Valliant AquaPlus VUI 362-7 Help!

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Hi all,

After some help with my AquaPlus boiler.

The boiler seems to be rising pressure on the gauge with the cold water service valve open as normal. I’ve closed the valve currently without use of the boiler as I’m getting a constant trickle of water through the outlet pipe to my driveway outside.

I can only assume a valve has gone which is holding the cold water pressure back (relatively high pressure mains supply in property).

Can anyone advise which valve I should be looking at getting replaced?

Thanks

Andy
 
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Images of underside of boiler and install.

image.jpg
image.jpg
 
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Those are your filling valves there, check that there both turned off first, if it keeps rising without the heating being on then chances are their passing or the plate heat exchanger is cracked, which is much less common an issue but the only other part internal to the boiler that would cause the pressure to rise constantly.

May find that the saftey (pressure relife valve) needs replaced if its been letting by for a while as well, but thats not something we can advise on in this forum as its a saftey device on a gas appliance and should only be touched by a competent fitter.
 
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View attachment 170659

Those are your filling valves there, check that there both turned off first, if it keeps rising without the heating being on then chances are their passing or the plate heat exchanger is cracked, which is much less common an issue but the only other part internal to the boiler that would cause the pressure to rise constantly.

May find that the saftey (pressure relife valve) needs replaced if its been letting by for a while as well, but thats not something we can advise on in this forum as its a saftey device on a gas appliance and should only be touched by a competent fitter.

Thanks @ScottishGasMan - how can I determine whether they are both off? Is it possible to check the cracked heatx plate easily?
 
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Assuming you know that there both isolated (open and close them so you can hear when its properly filling and when its not) the normal way would be to disconnect the silver flexible hose that joins the pair of them (which will get very wet and messy if you havent got them in the off position) then leave it over a bowl/bucket for a while, if it continually drips for a prolonged period then they are passing. if its just the water dripping out that was in the silver pipe and then nothing more then they are ok, which is also pretty much the only way to test the plate heat exchanger (ie if youve disconnected the filling loop and the pressure continues to rise and drip outside then thats the only part left it could be)
 
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Assuming you know that there both isolated (open and close them so you can hear when its properly filling and when its not) the normal way would be to disconnect the silver flexible hose that joins the pair of them (which will get very wet and messy if you havent got them in the off position) then leave it over a bowl/bucket for a while, if it continually drips for a prolonged period then they are passing. if its just the water dripping out that was in the silver pipe and then nothing more then they are ok, which is also pretty much the only way to test the plate heat exchanger (ie if youve disconnected the filling loop and the pressure continues to rise and drip outside then thats the only part left it could be)

Ok thanks should I do all this with the cold water inlet off? In the pic the far left middle ish valve with white paint on?
 
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Could you highlight where best on the pic to break the connection of the silver flex? As there is some sort of extra valve body in the loop with a black X type cap
 
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Make sure both the valves that @ScottishGasMan circled then undo the two nuts I have pointed in blue, but have a towel and bowl ready below the boiler as you will get a bit of water and if the valves are passing you will get a bit of a spray
image (1).jpg
 
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Thanks @ianmcd.

Just a few questions and then i'll give it a go:

1) Should i have the cold feed (white painted flathead screw) valve open or closed?
2) Boiler on or off
3) Do i need to let pressure out of the boiler first?
4) Any particular order to do these in?

The boiler has been off (at the RCD) for a number of days, and the cold water inlet valve closed due to the overflow wasting water. If i need to correct any of this first then i will do based on the answers to above questions.

Thanks for all your help! I hope it is these valves passing so it's an easy switch!
 
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you will need the water turned on to see if the valves are passing you wont need the boiler switched on and good idea to leave it off at the RCD while you check the valves, iwould remove the hose with the cold feed turned off wait till the water stops dripping, then turn the cold feed on and see if you start to get passing from the valves, no need to drain the boiler to do the test, if the valves are not passing leave the cold main on and leave the connection hose off , if the pressure goes up with the hose removed you need a new plate heat exchanger
 
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@ScottishGasMan @ianmcd

thanks for your help before I’ve finally got round to following your instructions after much nagging to sort the boiler from my wife!

soooo this is what’s happened...

Boiler off at rcd.

1) cold feed off - broke connection of silver hose at the two points identified, small amount of water (pipes length worth) came out. Dried it all off around the connections before step 2.
2) cold feed on - switched on fully open. Small bead appeared on gold valve, and then every 7 seconds or so the silver valve drops about 10ml of water.
3) left cold feed on, watched and waited pressure valve. No change to pressure, held as per picture.
4) checked outside overflow pipe, continually stream of exhausted water
5) cold feed off - so don’t waste water outside, and then on here to message the gurus
6) silver valve body still dropping water every 7 seconds whilst cold feed off.

any thoughts on next steps? Is it the inlet valves passing then?
 

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sounds like your pressure gauge is faulty and the pressure releif valve is opening, shouldnt be any water going to outside
 
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sounds like your pressure gauge is faulty and the pressure releif valve is opening, shouldnt be any water going to outside

pressure gauge on the front of the boiler?

the fact there is water coming from the disconnected outlets isn’t pointing to those passing then? Is that normal operation?

should the pressure be rising with cold feed on, silver flex disconnected? Or should it just sit doing nowt...?

What’s my next steps then?
 

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