Vaillant 837 losing pressure within 12hrs....

[Nasfirewall]

After having a Vaillant 837 combi boiler installed after reading several rave reviews it has worked fine for approx 3 weeks.

But now at first a drilling noise occured and was isolated to loose pipework making vibration noises. But a rad in the lounge has been making dripping noises as if one of the internal channels of the rad is semi blocked etc. this has got worse over time and within the last 72hrs the pressure has been decresing slowly but now drecreses very rapidly within say 24hrs pressure goes from 2.0bar to 0.0bar yes that is correct zero bar ie. no pressure in system so naturally the error code f22 appears (which is no pressure accordsing to system manual).

I have refilled the boiler now 5 times and having the same problem also intermittently error code f76 has appeared. When the f76 error appeared I rang up vaillant sevice and an engineer has been booked to come out this coming friday. I then emtied the boiler by using the external valve and refilled the boiler and hey presto it started to work again, but since then it has been losing pressure and making this funny dripping noise coming from the rad.

I have checked all the rads to ensure no leaking valves etc. and can't think of anything else to do now

Any ideas on what could be the cause and how to remedy it?

Nas

 

[technical engineer]

yes you have a leak somewhere or the prv is letting by you need to check all your rads and the boiler itself and make sure there are no leaks failing that you should then check the expansion vessel to makes sure it has the correct amout of air in

it could also possibly be air in the system but i doubt it air usually clears up after a while depends what noises the boiler is making as well

judging by the speed of which the pressure is going down internal leak sealer isnt gonna work either you must have a noticable leak somewhere other than that youll need to start taking up floorboards to look for a leaks so that should be fun

 

[Agile]

It may sound obvious but why dont you just call back the installer and let him deal with these problems under his guarantee?

If the Vaillant engineer finds the problem is the installers then it may be a chargeable call.

Tony

 

[gas4you]

If nothing coming out of prv pipe then must be leak on system.

Vaillant could charge £180 if no fault found

pressurise boiler then isolate ch flow and return under boiler. Leave as long as poss. If no pressure drop then leak in system.

 

[Agile]

Vaillant could charge £180 if no fault found

Dave really means "no fault with the boiler!"

If the leak is on your system then you should find it yourself or get the installer to test to see if its the boiler or system.

Tony

 

[Nasfirewall]

Thanks for the above suggestions..ok the drop in pressure ie. leak was from the outlet pipe that bleeds the system that has now been closed correctly and the pressure is being maintained.

The f76 code however did not go away and the boiler was still unoperational luckily I had not cancelled the engineer visit..he turned up although alittle late and takes off the front cover off the boiler checks the wiring by unplugging and plugging and hey presto the boiler comes back on but he mentioned that the primary heat exchanger seems to be at fault and that I need a replacement so he is coming back this thursday with a new primary heat exchanger.

his visit must have laster maximum 10mins, but the boiler has been working since friday but the pressure goes from 1.7 bar to 2.3 always fluctuating whenever i check it every 4-5 hrs. I have not put any more water into the system nor drained any water out.

So lets see what happens when he comes back this thursday and changes the primary heat exchanger.

Thanks.

 

[gas4you]

Strange, I've always been taught that if the heat exchanger stat operates it is a new HE needed, end of

Never been told it was resetable

 

[Agile]

Any guesses why he wants to change the primary heat exchanger?

They either work or they are blocked/scaled up or they leak!

Blocking or scaling is not the manufacturer's fault!

Tony

 

[gas4you]

Very, Very rare that these would scale or block, usually once the F76 has operated I would say that the excess heat has warped/damaged the HE in some way.

The good thing is for some reason he is swapping it (Maybe perhaps the old silicone seal had not been replaced )

In my limited experience, the F76 has only been caused by the installer NOT setting the boiler to purge its self after installation, no it's never happened to me , which again prompts the question as to why they would replace it foc

 

[Agile]

It does sound as if the owner has drained and refilled at least five times.

Unless that is done correctly as you say the HE could be damaged or warped.

Tony