Need to drain leaking hot water tank

[Rave]

Hi all,

I'm trying to help out an old friend here. I won't go too deep into the circumstances here, but long story short through some unfortunate circumstances he's got himself into a bit of a pickle. His hot water cylinder (in a cupboard in his upstairs bedroom) is leaking where the cold feed pipe goes in the side. It's leaking so much that it's completely soaked the floor of the room and is doing a pretty good job of soaking the kitchen below. It's been like this for some time as far as I can tell.

Now the obvious thing to do would be to call a plumber sharpish to sort it out, but the house is a complete bomb site and TBH it would be better to simply drain the tank and get the house completely dried out before proceeding. Building works are likely to be required, and a serious refresh of the hot water and central heating system. He can carry on living without hot water for a while. Once the HW tank's drained I can bung up the pipe from the header tank so he's got cold water.

So, how to drain the cylinder? Yesterday I tried closing the valve on the cold water feed pipe from the header tank in the attic- this is the pipe that goes in to the tank at the bottom and which is leaking. The valve seems to be knackered. In any case it seems that merely turning this feed off will not empty the tank, merely reduce the pressure in the hot water system to effeticvely nil so the taps don't work. I also turned off the feed to the header tank and returned today to find it empty, but the hot water tank is still leaking and still feels full when you tap it.

There are three other connections to the tank- one at the top, this I guess is the vent although there are other pipes coming off it as well as the vent pipe to the loft. There's one at the bottom on the other side from the cold feed which appears to come from the boiler downstairs- this I guess is where the hot water comes in? And then there's a takeoff about two thirds of the way up, which I suppose is a hot water out feed.

TBH it's well past the stage where water damage is an issue, so if I could simply stop the tank filling the rest of the water could be allowed to drain away before the drying out procedure could begin.

So- where's the water getting into the tank from? Could it be coming up from the boiler from mains pressure? Or somewhere else?

I will try and take a picture and post it so it's a bit clearer. Any ideas in the mean time gratefully received.

 

[Dan Robinson]

Tie up the ball valves in the loft. Or turn off the mains stop cock feeding he cold water cistern and header tank.

Turn off the boiler.

Run the bath until the water stops.

Now unscrew the nuts on the top of the cylinder and push a hose pipe in to the bottom.

Run said hose pipe downstairs and out the front door. Suck like buggery on the whose until the water flows out.

Go and by a dehumidifier whilst the water drains.


It could take a while for the water to drain.

This is of course assuming there is no drain of cock on the inlet, or that it is goosed.


Alternatively. Go and buy a cheap hoover that takes water, and drill a hole in the dome of the cylinder and suck water until it stops. if the hoover fills up, use an assistant to plug the hole with a finger while the hoover gets emptied.

Rinse and repeat until water is below the dome seam.

Now saw the top of the cylinder off and you can just suck the water out in stages.

 

[Rave]

Dan,

Thanks very much for the quick reply. I can easily get into the top of the tank by removing the immersion heater, assuming it will come out. Can easily syphon out of the window.

The boiler is off but the tank still seems to be filling somehow, and definitely not from the header tank which as I say is now empty. I've had a look at the pipes from the boiler downstairs going through the ceiling and none have any kind of valve on them that I can see. Irritatingly the boiler is a 'fixed to the floor' type making investigation of surrounding pipework difficult.

Just going to try and upload some pics now.

Edit:

The leaky joint is the lower of the two on the right hand side; this is the feed from the header tank that should now be dry. I suspect the water is still somehow getting in from the connection on the bottom left from ther boiler but I'm stumped as to how. The boiler is knackered and perhaps the valve it presumably has inside has failed. Could take the cover off and have a look.....

 

[xr4x4]

If that is the cold water inlet, it will keep leaking until the hot water tank is empty...which you will have to empty.

As the hot water outlet of the tank is at the top, it only takes a few seconds for the tap to stop flowing but the hot water tank still stays full.

 

[Rave]

I am loathe to remove any of the top inlets of the tank to syphon it until I'm sure that it's not filling from any of the other pipes (I am convinced that it cannot possibly now be filling from the empty header tank in the loft).

I'm deducing that it's still full by rapping the tank with my knuckles- very dull sound, no ringing at all- I'm guessing this must mean it's still full.

Is it possible that mains pressure is forcing its way through the boiler and filling the tank?

Thinking about it, if that was the case, then the mains pressure should be filling the header tank via the hot water cylinder?! Unless there's a one way valve fitted or something.

Perhaps I will risk trying to remove the immersion heater to have a look. do you need a special tool for them? It seems to have a very large (~5") nut at the bottom....

The amount of water in the tank itself is pretty immaterial compared to the hundreds of litres that must have leaked out already, so as long as I can stop the tank filling there's little to be lost by letting the remainder of the water leak out by itself.

Sorry for all the noob questions, I will arrange for a plumber to come on Monday if the leak doesn't stop, but it really would be good to stop it leaking myself to both save money and facilitate the job of completely clearing the house. This house is going to need thousands or probably tens of thousands spent to get it properly habitable again and in this case every penny counts, and my mate is unemployed and his parents are retired....

Oh, and we removed the boiler cover. No obvious valves inside.

 

[xr4x4]

I say again...... The only way you can empty the tank is to manually drain it.

 

[Dan Robinson]

The amount of water is very important if it comes out as a torrent rahter than a dribble.

If no water is coming out of the hot taps, then there is nothing filling the cylinder.

As stated - it will be full of water UNTIL you carry out my initial instructions.

I wouldn't bother with the immersion heater boss (3.5" BTW). You could end up in a worse state than you are now.

 

[Rave]

Righto. We'll go and perform some further investigation with the hot taps. I think it's a mixer tap to slightly complicate matters but I suppose now the header tank's empty there should be nothing coming out of it on either setting! Then I'll gingerly try and remove the top pipe nut. I only have stillsons and a big pair of those adjustable pliers- am I asking for trouble using those?

 

[Dan Robinson]

You should be fine with the top nut on the dome...

 

[Rave]

You should be fine with the top nut on the dome...

Well I took the stillsons to it, after getting my friend to shut off the main water feed to the whole house. I'm not a small guy, in fact my hobby is powerlifting, but I had to really haul on it, and after about half a turn the whole 90 degree elbow coming out of the top of the tank began to rotate and bend the 6" length of copper pipe joining it to the pipes on the wall. I had assumed that it was some sort of slip nut, but 30+ years after fitting it wasn't coming undone without a struggle! I tried removing the compression joint on the other end of the elbow but again nothing doing. So in for a penny, in for a pound, I took a saw to the pipe on the basis that 6" of copper pipe is worth about 50p and fittings are cheap.

Of course we couldn't find a hacksaw so I was using some completely unsuitable little straight hand saw which was probably designed for trimming branches or something. As is slways the way it would probably have been quicker to drive down the road and buy a hacksaw but once I'd actually cut a hole in the pipe I figured it would be easy going from there. 45 minutes of sweat and one slightly truncated finger later I was through the pipe and had removed the whole elbow from the tank, the top of the tank having a female thread. Poking my finger in revealed that at least it wasn't completely full.

The syphoning plan fell at the first hurdle when I realised that his garden hose has quick release fittings at both ends which are not designed to be removed, and which wouldn't fit in the hole. Luckily I found an old shower hose at the bottom of his garden and he does have a wet and dry vac, which we pressed into service. It took a while (about 12 tankfuls) to hoover out the rest of the tank, and the leak persisted the entire while, but eventually the water dried up and....the leak stopped! Yay!

So I'm very grateful for your advice chaps, which gave me the confidence to attack the tank. Thanks! It would eventually have drained itself through the leak but we must have hoovered 30+ litres out of it which would otherwise have had to dry off from the floor. As it is, the dryout can now begin, he already has a dehumidifier and I took mine round as well, so it might get done in a few days. I don't think I actually damaged the tank (beyond slightly bending the top) but it's so old it's not even insulated in any way so I daresay a new one is in order.

SO: now I only need to plug the feed from the cold water tank in the attic to the tank, so that I can fill it up again so he can run his washing machine and bathroom cold tap- for reasons I cannot fathom, the washing machine, which is apparently right next to the main stopcock, is fed from the cold water tank?!

The pipe coming out is a 22mm, but the plastic fitting connecting it to the tank seems to have a smaller diameter than that. I'm hoping that the synthetic cork I've just saved from my evening bottle of wine will be a good fit, with maybe some silicone sealant as insurance. If not, where can I acquire a suitable rubber bung?

Thanks again for the help chaps, I'm off to peruse the forum to see if I can help somebody else in another field that I might know more about rather than just being a hit-and-run leech....

 

[Dan Robinson]

there is such a thing as a drain-easy kit which has two large rubber bungs. Although it might be worth getting some proper lever valves to chop into the pipes after the cold water cistern.


Well done anyway - it can cause a fair squeaky rectum when manhandling a creaky old cylinder full of water.

Even worse when the bugger is still hot

 

[Rave]

there is such a thing as a drain-easy kit which has two large rubber bungs. Although it might be worth getting some proper lever valves to chop into the pipes after the cold water cistern.

That was in fact the plan- on my way over today I stopped by my local plumber's merchant- Water-Loo and showed them a pic of the defective stop valve. The guy there immediately discerned from the pic that the valve had female ends (or something) and told me that it'd be a real faff to replace, and that I'd be better off with compression fittings. He then sold me a 6' length of 22 mil pipe and a decent looking valve for a tenner, after I'd taken about 10 mins of his time discussing the problem. I've just looked at the price of copper pipe online and that 6' length is worth about £7.50! I quite honestly had 300 quid in my wallet at that point, as the backup plan was a plumber on emergency callout rates, and I don't know what plumbing stuff costs, but he has quite clearly done me a great deal. If it wasn't for time pressures tomorrow I would be trying that job. A bung up the end of the feed pipe will just be much quicker and has far less potential for cockups- I will make sure that my valve and length of pipe gets used when they get a man in to do the job properly.

Anyway, Water-Loo have been just as helpful to me in the past for similarly little reward (it was a cistern to toilet bowl seal kit last time), they really are top.

Well done anyway - it can cause a fair squeaky rectum when manhandling a creaky old cylinder full of water.

Even worse when the b*****r is still hot

No chance of it being hot- the water has leaked down the pipes. Like I say we got the cover off the gas boiler- it's completely soaked, and 30+ years old anyway. I think I've suddenly acquired a real project here with my newly reacqainted mate- his house needs a lot of work with not a lot of money to go round. At the very least I'm going to need to learn a bit of roofing and decorating....

 

[tomziggy]

Thank you for the information on this thread been useful even for me at such an amateur level . always criticized that im not able to do certain projects but im always amazed at the level of information you can find online so thank you.

on another note also think this site may be useful for other members it helped me.
Rita