cold rads

Guest111 · Mar 14, 2012

Can anyone give me any ideas with this one, potterton 1016 system boiler,5 rads and hw cylinder indirect feed,f&e tank 1 mtr above cylinder, rads in 10mm microbore. dosed system with fernox cleaner and ran for 2 weeks,drained down flushed out and refill and bleed.2 rads downstairs not getting hot neither are f&r pipes,if you shut all other rads down these 2 get hot and go cold when you turn others back on.only thing I can see is bleed nipples are at flow end of rad rather than return,pump set on 3 all trv,s on max.Anyone?

robsparky1975 · Mar 14, 2012

Might be better posting this one on the plumbing forum,dont suppose the system needs balancing,just a thought.

Megavolt · Mar 14, 2012

Sounds like system need balancing. Turn on all rads turn on heating leave on for a hour or so then basically go to the hottest rad and then using one of the lock shields valves give it a quarter turn to off then repeat on the other rads that are working well. Then when done all leave for 30 mins or so and if no improvement repeat

Geordie Spark · Mar 14, 2012

I'm thinking you have an air lock somewhere in the system.

Did you bleed the air out of the pump?

Is the pump working?

I there a bleed nipple at the hot water storage cylinder?

If you need to balance the radiators, you adjust the lockshield valves (They're the ones that let the water out of the rads.) so that the temperature of the water leaving the rads. is about 20 degrees Farenheit cooler than the water entering them.

Either use a clip-on thermometer on each valve, or just point an infra-red thermometer at each valve in turn.

(I wouldn't be too worried about which end of the radiators the bleed nipples are on btw. Some of them have the nipple on the back about half way along!!)

Guest111 · Mar 15, 2012

Cheers all, tried all of the above,was wondering if there was something blindingly obvious that I missed but not so it appears ,seconds out round 2,wonder who gives up first, me or the heating?

UNG · Mar 15, 2012

If all worked properly before you started then I suspect you have an airlock somewhere in the system had this problem on a system a while ago and the only way to clear it was to closed one valve on the rad and bleed the rad then close the second valve and open the first and bleed again this method eventually cleared the air locked in the system. You may need to do this a few times on each rad.