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Total Members Voted: 3

[Michael2.6]

What are you calling the hot water tank

The copper cylinder?

[chrisgixer]

You need to move your storage tank onto the roof.

Have wondered about that, hot water tank is on the landing. Cold water tank is in the loft.

We could extend into the loft for the sake of a tap, as a more sensible option though.

[MR MISTER]

What are you calling the hot water tank

The copper cylinder?

We call ours John.

[chrisgixer]

Chris, where is your pump in relation to your cold water tank ?

Pump needs to be a minimum of 1 metre below lowest point of the cold water tank .  Usual set up IMO is cold  tank on a stand in the loft & pump in bottom off airing cupboard . That should give a gravity head of 2.5 -3 metres  which should work fine 

Gravity hot water is dependant on the height of the cold header tank in the loft . The "head" between the hot tank & the cold tank is the critical factor . As long as the cold tank is in the loft , you can have the hot cylinder on the ground floor & hot water will still flow well to the upstairs  hot taps provided they are at least a meter or below the cold header tank .  .A pumped  Shower hot  should be fed off of a "surrey flange"  on the hot water outlet of hot tank, rest of hot water to house should be  direct from outlet of hot tank so should not be pumped 

Wot sort of plumber you using / . . . he sounds a bit " unsure" of himself 

HTH 

He is a heating engineer. He installed the new boiler. And fitted a new central heating system in in a friends house. Seems knowledgable generally, if you can get hold of the bugger. Although he did ask advice on the tap itself, and it was then suggested to change the tap, as mono blocks are "renowned for it" he said.

May be, but there must be away round it surely...?

I'm tempted to fit a hose from the mains onto the the tap and blast vold water up it to clear any sir lock, but I'm not sure that's wise on a hot tap?

I should add, as I've just realised, the hose won't work as there's a one way valve on that pipe anyway.

[chrisgixer]

What are you calling the hot water tank

The copper cylinder?

We call ours John.

Emersjohn.

[Michael2.6]

Nice one STEMO

[MR MISTER]

What are you calling the hot water tank

The copper cylinder?

We call ours John.

Emersjohn.

Grooooooaaaan. You daft bastard. 

[chrisgixer]

What are you calling the hot water tank

The copper cylinder?

We call ours John.

Emersjohn.

Grooooooaaaan. You daft bastard. 

[Taxi_Driver]

If a recent issue that was previously fine, then I suspect the flow switch on the pump is the culprit

Question is either if it is partially blocked or failing How old is the set up?

Problem has been present since that tap was installed. But now we have the pump fitted it refuses to flow at all until the pump is activated by the turning on another tap elsewhere in the house.

Changing the tap, probably would fix the problem, but as you dont want to do that, I'd suggest having a look on the pump to see if you can increase its sensitivity, if not try another pump that is more sensitive.
I used to have 2 pumps in a bungalow I lived in. One was a 3bar pump for the shower and a 1bar pump for all of the other hot taps.
BTW the 'head' height is from the cold water tank to the ground, not to the hot water cylinder.
In the bungalow the i had the hot water tank in the loft, with the cold water tank (coffin type) just barely inches above it.
So , try the pump options IMO

[Rods2]

I have recently looked at this issue as many taps now require a minimum bar reading to work. They are fine when the hot water is pressure fed from the mains with a combi boiler, but you cannot get enough fall from the cold water tank for the tap work. Where I am just getting all of the stuff sorted out for fitting a new bathroom I have gone for a more expensive (compared to cheaper high pressure) low pressure taps. My en-suite shower was always low pressure, so years ago I fitted a surrey valve and cold / hot pump.

On the continent they generally have no cold tank (ours is a Victorian intermittent supply legacy) and direct mains pressure to the hot water tank. The hot water tanks are very well insulated and use an immersion heater. The one in the Ukraine also have a built in thermometer. Where we are in the EU, cheap high pressure taps are becoming more and more common.

My suggestion would be to look at pump pressure sensitivity and if this doesn't fix it then replace with a low pressure tap.

Your tap has a 0.5 bar minimum which requires a minimum 5m (16' 5" drop). If your house has a standard 8' ceiling height plus 8" first floor rafters and 6" in the loft, then you don't have enough water head height where your kitchen cabinet and sink are 3' off the ground. If the loft height allows you could mount the water tank 3' off the loft floor on stilts, but this maybe a lot of work for no improvement or alternatively suggest to SWMBO that you have the perfect solution and she can keep the mixer tap, "we will have an inset into the floor sink to get the water pressure" and then beat a hasty retreat. 

[jonathanh]

simple answer, just use a pump for a situation with negative head such as the link below

http://www.screwfix.com/p/salamander-esp80cpv-negative-head-shower-pump-with-single-impeller-2-4bar/69296

[SIR Philbutt]

It sounds like the tap needs to be on the pump's cold and not the mains. The pump needs to see both flows to start

hth
P

Tap cold is on mains. Works fine. High pressure.

Tap hot is on pump from water tank on landing. The drop is barely a meter from the foot of the tank.

There is another hot tap in the downstairs loo. This runs ok, although that tap is furred up with lack of use. But it does flow. Just.

Is this a mono tap and is the cold to this on the mains or pump cold

[Andy H]

Monoblock tap with 10mm tails and the head from a roof tank should pass enough water to get the pump going.

I had a monoblock tap with 8mm tails in my last house fed by gravity. It was slow but it was usable (just).

I suspect either a fault or a blockage in the tap combined with some other problem in the existing pipework.

Because the ports are so small in a ceramic disc tap it is easy for them to get blocked with crap  (either swarf already in the tap or something stirred up in your pipework.)

It is difficult to fit a pump without introducing high points where air can collect and cause airlocks, worth checking that all the air has been bled from the system.

[SIR Philbutt]

You say you have a plumber

Why can he not fix the problem is it because of the price he has given you?

Is the boiler a combi or not

Oil or gas?

Plumber suggests replacing the tap due to the restrictive bore.

We don't want to o this as its exactly the tap we want.

Combi couldn't keep up with a pump. The two are not comparable, so we have to have a hot water tank to feed said pump. As said this is on the landing.

Its gas.

Absolute NO No  in my book  . . .  .you should never  use a pump on a combi boiler

PM   sent  Chris

totally agree with this - If it's a combi you do not need a tank or a pump everythis should run from the combi at mains pressure

[chrisgixer]

You say you have a plumber

Why can he not fix the problem is it because of the price he has given you?

Is the boiler a combi or not

Oil or gas?

Plumber suggests replacing the tap due to the restrictive bore.

We don't want to o this as its exactly the tap we want.

Combi couldn't keep up with a pump. The two are not comparable, so we have to have a hot water tank to feed said pump. As said this is on the landing.

Its gas.

Absolute NO No  in my book  . . .  .you should never  use a pump on a combi boiler

PM   sent  Chris

totally agree with this - If it's a combi you do not need a tank or a pump everythis should run from the combi at mains pressure

... obvious really, tbh. The whole system upgrade has been designed around the pump improving the shower. It was then improved further by increasing the pumps use to include all non mains fed taps. Good pressure, but bit noisy.