Hot water pump not kicking in on some taps

[DeltaFoxtrot]

Morning all, I’m having some issues with the Bristan Varispeed hot water pump that forms part of my system and am looking for some advice.

I moved into the property earlier this year and at that time the pump (mounted at floor level by the hot water tank) would kick in on the hot supply on both the bath mixer tap and the kitchen tap but not the bathroom basin tap. I did have occasional instances of it not kicking in on the kitchen tap but it would almost always work.

I’m in the process of having a new kitchen fitted and with the new tap (designed for high and low pressure systems) the pump will not kick in. It still works on the bath mixer taps though.

The cold water isn’t run through the pump and is mains fed, with very good pressure.

My question is how to get the pump to kick in on the kitchen taps again, and preferably on the basin too, which has never worked for me. Both will work if you turn the bath tap on to get the pump to activate. For context the kitchen tap that was working before is higher than the basin tap that had never worked for me. Is it a case of an issue with the flow sensor on the existing pump, do I need a new pump, and if so what sort, or is there an issue with the set up that won’t be resolved with a replacement pump?

Thanks in advance.

 

[Harry Bloomfield]

I would guess at the flow sensor requires adjustment..

 

[DeltaFoxtrot]

Thanks Harry. I can’t see any adjustment to the flow sensor though. All I can see is boost adjustment which seems to control how hard the pump works.

 

[Harry Bloomfield]

I was only guessing, I don't have one, never fitted one. Quote the make/model number and someone might be familiar with it, or be able to point to some online instructions.

 

[Deleted member 267285]

Are there any isolation valves fitted to the kitchen tap?

 

[DeltaFoxtrot]

It’s a Bristan Varispeed 50.
Yes there are isolators on both the kitchen and basin taps.

 

[Deleted member 267285]

Isolate the cold to both, and run the hot taps see if that kicks the pump in

 

[DeltaFoxtrot]

No joy with that, but I have found that if I switch on the hot on both affected taps the pump kicks in.

 

[Harry Bloomfield]

It’s a Bristan Varispeed 50.
Yes there are isolators on both the kitchen and basin taps.

Here is the parts diagram, it mentions a flow control..
https://www.showerdoc.com/newteam-varispeed-50-twin-pump-spares

 

[Harry Bloomfield]

No joy with that, but I have found that if I switch on the hot on both affected taps the pump kicks in.

Which means that one tap doesn't have adequate rate of flow, for the flow switch to turn on. There must an adjuster somewhere for the flow.

 

[DeltaFoxtrot]

Well after asking the plumber to take a look at it and a leak developing, leading to replacement hoses it’s now on permanently whether there’s water or not ‍ I’ve tried testing the system for air but it’s still doing it. Looks like a new pump needed after all!

 

[DeltaFoxtrot]

New pump fitted, all the taps work perfectly. Maybe those pumps don’t last more than 10 years in a hard water area..