Water pump cycling

ironmonkey

Hi all. Another advice thread. Any suggestions greatly appreciated. The water pump (grundfos pm1) which feeds the hot water tank and w load of other pipes in the utility room has started coming on every five minutes or so. It’s obviously more apparent at night but I think it’s the same interval during the day. Every five minutes or so for about 15/20 seconds.
I’ve checked everywhere for a leak. No running toilets, no taps dripping.
The system has been in place for four years and it’s underfloor hearing downstairs radiators up stairs.
Thanks all

ironmonkey

Picture here

Calahonda52

IMO, The bladder in the blue pressure vessel is gone.
If taking it off your self, just be aware it will be full of water so could be heavy.
I learned this from experience

ironmonkey

Thanks for that
In the blue fella on the wall here?

ironmonkey

Sorry for some reason that came out sideways

10-10-20

That kink in the flex-pipe to that pressure vessel could be a contributor too.

ironmonkey

The blue one is the pressure cylinder ?
This was mounted on the wall and then fell off banging that kink in the pipe. It was then remounted. That was a year ago now though. This cycling only started two days ago.
It seems that this pump is for hot water?