Radiators cold at the bottom part 2

[xanderma]

This is really a question for gasman...I've just read your very thorough replies to the earlier question from missieb, which I am going to try (or rather, get Mr X to try!)

However, I just wanted to run my scenario by you, to see if the same would apply.

We have had the same central heating system since the house was built 14 years ago. This summer, our boiler was changed as part of a house extension. It is a normal boiler (i.e. not a combi). We have the same number of radiators,although 2 have been changed from a single to a double. The system was drained during the extension. Our rads are now cold at the bottom, I wondered what you reckon?

Many many thanks.

[gasman]

Hi, xanderma,

You could certainly give the balancing method a try it may do the trick.

But i suspect that this may not be your problem. You see if a cleanser was not introduced to your system before it was drained down in the summer to enable your home improvements and a new dose of inhibitor put back in when it was refilled. Then i would guess that all the old sediment / sludge that has built up over the years has collected and lodged itself in bottom of your rads. ( If a cleanser had been used it would have stuck to the cleanser and simply flushed out ). And you now would not have a problem. So dont be suprised if the balancing trick does not work.

If balancing them fails, and you need some advice as how to get rid of the sludge / sediment then post again.

[xanderma]

Tried balancing, you're right it made no difference. Mr X is sure that inhibitor was introduced, but we don't remember anything about a cleanser being flushed through. Culd you advise again please, when you've got a minute (you could charge a furtune for this !!!!!!)

Thanks for your help again - people like you make AB the great community that it is.

[gasman]

Ok Here goes,
Nip down to your local DIY shop or Plumbers merchant and buy a bottle of 'Betzdearborn' Sentinel X400 Sludge Remover' �12.99 ish. And a bottle of Sentinel X100 inhibitor same price �12.99 ish. 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.

[gasman]

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 clockwis 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.

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 X400. 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 X400. turn the boiler back on & leave the X400 in the system for 24hrs to let it soften up the debris / sludge & do its stuff . And run the system as normal.

To be continued have to go to work now....

[xanderma]

gasman, at the risk of being over-gushy, you are a complete star! Thanks again for your quick and very detailed reply. Mr X is off to DIY store on way home tonight, we'll start the job tomorrow and await part 2!

Thanks a million times.

[gasman]

Part TWO ....

Now once all the previous steps have been carried out and the heating has been in back in operation for 24 hrs, it is time to roll up your sleeves & get down to business.

So turn on your heating 1hr before you intend to start and i suggest you start in the morning because this is going to take you the best part of a day to do if you've never done it before !!! Then when it is nice and piping hot you need to turn off your boiler again attach a hose pipe to the draw off point. I suggest you secure the hose with a small jubilee clip to the draw off point and wrap some old towels round it aswell because there will be some pressure going through it and combined with the hot water that is going to pass through it aswell it will soften up the hose and could possibly blow off making a terrible mess everywhere. You should run the hose to a nearby outside drain that is lower than the draw off point.
Now open up your draw off point and let the system drain down, after say 5 mins start to go round all the upstairs rads and open the bleed nipples ( starting with the highest one first and working your way to the lowest ). Then when the hose stops running open up all the remainder downstairs rads tallest to smallest . This may take some time and if you find water coming out of any rad quickley close off the bleed nipple, wait a few mins then try again. keep an old rag handy just in case there is any water ready to spurt out all over your carpets.

[gasman]

Once the system has fully drained go around and tighten all the bleed nipples on the rads, leave the hose pipe on, and the draw off point kept open. Then turn off all the rads exept the one furthest away from the boiler and also isolate the boiler aswell by closing the flow and return valves to it. Then open up the filling loop as if you were goint to fill and repressurise the sytem. All the fresh water will now be flushing round the sytem going through the only open rad and back out of the hose pipe. keep it flushing till the water runs clear. When you get fresh clear water running out of the hose turn off the filling loop then turn off the rad you have flushed out and turn on the next rad and repeat the above instructions. Do this to every rad working your way from the furthest one away from the boiler till you have flushed your last rad nearest the boiler. Then do the same for the boiler aswell. Now close the draw off point but leave the hose where it is and fill the system fully and pressurise it to 1Bar run the heating again for 1/2 an hr . Hope your keeping up with this !!!
Now go back to the earlier instructions just prior to this one and drain the whole system down again till it is empty.

[gasman]

check all the bleed nipples are closed the boiler is not isolated and the draw off point is closed and fill the system one last time and bleed all the rads. Run the heating for 1/2 an hr and go around and check that you have acheived your goal, all the rads are balanced properly and uniformly heating up with no cold spots. If any rads are still not operating properly then i suggest you actually take the rad off and take it into the garden and using hot water flush through the rad with it upside down with the hose pipe and fit it back on. Ok if all is well hopefully this should be the last time you need to drain down. So you can now introduce the X100 inhibitor using the same method as described to put in the X400 earlier.
Good luck xanderma.
Hope all goes well...
Gasman.

[xanderma]

gasman, I'm sending you a virtual box of choccies and a huge bouquet!

Thank you so much for your brilliant answers. Unfortunately Mr X 'forgot' to do part 1 yesterday (it had a lot to do with an appointment to watch Hull City of all sad things!) so it'll probably be next weekend now before he can do the job. I'll let you know how it goes!

Many thanks again, and well done on being the most helpful AB-er ever!

Diane