Underfloor pipes are an issue
QWe have a leak in our central heating system. After we switch it off, it takes about two hours to lose five litres. The piping is under the floor, so it is not simple to find. One suggestion that’s been made is that we simply replace all the pipes – but I would have thought that a mechanic, probably testing pressure drops around the system, would be able to locate the length of pipe that has the problem.
AFirstly, water expands when heated, so if you fill it to the brim when cold it will leak out as it expands when warming up, then the level will drop as it cools down.
Pascal’s law says that pressure is equal throughout an enclosed system, so there is no way one could use pressure to locate a leak.
If it really is a leak then you should find plenty of water with antifreeze in it in the boat’s bilge – do you? It could also be in the boiler’s heat exchanger.
I don’t understand why boat-fitters try to hide all the services under the floor: it makes fault finding so much more difficult. If I was sure there was a pipe leak, I would do as suggested and re-pipe the system above the floor (box in if you like, but make sure the boxing unscrews and lifts away).