thermostatic shower, do i need to pump the hot water?

timmer3

hi. i'm renovating an old house and hoping to get some advice on the kit i'll need for the shower. i like the idea of just having a valve and shower head in the bathroom without all the noise and clutter of a big white plastic unit. i've read all the threads here about showers and i'm leaning towards getting pressure from the cold water tank only, and heat from the immersion. if i raise the cold water tank to the ceiling of attic i'm hoping there will be enough gravity to get reasonable pressure. the thing i'm not so sure about is the pressure from the hot water tank. at the moment it would be at the same height as the shower. is this ok to supply this kind of low pressure hot to a thermostatic valve?
the bits i'm looking at so far are this thermostatic valve and this shower head. the instructions for the valve only specify a "working pressure" of .1 to .5MPa.

thanks for any help.

Pete67

.1 to .5 MPa is the same as 1 to 5 bar working pressure. To get one bar pressure the storage tank in the attic need to be 10m higher than the mixing valve. This is hard to achieve unless the shower in on the ground floor of a 3 story building.

As the hot water storage cylinder is supplied from the cold water storage tank, the hot and cold water pressure at the mixing valve should be the same.

Often the easiest way to get a really good shower in a domestic setting is to use a shower pump to boost both hot and cold supplies to the mixing valve. There are many models to choose from, and they are commonly installed in the hot press adjacent to the cylinder. The pump should have its own dedicated cold water supply from the storage tank to prevent you getting a roasting in the shower if someone flushes a loo etc. The hot supply to the pump is generally taken from a dedicated fitting on the top of the cylinder designed to prevent air being drawn into the pump.

For example, look at the Showermate Twin pump shown here

From Stuart Turners website:




Positive Twin Pumps
A positive twin pump is designed to be installed into both the hot and cold services to boost both supplies equally and should ideally be installed on the floor of the hot water cylinder cupboard.



A positive twin pump can be used to:



Boost both hot and cold water to a complete bathroom, cloakroom and kitchen.
Boost hot and cold supplies to a high performance shower system.
Boost hot and cold water to a complete house.


Modern Plant are agents in Ireland and off good technical advice and support.

timmer3

hi pete. this is great, thanks for the detailed post. i understand it a lot better now. i can see i'll need the twin pump to use the thermostatic valve. i'll look up modern plant when i'm ready to start work on the bathroom. electrics are first on the list!
cheers
tim.