Increasing hot water flow

Where's the header - feed tank?

In the loft and I can't raise it any higher.

The big snag is most taps these days are designed for high pressure systems. Although you can still get ones for low - but at a price, and you'll have to search. Had the same thing with a posh kitchen 'mixer' so as you've suggested used a pump for the hot water. The rest of the house is ok having the correct taps.

But my basic plumbing is done for a low pressure system - large pipes with bends rather than elbows and carefully designed runs.

Where is the HW flow poor, all taps, or just some?

Normally, gravity fed HW flow is fine for taps.

except mixer, or any other ceramic taps.

F :

Actually the gravity works on the surface of the header tank, which I guess is in the loft. The height of the cylinder isn't particularly relevant.

I've done the former and it works fine. Downstairs hot water (basin, sink) is gravity fed. Upstairs hot water (bath, shower, basin) comes through a single shower-type pump. Cold water is either through the pump (bath, shower) or direct from the mains. A bit of complicated to explain but it all works well in practice.

install a mains pressure tank.

Where is the dribble? Is it a mixer tap? what are the other taps like?

That's assuming you have decent mains pressure. And a pump is cheaper anyway.

But not nearly as good.

On my kitchen mixer, the hot flow is actually greater than the cold with the pump. But I do have pretty poor cold flow here.

All. The flexible connectors and mixers don't help but it's always been poor.

Presumably a tee from the shower pump HW outlet would do the trick, though I'm a little concerned at any side effects on the cold water side of the pump as it will be totally closed when a hot tap is turned on.

I had considered a separate pump on just the HW supply out of the storage cylinder but I expect that would cause problems as both pumps would run with the shower turned on. I can't isolate the shower HW from the rest of the house.

I'm surprised you say all. The cold feed to the hot water tank is usually in 22mm. Also the shower take-off point is not normally the same as for the taps.

Is there any gate-valve or other restriction in the flow? If one hot tap is on, does it make a major difference to the others.

One thing I have done is to use a under sink heater which can run off from mains. Whilst it may not sound economical, the fact that a gallon of water doesn't need to be drawn before getting hot offsets the extra cost.

The cold feed connection into the bottom of the cylinder may be blocked up, as also the top cylinder connection where the hot water draw off is, these scale up quite quick if in hard water area's. If you check the bottom connection drain down well, and be carefull as sometimes the brass connection dezinctifies and can break off

if so install water softener before doing ANYTHiNG else.

It never fails to amaze me that people will put 3 grand or more of expensive plumbing at risk for the sake of a 600 quid softener, and 5 quid a month of salt.

Never used one but there are 'electronic' mains operated units available in the market place that claim to reduce / remove scale build-up over time. Anyone had experience of them? Especially if you have examined pipe internals before and after fitting? If any good cheaper than a softener to buy and run.

Gio

I've not got a water softener in this part of London where the water is pretty hard and not had any problem with my 'plumbing'. Of course you do need to de-scale some things occasionally.

Only one here who claims they work was dribble. QED.

To be fair, when you look at the small print on those, the claim is that the magnetic filed influences the type of crystalline material deposited, rendering it soft and flushable, rather than hard and scaly.

Its almost plausible, but there is no real independent evidence to back it up.