Hot water feed from cylinder for shower pump

[Jonesminor]

Hi,

Wondering if an extra flange is necessary for a shower pump? I've seen conflicting advice and some say a feed from somewhere below the vent tee would be ok.

We're remodelling the bathroom and adding a shower mixer. Hot water is from a vented cylinder with a loft tank. Mains cold is good pressure so we're looking to pump the hot only for the shower. Pump will be installed next to the cylinder.

The airing cupboard is super pokey and I'd rather not disturb the top fitting unless necessary.. I'd probably get a pro in for that.

Thanks

 

[echoes]

An Essex flange towards the top of the cylinder is better. They are a bit fiddly to fit and involve drilling your cylinder.

You'll need to provide balanced pressure h&c to your shower valve. It could be done with a pressure reducing valve on the cold, but pumping both hot and cold would be better.

 

[Jonesminor]

Hi

Thanks for info.

Can see this turning in to a can of worms.. I've looked into an essex flange. Fairly sure the last time we tried to drain the system to replace a valve, the hot water cylinder drain didn't flow when opened.

Interesting comment re the balancing of the valve.. I can take a feed from the tank through a pump but what could happen if the cold was mains fed? Won't the header tank be more prone to emptying if both hot and cold tank fed and pumped?

Thanks

 

[echoes]

Well you will need to partially drain the cylinder to fit an Essex, so that might be problem.

Next best option is a Surrey flange, which fits into the top of the cylinder. This requires draining the water from the very top of the cylinder, but you might get away with lots of towels.

Last option is to tee off the almost horizontal hw outlet close to the cylinder, but it's the worst option and you might get air drawn through the pump.

Yes the cold water cistern will empty quicker if the cold is also pumped. It should have a capacity of 50 gall.

If the cold is mains fed, your shower valve will have to cope with hot at whatever pressure the pump gives (e.g. 2 bar) and cold at whatever pressure the mains is e.g. 5 bar, or less, or more.
I have had a hot-only pumped shower, but used a PRV on the cold feed set to match approximately the pumped hot pressure. It worked ok. Got sick of the noisy pump pretty quickly though.

 

[gas112]

6 inches minimum below vent tee is perfectly ok and wont draw air in

 

[Hot&Cold]

There is a shower mixer (ideal standard trevi boost) valve which is designed for uk cold mains/hot tank.

It needs professional installation,testing/commissioning so maybe beyond the diy approach.

 

[gas112]

a venturi shower not exactly rocket science to fit one

 

[Jonesminor]

Thanks for the info everyone.