Pump Cycles when Hot Water Turned Off

[r.rain]

Hello All

I have just realised that my pump which powers my thermostatic shower cycles on and off when I turn the hot water tap off in the bathroom (haven't tried any others) The pump only powers the shower and is fed from an essex flange installed into the HW cylinder. This cycling also happens when the shower thermostat it set to a certain temperature and the shower valves are off, see other postings!

I'm guessing here that there is something wrong in the way I installed the Essex flange or there is air somewhere in the system?

Anyone have any ideas on this, surely this should not happen.

TIA

Cheers

Richard

[Capitol]

You need a 22/28mm check valve in the output side of the pump IMO. The cycling is caused by water surging backwards and forwards through the flow valve. This is another indication that the input to the pump (and possibly also the hot water tank) is inadequate, and the pump is trying to suck water from the hot water tank air venting system.

Regards Capitol

[r.rain]

Hello

Is this the same as a non return valve?

What is the hot water tank air venting system? I have a vent pipe that exits the top of the HWC which goes to the Cold water tank (The One that feeds the HWC).

Cheers

Richard

[Set Square]

I presume 'One' refers to tank and not pipe!

[You should have a vent pipe from the top of the HW cylinder which goes up and over the top of the cold water tank. You should *also* have a feed pipe from the bottom on the cold water tank, feeding into the *bottom* of the HW cylinder.]

Going back to the original question, what is supposed to trigger your pump - is it flow, or pressure?

[r.rain]

Flow is supposed to trigger it, I think. I dont understand why by turning my hot water taps off should force the pump to cycle. I thought the whole idea of having a flange was to keep these things seperate so they would not interfere. Damn shower has given me soooo much grief and everyone I speak to has a different opinion. Should of stuck with a power shower all in one jobby like I ripped out...........

I'm waiting for another call back from the pump people Stuart Turner at the moment

Cheers

Richard

[John]

1. Is the pipework for the pump "elastic" i.e. plastic?
2. Is the feed pipe from the cold water header into the cylinder restricted in any way?
3. At the end of the day is it really important that your pump pulses or not?
4. Can you not incorporate an interlock with the shower room light or fan?

[Set Square]

The Essex flange ensures that hot water is drawn from a point some inches below the top of the hot cylinder - thus preventing air from being sucked in from the vent pipe.

It sounds as if something is causing a small amount of flow to occur at the point where it is detected by the flow switch. Does the pump cycle continuously once it starts? What are the approx on and off times?

Where does the cold feed for your shower pump come from?

Does the problem still happen if you turn the bath tap off very slowly rather than suddenly?

Hopefully, the pump is on a separate electrical circuit with its own isolator switch - in which case, as a short term solution, you can turn it off when not required.

[r.rain]

Yes it is

Haven't checked that but would hope not, I dont seem to have any other problems

Not when the hot water taps are turned off, this just happens the once. What is more concerning is that this happens when the thermostatic control on the shower is set to hot and both flow vlaves are off. In this case sometimes the cycling won't stop until I move the dial to another temperature setting. It may just be that the cycling would eventually stop but it really shouldn't be doing this surely.

Thanks for your response

Cheers

Richard

[r.rain]

When the hot water taps are turned off it only cycles once on and then off for 1 second in duration. Other times when it happens after using the shower it will continuously pulse on and off like every second or so and it seems a steady rhythm until I move the temperature gauge when it will stop.

Not sure will have to test that one out.

It is but it's in the loft, which is where the HW cylinder, Cold tank and pump is located. I decided against one of those horrible string pulls.

Cheers

Richard

[Capitol]

Yes. Screwfix 11124. There is probably some air being released/trapped in the pipework, or a degree of expansion/contraction in rubber connectors, so when you turn off the water flow, some water runs backwards through the pump, over does the correction, then the water flows back through the pump in the normal direction, causing the pump to turn on. Then the cycle repeats. Another solution is to adjust the flow valve to make it less sensitive. This problem normally occurs in the hot supply, so a check valve in the pump hot output usually prevents the problem from happening.

Regards Capitol

[r.rain]

The pump expert thinks this too, he suggested fitting a bleed valve in the pipe work, never seen these before only in rads. He also thinks there is a problem with the shower valve too. I have the shower engineer coming Friday so hopefully he can get it fixed for me.

Thanks for all your help

Cheers

Richard

[r.rain]

The pump expert thinks this too, he suggested fitting a bleed valve in the pipe work, never seen these before only in rads. He also thinks there is a problem with the shower valve too. I have the shower engineer coming Friday so hopefully he can get it fixed for me.

Thanks for all your help

Cheers

Richard

[r.rain]

The pump expert thinks this too, he suggested fitting a bleed valve in the pipe work, never seen these before only in rads. He also thinks there is a problem with the shower valve too. I have the shower engineer coming Friday so hopefully he can get it fixed for me.

Thanks for all your help

Cheers

Richard