Retro fitting Surrey/Essex flange

[Rob Graham]

I'm looking at changing my electric shower to an 'ordinary' one but will have to fit a booster pump on the hot water - there's about 2m of head. My HW tank has a vent takeoff and I see that that is not acceptable. Are these other flanges straightforward to fit and are they available at plumber's merchants?

On the basis that I don't have access to the sides of the tank unless I take it out, the Surrey flange looks preferable.

I see that the recommendation is for the pump to be on the floor near the tank. That is impossible in my set up - I'm in a cottage and the HW tank is in a box at ceiling level; what are the criteria that require the pump be so close to the tank ?

Rob

[Ian Stirling]

Avoiding ca

Avoiding cavitation on the pump inlet. If a pump tries to suck hot water, then bubbles may form. To paraphrase a South Park guidance councillor "Bubbles are bad..."

Placing the pump on the flor of the box will be OK.

[Capitol]

From your description, the Surrey flange seems preferable. The pump does not have to be located close to the HW tank, although this is often the best solution. If you plumb the flow to the pump in 28mm as far as feasible, then the flow into the pump which is determined by the diameter and length of the input pipework will be greatly improved. As an example, increasing the feed pipe diameter from 15mm to 28mm increases the flow by about x5 for small head values, according to my tables. Also, putting the pump as low down as possible helps. Remember that if the pump is only operating on the shower feed, then the 28mm pipework will have to be filled with hot water before you can shower and the pipework will be full of hot water afterwards. The amount of hot water wasted under these circumstances can be considerable if the pipe run is long.

Regards Capitol

[Rob Graham]

It doesn't get any easier does it ?

I'm looking at a 10m plus run - are you saying that that whole run should be in 28mm ? Or is it just the feed to the pump ?

What are the tables you refer to? Are they on the web?

The more I look at this, the more I see difficulties. I cannot get the pump close to the tank and be low at the same time - in fact because the tank sits in between the ceiling joists with its top level with them and is effectively in a high cupboard, the only place to put it close is level with the top ! Either that or is will really have to go at the shower 10m away - which is what one of these power showers would have anyway isn't it ?

Had another look at the tank layout - the tank actually sits just above me and the cupboard extends over my computer desk. I could put the pump into that cupboard but would have to make some effort on the sound proofing.

Rob

[Ian Stirling]

Most tanks sit on the floor of the attic. The pump sits on the floor next to it. If you can fit the pump into the tank cupboard, on its floor, that will be perfectly fine. It's the level relative to the top of the tank, not the absolute level that's important.

The concern is that the pump needs a goodly supply of water. If the pipework cannot supply this, it may start cavitating, and doing damage to itself, as well as having poor flow.

[Capitol]

Query first. Is the pipework feeding a complete bathroom suite as well?

OK, having read more of your situation, I think you may well be better off with a negative head pump. Mount the pump local to the tank and accept that the I/P pipework will have to be 22mm and the O/P pipework 15mm. The noise problem can be alleviated by sitting the pump(which should have rubber feet on it ) on a terracotta outdoor plant tray ( 1.5 x 12 x 12ins)( to catch the drips from the pump seals, which can occur from time to time) then on a piece of foam rubber backed carpeting. Couple the input and outputs with full bore flexible connectors to reduce vibration transfer. Full bore connectors are very difficult to obtain, I've just paid a fortune for specially made full bore 22mm hoses, which looked to be 19mm, but which had an internal bore of 13mm when I measured them. Make sure that the pump connections are accessible for inspection at all times. There's nothing worse than an unexpected flood! Personally I always insert full bore ball valves either side of the pump, so that I can drain down to work on the system at any time.

My tables are a small book by Thomas J Glover called Pocket Reference. It's a US publication, so you have to adapt the figures to UK gallons etc. It's particularly good at letting you calculate the probable losses in a pipework run on a bend by bend and pipe diameter basis. It also gives a useful collection of data on many diy/engineering topics.

Hope this helps Regards Capitol

[Andy Sithers]

I've just a pretty much identical job. Hot Water Cylinder is at floor-level (first floor), Cold tank in attic. No room for pump beside HWC, so I installed on shelf just above tank. Mounted on 40mm worktop, then on its rubber feet, it's *really* quiet (it's one of these, and I'm very pleased). Previous house had a cheaper pump (Aquaforce???) on floor beside HWC. Bloody noisy - couldn't really use it when the kids were asleep.

Pump is fed via 22mm from Surrey flange and dedicated feed in CWT. Fitting flange was a pain - I've a very old tank and numerous adapters had been fitted previously. Also , don't do what I did and fit the MI fittings *before* siting the flange - they made the flange stick out too much, and fouled on the top of the immersion, so I couldn't screw the flange in place.

Outlet is 15mm, running 10m or so through attic to bathroom TMV, which serves bath and shower. Loo / sink still on tank connection. Bleed valves at highest point to allow filling. Not sure I needed these, but that's what the manual said.

Only problem was commissioning the pump - lots of air in inlet pipes. Bring your own bucket.

HTH

Andy