How to loose a rusty drain cock in central heating system

[michael2008]

The drain cock in my central system is rusty outside, looks green. I couldn't unscrew it. How can I unscrew it and drain the central heating system. Thanks for any tips!

[justlead1]

Hi. There are two type of Doc. One that screws into a 1/2" bsp. fitting or the type that are soldered into a capillary fitting. It is not unusual to find this problem, with the soldered type unless the washer assembly is removed prior to heating the washer often welds its self to the seating. Any how. Turn off the supply to the heating system. Find a rad at low level, turn off both wheel head and lockshield valves. have a rag handy and remove plug at to of rad, once removed screw in a 1/2" fitting that will allow the conection of a hose. (Doc Or copper to irn with a small peice of 15 mm copper tube.) fit hose and open valves on rad. this will drain down most of system and reduce the pressure at the point of failed fitting allowing you to remove and replace with less flooding risk. Go Luck

[kwakerdude911]

never heard of a drain cock for central heating being outside
hope u not meaning the outside tap

[unguided1]

drain cocks outside the house arnt that uncommon. I worked on a site where the brickies installed silver boxes underneath floor level for us to put our drain cocks in. but I have over the years been to a few where drain cocks have just been left stuck out side and they have frozen and split the pipe, they are a pain to repair.
but I agree with the above comments, first make sure it is a draincock for the heating.

[stevetheplumber]

never found one that wouldnt undo just need to hold against so you dont turn the pipework worse case use some heat to loosen and have a new washer to hand some have a stuffing box that needs to be taken of firt these are idenfiable by a knurled top

[Bernie2]

Don't forget, there are two types of drain off cock usually used on heating, Type A has a packing gland nut and type B doesn't.

Type A is about £1 -£2 Type B 60p - 97p. Might not sound much and you may wonder why they all use type A unless its specified they do. But times £1 difference by about a 400 houses site and its £400 extra cash.

Soak in WD40, go for a cuppa, soak again then go for another cuppa, come back then start work. Usually works.

Don't be tempted to force the spindle out they can snap like carrots. And make sure you have a replacement washer as they can get a bit chewed getting the spindle out.

Oh! Aye! I think there are a few different size of drain off washer as well, get a collection if you don't know the exact size of the one your taking out.
You can also make it easier to drain again by putting some High Temperature Silicon grease on the spindle when you put it back.

One word of warning, as somebody has already said, both type can get jambed in their seatings.

But watch out for type B, the spindle can easily come right out of the fitting and unless your super Plumb your going to get wet trying to jamb it back in the hole so you can turn it down a bit.

And don't be fooled, you can sometimes take the spindle right out and get no water, the outlet hole gets blocked, so get a bit of wire ready to push in to clear it out and get the spindle back in before you have to swim for it.

Its best done with the water cold, doing it with hot water is Asbestos mans job.

Also type B usually leak from around the spindle when your draining down, so watch the carpet.

So do type A by the way, but they are a bit better and seems to stop leaking if you turn them right out so that the shoulder of the spindle locks against the gland nut. But then they are often harder to free and you may have to take the gland nut off and free it like a type B.

Also an oldish system and even some new ones, can usually be expected to have sludge in it.

And no it doesn't wash off carpets easily or yourself come to that.
So plenty of visqueen or a poly sheet and loads of absorbent dust sheets, rags and at least one bucket required as well as a good hose.

Its best use a decent hose not the Plumbers usual 10p one that collapses into a jelly if a bit of warm water goes down it, especially if you intend to hot flush the system.

Thats about all I can think of off the cuff.

Incidentally I listed it all because at some time or other I have found these things useful.

Yes well! Fair enough I've probably been required to get carpets cleaned in my time, got soaked and broken spindles and loads of other things related to draining down.

Thought I might as well tell you, might save you finding out for yourself.

Mind you we probably do find out for ourselves at some time.

[365drills]

Yep I put my own drain cocks in when I did my house.

And I stuck them all outside.



The yellow is some foam I sprayed to keep it warm in winter and prevent cracking.

I was going to put it into a little box but I got lazy.



And this is the reason why I did it. I laid a liquid resin floor in the kitchen. Its a self leveling compound that floods all the pipes and then locks them in forever.

Any mistakes with your c/h then you have to dig up the whole lot....

So I thought it smart to put drain plugs outdoors....

[secret squirrel]

365 drills, nice kitchen,

Thanks, for that in depth reply, Bernie2, I have printed in out and kept it in my file of useful bits. I'm sure it will come in handy and when it does I would have forgotten it.

I must admit I would never have looked outside for a CH draincock.