Vaillant Combi WCW T3W, pressure leak!

[Khalid]

Hi there,
Few days ago I replaced the pump. Because the old pump was original, I had to undo the tank which sits above the burner. When I put every thing back and pressurized the system, found that tank's pipe opposite to the pump side has a leak in it.

Now when boiler stops due to the loss of pressure, I have to build up pressure and release the air from the pump's AIR VENT to get it working again.

New tank costs around £200. Is there any way of repairing the leak? Because its a very small leak and it take about two days for pressure to go down, can I use the car radiator leak stopper (can't remember the name at this stage)?

Regards

 

[DP]

It is the heat exchanger that is leaking. You will need to replace the HE. Use of aforementioned stuff will cause more problems. Find it difficult to comprehend why the pump should be changed just because it looks old.

From the post, it would appear the boiler os OF. As such it should be checked by someone who knows what he is doing. Such appliances can kill.

 

[Khalid]

Hi there,

I had to change the pump because it would run for couple of hours and then stop. Sometimes it worked by thumping on the side or if its left to cool down then it would come on after 20-30minutes.

I had someone round to get it working, but for leak he said HE needs to be taken off, dried and repaired, whole process could take few days.

Thanks

 

[DP]

On this boiler pump run is essential to fire the burners. I would be inclined to think that the pump running for that length of time indicates a fault elsewhere.

You will not be able to repair the HE.

Central heating demand should fire the burners which will then go to low flame (having heated primary water within the boiler). If no flame do not change any parts but diagnose the malfunction.

Do you have a multimeter and a U gauge? You will also need the boiler installation manual. Can you give full details of boiler symptoms.