Shower Pump intermittent every 10 seconds!

[pangers101]

Hi all! I've just moved into a house that has a shower pump in the loft, together with a cold water tank just above it, and the hot water cylinder on the ground floor. The upstairs shower makes the shower pump run when it's turned on, but it cuts out for around 0.5s every 10 seconds. It seems very strange that it cuts out at regular 10s intervals?! The shower pump seems to be a dual impeller negative head pump...

I've tried a few diagnostics so far (bear in mind I don't know much about shower pumps).... I tried a new capacitor, bled for air locks, and also checked the pressure in the pressure vessel was around 1.3bar. It still does it!

There is evidence of some leakage from the pressure vessel (maybe the blue lines shown below) - I don't know if this could be the cause of anything? The PCB underneath it doesn't have any sign of water ingress, but it looks like historically water has been running down the side of the motor. Seems strange if it was water damage that it would stop at exactly 10-11 seconds every time?

If anyone has any ideas it would be much appreciated!

 

[pangers101]

Does anyone have any ideas what this might be please? Cheers

 

[Johntheo5]

Post a photo or give details of make/model, the flow switch(s) may be faulty and the pump may be just start/stopping on the pressure switch.

 

[pangers101]

Thanks, the photo should be above... its a Techflow Turbo 3NH. Whereabouts is the flow switch located and is there any way to check this please?

 

[pangers101]

Also would the pressure vessel slight leak have any impact on anything... maybe air ingress?

 

[pangers101]

Okay I've found a vaguely similar manual and located the flow switches. If I put a magnet on top of these whilst the pump is running then it runs continuously instead of stopping every 10 seconds. As soon as I remove the magnet it goes back to being intermittent.

The magnet makes the pump run continuously no matter which side (hot / cold) flow switch I put it on... any ideas what this indicates please and what I need to do?

Pic shown below with red circles on where I put the magnets (flow switches I think)

Cheers!

 

[Agile]

A test of the flow switch would be to run a tank fed hot tap at about 4 litres per minute.

Sometimes shower pumps have an overheat device but that would take a few minutes to get hot after starting. Does yours do this cutting out immediately after it is turned on?

 

[pangers101]

Yeah the pump just feeds the shower... as soon as I turn the shower on the pump starts, it can be a little rough starting but then works fine, however stops for 0.5s every 10 seconds. The magnet test above seems to get it to run continuously so I'm not sure what that means? The previous owner thought it was air that needs bleeding but I don't think it's that, what do you think?

 

[Johntheo5]

Okay I've found a vaguely similar manual and located the flow switches. If I put a magnet on top of these whilst the pump is running then it runs continuously instead of stopping every 10 seconds. As soon as I remove the magnet it goes back to being intermittent.

The magnet makes the pump run continuously no matter which side (hot / cold) flow switch I put it on... any ideas what this indicates please and what I need to do?

Either of those switches should keep the pump running as you may only require cold or hot water only so thats why either one will keep the pump running, it looks like both have failed, removing one might show up something internally.

Pic shown below with red circles on where I put the magnets (flow switches I think)

Cheers!

 

[pangers101]

Thankyou! Do you mean the switch internal to the pipe or the black sensor on the outside?

I've tried tracking down Techflow but can't find any existence of it - not sure if they're out of business. Would it be new pump time or are there any spares anywhere that fit? I've tried Googling but can't find anything so far

 

[Johntheo5]

Thankyou! Do you mean the switch internal to the pipe or the black sensor on the outside?

I've tried tracking down Techflow but can't find any existence of it - not sure if they're out of business. Would it be new pump time or are there any spares anywhere that fit? I've tried Googling but can't find anything so far

The black sensors look like the pressure switches but not sure, there must be something inside the pipe(s) that rises up to energize the flow switch when flow commences so maybe open one side up and have a look inside.

"In a flow switch assembly, a magnet is placed within a piston that is loaded against a spring which compresses when water flow starts."

 

[Agile]

It could be that the shower flow rate is insufficient to keep the flow switch on.

You should measure the hot flow at the shower head. The manual should say what flow rate it will turn on at. The one here turns on at just 1 li/min.

Now have you been cleaning the shower head holes of lime scale? Easiest done with a pin or paperclip or acid.

 

[pangers101]

Thanks guys, I've tested the flow with the pump running and it's between 7-10 litres per min.

 

[Agile]

Well without knowing the pump spec that is going to be way over the minimum.

A typical combi boiler is about 2 li/min!

Might be worth inspecting the magnetic floats in case something is partially restricting their movement.

 

[HERTS P&D]

Time for a new pump:

Stuart Turner Monsoon Universal Regenerative Twin Shower Pump 3.0bar - Screwfix

Order online at Screwfix.com. Positive and negative head. 3.0bar. Premium quality brass pump designed for installation into vented systems to pump both hot and cold water supplies, boosting both equally to an individual shower, complete bathroom or whole house. FREE next day delivery available...

www.screwfix.com

Andy