Central heating acting up

PoGee

It's a conventional system around 32 years old. It was working fine this morning but when I turned it on again around midday, found that the radiators on ground level (apart from the one directly below the immersion tank in the lounge which is hot) are cold. The ones on upper level are hot. The one in the hall where the thermostat is + dining room are luke warm. The kitchen and living room ones are cold. I also hear loud bubbling noises, which I think are within the immersion tank or within pipes but not sure. What could be going on? I'll try bleeding the radiators later but just wondering why all was working well this morning. Hope someone can help.

Rodders53

Neighbours, friends, family that you can ask?  Or your favourite heating technician / plumber that maintains the system?  Probably needs hands-on to see the installation and investigate - but the regular maintenance person may have a simple idea for today and visit in 'non emergency' hours.

Have you powered off the system entirely. 
Waited a few minutes.
Then powered up again.

Doing that may 'reset' something stuck.

Pump failure so circulation is just via gravity?

Motorised valve fail?  (Latch open via manual lever temporarily).?

You've really not given any useful information about your "conventional" 32 year old system to be frank.

PoGee

It's a glow worm ultimate. Cold water tank in loft. Going to call favourite heating engineer tomorrow.

WIAWSNB

Weird one, and best it's looked at first hand.
The boiler appears to be 'working', so that's good 😊 

jennifernil

Sounds to be similar to ours…..header tanks in loft, HW cylinder in airing cupboard.

PoGee

Think I've got a gremlin. Bled the radiators. Switched back on and now working thank goodness. I've saved up for a new system but want all pipes renewed as they're 35 years plus. Previous owners had oil heating. Engineers v reluctant as saying it'll be an upheaval but I'm ready to either move furniture into garage for a week or chuck out. No gurgling noises either now. Thanks for reset tip Rodders53.

Mr.Generous

It's a circulation problem, sludge in the pipes. Drain and refill with a cleaner, use 2 bottles if its a big system, run the heating on high for a week then drain and fill again. You might need to do this more than once if its badly blocked. Better on the drain down if you can drain off all downstairs rads, get more sludge out. The bubbling noise sounds like kettling, ie the water cant get round quick enough and is actually boiling in the boiler. Turning the pump up helps it circulate. Check the header tank when the heating is on, if its a bad blockage the water will be flowing into the header tank - which it shouldn't.

WIAWSNB

If you are up for doing MrG's suggestion, then stick a magnetic filter in to the return pipe to the boiler too. That'll keep catching sludge that hasn't been got rid of initially.
But I guess it depends on when you hope to have it all redone.