Inherited system problem

[Bogart]

Been 12 months since we moved in here and inherited an right old system. Normal loft space expansion tanks etc with 25 rads of varying quality from okish to downright useless, replaced one as it had a pinhole, and a few others waiting in the wings for the same treatment. Anyway I digress, basically have just replaced the CH F/E tank. On firing up the system, a right old Camray boiler, seemed ok except very few of the rads got warm. Boiler kept cutting in and out as if reaching temperature setting. Noticed 2 things firstly the vent pipe into the new tank had disgorged a lot of brown water and that the Honeywell Automatic Air Vent EA122, next to the boiler was venting steam, not really sure what is going on here as all I have done is swap one tank for another. Any ideas?

 

[Dkdc71]

Sounds like it is airlocked no water in boiler or system

 

[king of pipes]

Your system is airlocked a plug of air can stop the circulation through your heating system vent the radiators again with the heating off but the motorised valves locked open air bleeds slowly on the radiators also check you pump and make sure you vent it aswell unlock the valves and try again , i would plan to upgrade the system and change the worst of the radiators may be in the spring as winter is only round the corner regards kop.

 

[Bogart]

Airlock sounded a good possibility to my mind. Oddly though the pipework in the airing cupboard was nice and hot but rads not, a couple upstairs just warm. Like the rest of the place the, as I have said, has a right odd setup. The boiler is in an outhouse some 20m from the house the airing cupboard is on first floor landing so all in all around 25m odd of pipework before it gets to the pump. I have not tried to run hot water alone, suppose I could do that if that works put thinking cap on again. Have got 5 new rads to install before winter and like suggested all remaining next year.

 

[Bogart]

As suggested me thinks was airlock. After running the pump on varying speeds for a good time and bleeding at every point I can think of started the boiler with just the hot water selected. It ran fine I then switched the CH on as well and rads heated up, eventually. So I will have to repeat all this when I change the rads, so be it. Balancing will be a lifes work but should be worth it. I have couple of weeping lockshields but no great shakes. Does fall into line with the fit it and forget mentality, all lockshields were fully open. Now finally are auto radiator air vents worth the effort, and cost?