I have a gravity fed hot water system with a pumped central heating system. In my loft I have a Feed and Expansion tank with a hot water cylinder. My central heating boiler is in the kitchen with the pump directly above it. Due to the immersion heater and the position of the cylinder right next to the roof beam i could not access the immersion fully so I decided that I would fit a new cylinder and re position it so in future any problems with the immersion would not exist. I purchased a new indirect cylinder as i thought that my old one was the same, first mistake, I drain all the hot water and central heating systems and fitted nice new cylinder in new position and filled up heating system switched on immersion,lovely hot water,great I thought, ah but what about the central heating, it was not filling up. The wise members among you will already know what I am going to say,fitted wrong cylinder should have replaced it with a primatic cylinder. When I looked inside the old cylinder that is what it was. So now I need to address the problem of how to supply my central heating system. I have been advised that I can fit a second F.E tank with a feed and vent pipe to my new cylinder My boiler has two 28mm pipes for feed and return and the pump has a 22mm pipe. With the 22mm pipe it would have gone back to the hot water feed in the loft. I would be grateful of any advice.