Hot water doing strange things upstairs....

[p3dro]

Hi all,
Last year around March/April we had our upstairs bathroom re-fitted. We had a new shower with mixer tap, a new sink with mixer tap and a new bath with mixer tap, plumbed in that order / sequence.

All has been working perfectly until about a week ago....

We started noticing a single squeak (a bit like a bird was trapped in the rain-shower head, every few minutes. Almost like a single droplet coming out but in reverse! No mount of jiggery with the mixer controls stops the noise.

Not sure if that has anything to do with the bigger issue though, which is, we are now unable to get hot water out of any of the upstairs taps (bath, sink, shower) Opening any of them to full just wont fire up the boiler!

Interestingly the kitchen tap next to the boiler fires up fine and hot water comes out no problem.

The only way to get hot water upstairs is to open the tap you want, and then while its running, open (on hot) one of the other taps in the bathroom momentarily! The boiler then fires up & we can close that tap and carry on with the sink / shower / bath running which the boiler continues to heat water for.

The pressure is really good on hot and cold upstairs, and the boiler is heating the rads well with the correct pressure (1.5)

I've heard a couple of theories that perhaps one of the mixers has failed and therefore cold is circulating in the hot pipes and therefore not firing the boiler. Or that the pressure is too low for the boiler to recognise with just 1 tap upstairs by itself but why has this only just happened now - anything to do with the change in weather / mains water pressure mains temp??
Or perhaps even there is a fault in the boiler that is not as sensitive as it should be...

P.S. Boiler is a Baxi Potterton MAIN Comi 30 HE

Can anyone please point me in the right direction or know of a way to test any of the potential causes? Does the above sound familiar? Is the 'shower squeak' linked??

All advice gratefully received!

Thanks very much,
P

 

[terryplumb]

The issue is more likely to be on the boiler ,rather than all three taps suddenly not giving sufficient flow to trigger the boiler.
Is your boiler regularly serviced, properly ,not just a ten minute peek and probe job ?

 

[p3dro]

Hi Terry, thanks very much for your reply!
We moved in, in mid 2019. It was not serviced in 2018 but was in 2017 apparently according to the seller's paperwork (gas safety cert - it was a rental before we bought)
We had it serviced in Jan 2020. It is due it's annual service this month.
Is there a particular part within the boiler that can fail and may cause this issue if not cleaned / replaced??

I thought the same as your suggestion re the 3 new taps & their flow however, where I get brain-freeze is - if just 1 of the new mixers were to stop functioning properly and let cold water in through to the hot pipes, could that be somehow coming out of the other 2 hot taps when opened and thus not allowing sufficient drawing of hot water through from the boiler?

I hope question makes sense?

Thanks again,

P

 

[terryplumb]

Your boiler needs a flow of around 3 ltrs per minute ,from a hot tap, to trigger the device in the boiler that kicks the boiler into life to heat your tap water. If you turn on fully one of your hot taps ,(that currently does not fire up the boiler), run it into a bucket for 1 minute ,then measure how many litres of water is in there.
If it's less than 3 litres ( which would be pretty dire flow) then the tap is an issue. If it's considerably more than 3 litres the boiler should fire up . If it doesn't the boiler sensor is duff.

 

[p3dro]

Thanks again Terry....I'm off to find a bucket!
P

 

[terryplumb]

Ha ha ...don't kick it

 

[p3dro]

I measured 8 ltrs per minute! Did it twice at different times to make sure...
P