These questions come from an experienced electrician but an inexperienced plumber! I'm just buying a house which needs just about everything replacing. The house currently has a Creda electric warm air heating unit (original from 1967) housed in a huge cupboard in the kitchen. We would like to do away with this and remove the cupboard if possible to give us a lot more space in the kitchen. What are these electric warm air units like in terms of efficiency, reliability and cost to run? Hot water is currently provided by means of an immersion heater in the cupboard on the landing. A loft room is planned and the staircase will go straight through this cupboard. We now need a solution for a central heating system (fortunately it all looks like it needs replacing anyway). I'm thinking a combi' boiler is the only real option, but is it possible to fit the combi' in the loft and vent the flue up and out of the pitched, tiled roof? It is a mid-terrace house without any real options for mounting it on an external wall, except in the dining room, which is far from ideal. The other concern that I have is the pressure of the hot water. What is the pressure of the hot water dependant on? Is it the incoming mains pressure or the boiler size or type, or is it something else? With the combi, we'll be doing away with the cold water tanks; does the cold water supply the cold taps directly or does it go via the boiler first to regulate the pressure? I've been told not to oversize the boiler and to size the boiler so that it's just about the right size so that it runs flat out. Is this correct and why so if this is the case? I've been looking for textbooks to help me learn about plumbing and central heating but it's hard to find one that's a good balance between the DIY virgin and the technical industrial gas and controls engineer; any recommendations? Any advice on my plans or alternative ideas would be much appreciated and well received. Many thanks, Liam.