heating rad

[johnycarper]

I have an old cast iron radiator that was not getting hot so called a plumber out who says it was blocked and needed flushing out.I did this yesterday and took it off the wall and managed to get it outside(very heavy) and flushed it through with the hose,put it back on but still not working properly.It gets warm at the top but the bottom is cold any suggestions..The rest of house is ok.

Thanks.

[sid]

Flushing the radiator often does the trick... was there a lot of black sludge in there? If so, the pipes in that area of the house may also be blocked, or maybe just the valves each side of the radiator? Perhaps you could flush the pipes? That may be a bit of a hassle now that you've re-hung the radiator.

Is this an upstairs room? Did it get warm previously? I'm wondering about the pump... perhaps not pushing the water around sufficiently well? The upstairs rads often get warm by circulation/convection ( I have an "anti-siphon" valve on our radiator circuit to overcome this). Perhaps the whole system needs to be flushed?

[johnycarper]

Hi Sid,

Thanks for the reply,yes when I flushed the rad a lot of black sludge came out as its the longest point from the pump which is only 2 years old by the way.If I wanted to flush the pipes is it possible that I just turn the water on as to fill the system and then open the tap in the cellar and let the water go out that way.Would this get all the sludge out as we are a two storey longere and not sure all the water would push through,.,the rad used to get hot.

Thanks for your help,

John

[Quillan]

You need to empty the system and then refill but adding a flushing agent. Run the system for a while as directed by the instructions for the flushing agent, empty then refill adding an inhibitor and antifreeze, they normally come as one liquid these days. There is loads of stuff on the web about flush and refilling.

[johnycarper]

Thanks for that its worth a try any idea what its called in France.

John

[johnycarper]

Just as a thought do you think its worth while me flushing the system just by turning the fill up tap on and then turning the drain tap on and leave it flushing through for a while.

[sid]

Without seeing the system it's difficult to be certain, but there's no guarantee that just turning on the filler tap and opening the drain will actually flush the whole system; the water may just take the shortest route, in fact almost certainly will.

There is a school of thought which says that you shouldn't drain the system, as the fresh water contains more oxygen and will cause more rust inside the cast iron radiators, but I don't think you have much choice to get it working now. If you do as Quillan suggests and after cleaning add an inhibitor this will help and it'll also help to protect against freezing. I just haven't worked out where to add the inhibitors! I think the heating engineers use a special forcefeed pump.

My system has been drained a couple of times in recent years, once to change the boiler and another time to move/add radiators. It's still working. [geek]

 

[Quillan]

Whatever you are going to do you need to get the flushing concentrate and afterwards the inhibitor/antifreeze in to the system so lets deal with that first.

The first most obvious thing is to drain the system. There should be a drain tap at the lowest point of the system, If you have a floor standing boiler it will probably be very close to it. When draining you also need a radiator bleed key and remove the the bleed nipple from the highest and furthest radiator in the house.

TIP - Personally I would drain in to a couple of buckets and count how many litres of water was in the system. You will need this to calculate how much flushing and inhibitor/antifreeze you will need.

Once drained turn off the drain tap and attach your fill hose. Now to add the flushing agent you need to find some access point. The most favorite place is a towel radiator in the bathroom which normally has two 'bungs' at the top, one is a blank and the other has the bleed nipple inside. You can remove either one and get a small plastic funnel and stick it in. Now pour in the liquid. sorry about the caps but BOTH THE FLUSHING AND INHIBITER/ANTIFREEZE ARE TOXIC, READ THE INSTRUCTIONS AND ALWAYS WEAR GLOVES AND GOGGLES, COVER YOUR ARMS AS WELL.

If you don't have a towel radiator as described and shown if the video then you can buy a filling kit from Screwfix for about £5, link below.

http://www.screwfix.com/p/no-nonsense-filling-kit/98940

If your buying the chemicals in France then you might try printing off the photo from the Screwfix website and taking it with you. Basically you take off one of the bleed nipples or the whole bung, screw in the appropriate adapter, attach the pipe and then a cheap plastic funnel (I found mine in the kitchen utensils department in a big supermarket although I have only done this in the UK).

Once all the liquid is in put the 'bung' back in and then with the nipple you left open to drain the system start to refill it. Below is a link to a YouTube film about adding either the flushing liquid or the inhibitor/antifreeze..

http://www.youtube.com/watch?v=BI3S8B7f_vY

Most flushing chemicals require you to run the system for an hour or two then empty. Different makes have different instructions and you should follow them.

Once the flushing is complete empty and repeat the above to add the inhibitor/antifreeze. Personally I like to do a second flush but just with water, no need to run the system just wait till the water comes out the bleed nipple then let it drain.

The amount of inhibitor/antifreeze will depend on how cold it gets. The colder it gets the more you add. The inhibitor will also protect old cast iron radiators from rusting from the inside out.

My two most favorite inhibitor/antifreeze makes I have given links to below. Both have products that are recommended by cast iron radiator manufacturers.

http://www.fernox.com/fernox+home (My favorite and lots of excellent info on their website. My family have used their products for two generations and it is available in France).

http://www.sentinel-solutions.net/ (Never used their stuff but it is highly recommended by plumbers in the UK, don't have a clue if you can get it in France)

Hope that helps.

[sid]

Excellent! Thanks Q, I got some useful info from that, especially the tip about collecting into a bucket to calculate the capacity, so the OP should be better equipped now!  [B][B]

[johnycarper]

Thanks for all the advice which I will take and get some of the flushing chemicals,I did try and turn off all the rads except the blocked one and it seems to have worked.I guess all its done is move all the muck to the next radiator but at least I now know it will works when sorted.

John