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Radiators suddenly gone cold!!!?

I'm at my wits end!!! This is now my third posting about this and I really think I'm going to scream! 2 out of 8 radiators will not heat up. Inlet pipe is roasting hot but not the rads. I've bled the rads, checked the pump, water tank is fine, drained and refilled the system 4 times now, have switched off working rads to push hot water through, but STILL nothing! I've turned one LSV off and drained off a few pints of water to see if there was an airlock in the rad, but the water just kept on pouring. Same with the other rad. One rad is upstairs, one is downstairs. System HAS been treated properly since we had it installed a few years ago, and theres been no probs til now. All other rads are absolutely fine, but it's just these two. I've tried all the advice I've been given from this site already but nothing's working: can someone please, please offer some more advice before I attack the stupid system with a massive sledgehammer!!!
Thank you in advance!!

Pamela
February 2007

Heating, Home Heating Systems Suddenly Cold Third

SUCCESS!!!!! GOT ALL MY RADIATORS WORKING NOW- THANKS TO THE ADVICE FROM FOLK-IN-THE KNOW ON THIS FORUM! THANKS A MILLION FOLKS!!!!!

PAMELA
February 2007

Forgot to say, that when the inlet LSV is open (I assume it's the inlet as it is the one that usually gets hot first) and I'm bleeding it, the pressure of the water drops to barely a trickle.

Pamela
February 2007

I've tried the "close one LSV, open the other one and drain lots of water"- this has been successful with my upstairs rad, which is now as hot as the other 6 working rads in my house. However, the downstairs open rad is still not heating. The inlet pipe is now not even luke warm. I have closed off the other working rads, and drained the tank and attached a hose pipe to the drain valve and turned the hose on- forcing water through the pipes backwards. The tank did fill successfully, dirty water and a few airbubbles also appeared. Refilled system, AGAIN, put it on to heat, tried the "close one LSV, open other, bleed lots of water, swap sides" and guess what- still nothing!!!! Argh! Any more suggestions????

Pamela
February 2007

im a plumber and recently met a similar problem on a job where there were 15 radiators in a large home vaillant system boiler 2 years old, 1 room stat for both floors all rads on top 1st floor heat perfectly no air or dirty water, ground floor intially when drain valve was opened was black then clean water, 2 of the 6 rads on the ground floor wouldnt heat at all not the flow pipe or the return, british gas guy came in 2nd time replaced the heat exchanger 1st time was the pump, only after the british gas guy left i decided to fit a pump on the 22mm return pipe as well as having a pump in the boiler, and presto rads on

Raj
February 2007

I would say probably not a blockage if you tried as I suggested ie, closing one valve on radiator and drawing water through rad air vent, then close that valve, open other end valve and draw water through vent again. If you get water through both valves, it suggests not a blockage ( probably a good idea to have all other radiator valves closed when trying this)

Pete
February 2007

Hi Pete, I really appreciate all your advice. There is an automatic air release above my boilers, and also a manual air release. I've tried opening the manual one but all that came out was a whole load of water. Could it be a blockage in the actual pipework? I know I'm clutching at straws now but I'm really reluctant to call out a plumber- I've had few too many dealings with dodgy plumbers in the past!!!

Pamela
February 2007

Hi Pamela, my thoughts are still that you have an airlock in the system somewhere, you will appreciate that not seeing the system I cant give you positive advice, I can only suggest things to you.
I am wondering if maybe you have any air vents in the pipework that need bleeding, look at any highpoints, I have known cases where pipework has to be run in a loft or up and over a door frame, these are the types of area where you may find air vents that need bleeding.
Dont get the sledgehammer out yet... lol

Pete
February 2007