Worcester 15/19. Draining system for winter

[MrsS]

Hi
Can anyone give me some hints on how to drain the central heating system off a Worcester 15/19 boiler? The house owner lives abroad and the tenants (who installed the second-hand boiler) have done a runner, and I need to sort it out before the real cold sets in. I have turned off the mains water outside the house, but can't find any visible means to drain off what is left inside. Do I do radiators one by one, or is there some way to drain tham all at once? (I have never had central heating in my own house, so am completely ignorant....)
Also - is there any reason why the cold water header tank in the loft should still be full of water? Or would that just be idle workmanship and do I need to try and empty it somehow? It doesn't seem to be connected to any taps, so I can't just open a tap to pour it out.
Thanks in advance for any help you can give me - boiler plumbing leaves me in a state of bewilderment.

 

[Burnerman]

Presumably this is the Danesmoor boiler rather than the Heatslave combi?
The tank in the loft is the flow and expansion tank (about 4 gallon) and the level will be undisturbed until you let some of the radiator water out of the system.
There should (may) be a drain off cock at the lowest point of the system but you can't guarantee that all water will be drained.....at the very least all the radiator bleed valves must be open to help this.
The boiler similarly should have a drain cock at the bottom on whichever side the heating return pipe enters the boiler.
If the house is likely to be empty for a long winter period, the copper cylinder must be emptied too - if there is no background heating - and likewise water feeds to the bath etc.
John

 

[MrsS]

Thank you John.
The boiler is a Heatslave combi. (I suspect the tenant took it out of another house to install it, and I'm aware that it is now obsolete....).

Thanks for info about the loft tank - I was worrying that it may have been the original header tank and was going to need a bucket to empty it

Why is there still a need for the copper tank if the hot water comes from the cold water feed through the boiler? I found the tank and knocked it a few times - it sounds like it might still be full, but I can't really tell, since no taps seem to run off it.

The house is a few miles from where I am just now, but I'll go and have another hunt for drain cocks by the boiler and at the lowest radiator.

At the moment I have turned off the stopcock in the garden and left all the sink, basin and bath taps open. I have also flushed a bag of salt through each of the toilets. Once the radiators and boiler are drained, I assume it should be ok for the worst of the winter. The minus-20s are not unusual, and it is snowing right now.

If I can't find it, or make a mess, I hope I can come back here and beg for help again?

Thank you
Jo

 

[Burnerman]

A good boiler, the Heatslave! By its very name, it stores a good few litres of water in its internal tank, and that must be drained. The drain cock is usually bottom right, at the back where the central heating return pipe is.
If you lift the boiler top off to expose the guts, you'll find 3 air bleed points (square, radiator bleed key size) and these let air in as the water drains out.
I guess your loft tank is redundant, from an earlier system....I would imagine it would be empty! Certainly it should be, and the supply capped off or disconnected.
To deal with -20 deg there's obviously quite a bit of luck involved as any residual water will freeze, but so long as there's some space for expansion, all should be ok. The drains will be fine but some salt in U bends etc does no harm.
Obviously on recommissioning there will need to be some inhibitor reintroduced into the central heating system.
Be lucky!
John

 

[MrsS]

Hi John
Thanks again.
The radiator system goes from boiler to upstairs, then feeds the downstairs ones from above.
The only way that seemed to drain anything was to undo the bleed holes and let the water come out. I did this to the downstairs radiators, assuming that I was draining the upstairs ones at the same time?
Now, my next question.... Having done that, I assume there is still going to be water in the downstairs radiators and pipes to the level of the bleed valves? How do I get rid of this? There are no visible joints on which to attach a hose.
I realise that I am a complete ignorant when it comes to heating systems, but am very grateful for your help.
Thanks
Jo.
PS: The old header tank in the loft is still full. I assume I will have to use a bucket to empty it. Whilst cursing the cowboy who put in the system.

 

[Burnerman]

Jo, just have a look at Toolstation 40214 (rad valve with drain) and 71396 will you?
If you can find any of these, the job is much simpler and there should be one at the lowest obvious point, somewhere!
If there isn't any, then the done thing is to crack open a radiator joint but the water sprays everywhere and is a devil to catch! We've all bunged a Tupperware dish under the rad before....
As for the loft tank, well the water will be very unsavoury looking by now and the tank is really quite small. Goodness knows why it was left there, especially full!
Check - if you press the ball valve down, does water flow in? The outlet pipe must be capped, wherever it is.
John

 

[MrsS]

Hi John
Nothing that looks anything like either of those! That was just the sort of thing I was looking for before I posted on here, thinking that it couldn't be very difficult to drain a heating system by myself. I must have been delusional. I think I had also assumed that the guy who fitted the system might have known what he was doing. Delusional again...

But - should I buy a couple and attach them to the downstairs radiators' pipework before next winter? Which one is best/easiest?

Another thought - how do I drain the leftover water from the pipes under the floor between two of the downstairs radiators? Being at a lower level than the visible pipes, I can't see how it would be possible. I suspect there may be an obvious solution that has bypassed my non-plumbing brain?

Loft tank: Before I turned the water off, nothing came in when I pressed the ballcock (is it more PC to call it a 'valve' nowadays?), and nothing flows out through any taps when the mains supply is off. The outside stopcock is now off and, after spending a couple of hours last night holding jugs and hoses up to radiators, I'm not going to turn the water back on just to experiment with the tank. If I can't find the cap on the outlet pipe for a drain, I will attempt to siphon it off with a hose through the loft hatch and out of the nearest window.

So far, you are my hero of the week. Thank you for your help and patience.
Jo

 

[Burnerman]

Certainly, not having any drain downs is a bit of a bummer really - and I'm somewhat surprised!
No matter - 71396 is simply fitted into a compression tee piece and is a very worthwhile addition for the future.
As for the pipes below the floor -well you can't drain them without disconnection....I don't know how easy it is to access these or whether the pipes are actually lagged now - it would be just typical if they were below a laminate floor!
As for the loft tank, it would seem that its supply has been removed at some point, and the outlet capped elsewhere. Water freezing in the tank is no big deal - the tank would cope with that so it just leaves the outlet pipe I guess. Syphoning the tank is one way (but you don't want a mouthful of that) so one way is to submerge a length of hose into the tank, getting the hose full. Putting a thumb over one end and over a bucket whilst keeping the other end submerged and the syphon should start automatically if the end is low enough....failing that, a wet vacuum cleaner could be the way to go, if you have one.
Have fun
John

 

[Madrab]

If you go to petsathome, buy a fish tank syphon, all you do is shake it up and down in the water to start the syphon action, attach the long hose to the other end, job's a guddun