Central Heating Drain Valve

[drewb]

Hi,

I need to drain down my system and put some descaler in for a few days then drain again and add inhibitor.

I have taken the radiator that was blocked off completely and successfully removed blockage using a garden hose.

Its an open system fed from a tank in the loft.

I'm unsure where the system drain is located. All of the downstairs radiators have something like this although the white cap is located in a horizontal position as opposed to vertical and is not a screw cap.

All of the online videos seem to use a different valve that is at 45 degrees from horizontal / vertical.

Below the boiler, there is a single pipe but I dont see a valve anywhere. Pipework above the boiler is boxed in.

How do i find the drain off valve for the system?

Thanks in advance for any advice given.

 

[JohnD]

please post a photo of the actual valves on your system

the one you show includes a hose connector on the tail, for a drain. I don't know if that is actually what you've got.

If you can't find any drain cock, you can drain the system by loosening a radiator valve. Very often a 3/4" bsp connector for a garden hose or washing machine hose will fit, which is quite convenient. Once it is drained, you can fit one or more drain cocks for future use.
http://www.screwfix.com/search.do?fh_search=drain+cock&fh_view_size=20 get the more expensive glanded type "A" as it leaks less in use

The drain cock should be at the lowest point of the system. Sometimes it is under a loose floorboard next to the back door so you can put a hose outside. If you have radiators fed by pipes that come down from the ceiling, each will need a drain (you can get radiator valves with drain cock incorporated, they are a bit cheap though).
like this

Have you got pipe cutters and other plumbing tools, and can you do diy plumbing?

 

[drewb]

Sorry. I have enclosed a pic now.

All rads on ground floor are similar except the one near fron door does not have a trv at the other end. All other rads have trv control.

House is on two levels with header tank in loft.

The ground floor is concrete so I would all rads on ground floor are at same level.


My concern is whether I need to drain all ground floor rads individually.

I've never down carried out diy plumbing but always willing to give things a go.

Untitled

• drewb
• 12 May 2013
• 1

 

[JohnD]

your photo didn't work

click on "edit" to edit your post

then

click on "show my images"

then

click on the pic you want

then click "preview" to see how it will look

then click "submit" to publish it.

 

[Phill Peck]

The bit between the valve and the radiator has a hose connection on it

To used this to drain you need to use a radiator bleed key where the hose connects to undo the screw then put the hose on and open the rad valve.
You will get water coming out until the hose is attached, put down towels and a tub if it fits(old ice cream tubs usually fit) and have your hose ready rolled out to a drain or outside some where.

They are not an ideal drain point given what I have explained above

 

[drewb]

Hopefully, pic sorted now.

 

[drewb]

Sorry for stating the obvious here

So, I can just use any downstairs radiator to drain system?

Or it is a case of drain from one radiator downstairs and see if the others have emptied?


Thanks

 

[kbdiy]

Depending on the pipework configuration you may need to drain from each radiator using the method described above. You might need to open the adjacent valve fully by removing the cap and turning the head anti-clock to fully open the valve. Count the number of turns and make note so you can reset the valve when you refill.

I would suggest that while you are draining down it might be worth draining from all rads and giving them all a good flush. If you've had one blockage it would suggest that the whole system could be quite 'sludgy' and need a good clean. A cleaning chemical rather than a descaler might give better results as well. I would:
1) drain down, remove each rad and flush until clean;
2) refit, refill with cleaning agent such as Sentinel X400 or X800;
3) run for a few hours/days
4) drain, flush and refill with inhibitor and descaler

Just did a similar exercise with my own system which has hopefully improved its performance!

 

[drewb]

Thanks for advice.