DIY question - header tanks

[Crackle]

New house has got two in the loft. I noticed one of them is weeping from somewhere, looks like the overflow. So as I'm not using it, I've drained it. That's fine but what is the other one, they're not connected and the other one is really scummy, like it doesn't get much use. Is it the central heating? I'd like to drain it too but haven't a clue how. Both will go when the central heating is re-done with a megaflow. All help appreciated.

 

[Amanda P]

It's usual for a house to have one header tank for cold water, and a second, smaller one for the central heating.

Cold water header is being constantly used and replaced - it usually feeds everything in the house except the kitchen sink and maybe the outside tap (but not always) - so it's usually pretty clean.

Heating header isn't really circulating much. It's there so that as the water in the heating system is heated and expands, there's a place for the extra volume to go. Then as it cools and contracts, some is drawn into the pipework from the header again. So it's often pretty scummy and scaley. This is normal and isn't necessarily cause for concern: you won't be drinking it or washing in it.

To drain the heating header, you'd normally drain, or partly drain, the whole heating system. The lowest radiator, or the lowest heating pipe, in the house, normally has a drain cock with a place to attach a hose.

To drain down, first you need to stop the heating header re-filling. There may be a gate valve on the pipe leading to it which you can close. Otherwise, tie up the ball valve with a bit of wood bridging the tank and a bit of string. Attach a hose to the drain cock, dangle the other end outdoors somewhere (below the level of the cock, obviously), and open the cock.

This will drain the whole system, boiler, radiators and all. It's quite important (very, very important, really) that your boiler does not decide to start up while there's no water in it, so make sure this can't happen by switching it off thoroughly before you begin. Once dry, of course, your heating won't work.

To re-fill it, close the drain cock and open the gate valve or untie the ball valve. You should add corrosion inhibitor and anti-sludging stuff at this point, by pouring it into the header (it may be a lack of this that's made the header so scummy). Fernox is the usual stuff; you can buy it at B&Q or plumbers' supplies places.

If your system's well-designed, it should refill with no problems. But you should bleed all the rads and the boiler just in case once it's full. Some houses have legs of piping that can be very hard to get to refill. If yours is old, or has long legs of piping to distant radiators, or if you're not confident about any of this, or if it's crucial that your heating continues to work (probably is if you're on holiday over Christmas!), I suggest leaving it alone and getting the whole thing serviced by your freindly local heating engineer - or he'll sort it when he installs megaflow anyway.

 

[yenrod]

It's usual for a house to have one header tank for cold water, and a second, smaller one for the central heating.

Cold water header is being constantly used and replaced - it usually feeds everything in the house except the kitchen sink and maybe the outside tap (but not always) - so it's usually pretty clean.

Heating header isn't really circulating much. It's there so that as the water in the heating system is heated and expands, there's a place for the extra volume to go. Then as it cools and contracts, some is drawn into the pipework from the header again. So it's often pretty scummy and scaley. This is normal and isn't necessarily cause for concern: you won't be drinking it or washing in it.

To drain the heating header, you'd normally drain, or partly drain, the whole heating system. The lowest radiator, or the lowest heating pipe, in the house, normally has a drain cock with a place to attach a hose.

To drain down, first you need to stop the heating header re-filling. There may be a gate valve on the pipe leading to it which you can close. Otherwise, tie up the ball valve with a bit of wood bridging the tank and a bit of string. Attach a hose to the drain cock, dangle the other end outdoors somewhere (below the level of the cock, obviously), and open the cock.

This will drain the whole system, boiler, radiators and all. It's quite important (very, very important, really) that your boiler does not decide to start up while there's no water in it, so make sure this can't happen by switching it off thoroughly before you begin. Once dry, of course, your heating won't work.

To re-fill it, close the drain cock and open the gate valve or untie the ball valve. You should add corrosion inhibitor and anti-sludging stuff at this point, by pouring it into the header (it may be a lack of this that's made the header so scummy). Fernox is the usual stuff; you can buy it at B&Q or plumbers' supplies places.

If your system's well-designed, it should refill with no problems. But you should bleed all the rads and the boiler just in case once it's full. Some houses have legs of piping that can be very hard to get to refill. If yours is old, or has long legs of piping to distant radiators, or if you're not confident about any of this, or if it's crucial that your heating continues to work (probably is if you're on holiday over Christmas!), I suggest leaving it alone and getting the whole thing serviced by your freindly local heating engineer - or he'll sort it when he installs megaflow anyway.

And no post charge for that advice !

 

[Amanda P]

Indeed.

A Megaflow system, I now find, is a mains-pressure one. So it'll have no header tank. Scumminess resolved. Leave it alone until the plumber comes.

(Could have saved myself a lot of typing if I'd checked first... Still, nowt else to do in the office today...)

 

[Crackle]

Uncle Phil, thanks for that reply, great stuff. I think the weeping header was from its overflow. Lack of use has allowed the ball level to rise higher than it would normally and the overflow pipe is broken and it's been seeping slightly. No real damage luckily or nothing that isn't going to be stripped and re-decorated.

I won't drain the heating just yet, leave that to the plumber, unless it's the tank leaking. I won't be using the heating, though I might put it on to dry out the slight dampness on a couple of walls now.

Old houses eh <tut>

 

[mickle]

Great post Uncle Phil.

Crackle, it's inevitable that the washer in the stop-cock eventually lets by as the rubber deteriorates and it's quite common to find that the compression fitting for the overflow pipe isn't water tight meaning that rather than flow into the pipe it leaks through the hole and down the side of the tank. This can go on for years until it gets so bad that someone notices it. It's a very cheap and easy fix.

Friends of Ms Mickle had a meter installed in their flat a couple of years ago and were astonished by the increase in their water bill, it turned out that their system had been letting water straight through and out the overflow like a bath tap. The overflow serves two purposes, draining the water when the valve fails and providing a visual indicator but whoever had installed theirs had run the pipe straight in to the drain. Their reckoned it had been flowing like that since it was installed. Twenty years ago!

 

[Twenty Inch]

Indeed.

A Megaflow system, I now find, is a mains-pressure one. So it'll have no header tank. Scumminess resolved. Leave it alone until the plumber comes.

(Could have saved myself a lot of typing if I'd checked first... Still, nowt else to do in the office today...)

Not wasted, that was really helpful, thank you.

Crackle, you can and should fix the weeping overflow. It's usually just pipe held in with two nuts, one on either side of the the tank wall, and rubber washers. Undo them, clean it up, and remake the joint. I've used plumber's sealant before on mine as the joint wouldn't tighten enough for a good seal. Available for a couple of quid in hardware stores and useful stuff to have around.

 

[peanut]

bloody typical wheres a plumber when ya need one eh eh!?
.........then along come three at once !

 

[Crackle]

Thanks for the further advice chaps. What Im not sure about is where it's leaking. It seems to be fractured where it goes through the wall, so it could be there rather than at the tank.

I would try to fix it, even though it's the filthiest loft I've ever been in, if I was keeping it or living in the house but at the moment I'm doing neither so Iwas just concerned to stop it leaking.

Just going to head back over this morning and double check it's all OK. Water pipes and empty unheated houses worry me slightly.

 

[bonj2]

if you're getting rid of it anyway, then much simpler than understanding uncle phil's lengthymonologue would be to just whack a bucket under there and drill a hole in the thing.

 

[Crackle]

if you're getting rid of it anyway, then much simpler than understanding uncle phil's lengthymonologue would be to just whack a bucket under there and drill a hole in the thing.

Damn you Bonj, I've spluttered coffee all over my clothes