Hot water but No circulation on Central heating?

[ERMINTRUDE]

I have inherited a fully pumped heating and hot water system with diverter controls. The boiler is an Ideal Classic LXFF260. Last year I changed one of the motorised diverter valves with an identicle valve. I also changed two radiator thermostats. Having drained the system I re introduced Fernox Rust inhibitor. The central heating and hot water system have been working perfectly up until tuesday when I bled a rad. The hot water works OK but the central heating is not Circulating. If I have the hot water on and open the motorised valves a couple of Rads warm up. I have introduced a Fernox restorer toady but no joy. Does it mean a full flush through?

 

[clf-gas]

which valve did you replace, hot water?, if so maybe heating valve failed.
is it doing anything when calling for heat. ie, lever moving.

 

[ERMINTRUDE]

I replaced the central heating motorised valve as it had seized shut. Both motorised valves appear to be working fine. The manual overide levers operate smoothly and I can hear the motors working when I manually operate them.
I popped up into the loft yesterday and noticed a gell type residue around the water mark in the header tank. Some was lying as sediment at the bottom of the plastic tank. I suspect that when I bled the radiator earlier in the week it drew some into the pipes. I have cleaned the header tank out and put a Fernox Restorer into the tank before filling . I have then drained the system enough for the restorer to enter the pipes.
The pump operates well when the hot water is switched on.
The boiler heats the water well. But the central heating is still not circulating.

 

[gas4you]

Can you here the motor opening/shutting when call for heat electrically? Are you sure you have wired it correctly?

 

[ERMINTRUDE]

The replacement valve went back exactly the same as the original.
The system has been up and running for about eight months since the valve was replaced. Everything was tickaty boo until I bled the Rad earlier in the week.

 

[gas4you]

Ok but can you here the motor turning when call for heat on/off. Not with manual lever

 

[kevplumb]

why not take the head off and see if the spindle is free and the motor is actually doing anything

 

[ChrisR]

Sounds like an air lock, unless it's some of that gelatinous stuff.
If there's a bypass, can you close it and put the pump speed on max, close working rads, to maximise flow.
Or it could be the toady couldn't get along the pipes, poor little chap.

I have introduced a Fernox restorer toady but no joy.

 

[ERMINTRUDE]

I have taken the Motorised cover off. I have taken the spindle cover off and wound the spindle round until the arm activated the switch.
The central heating has jumped into life.
Well you are the professionals and I'm not.
I bow to your superior knowledge.
I can not believe the motorised valve packed up after only eight months to ten months use.
Thank you from me thank you from her and once again thank you from our one year old de frosting daughter.

 

[kevplumb]

 

[gas4you]

It will be under warranty for at least 12 months

 

[berrylodge]

Hi guys,

You would not believe how useful this topic has just been to me. We have no heating since last night and we canno get a plumber until Monday at the earliest.

I am an IT technician and not a plumber, I can put my hand to most things including basic plumbing but I don't know the first thing about central heating. I found this forum through Google after searching for "poor radiator circulation" and read this particular topic, I had the problem temporarily resolved in 10 minutes and we are warm again. It also gave me great pleasure to tell the plumber wo came on Thursday and told me there was nothing wrong with our system, what the actual problem is.

Sorry to ramble, I just think people like you guys need recognition for all of your help in matters technical. Thanks so very much for keeping my wife and young daughter happy.