OT: [DIY] Shower Pump and WC cistern

[Andrew May]

Sorry to interrupt all the Brexit discussions but there may be one or two here who can answer a DIY related question.

Scenario: One bedroom flat with cold water tank and hot water cylinder in the flat - so very little in the way of water pressure. Have added a pump to the whole system that on the whole works well. Turn on tap, pump turns on, plenty of water pressure. Turn off tap, pump turns off. Turn on shower, pump turns on, plenty of water pressure. Turn off shower, pump turns off.

But the WC cistern has a ball valve. Flush WC. Cistern empties. Valve starts letting water in, pump turns on, pump turns off, pump turns on... until the cistern is full.

Is there any way of preventing this? I guess what I need is a cistern valve that will fill the cistern fast enough that the pump never turns off.

What does the team think?

[www.GymRatZ.co.uk]

I'd kind of switched off completely to all that stuff and eradicated a few persistent offenders from my feed nice to have something to tax the grey matter. :)

I'm not suggesting this is the solution but throwing it out for discussion:

I wonder if a C/H expansion vessel plumbed into the cold feed would help? It would have to be down-stream of the pumps flow-switch but the way I'm thinking it would act as a pressure buffer providing it was pressurised to slightly lower than the pumped pressure. If you had one with sufficient charged volume to match that of the toilet cistern it /may/ fill the loo in one pump cycle.

My thinking is telling me that you might want to consider a 1-way valve to prevent stored pressure in the expansion vessel from feeding back into the header tank.

Things to consider /might/ be premature wear of the expansion vessel diaphragm with so many "full cycle" operations but you might get that info from manufacturer.

Again, not saying it's the answer just a possible solution to consider and one I think I'd certainly try as it's only tapped off the pipe and wouldn't cause a problem if it didn't work as planned.

Thoughts?

Cheers - Pete

[www.GymRatZ.co.uk]

p.s. I very nearly put a filter on to not see subjects with OT: to cut down on political banter so by adding it in a whimsical way you may just have eliminated some of the very people you were targeting for a non-brexit, D-I-Y related solution.

:)

[Nightjar]

Does the WC really need a fast fill? I would fit a low pressure valve and feed it direct, bypassing the pump.

[Chris J Dixon]

I'm wondering if the flat actually has the (mandatory?) feed to cold taps direct from the main?

I would agree that you shouldn't have the pump feeding the cistern.

Chris

[Capitol]

Adjust the flow switch in the pump so that it stays on until the cistern is filled. Works for me.

[Andrew May]

WC does not need a pumped supply but bypassing the pump would mean running a dedicated feed under a concrete floor back to the tank.

[Andrew May]

It does to the kitchen, not to the bathroom.

[Andrew May]

I have not found a flow switch. I will take a look. But what will the effect be? Turn it up and the pump will keep running even though there is not enough water being taken? Or turn it down so the pump doesn't come on if only a small flow is being used?

[newshound]

My cisterns are both off the mains. Any way you can tap off the feed to the tank, or extend from the kitchen tap?

[Andrew May]

Not easily. Pipework is all behind tiled walls. When the bathroom is replaced, maybe but until then I was wondering if there was an easy fix to stop the pump cutting in and out.

[Capitol]

The flow switch is normally a tapered magnet cylinder inside the outlet flow pipe which is moved by the water flow,past a set of externally nounted switch contacts which clamp to the outlet pipe. The external contacts can be moved up and down the mounting point to determine the flow rate at which the pump operates.

[Scott M]

Presumably the morse message of pumping is more pronounced as the flow is reduced by the ball-valve? In which case, one of the pressure balanced type which give constant flow until they shut off. IME the FluidMaster sort are quite high flow.

[Andrew May]

Just to follow up on this - it was easier than I anticipated. It turns out that the ball valve has a choice of flow restricters, a white one installed and a red one clipped to the arm. Swapped them over and it fills without turning off the pump until it has finished.