Bleeding central heating

[Polar Bear]

Just given the system a check for the impending cold nights.   I never know whether to start at the rad furthest away or the nearest rad.   Regardless, it's done now.

[rogerzilla]

It doesn't matter - not like bleeding car brakes, where you usually start furthest from the master cylinder and work back.

I did this today too.  I also drained the sludge filter because BG don't normally bother.  These filters are cunningly designed to spray black crap all over your kitchen but after last year's cleanup, of Exxon Valdez proportions, I am wise to them.  Basically you open the drain valve (a small brass ball valve) and it just drips slowly and unimpressively.  After about two minutes, the plug of sludge in the ball valve hole will let go and the entire Pacific Ocean, mixed with colliery waste, will suddenly try to come out.  Make sure you have your hand on the valve ready to shut it off when this happens...

[Gattopardo]

Sludge trap Thought that running an inhibitor would stop that.

[Wombat]

Nope!

I suspect some of the inhibitor function actually converts nasties into comparatively harmless sludge.  One inhibitor type I used (a Fernox one) seemed to turn the water in the feed tank into 'orrible black filth, which was a bit puzzling.

I use a Sentinel one now, and there seems to be no black sludge at all.

[Wowbagger]

I have just registered on mybuilder.com, as recommended by the excellent Peliroja OTP, for our system to be power-flushed. Dez and I spent a good deal of last winter attempting to bleed the system and actually get some heat into the distant radiators. It's a messy system with a bit added on when we had the extension built and I suspect that there's a monster airlock somewhere. We have 14 radiators, the originals being 5 upstairs and 3 downstairs. The new bit has 6 downstairs and, this being a long, thin house, the most distant radiators are about 20 yards away from the boiler.

[mrcharly-YHT]

I suspect some of the inhibitor function actually converts nasties into comparatively harmless sludge.  One inhibitor type I used (a Fernox one) seemed to turn the water in the feed tank into 'orrible black filth, which was a bit puzzling.

I think that the inhibitor is converting the iron oxides

Tannic acid chemically converts the reddish iron oxides into bluish-black ferric tannate

[Canardly]

I have just registered on mybuilder.com, as recommended by the excellent Peliroja OTP, for our system to be power-flushed. Dez and I spent a good deal of last winter attempting to bleed the system and actually get some heat into the distant radiators. It's a messy system with a bit added on when we had the extension built and I suspect that there's a monster airlock somewhere. We have 14 radiators, the originals being 5 upstairs and 3 downstairs. The new bit has 6 downstairs and, this being a long, thin house, the most distant radiators are about 20 yards away from the boiler.

Dont be surprised by a bill in excess of £400 Peter. It is an expensive process. Do you have a magnetic filter fitted? If not, might be worth considering having one fitted whilst you are having the system purged. e.g.

http://www.gasapplianceguide.co.uk/magnaclean_system_maintenance.htm

https://www.youtube.com/watch?v=sBwKsvXj1JY

Cleaning the filter should be part and parcel of having the boiler serviced.

[Blodwyn Pig]

Don't forget, when bleeding, make sure the boiler is OFF, and not pumping water round,  and also you may need to top up the pressure in the system afterwards, (depends on system) otherwise the boiler wont work if pressure is too low.

[offcumden]

Do you have a magnetic filter fitted? If not, might be worth considering having one fitted whilst you are having the system purged. e.g.

http://www.gasapplianceguide.co.uk/magnaclean_system_maintenance.htm

We're due for an annual service, and the reminder letter came with an 'offer' to install one of these Magnaclean filters - think it costs £175. The blurb sounds plausible but, given the radiators and piping are 40yrs old (new condensing boiler c.4yrs ago), is it really worth it?  No sign of sludge build-up - rads hot all over - and soft water area. The cynic in me suspects another money-making gambit.