We had to drain down the central heating system due to repairs,we fix repair and flushed out the system,we refilled and vented from the lowest to highest rads, vented pump ,top rad heated,next two rads warm other two rads cold ,one on the same floor as the secound two and one on the ground floor,tried venting every thing again,no luck,tried turning off the hot rad ,no luck.So we drained down the system again this time only the top rad heated. what else can we try. doug

Empty cooling system and reverse flush the heater core with water hose till water comes out clear. Then reverse procedure till water is clear. Fill system with water and turn car on, while car is running open drain plug and continue to keep radiator full while draining it at the same time turn on your heater with heat on high and blower on high When water is clear flush system and wait for engine to cool down. Refill with antifreeze and turn engine on, check for leaks and to see if you have heat. If still no heat change heat core.Let me know how you make out.

Back flush out that is disconnected and connect mains hose to heater and power out keep revers flushing don't use Cir on alloy but u can get central heating flush that will work its called FERNOX system cleaner very good us this i system first run to work a few times then drain then reverse flush good luck iv used it very good

think the heater core is partialy blocked ,drain coolant antifreeze and fill with water then add some caustic soda say a half a cupfull then run car for a day or two till the heater starts blowing hot then give a good flush and refill with the antifreeze ,cant say it will work but their is a good chance it will work

Bad heater core.

Vent pipe may need cleaning out, vent stops up your system has to get air to work so it will take it from where it can get it and the toilet maybe the easied place.
You may have a vent pipe that may be partly blocked or clogged up. To check a vent pipe out you can have someone fill a sink or tub up to the flood level rim and plug the drain. Have them remove the stopper and watch the toliet you have had issues wit to see any water movement. Once you deteemine which one is the cause you can snake the vent pipe or run a water hose down the vent and turn it on to flush out the vent pipe.

Hope this will help you out.

Hello! Replace the thermostat, it is defective...I would suggest flushing the cooling system with the heat set to high...Your engine requires Dex-Cool anti-freeze...It, due to electrolysis, has a tendency to "clump" blocking proper flow...Drain the cooling system...Fill with plain water...Allow engine to heat up and when the thermostat opens shut down and drain...Do this three times or until water is clear...Replace thermostat and refill with Dex-Cool...Allow all air to escape before installing cap...

Guru............Saailer

I’m happy to help further over the phone at https://www.6ya.com/expert/david_6df67de3b14de867

have radiator system flushed at a radiator repair shop

yes it is possible toupgrade the system to a sealed one using a system boiler as you mentioned. the thing to bear in mind is to upgrade the radiator valves to pressure rated ones 10bar.
The probable cause of the over heating is down to the system being sludged up/cold feed blocked, or possible pump circulating problem?
I would recommend the installation of a magna clean filter to help keep the new boiler clear from system debris.I would definately power flush the system, if the system is a twin two port valve system then a automatic bypass should be fitted, all of this done by a corgi registered gas engineer

Kindly

Richie

Since you have done a good job bleeding the system, I will suggest that the impeller on the pump is bad. Many times these will simply deteriorate in the volute causing the symptoms that you describe.

This looks like it is in the wrong forum. Try reposting this in the heating section of the FixYa web site to get more responses.

I have heard that there is a spray you can use that will not damage your system and seals the leak when it comes in contact with oxygen