I had a potterton netaheat boiler which I decided to replace with a new Vaillant 418 condenser boiler.....The installation was fine, but then I realised that it needed a permanent live feed and a cable from the boiler to the CH pump to allow `over run` The boiler installer has washed his hands of my install, saying he is NOT an electrician and my current problems are not his !!!! ( tought £500 for install only would have covered this ) Anyway I am having a new cable run ( At MY expense) from the control panel in the airing cupboard to the boiler in the kitchen, which will give me the extra features of the 418.
My second problem is that there seems to be a lot of air in the heating circuit ( BUT not in the rads) When the 418 is on hot water only it only runs for less than a minute then cuts out ( Over temp !!! ) but on heating it runs fine at 72oC ( Nut with sone gurgling noises ) The CH pump and hot water cylinder were moved to the other end of my landing when I had an extension built, but the flow and return to the expansion tank were left connected at the old position......I am told this may be the reason why I get so much trapped air.
So do I need to get these pipes re-sited to the new position of the CH pump and HW cylinder ( will not be easy) or can I fit a vent between the 3 port valve and hot water cylinder to get this `trapped` air out.....not sure if this will be enough to get myHW system working without tripping out all the tiem
PS the HW works if the CH AND HW are called for t the same time
Hope this is clear