Pumped hot water system losing pressure

I have a Stuart Turner Monsoon 2bar pump for my hot water system fed from a hot water cylinder. It's still under warranty.
The pump keeps cycling for a few seconds every few minutes, night & day, despite no hot water being used. If I isolate the output side, the cycling stops.
My cold water supply is more than 2bar judging by the pressure at the taps.

Stuart Turner technical support say I'm losing pressure in my hot water system & the pump or its non return valve aren't at fault as proven by the isolation valve test. They suggest I get my system pressure tested. They say it could be caused by a mixer tap feeding back, a water leak or some other reason.

Not being an expert, all I can say is I'd have noticed a water leak by now (ongoing for 2 years) if I had one. As cold pressure is higher than hot, I can't see a mixer tap being the problem. I've no idea what other reason there could be.

Before I call in a plumber to pressure test the system, does anyone have any suggestions about what could be causing the problem?

Many thanks.
Paul

 

Are you sure you're actually losing pressure and that the pressure switch isn't faulty? Do you have a pressure gauge you can monitor? Turn the power off to the pump for a few hours and confirm that the pressure is in fact dropping.

 

Are you sure you're actually losing pressure and that the pressure switch isn't faulty? Do you have a pressure gauge you can monitor? Turn the power off to the pump for a few hours and confirm that the pressure is in fact dropping

If I switch off the electric supply to the pump, all I get is a very low pressure feed as the pump isn't boosting it - hence the need for a pump in the first place.
The pressure switch could well be faulty but they say the pump isn't at fault & want to charge me £120 for a call out if it's my system rather than their pump that's causing the issue.
I don't have a pressure gauge.

 

That is really a strange way to boost pressure to a shower. That pump has a hot and cold section.

Here in the States we increase the household pressure and the shower pressure rises accordingly.

According to the specs on that pump is monitors water flow to trigger... not pressure.
Monsoon U2.0 Bar Twin - Domestic Water Boosting Shower Pump

I agree a pressure gauge would be helpful but where would you connect it ? That is a problem. There are no fittings at the pump that I can see.

 

It's a single sided pump. Only the hot is pumped, as cold is high enough pressure anyway.
HTH

 

Other than a pressure switch potential issue, does anyone have any other suggestions for me please?

 

Is this the only location where the hot water pressure needs to be increased ?
I'm still stuck on the need for a booster pump.

 

It used to be common plumbing practice in the UK that hot water was held in an insulated cylinder fed by a header tank. The pressure at the tap was only as good as the height of the header tank above the tap. In my case, perhaps only 6 feet in an upstairs tap. Therefore, pressure is low & a pump is needed between cylinder & tap to boost pressure.
Cold water is at much higher pressure as the header tank (reservoir) is up in the hills.

 

I understand the header tank for hot water but you would expect it to be the same pressure as the cold water as it's fed with the same cold water source.

Anyway... I'm not sure there is anything I can add to help you not being totally familiar with your system.

 

Thanks for the help pjmax.
Cold water is at mains pressure ie full bore from a 15" pipe in the road directly connected to a huge reservoir via massive pumps. Hot is very much lower pressure as the water head is only a few feet hence the need for a pump for hot only.
Crazy Brits eh?