Black water comming out the radiator when airing ?

Kristok

I have two radiators in the house that are barly warm, rest of the house is fine just these two. I tried airing both of them and no air comes out just black water straight away, This water comes out different each time, clearish sometimes and black like oil others. Any ideas what this is ? is it normal and can i clean it if its blocked ? If it is normal any ideas why they wont heat, one is slightly hot the other is barly warm.

Lex Luthor

Kristok wrote:

I have two radiators in the house that are barly warm, rest of the house is fine just these two. I tried airing both of them and no air comes out just black water straight away, This water comes out different each time, clearish sometimes and black like oil others. Any ideas what this is ? is it normal and can i clean it if its blocked ? If it is normal any ideas why they wont heat, one is slightly hot the other is barly warm.

Chances are, these are probably the last 2 rads on the loop for your heating system. I had this problem a few years back and the last & 2nd last rad never got hot. SO I got the rads balanced and now they all heat up. What's probably happening is the first 5-6 rads are getting too hot and the rest are suffering. By the time the hot water gets to the last 2, it's all used up.
I did mine and it nearly took a full weekend but worth it. I also jacked up the pressure a little on my boiler, increased the nozzle size and turned up the water circulating pump to the next level. I only did the latter due to the fact we added 2 extra rads to the house.
Check out http://www.diydata.com/projects/centralheating/balancing/balancing.htm
It's the site I referred to when I did mine and explains the procedure.

As for the black water, I've seen that before.....wouldn't worry about it.

Alun

I've been meaning to do mine for years, but .... how do I know what order the radiators are in?

Kernel

Lex Luthor wrote:

As for the black water, I've seen that before.....wouldn't worry about it.

As far as I know the black water is normal, just de-oxygenised water or some such thing. Happens when the same water is in the system for so long. Either that, or the house is evil and you should call an exorcist.

Kristok

one of them is right beside the boiler its either first or gets a seperate feed than the rest of the house cause it always gos on the rest we can turn a valve to stop the heating, just the way it was setup, the other one i think is where the water for my room in the attic is taken from and that is always really hot. There was never a problem with these two just the last year they have been getting colder and colder. I dont think the black is suppose to be there, its not black comming out of the other rads when i air them just these two and it gos clean for a bit then black.

kadman

It seems this is a common problem, cool rads.

http://www.boards.ie/vbulletin/showthread.php?t=144422

Sounds like sludge build up, according to old threads. The black stuff is iron oxide sludge, a by product of heating , cooling, heating, corrosion ect. Flushing the system might help, and add Fernox or similar to the water in the radiator/ boiler expansion tank on re-filling. If in doubt, google, or get professional help.

kadman

rooferPete

Hi,

The rads have been getting cooler over time and they are the only ones with black water ?

The black water is normal in radiators, if this has been happening over time it might be the pump wearing out or not set correctly.

I would take care with Fernox products I have been told they are supposed to be used from the start and can cause problems when added at a later date.

The fact that the other rads are showing clean water could also mean a leak in the system, an attic rad suggests a sealed / pressure system.

Might be time for a good service.

Lex Luthor

Alun wrote:

I've been meaning to do mine for years, but .... how do I know what order the radiators are in?

what i did was let the system cool down, then switch on and get ready to feel the inlet pipe of each rad to see which one heats up first.
My boiler is in my utility room and the rad next to it wasn't the first one so they don't normally follow a logical order, but typically its downstairs first, then upstairs.
First for me were the 2 in the kitchen/diner, then living room, hall, then upstairs to master bedroom, ensuite, main bathroom, 2 other bedrooms, then back down to the converted garage room and last one beside boiler.

Once you get the ones downstairs done, you might have to start all over again and do the upstairs. Thats why it took me 2 days as I did one floor/day.

Alun

Lex Luthor wrote:

Once you get the ones downstairs done, you might have to start all over again and do the upstairs. Thats why it took me 2 days as I did one floor/day.

Luckily I live in a bungalow