In our self-catering cottage, we have a hot tub fired by an external wood stove with a water jacket. The cold water pipe delivers from the tub to the bottom of the water jacket and the heated water rises to the pipe at the top which delivers back to the tub. We had guests recently and they reported water leaking from the top of the jacket into the firebox making the tub unuseable. Is this just wear and tear? (It's 2 years old). Or if the stove is overheated can this happen? Or, can rough loading of logs into the stove (ie. ramming in logs) cause the seal to be broken? They want their money back, but if they caused the damage, I'm reluctant to do so.