Suspected Leak in Hot Water system vs Cylinder behaviour?

[stormyuk]

Yes, you could say "nothing to see here, move on" but is intriguing if nothing else but very few would notice that small change in usage anyway.
Would that period of no usage coincide with heavier cold water usage I wonder.

No water usage at all, I've purposefully not used any water at all for that time period to get a read on the behaviour.

So it's probably likely in normal usage scenarios it's probably letting more water into the tank but, this is an almost fake scenario with no water usage over that time frame.

It's definitely something on the HW side considering if the cold supply to the tank is turned off water usage is exactly zero over the same time period.

 

[John.g]

Maybe your neighbors were using more water during this period resulting in lower mains pressure at your stopcock.

 

[IND_Nick]

Do you know what the main incoming pressure is at your property. It could simply be that in the morning as more people are using water the pressure in the mains is lower, during the day the pressure increases in the main and this pushes through the combination valve and into the expansion vessel capacity, especially if the mains pressure, in the morning, is below what the PRV would shut off on.
If you had a leak of 1 ltr a day it would normally be very apparent quite quickly.
Just a thought.

 

[John.g]

Something like that but if a PRV is working properly then it should only open if there is some demand for water, however little, and any mains pressure rise shouldn't open it as its balanced unlike a PRV (safety valve) on a boiler which isn't balanced. When used as a Auto Fill valve for system make up (and left open) they must also be drop tight.

 

[stormyuk]

Do you know what the main incoming pressure is at your property. It could simply be that in the morning as more people are using water the pressure in the mains is lower, during the day the pressure increases in the main and this pushes through the combination valve and into the expansion vessel capacity, especially if the mains pressure, in the morning, is below what the PRV would shut off on.
If you had a leak of 1 ltr a day it would normally be very apparent quite quickly.
Just a thought.

No not sure on my pressure, think I am going to see if I can buy a cheap gauge as that's something I can probably check easily with say my outside tap which is pretty much at the stopcock.

Speaking to my neighbour again with the same Tribune XE his system exhibits similar behaviour although he's not logged it like me..

He is often away and after he has been away for a week (he turns his stopcock off while away) after he returns and puts the water back on his tank 'fills' for a while.