Vaillant Turbo Max boiler losing pressure

[LondonGirl4]

In the last week my Vaillant boiler pressure is dropping to zero several times a day. I can re-pressurise it easily enough but I am worried that I may have a leak in the system. I can't find any leaking around the radiators. When I got home at 6 last night it was at zero again although I had increased it to 1.5 that morning. The heating is working ok after I increase the pressure. I had to re-pressurise at least 3 times last night and it was on zero this morning. I paid over £100 for a scale preventing thingy and my central heating boiler and system is on a British Gas service contract. I thought it was expensive at £21 a month and am trying to cut down on expenses, so I rang them up and they said I could change it to £15 a month but that would mean I have to pay £50 each time something needs doing. (I asked if it would still be £50 even if the cost of repair was a few pounds and they said yes!!). As I had paid for the scale preventer I thought reducing the payment from £21 to £15 would be ok as I thought I would not have as many problems with it. WRONG!! Typical, now I've got problems with the flipping pressure dropping! AAAAAAAAAARGH!! Any ideas? Thanks.

 

[Agile]

Look up the FAQ on this site about PRVs.

Check your PRV vent usually through wall to the outside. It may be dripping.

Problem may well be due to faulty expansion vessel.

Tony

 

[Whitespirit66]

I asked if it would still be £50 even if the cost of repair was a few pounds

There is a make believe world, far away, where boiler repairs only cost a few pounds. Meanwhile, back on planet earth, boiler repairs very rarely come into the 'few pounds' category.

 

[ianniann]

Losing pressure, losing water. Losing pressure fast, losing a lot of water. Should be easy to find. Look for a random skinny pipe ending in thin air and squirting out hot water.

For a more scientific approach:
1. Pressurise system to 1-1.5 bar.
2. Turn on heating.
3. Watch pressure guage.
Does it climb steadily to less than 2.5 bar and then slowly decrease? Climb steadily to over 2.5 bar and then squirt hot water over your feet?