Boosting water pressure

[PhilTilson]

One for the plumbers out there!

I have a 'standard' plumbing installation comprising cold water tank in loft, indirect hot water cylinder in (upstairs) airing cupboard and modern condensing gas boiler downstairs.

I have recently renovated the bathroom, but many modern taps, especially thermostatically controlled ones, require a minimum 0.5 bar. The shower head is only about four feet below the tank water level - not much more than 0.1 bar! So showering is barely adequate - and that's with a non-thermostatic tap. 'er indoors requires thermostatic control, so I am looking to boost the water pressure.

There seem to be several alternatives. My own preferred option would be to put a double-ended pump (like the Salamander) in the loft where the two 22mm outlets come from the cold tank (one cold supply to taps, the other cold supply to the hot tank).

But all the info from Salamander insists that the 'hot' side of the pump is fed from the hot outlet from the tank - which would be a plumbing pain. I don't want to mount the pump down in the airing cupboard if I can help it.

Can somebody please explain WHY I can't just put the pump on the two cold feeds? Pressure is limited to about 1.5 bar with this pump, and the cylinder is rated at 6 bar, so no problems there. I can't for the life of me see the problem - but no doubt one of you can!

Phil

 

[stardanny]

The reason why you can't put pump in between cold tank and cylinder because of the open vent pipe. If you do, water will come out of vent when pump switch on, cold tank will get hot, distort the tank.

Pump has to be fitted after hot outlet on top of tank after the vent or better with a Surrey flange.

Dan.

 

[coliholic]

So ywant to take the two cold supplies in the loft, put them into the pu.mp and expect one of them to magically supply hot water from a cold feed? Err no, it doesn't work like that.

You need to fit an essex flange to the top hot outlet of your tank and then run that hot outlet to your pump and take it from there. Although it's preferred to have the pump as close to the hot tank as possible, I can't see any real reason why thepump can't be in the loft a few feet away.

http://www.mytub.co.uk/product_information.php?product=317955

 

[PhilTilson]

Funny how often you post a question, only to twig the answer shortly afterwards!

You are quite right, stardanny - of course it would! I blame the fact that I have been using unvented systems for so long!

And no, coliholic, I wasn't expecting some kind of divine water heating! I think stardanny got what I was after.

Ah well, it was a nice idea....

Phil