Leak on central heating pipes

ThisIsWeird

Tulips2lips said:

ThisIsWeird said:

We need photos!

These are the photos of the boiler with the small tank above.  The overflow from this tank used to drip but stopped by itself.  The condensate pipe occasionally runs when the boiler is off.

Well, I'm guessing that is, indeed, a Heat-Only boiler as you said, and has a small F&E tank above it to keep the system filled - that black insulated tank.
It's in the garage, which is on ground level, so I'm equally guessing that your house is a bungalow, since that wee tank needs to be higher up than any radiator. 
If you have a pipe leak with this kind of system, then the wee tank will keep replenishing the lost water, so the leak won't stop until you cut off the supply. You have done this by turning of your mains stopcock, but that means no water to the rest of your house either.
In order to just shut off the boiler and radiator supply, you need to either find the shut-off valve to that black tank, or else to tie up the ballvalve inside it. The former you can search for yourself, but the latter will need someone who knows what they are doing to climb a ladder of some sort to gain access to inside that tank.
The plumbing doesn't look old, so almost certainly there is a valve there somewhere. 
Once you shut off the supply to the boiler and radiators, the leak will stop, and you can carry on using your hot cylinder with its immersion heater as you wish.
First thing - have you turned the power off to the boiler? There should be an obvious power switch on the wall next to it.
Next step is to figure out how to stop that black tank from refilling the boiler.
A wide photo would help, one showing everything. Then we can target some close-ups.
Are you able to get up to that black tank? If so;
1) look for a 15mm pipe that goes in to its side near its top. It should be joining to a brass fitting mounted on the tank - that will be the ball valve. Look for a fitting on that pipe that may have a screwdriver slot on its side, or any other type of valve. Post close up pics if you need to. Trace that pipe all the way down, looking for a valve.
2) look for a thicker pipe - 22mm - that is coming out the side just above the tank's bottom, and that heads to these sleeved plumbing pipes you've shown us above the boiler. Check that pipe for a shut-off valve. (There shouldn't be one on there, I understand, but have a look if you haven't found one on the first pipe). Again, post photos if needed.

I'm guessing that the  noise you heard when you had that leak was the sound of that black tank refilling - it would be a bit like a toilet cistern refilling, and can be quite noisy. Also, being in your garage, the noise probably travelled through your house wall, whereas most folk have that tank in their lofts, so a lesser sound from above.
Anyhoo, power to boiler off. Examine that black tank. Take photos.

ThisIsWeird

Tulips2lips said:

Another possible issue - I'm not sure if that pump has been installed at an acceptable angle - it looks at around 45o, so that end nearest us might have dry bearings. Also, shouldn't the electric box be on the top?

As for the screw embedded in the wall to provide support to it, well...

When you do call out a plumber to sort the leak, T2L, you may wish to ask them to check it all over.

I wonder if the noise you were hearing was even a dry-running pump?

Tulips2lips

ThisIsWeird said:

Tulips2lips said:

Another possible issue - I'm not sure if that pump has been installed at an acceptable angle - it looks at around 45o, so that end nearest us might have dry bearings. Also, shouldn't the electric box be on the top?

As for the screw embedded in the wall to provide support to it, well...

When you do call out a plumber to sort the leak, T2L, you may wish to ask them to check it all over.

I wonder if the noise you were hearing was even a dry-running pump?

Thanks very much!   I'll take photos today but before I forget, the noise can't be heard in the garage and after the water being off since Monday the noise is still in the bungalow.  Do you think that's a long time to empty that little tank if it's a leak?  

Tulips2lips

I've looked for somewhere to turn off the water but can't see anything.  The pipes then go through the wall into the bathroom airing cupboard/cylinder and up to the loft but there's nothing in that cupboard either, can't get into loft unfortunately.

ThisIsWeird

Tulips2lips said:

Thanks very much!   I'll take photos today but before I forget, the noise can't be heard in the garage and after the water being off since Monday the noise is still in the bungalow.  Do you think that's a long time to empty that little tank if it's a leak?  

T2L, please ID the power supply to the boiler - it should be a wall switch near the boiler. Find this, and turn it off. Then tell us if the sound is still present.

That is really a priority. Please do this now.

ThisIsWeird

Ok, after you have done this ^, please have a look at this pic:

YELLOW: That's the 'feed' from that wee tank to your boiler. I doubt it'll have a valve on it, but trace it all the way down until it reaches a pipe fitting to see if it does.

ORANGE: Not sure if this is the EXPANSION or the mains supply to the tank. You really need to get up there and follow it with yer fingers to see if it points down in to the tank, or goes through its side. If you cannot do this, you need to find someone who can. That paperboy/girl - grab them and don't let them go until they do this for you.

GREEN: Again, I don't know. See (2). It'll be one or the other. We need to know.

PURPLE: Is the pump running? Is it making a noise? Is it VERY hot...?

GREY: That white plastic pipe is the overflow, and heads outside. Don't worry about it...

Tulips2lips

ThisIsWeird said:

Tulips2lips said:

Thanks very much!   I'll take photos today but before I forget, the noise can't be heard in the garage and after the water being off since Monday the noise is still in the bungalow.  Do you think that's a long time to empty that little tank if it's a leak?  

T2L, please ID the power supply to the boiler - it should be a wall switch near the boiler. Find this, and turn it off. Then tell us if the sound is still present.

That is really a priority. Please do this now.

The power is in the kitchen under control panel and has been switched off since Monday.

Tulips2lips

Here's the photo of the power switch.  It's been off since Monday.  There's no sound at all from that green pump.

ThisIsWeird

Tulips2lips said:

Here's the photo of the power switch.  It's been off since Monday.  There's no sound at all from that green pump.

So where the hell is the sound coming from?

Tulips2lips

ThisIsWeird said:

Tulips2lips said:

Here's the photo of the power switch.  It's been off since Monday.  There's no sound at all from that green pump.

So where the hell is the sound coming from?

Not a clue!  I thought it was water running through the pipes but I think if it was another leak it would have stopped by now?  Would a leak on the water supply pipe be heard on all pipework including CH pipes?  I understand that noise could travel even with internal SC turned off.  I can't turn external one off in kerb as it's old.  What are your thoughts oh wise one?😁