Central heating nightmare!

[Lorzy Lor]

Our boiler used to crash and bang, and sound like it was going to blow up! This noise happened when it was on for a few hours every so often. We had a bathroom fitted last May and they completely emptied the heating sysem of water. This remedied this problem however it has just started happening again! Should i bleed the radiatiors, from the top of the house down, and will this fix the problem? (I did used to do this before, and the evil noise kept coming back! Its a freaking nightmare!!!) : o

[gasman]

By Bleeding the system this may reduce or temp. postpone the problem but to cure it for good it sounds as though the heat exghanger is scaled up in the boiler and requires de-scaling or even re-placing. Try using a good descaling product in the system then a cleanser and finaly a new dose of inhibitor.

[SteveSxx]

This is something that I have considered doing - how do you get the de-scaler into the system and how do you remove it afterwards ?
My system is sealed - save for a tap which is used occassionally to top it up (by a meter on the boiler)

[Lorzy Lor]

Thanks very much for taking the time to reply! ;) As SteveSxx says Mr Gasman, how would i go about this task? I dont even know how/where to put this stuff in!! :( Is it something i need a professional to do?!! :)

[gasman]

Ok Here goes,
Nip down to your local DIY shop or Plumbers merchant and buy a bottle of 'BetzDearborn' Sentinel X200 boiler de-scaler �12.99 ish. It Restores Boiler Efficiency and Eliminates Kettling, (Which is what i suspect you have). Then turn off your boiler and with a rad key let out all the pressure by slackening the vent nipple on the highest rad (usually the towel rad in the bathroom if you have one) use a suitable container & a cloth to catch the water, if you have carpet down then make sure you put down a suitable protective covering as any spills will permanently stain. When it stops flowing all the pressure will have gone and it will be safe to open up the system.
Now put a suitable container underneath the draw off point fitted to your system it will prob be at the lowest point in the pipe work and also some under your boiler aswell. ( these are the small brass valves that have a ringed spout that you can attach a hose pipe to ). Turn the square lug that is on the end of it using a suitable tool ( small adjustable or pliers / grips ) anti clockwise to open it up and let out some of the fluid from your system. Not too much at this point just say five litres or so. If you cannot get a tub under it then attach a small length of hosepipe to it and run it into a mop bucket or somthing similar. Then tighten it back up again.

[gasman]

Now you need to go back upstairs and the rad you have used to depressurise the system ( the bleed valve should all ready be open from earlier) . Then this rad will be half full now or even empty depending how much fluid you have drained off, you can now undo the whole bleed valve assembly and remove it from the rad ( the whole 3/4" nut i am refering to not just the bleed nipple ) then using a funnel and a tightly packed cloth around it poor in the X200. Put back the bleed valve & tighten the bleed nipple as well. Then back to the boiler and re-pressurise the system back to 1 bar and bleed the rad that you have used to put in the X200. turn the boiler back on & leave the X200 in the system. ( No Need to Flush - Stays in System ).
All should be well from now on. Good luck. If you do need to flush and cleanse then post back.