There are a couple of tiny leaks in my heating system. As in, a few drops an hour, the pressure drops over the course of weeks.

Is there something you can put in that’ll seal the leaks, kind of like Radweld for car radiators?

Actually come to think of it, I have a bottle of Radweld in the garage…. (joke)

Yep Fernox Leak Sealer should do it
Linky
Go to a plumping merchant, most of the big ones stock it (Plumbase etc).

If you know where it’s leaking from, why not fix it?

Well, it’s somewhere behind the boiler, and it’s also from one of the motorised valves. They are both very small, so if I can patch it up rather than have to drain it and replace valves, I will.

Think I’ll stay away from the plumping merchants till after xmas :):)

Your just letting your self in for a world of hurt.

A leak in a connection is one thing but in valves and you want to put in a chemical gunker …… Lovely idea.

I would think of a suitable analogy but i cant think of anything you could relate too….

Stick in some stans sealant or an egg white ?? …. Will be about as good for the system.

and it’s also from one of the motorised valves.

gotta say, bite the bullet – new valve.

is the valve inside the boiler, or is it a regular 2-port/3-port motorised jobbie?

It’s in the airing cupboard. Just a straight through on-off job like a tap with a motor and gearbox clipped onto the top of it.

If I can work out how to drain it down without making a huge mess.. maybe…

Can you try freezing it please ? And record the outcome ?

A long hose is your friend to drain

I could just do what I did when I changed the downstairs rad – just drained enough water from the lowest point to equalise the pressure (a few litres), and create enough a vacuum up top to stop the water running out.

Of course, I’d have to make sure to do the downstairs tap back up before removing the valve at the top…!

Right. Took the valve off, took it to the plumbers place. Turns out after long humming and hahing that it’s only available with the actuator and I could only get after Christmas.

So I twiddled it and oiled it until it stopped feeling gritty, and refitted it along with some more inhibitor. No leaks so far!

Did you not try to tighten up the nuts first?

It wasn’t leaking from the threads where it was fitted, and the valve itself is not adjustable or tightenable like a normal tap.