Drain Cock types for central heating

[rednaxela]

Hello all,

I am putting together a list of parts that I will need to extend my central heating system (15mm) to my extension.
In screwfix, I have seen two types of drain cock.

Drain Cock 15mm Type B Light Pattern
Drain Cock Type A Heavy Pattern Glanded

Would anyone be able to explain the difference to me?
I was planning to have a drain at the bottom of each radiator.

many thanks in advance,
Alex.

 

[bobthebender]

I use these valves with a built in drain off.

 

[TicklyT]

The first one doesn't have a gland on the shaft, and as much water runs up the threads and out onto the floor as runs out the outlet when you open it, so it's almost a waste of time fitting it.

The second has a gland on the shaft so it doesn't leak (in theory)

Have you considered using http://www.screwfix.com/app/sfd/cat/pro.jsp?id=11074&ts=60568?

 

[rednaxela]

Thanks for the info. I'm going to buy those

My radiators from Screwfix came with valves, however I discovered last week that they seem to have disapeared with the plumber following 1st fix pipe fitting I can't prove anything as the extension was a mess at the time and could have been mixed.
Then the pipework leaked and they had to come back. (I want to finish the job myself as I am confident in soldering now and have lost trust with them)
your solution will fix both problems.

Thanks for your help, I love this Forum.

Alex.

 

[gas4you]

If you buy type A don't get Midbras. Their latest ones that I have had do not have the 'O' ring on the end, so I took them all back and demanded the Eagle make that come with them

 

[ChrisR]

Even the better type are rubbish unless you buy a good make, then they're still unreliable.

The rad valve drainoffs are rather slow - no good for flushing through.

Unless you can use use these (excellent but a bit ugly)
http://www.bes.co.uk/ item 13180

you might like to do it this way. A pipe goes from the second rad valve to outside, say through an air brick. The drain valve has a lockshield cap on it, natch.

 

[JohnD]

I recently used one of these in the pipe coming up from the floor to a radiator beside an external door. You can screw a washing-machine hose on the outlet when you need to drain,or a fitting for a garden hose (it is 3/4" BSP). I thought it best to put a Blank Nut over the open end just in case...

Because it so big it gives a much quicker drain and better flushing flow for a dirty system than the rad valves with drain-off (but I normally use them as my own syst is so clean)

 

[Gasguru]

Except the O ball seatings and the spindle O ring can't take the heat so will eventually leak.

 

[JohnD]

 

[hpf]

Can any one help me ? What is deferent A and B type Please Thanks

http://www.bes.co.uk/products/098.asp#7494

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[Nige F]

Type B are what I clean from Drains

 

[DeltaT]

Type A MT cock has a gland as stated above & will not leak when draining the system. Type B have no gland, so the water pizzes all over your shag pile!!...........

 

[Andygasman2010]

You piping more than one rad? You don't need a drain-off on each rad unless they're idividually drop fed.

 

[jerseytaylor]

chris r

nice idea going to put that to use on mine