vaillant thermocompact VU GB 242/1E

[terryb242]

Hello Chaps,

firstly let me say that I am not fixing or advising anyone else to fix their boilers, I just want to fix my own and save having to spend wads of cash the wrong side of Christmas only to end up replacing it.

My boiler is 10 years old and attached to a Vaillant 150/4 cylinder. Neither units have had any parts replaced, and have always worked fine. The heating and hot water heat up quickly (as always). I have the installation and servicing manual.

The boiler stopped working last week showing a flashing yellow ignition indicator light. The pressure was showing at 1 bar, but I topped it up to 1.2 and reset the boiler, which fired up and worked fine for a few cycles then failed again.

The pressure is steady at 1.2 bar, the pump is running smooth and quiet, the differential pressure switch actuator moves and the switch 'clicks' (I will check continuity over the weekend). The boiler keeps failing but starts immediately when reset (tedious). It can fail after one cycle or 10, there doesn't appear to be pattern, but I will observe it over the weekend to see at what point it fails.

Has anyone experienced this fault before..? I (probably like you guys) just like fixing things, and I promise £25 to anyone, or their nominated charity who can provide the solution, and yes, I will be honest about it, and pay up.

Thankyou,

Terry.

 

[Bunnyman]

It has to b pump slow or stickin or pd valve failing to lift it's usually the pipes blocked where they enter pd valve rather than fault on valve itself

Untitled

• Bunnyman
• 26 Mar 2010
• 499

 

[terryb242]

Hello Bunnyman,

thankyou for your response. If the pipes are blocked will a system drain and filling with cleaner clear them or do I need to stick a hose on them..? Does the pump just unscrew and pull off.? and can I legally do it myself.?

Regards,

Terry.

 

[terryb242]

Ok.... drained and flushed system to change some valves, and heating worked fine for a week before the fault returned.

The pump seems strong, and the flow switch actuator lifts within seconds. However, when the demand is removed and the pump stops, it takes about 30 seconds for the actuator to 'fall' and close the switch. As soon as the switch closes, the yellow light flashes. Again, resetting clears the fault - hope this helps narrow it down.

Do the electronics 'time' how long the actuator takes..?

 

[terryb242]

Bunnyman..?

 

[terryb242]

Anyone..?