Shower issues

[Matt7x5]

Had a new bathroom fitted approx 4yrs ago now had issues with the Salamander pump from day one so swapped to Stuart Turner got a 2 bar Positive head pump but still had problems so got a plumber in who told us it had been installed incorrectly. Had a Surrey valve fitted to the hot water tank & a dedicated pipe from the hot water to the pump also had a new Stuart Turner 2 bar Universal pump installed however we started to get no hot water coming through if you turned the shower to cold it blasted through but turn it to hot only got it dribbling out eventually after turning from cold to hot numerous times the hot water would start coming through full force & the shower would work pretty much ok for the rest of the day. After googling & talking with the plumber plus having an issue in the past decided to change the thermostatic bar. When first done all worked ok but next day got same issue but if you switched to the hand held it starts running fine & can switch back to the overhead. Anyone got any ideas why it is doing this? Everything is now plumbed as it should be now

 

[terryplumb]

Is the cold feed to the shower from the same storage tank that supplies the hot water cylinder ?
For some reason there appears to be insufficient flow on the hot water to trigger the pump.

 

[plumblddy]

It sounds like there is air slowly building up in the hot feed somewhere, eventually causing an airlock which is slowing the flow enough to prevent the pump being triggered. Where is the pump located in relation to the hot water cylinder?

 

[Matt7x5]

Is the cold feed to the shower from the same storage tank that supplies the hot water cylinder ?
For some reason there appears to be insufficient flow on the hot water to trigger the pump.

 

[Matt7x5]

It sounds like there is air slowly building up in the hot feed somewhere, eventually causing an airlock which is slowing the flow enough to prevent the pump being triggered. Where is the pump located in relation to the hot water cylinder?

The pump is in the loft situated below the cold water tank & the hot water cylinder is in the airing cupboard. Not the preferred location but it worked fine for a couple of years where it is.

 

[Madrab]

Have you checked the pump's EV pre-charge?

You are right though, the position isn't the best.

Everything is now plumbed as it should be now

Unfortunately though, have to say, it's not really, it is in a non preferred location, as per ST's MI's. Experience has proven that most flow/air issues come from pumps that aren't located by the base of the cylinder.

 

[Matt7x5]

Yes I have checked the pressure vessel & the pressure on that is ok. Can it cause problems if the pressure is higher than stated?

 

[plumblddy]

Have you checked the pump's EV pre-charge?

You are right though, the position isn't the best.


Unfortunately though, have to say, it's not really, it is in a non preferred location, as per ST's MI's. Experience has proven that most flow/air issues come from pumps that aren't located by the base of the cylinder.

What he said.....

 

[plumblddy]

A pump maybe worked in that loft position before but once you start changing things, all the little tolerances on each individual bit of the system cam combine to make it a borderline situation.
Maybe your shower valve is more restrictive. Maybe feed pipes have got a bit furred up. Maybe an isolating valve has been added or maybe one is blocked or corroded.

Some things to try -
See if the pump operates okay without the shower valve on. You can fit temporary isolation valves on the outlets for this purpose.
Check the filters on the shower inlets and the pump
Can you remove the non return valves from the shower inlets (if it has them)?
Check for any dips and rises in the pipework on the pump feeds.
Remove any old corroded fittings.
Feed the hot side of the pump in 22 not 15.
If all else fails you'll have to site the pump at the base of the hot cylinder, where it should be.

 

[Matt7x5]

A pump maybe worked in that loft position before but once you start changing things, all the little tolerances on each individual bit of the system cam combine to make it a borderline situation.
Maybe your shower valve is more restrictive. Maybe feed pipes have got a bit furred up. Maybe an isolating valve has been added or maybe one is blocked or corroded.

Some things to try -
See if the pump operates okay without the shower valve on. You can fit temporary isolation valves on the outlets for this purpose.
Check the filters on the shower inlets and the pump
Can you remove the non return valves from the shower inlets (if it has them)?
Check for any dips and rises in the pipework on the pump feeds.
Remove any old corroded fittings.
Feed the hot side of the pump in 22 not 15.
If all else fails you'll have to site the pump at the base of the hot cylinder, where it should be.

Thought the issue might have been the thermostatic shower bar so had a new one on & still the same. What's strange though is once you get the hot water coming through then the shower works fine most of the day. The plumber I use said all the pipe work is as it should be now so as you said it's probably an imbalance & will need to move the pump position.

 

[Johntheo5]

IS the pump single ended with just the hot pumped? or is the cold pumped as well? Is the pump actually running when the hot problem commences?

 

[Matt7x5]

No it pumps both when the problem occurs the pump is running. If you turn the shower to cold it comes out full force but if you turn it to hot then water just dribbles out cold eventually sometimes by turning from hot to cold a few times or just leaving it on hot then hot water starts flowing full force. Then the shower works pretty much ok the rest of the day.

 

[Matt7x5]

Thought the issue might have been the thermostatic shower bar so had a new one on & still the same. What's strange though is once you get the hot water coming through then the shower works fine most of the day. The plumber I use said all the pipe work is as it should be now so as you said it's probably an imbalance & will need to move the pump position.

Only problem is there isn't any room to put the pump at the base of the cylinder so just wondering if it's ok to put it as close to the base as possible?

 

[Johntheo5]

Can you post a few photos showing surrey flange and pump position, pipework etc?

 

[tincup]

The pump needs to be at the base of the cylinder to detect hot water flow. if it was above the tank it would likely get a air pocket when pump switched off and the water returned to the tank.
The set up better suits a negative head pump but they cost more.