Cold rads

[Nightmarerads]

Hi,

I've got a problem with my rads Recently, I put a sludge remover in the system and left it a couple of weeks. Every thing worked perfectly during this time, hot water, hot rads and I might also mention that a new pump was installed at the same time the chemical cleaner was introduced to the system.

The problem occurred when I drained the system down to flush out the sludge remover and add an inhibitor. Everything seem to be going to plan until I fired up the central heating. The pump clicked into life and heated up very quickly however, the supply pipe leading directly from the pump that, I assume, propels the hot water round the rads, was cold, as were all the radiators.

I found one massive airlock in an upstairs rad, which was successfully bled until water manifested itself from the bleed screw. Having checked every other rad for air, decided to fire up the boiler but again, nothing.

The situation stands as this, no problem with the hot water but all the rads are cold, including the rad feed from the pump itself. One side of the pump pipe work is boiling, the other is freezing. Can't find any airlocks in the rads, whats going on

Any help would be really appreciated, thanks.

 

[Slugbabydotcom]

I'm making a few assumptions here as you didnt read this >>> http://www.diynot.com/forums/viewtopic.php?t=6026
Assuming you are talking about a Y plan system in between your diverter valve and the flow connection on your cylinder there should be a pipe that sticks up and ends with a bleed valve that usually has a big flat screwdriver slot on the top. put a towel round the pipe and bleed the air from this valve which should only need opening about ¼-½ turn. You may have to do this several times.
After that if you still have probs close every rad barring one and run the system . All the energy from the pump should force an airlock through to somewhere that it can be bled off. Always make sure one rad is left open as you go round the rest of the system.
Dont forget that when bleeding rads to turn the system off as you could introduce more air into the system if you don't
Get back to me if you still have probs

 

[Nightmarerads]

Hi,

Thanks alot. I'm not too certain if there is a diverter valve on the system, as I vaguely remember a plumber looking for it oncewith no success. The boiler I have is a Potterton Kingfisher, if that helps.

I'll have another look over the system tomorrow and try to impliment your advice. Thank you very much, I appreciate your time and reply.

 

[Nightmarerads]

Incidentally, the system is gravity fed. A new pump was installed a couple of weeks ago 'Grumsford' I believe it's called and the power setting is on stage 1. Apart from the pump (new) and boiler (15 years) the pipe work, rads and cylinder etc are all in excess of 40 years old. Having said all that, it was perfect until I started draining it down to add the inhibitor.

Thanks

 

[Slugbabydotcom]

Not a Y plan if its got gravity HW so its probably just airlocked then. Turn the pump speed up to full and do the 'turning all the rads off bar one' thing and see how you get on. Turning the pump on and off for 30 second intervals can sometimes help.

 

[Nightmarerads]

Hi,

Thanks for your help. One other question... Each rad has an individual thermostat, you mention 'closing the rads off' would this be done by reducing the thermostats on each rad to zero? or is there another way to switch them off?

Once again, thank you.

 

[Slugbabydotcom]

Using just the TRV's [Thermostats] is sufficient