[mrs bouquet]

Fortunately, it is located in the garage, otherwise I would have a bigger problem.    It was serviced about 3/4 weeks ago.   But I have a new plumber who lives in the village.  He is very experienced and will come to me on the way, because he lives along the next lane.
But, we cannot find out where the leak is coming from   .     He came again yesterday about 11 ish, and then left telling me to go out every half hour, when the boiler comes on at 4pm, until 7pm.  This I did with my torch, (and the crick in my neck) and checked where he told me to.   Nothing, no signs of water either to the torch light or by touch.    This morning at 10am the boiler went off.   I went outside, and the trays were wet and water over the garage floor.   Checked allthe pipes and joins etc, as instructed.   The expansion tank, shows water around the middle, but having covered it with a dustbin liner yesterday, decided the tank isn't leaking but it is getting splashed.
I have even been looking upward to see if the garage roof is leaking, but it is not.  The water and the rads are all working and I have to keep my eye on the needle on the boiler to make sure the water level hasn't drop into the red zone.
I am mystified, so is the poor plumber/CH engineer.   I so hope I am not going to need a new boiler, I haven't got the dosh.   He assures me It won't come to that, but it is finding the cursed leak.
Can you imagine if this was going on with the boiler in the house.     Meanwhile to is pouring with rain, blowing a gale, and I am supposed to be going to a Christmas party.      Well that's off !!
If you have got any ideas where to look next, please let me and the plumber know.    Regards, Mrs Bouquet

[Lardman]

Your luck really is almost as good as mine isn't it.    What's the boiler make & model - Does it only leak when it rains?

[grinling]

Are you having to top the boiler up?
Is the leaked water warm to the touch?
Did this guy service the boiler?
Is this guy qualified for your boiler?

[mrs bouquet]

It is a Mains Boiler, and yes he is qualified, and yes when the needle gets low he runs round and tops it with water.   
However, yesterday I was supposed to be going to a Christmas party in the afternoon, but having spent a while in the garage emptying out the water trays, and wiping up, and setting it up again, I forgot the party and just popped out locally.     When I got back, went to the garage (Now paranoid !) and water was in the trays, I bent to look under the boiler and a drop fell on my head.   Opened the cabinet which houses the boiler, and opened the boiler flap, I could see water to the left (which was were I always thought it was coming from).   Rang the CH Engineer, and he was here in 5 minutes.       OK, the boiler needs a new "O" Ring on the pipe leading to the heat exchanger.  (Greek to me )
He is starting a completely new installation and working all over the weekend.  My part will be there on Thursday,   so he will probably come to me next Tuesday.   He told me to leave the heating on 24/7 because I said I thought it only leaked when the boiler was off.    Now it is on, and there was no overnight leaking.
I am so relieved, although I shall watch and ring if the water level goes down, nd he will swing round.
Thank the Lord it is located outside, but if anybody has one indoors, I would suggest a tray permanently under the boiler.  My ceilings would have been down if it had been in the house.
So hopefully another thing dealt with before I reel onto the next       
Thank you for taking time to read this, and your replies.      Mrs Bouquet

[Goosegirl]

An O ring is like the little round black rubber jobbies that you seen on hosepipe fittings to stop leakages when the pipe is running under pressure.

[mrs bouquet]

In theory then quite straightforward, except he has to take the housing cabinet down first, to be able to take the actual boiler side off, to get at it.    A cheap and cheerful rubber/plastic ring - £150 bill, but its his labour, time, and the 7 times he has "popped" round and topped it up etc.     Never mind eh.   Mrs B

[WeavingGryphon]

I'm so glad to hear that it's getting sorted and you'll be reliably  and safely warm.  . Not so glad it's so expensive.

[Aidy]

We had a interesting experience!

The good lady of the house decided we needed a new boiler as ours was 17 years old (not broke so why fix it( just saying))
So a new boiler was fitted and next morning zero pressure! Steve the gas man came round and said must be a leak in the system  but we didnt have one before.
Over the course of 10 days crawling under the sub floor checking joints etc we could not find anything 
Perhaps there is a fault on the boiler? Phone the manufactures and they went through everything Steve had and said to him... "must be a leak on the pipework" (rules of site do not allow to say my reply)
I was still 100% convinced a fault, physics was on my side so we decided to cut the blow off pipe and put the a bottle on the end to catch any water the boiler may dump.
Guess what, next morning we had a bottle if water.
Parts replaced and we have a working non leaking boiler.
Wife has learnt a very valuable lesson which I will ensure she never forgets

[mrs bouquet]

Isn't it so annoying when stuff like that happens.  I have a hard time of it because I am "just a silly old lady"
Anyway, my man is coming at 9am in the morning and I have to turn the boiler off at 8.30am.
Since he told me to leave it on all the time, there has been no water at all.   The trouble is, I could get used to being warm all the time !    but I cannot afford it !!   Mrs Bouquet