Vaillant Turbomax 24E combi boiler constant rising pressure

[thomo2710]

Hi all,

Have the afore mentioned boiler at its causing us some hassle.

We have just replaced all the rads and run new copper pipe throughout the house (renovation)

We filled up the system successfully and have no leaks.
Rads get warm throughout, boiler functions in the sence we get hot water.

Had a few airlock issues but we feel we have sorted that, may still be a little air floating around mind.

Thing is the pressure guage just keeps rising even though the filling loop tap is set to off.
We filled to 1.25 bar, turned the filling loop tap to off, turned the main water supply off and turned the boiler off. 2 hours later the needle was approaching 2 bar and still steadily rising.

I drained the system down to 0.5 bar and went home for the night, next morning it was where i had left it if not slightly lower.

Filled up again last night to just under 1 bar, undid the filling loop tap connector to see if the valve was passing and saw no water in 3 hours from it.
Just before i went home for the night i checked the pressure and it had risen to 1.5 and was still creeping up but extremely slowly this time, even with filling loop tap set to off and the mains water being off so the only water and pressure in the system was that that was already in there.

I did notice a wet patch underneath the 1 way valve that the filling loop plugs back into and i could pop my finger in and feel water so maybe that is leaking a little but surely that wouldnt be the cause of the pressure guage rising.

Do i just have a faulty pressure guage or could it be something more sinister?

Many thanks

 

[ChrisR]

Well you'll have to leave the filling loop disconnected to prove it, (as required by the water regs, though not many do.)
Maybe it "lets by" a little at night when the pressure rises.
But the next suspect is the plate heat exchanger - the one for the hot water. It has tap water one side and boiler water the other.
They do fail occasionally.

 

[thomo2710]

Just checked it and overnight with filling hose undone and no water entering the system it has risen from 1.5 to 2 bar.

There is more water in the 1 way valve at the other end of the filling hose though but the floor looks dryish no its not leaking much.

 

[thomo2710]

what should be my next steps to get to the bottom of this problem please?

thanks

 

[onlyfitidealboilers]

likely to be pin hole in plate heat exchanger isolate the cold water vlv under the boiler, turn on the hot tap an no water should come out, then keep an eye on your pressure gauge if it stops riseing new plate hex req.

 

[mrgas]

As Chris says, If your filling loop is disconnected and the pressure is still rising then the only other thing to do is replace the plate heat exchanger.

 

[The831Bunny]

Agreed, sounds like plate heat exchanger passing, but as you know VERY rare. Have had same symptoms with a blocked (partially) manometer. You fill it to say 1.5 bar and because of the blockage it creeps up to 2 bar or more a few hours later. Usually debris where the capillary plugs in.

Drain the boiler out and make sure the gauge drops immediately.

Bunny

 

[Blooflame]

Actually I've had plenty of plate to plates passing ..it's more prevelent than you think

 

[Aulus]

Is gas buildup in the rads a possibility?

 

[jackecole]

good thinking there.... that'd make the owner blled the rads often though and surely reduce the pressure?......

 

[thomo2710]

well Wed night i bled the rads of air (wasnt any at all, all water)

Turned mains water off and ran the water to the sink to clear anything lurking araound.

Pressure was on 1.8 and when i checked Thur morn it was down to 1.7.

Last night turned the mains water on, ran some taps for a bit, filler pipe still disconnected and boiler still turned off.

It dropped from 1.7 to 1.6 over night to this morning.

tonight i am going to fire the boiler up, run some water around the CH etc and see what happens when left overnight with mains water/boiler on as it normally would be.

 

[Bunnyman]

Hi mate ur goin round in circles an wastin ur time. It can't be gas build up in rads that's rubbish ignore that.leave ur mains on an disconnect fill loop If pressure rises overnight it's the dhw ht exch as 831bunny said it cannot b anythin else unless someone has left an old fill loop from a previous installation lurkin somewhere.if the pressure does not rise overnight reconnect fill hose an leave overnight again if it rises change fill loop taps it cannot b anythin other than these 2 things If the mains is off an still rises as 831bunny said u might have a partial blockage in manometer tube causing very slow response

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[thomo2710]

leave ur mains on an disconnect fill loop If pressure rises overnight it's the dhw ht exch as 831bunny said it cannot b anythin else unless

Thats what happened last night, mains water on, boiler off and filler loop disconnected. It dropped from 1.8 to 1.7. So we can now dismiss the Heat Exchanger as the problem??

unless someone has left an old fill loop from a previous installation lurkin somewhere

not that i know of

if the pressure does not rise overnight reconnect fill hose an leave overnight again if it rises change fill loop taps

I will replace the filler hose tonight anyway as the 1 way valve is a bit suspect

Thanks for helping!

 

[Blooflame]

The only thing it can be is the plate to plate, nowt else, otherwise we aren't getting the full info from you here. If the boiler is running then it will naturally rise in pressure. Are you saying that the pressure rises whilst the boiler is off?