Hot water pump questions.

[Porky Parcheesi]

We have a booster pump in the cylinder cupboard. It's a simple installation (it is just fitted in the hot water supply to the house), but works okay. But there are, as some of you will no doubt be anticipating, a few niggles. Firstly, I would much prefer if it was just activated when the bath mixer tap was operated. At the moment, it responds to any hot tap in the house, which seems over the top, and causes unnecessary noise in the bedroom next door to the cupboard (especially in the early hours). Secondly, you can hear bubbles going through it. This adds to the noise, and I worry a little about cavitation.

So, I imagine a few things I can do about it. I'd like to give the mixer tap it's own pipework. Problem is, I don't want to rip up all the floorboards, so I'm wondering if I can either send the pipe up and over via the loft. Would that be the most usual answer? I can also stick the pump under the bath. The manual says this is possible, and may be the simplest option. Trouble is, then I would still have the problem of the air bubbles. To solve that problem, I could fit one of the various flanges to the supply for the whole house, but then we'd be losing some hot water at the top of the tank. Having said that, since you'd only care about that if you were in the bath, and the bath supply would now be going through the flange anyway, how much of a problem would that be?

Anyway, thanks to all who read this far.

[Grimly Curmudgeon]

Disable the on-board flowswitch and simply fit one in the feed to the bath hot. A lot easier than running or altering pipework.

[Porky Parcheesi]

That is one of the options I've considered, along with putting one in the cold feed to the bath, too. The pump only does the hot water, which means that if you have the mixer on cold when you open it, the hot water never gets to flow. That seemed to me a cheap way of solving that problem without getting a twin pump.

Can I manage without the (surrey, essex, whatever) flange, do you think? Or should I put one in that feeds everything, as I already considered doing?

[John Rumm]

You can so long as you don't go higher than the main cold tank...

Not much. You could use (or make) a warix flange easily enough, and that saves cutting holes in the tank.

[Porky Parcheesi]

A home-made warix flange? Sounds interesting. Would you mind sharing a few instructions? I can't find anything on the web.

[amcmaho]

No. The air bubbles (that come out of solution when the cold water is heated) will airlock the pump. It may work without, but not as well.

Have a look at the price of such flanges from the usual suspects (BES, Screwfix, Toolstation, etc.) before spending time making one.

[John Rumm]

I really ought to get round to drawing one of these for the wiki ;-)

Assuming your tank has a 22mm compression fitting at the outlet, you will need:

Some 15mm and 22mm copper pipe, a 15mm female to 22mm male end feed transition fitting, a 22mm equal tee.

The home made version ends up the connections reversed from the commercial one. i.e. the side outlet connects to the vent / normal hot water, and the top to the pump.

Start by taking a 10" length of 15mm pipe. Place the transition fitting on the end *the wrong way around* - with the 22mm section on the pipe first. Slide this down the pipe (forcing it past the end stop dent in the side) so that you have about and inch or so poking out the normal

15mm end of the fitting, and the rest hanging out the 22mm end.

Now cut a about 1.5" of 22mm copper pipe, and fit that to the bottom of the equal tee. Slide the long end of the 15mm pipe down through the top of the 22mm tee such that the pipe pokes out through the section of 22mm pipe at the bottom. Fit another bit of 22mm pipe to the tee connection and solder it all up.

You now have a fitting where the bottom section is a pipe within a pipe concentric section. The 15mm pipe forms a dip tube connected to the top of the fitting then the pump. The side connection forms the main vent / HW take off.

[newshound]

This almost matches the ingenuity of those Africans who can forge replacement land-rover springs out in the bush!

[Porky Parcheesi]

Thanks, I like it. I probably have most of that lying around anyway. I think our hot water tank is a bit unusaul, in that the threaded bit sticks out, and the 22mm pipe has a flare, which is pulled down onto it by the nut. Judging by the design of some flanges I've seen, my guess is that most tanks have the thread going inside (some come with a threaded adapter, which I'd have needed to use). But if I can salvage enough of that flared pipe (by no means certain, since it has a bend very close to where it somes out of the tank), then maybe I could make something similar.