Help needed, how can you tell if you've put a nail through a central heating pipe?

Swafe

Hi guys, I've had a broadband company install fibre and told them to avoid my old radiator microbore pipework, however, they then nailed a tack straight over the top of it. There are 2 pipes which are covered by a few coats of paint by its not obvious where the paint ends and the pipe starts. The nail, hopefully, has gone between the two pipes but it's awfully close and if its missed it, it's probably only by a millimeter or so. 

As it's summer my system isn't working, if did go through the pipe would it be filled with water still and would water have escaped? Or would I need to run the system up and get it properly flowing before any water might show itself? It's absolutely roasting today so Id like the piece of mind without having to roast myself alive but willing to take one for the team if that's the only way to find out.

I guess a secondary question is if it has gone through the pipe, what pressure does a system normally run at (old baxi back boiler) and is it feasible that the layers of paint could contain the water for a period or am I likely to find out pretty sharpish if there's an issue?

Thanks in advance 

marlot

There will still be water in it during the summer, but there won't be any pressure.

If you're unsure, it'd better to find out now, rather than when it's cold.

born_again

How about running system to find out. If it holed you will soon spot a jet of water.

grumbler

marlot said:

There will still be water in it during the summer, but there won't be any pressure.

In a sealed system (combi/system boiler) the pressure is the the same all year round.

In a gravity system (with an expansion tank in a loft) the pressure is the same too, but can be slightly higher when the pump is working)

bryanb

Have you pulled the nail out? It could be keeping the water in.

grumbler

bryanb said:

Have you pulled the nail out? It could be keeping the water in.

Once I hammered a nail exactly through a gas pipe under the floor board - two holes: in and out. It took me weeks to smell the gas and to realise what I've done. And I feel all odours very well.

Swafe

I've not pulled the nail... I could pull it but I'm not sure I'd be able to see if it's been through the pipe the way it's gone in so I plan to keep it in just incase it springs a leak and it's holding the water in place.

It's a gravity fed system as far as I'm away so there should be some pressure but will give the heating a quick blast tomorrow and hope for the best...

ThisIsWeird

Swafe.

You need to know, whilst you can sort it. So pull the darned thing out. Look for a damp patch forming.

Turning on the heating is unlikely to make any difference - as Grumb says, the water is there in the pipe regardless of whether the system is running.

If a damp patch appears, push the nail back in, and contact the BB company. (And your insurance if they are less than super-active).

twopenny

I had to run my heating for a while in this weather.
Rads heated and then cooled as the thermostat kicked in.
It wasn't that bad so give it a go.

FreeBear

ThisIsWeird said:

Swafe.

You need to know, whilst you can sort it. So pull the darned thing out. Look for a damp patch forming.

Turning on the heating is unlikely to make any difference - as Grumb says, the water is there in the pipe regardless of whether the system is running.

If a damp patch appears, push the nail back in, and contact the BB company. (And your insurance if they are less than super-active).

There may well be two taps next to the hot water cylinder - One to feed the DHW tank, the other for the central heating system. Check that you can close the taps if needed before you pull the nail out. If water is leaking, then shut the taps off and drain the system down.

ThisIsWeird

Good point, Freebear.
What type of CH do you have, Swafe? Combi boiler or conventional? Does it have a pressure gauge?
(One with a pressure gauge will have a more limited quant of water in is, so worst case it should stop leaking after a few litres loss. A vented system, with a cold water tank in the loft, will continue to leak...
So, as Freebear suggests, it's worth finding out how to stop the supply of water, and to drain down if it's necessary.
But, if you think there's a fair risk of the nail having damaged a pipe, I think you need to have it confirmed, 'cos there's a good chance it'll reveal itself when you least expect it.
Any chance of some close-up photos?