Wondering should i change a system boiler with a combi if I have underfloor pipes in a single storey 2 bed 90s bungalow There are only 9 bungalows in the close and I was told 2 of these had leaks in floor when they changed to a combi by a neighbor. He said as he was an engineer he would not advise the change as it was something to do with the different pressures the boilers operate on. What are the issues ? is it not advisable to use a combi for under floor piping. wouldn't I just need to suck out the underfloor pipes and cap them off and then run new pipework down the walls. I must admit I did have a burst water pipe in my previous house and that was a under floor network also with a combi boiler. It doesn't put me off though as I need the space downstairs as well as the loft space. Any advice on this subject would be much appreciated , cheers guys.