I have an 18 year old central heating system, run with a gas boiler, and has a DFIHWC There is one small water tank next the cylinder which holds about a gallon of water. I cant find any information on the princple of how this type of cylinder works. There are no tanks in the loft, however there is one pipe which goes out the top of the boiler (in one cupboard upstairs) into the ceiling and goes directly into the top of the DFIDHWC (which is in another upstairs cupboard).
Can anybody please tell me how these cylinders work or point me to somewhere I can get info about them from. I have googled the internet to death about them, and can find nothing about the princples of how they work.
If anyone can help, I would be really thankful.