I'm in the process of converting part of my house into a holiday let but have had 2 different solutions suggested on how to heat and provide water to both properties. I only have oil as the fuel option. 1 plumber has quoted for 2 separate boilers; one is a system boiler to replace our current one in the main home, which we were going to do anyway because it's very old, and a second boiler - combi - in the holiday let as space is very limited in there for HW tank etc. This gives 2 completely separate heating and water systems. The other plumber has suggested one big system boiler and a mains pressure hot water cylinder (all located in the main house) for both properties with various zone valves etc to effectively make heating and water controllable from each property. The quotes are fairly similar so I'm unsure but leaning slightly towards the mains pressure tank solution as I also have a oil fired Rayburn which is on all the time and is currently providing all our hot water so I'm assuming that could also be connected to the mains pressure cylinder to supplement the heating for hot water and central heating? Any advice on which way to go would be much appreciated, thanks.