Shower pump on pipe with vent?

[James1979]

Hi - this is a complicated setup but will try to explain...

Hot water cylinder already has an Essex flange that I fitted which leads to a 2.6 bar Stuart Turner pump. This only feeds one shower at the moment - negative head but universal pump fitted.

The rest of the hot water taps are supplied via the normal supply pipe from the top of the cylinder that comes out in 22mm down through the floor to taps and tees up to tank for vent pipe.

Issue is that since having some work done and kitchen moved, the pressure at the hot water taps is now very low. The pump I've got would be strong enough to do them all but my question is whether I can just splice into the 22mm that also has the vent pipe on it and cap off the exit pipe from top of tank or would the pressure from the pump also force water out of the vent pipe?

Thanks in advance,

 

[Madrab]

Did you have taps/pipework changed? Chances are the new stuff isn't designed for gravity fed hot water and shouldn't have been fitted with your setup.

No, you wouldn't want to pump the same pipework that the vent is on.

The way around it would be to cut and cap the supply pipe after and below the tee where the vent heads up to the cold supply area and down to the house HW supply, that way all you'll have is the open vent heading up.

Then connect the outlet of the pump, that's being fed via the essex flange, to the main HW supply pipework that was cut and tie the shower supply into that too, that way everything is fed from the pump outlet and the vent is just the vent. That being said it's not ideal and you could come across issues if any of the HW pipework/outlets, that have previously all been very low pressure, has issues with the increased pressure.

 

[James1979]

Hi - thanks for the reply - that all makes sense to me. So the pipe leaving the top of the cylinder would only 'feed' the vent pipe into the tank?

Pipes were changed with the building work but only 15mm copper for 15mm speedfit but run is increased a fair bit so I thought that would explain pressure drop. 2 new mixer taps have been fitted (one in utility and one in kitchen) but they replaced 2 old mixer taps so didn't think that would be an issue. Is there something to look for on new taps that makes them more suitable for gravity fed?

I'm guessing ideal situation is a separate smaller pump (1.5 bar?) to feed HW around house - only issue is providing it with a dedicated hot water feed as there's already an Essex flange unless the Essex flange pipe can be tee'd before it reaches existing pump so it feeds two pumps?

Thanks again- really helpful.

 

[Razor900]

You don't say if the existing pump is single or double impeller?

Its a bad idea to run a twin pump on one side only it kills them

 

[James1979]

Hi - it's a double with both sides hooked up to the shower. They'd both still stay connected but the hot would be used twice as much so guessing that is not good? Might have to go for the separate pump solution.

 

[Madrab]

Yes, it would only be a vent.

Mixer taps aren't all made equal. When you have a gravity fed system always check the min that the tap will work properly with (0.1bar), either that or they will be referenced as low or high pressure taps.

What ST pump do you have?

You can't run 2 pumps from the same feed, one or the other will get starved.

 

[just pumps]

You don't say if the existing pump is single or double impeller?

Its a bad idea to run a twin pump on one side only it kills them

Some now have a tube running from one end to the other so you don`t, think ST do it on some pumps.

 

[just pumps]

What ST pump do you have?

You can't run 2 pumps from the same feed, one or the other will get starved.

That really depends on how they are supplied.
https://www.diynot.com/diy/threads/shower-pump-replacement.566971/

 

[Razor900]

Some now have a tube running from one end to the other so you don`t, think ST do it on some pumps.

Thats good to know. Do you know any specific models that I can look up it may come in handy some day

 

[just pumps]

Thats good to know. Do you know any specific models that I can look up it may come in handy some day

Can`t be certain, remember coming across it a few months back on ST site when trying to help a poster, start with the Monsoon range.

 

[Madrab]

That really depends on how they are supplied.

Surely if they are fed from a cistern supplied single 22mm pipe then either one or both could be starved, even a 28mm feed may struggle depending on the pump(s) and shower output? I was always of the approach never to have more than one pump on a single pipe?

 

[just pumps]

Surely if they are fed from a cistern supplied single 22mm pipe then either one or both could be starved, even a 28mm feed may struggle depending on the pump(s) and shower output? I was always of the approach never to have more than one pump on a single pipe?

I agree in general terms when fed from a tank and await intel on just how the OP has fed two for years unless there is a strict one pump in use at all times policy.

 

[Madrab]

Hot water cylinder already has an Essex flange that I fitted which leads to a 2.6 bar Stuart Turner pump. This only feeds one shower at the moment - negative head but universal pump fitted.

await intel on just how the OP has fed two for years

I think the OP has only one pump at the moment?? Or did I misread something along the way?? I think the 2 pumps may be aspirational?

Thats good to know. Do you know any specific models that I can look up it may come in handy some day

Not sure if ST use that tech but I do know that Salamander uses a crossover tech, allows the non open side to be fed and release flow to the side that's open, they use it on their CT force pumps I think.

 

[Madrab]

how the OP has fed two for years

Ah, are you talking about another thread where the OP has 2 pumps that are now leaking?

 

[just pumps]

Ah, are you talking about another thread where the OP has 2 pumps that are now leaking?

It is the thread that I sent a link to, one for main bathroom and another for en-suite, both need changing.