CH Experts - Correct solution to renew seal?

[Leonardo]

Hi all,

Pics: Main drain for the CH system - at the lowest point of the system.

It is 25 years old - and I cannot easily replace it.

It is leaking.

Q: How does this particular drain plug/fitting create its seal (when tightened).

It is directly exposed to the elements all year round.

Is there likely to be some sort of rubber washer or diaphragm inside?

If its simply a washer - whats the right type of washer to choose (given it's purpose and exposure to extreme cold during winters)?

It's leaking and I'm losing pressure in the CH system - simply tightening is not sorting the problem.

Leonardo.

 

[ShaunCorbs]

Arctic Products MT Drain Cock Tap Washers ½

Replace the washer, but will require a drain down

 

[snowhead]

When you unscrew the inner there will be the remains of a washer on it with other bits stuck to the remaining seat.
Scrape the seat clean then fit new washer.

As it's a sealed system you'll loose some water to start with then it'll stop.
It won't matter if it does keeps coming as you'll be outside anyway.

One of these;

Draw off cock washer | eBay

 

[rpm]

Arctic Products MT Drain Cock Tap Washers ½

Replace the washer, but will require a drain down

Unless it is full of sludge?

 

[king of pipes]

As above time for a drain down and flush out unscrew the square section all the way out to revael the old rubber washer or whats left of it , clean up and replace with a new washer and refit. Cheers kop

 

[London Gas]

As everyone else has said, just take it out and pop the new one in, if you are unsure of the washer get a few!

 

[Best]

It can be very easily done without a drain down.
But if any work in future requires a drain down, or system flush, then leave it until then.
I very regularily replace the washers in draincocks if they are leaking or old washer seized and heat damaged, while system is full of water. I usually have no choice as it is by far the fastest way to have a fully working drain point.
I also do it where draincocks are inside homes and garages, so that one being outside is very easy.
Really a plumbers job though, but if you wish to risk it, get a new washer, plus you might consider have a new draincock with similar works you can rob in the hope they fit that one. Just put a hose on the drain and then screw out the works. If entire washer doesn't come out with the brass nut, have a small slotted screwdriver to poke the washer out. (Might require a bit of levering to break and remove an expanded or hardened old washer).
You will get a lot of water coming out, but nothing usually that can't be stopped with holding something against it while you work.
Only touch it when heating system is cold and electrically isolated.

 

[townfanjon]

When you say loosing pressure is your system sealed , i.e you fill it via a filling loop

 

[Best]

When you say loosing pressure is your system sealed , i.e you fill it via a filling loop

Good point! No mention of tank fed, so going to be easy to take the pressure off system if it's sealed and replace washer.

 

[Last Plumber]

I always smear a wee bit of silicone grease on the washer when I change them. It will help prevent it sticking in future. (Not forever obviously).

 

[Best]

I always smear a wee bit of silicone grease on the washer when I change them. It will help prevent it sticking in future. (Not forever obviously).

Reminds me I used to unscrew the works from brand new draincocks and carefully wrap the rubber washer in ptfe tape to prevent it sticking. Used to do that on oil boilers where the draincock was directly into the boiler. Maybe a bit mad.
It is the heat that damages the washer, so if a draincock is installed on a long dead leg, or on a pipe that is dropped down below the rest of system, then the washer seems to last.
If possible it is IMO best to have a screw-in draincock, into a female fitting, so you just need to undo the nut and swap entire lot.
Some 1/2" screw in draincocks came with a tapered edge suitable for using a nut and olive, which is very handy.

 

[townfanjon]

Good point! No mention of tank fed, so going to be easy to take the pressure off system if it's sealed and replace washer.

Yep , “great minds “lol

 

[firemant]

If the jumper (mechanism) remains in the valve after removing the nut, the best toll is short ling nosed piers, to grip the stem and pull forward.

 

[firemant]

f the jumper (mechanism) remains in the valve after removing the nut, the best tool is short,sturdy, long nosed piers, to grip the stem and pull forward.
If the jumper comes out, leaving the washer, use a thick screw or a crew extractor to wind into the washer hole,then pull to remove.

It is best to buy a replacement cock. Remove the mechanism, to be ready to insert as soon as the assembly is removed. This is a type B draincock:

Midbrass brass plain shank drain cock (Type-B) 15mm | Plumb Center