

Using a single pump on just the hot supply to match the cold pressure is rarely, if ever, as successful as a twin pump for both hot and cold, fed from sources at the same pressure. For a gravity hot water system, the cold water storage tank regulates the pressure in the hot cylinder, so is the best source for the cold supply.

 

[nickdesign]

Hi Guys,

thanks for the replies, the cold supply is already pumped as it comes through a communal system and the pressure of that is approx 2 bar, so am only using the pump on the hot to match that, therefore ensuring a balanced supply.

 

[ChrisR]

No, you're not ensuring anything is balanced doing that.
The problem comes if there's another drawoff, say from the cold. The cold pressure in the shower drops, and you could get scalded.

A thermostatic mixer would be some protection, until the day it got scaled up or stopped working like thay all do sooner or later.

I'd use a Pressure Balancing Valve in addition to the extra pump, and a thermostatic mixer as well.

"Hot" water could be hot enough to produce full thickness burns in a couple of seconds.

 

[nickdesign]

the shower has got a thermostatic mixer as far as I'm aware

 

[Agile]

You have not explained how your hot supply is derived and consequentially what pressure its likely to be.

Tony

 

[nickdesign]

The hot supply is delivered by a cold tank in the roof space which flows down to the basement where it is heated by the boilers and then circulated though the system utilising the downward pressure of the original cold water feed.

 

[Agile]

Is the hot stored in a cylinder?

Tony

 

[nickdesign]

yeah hot is stored in chlorifiers.

 

[Agile]

yeah hot is stored in chlorifiers.

Is that to add chlorine to the water to make it safe for taking showers and baths?

 

[nickdesign]

sorry typo - meant to type calorifiers

 

[Agile]

Well in that case you have seriously unbalanced supply pressures.

Its not clear to me if you actually NEED more HW pressure? If not then a pressure reducer on the mains would help but far better would be to use the roof tank to supply cold water to any showers or other mixing devices.

Alternatively if you must boost your hot water then it may be necessary to have pressure reducers on both cold mains and the shower pump to give both a stable supply pressure.

Tony

 

[nickdesign]

I understand that the supply pressures are unbalanced.

Hence why I am putting a pump on the hot supply as it is a much lower pressure as the cold supply entering the flat.