Water heaters in homes used seasonally fail differently from those in daily service, and on Seabrook there is a second factor — many of them are getting on in years.
Sitting idle is hard on a tank
A heater that runs hard for a week then sits untouched for two months corrodes internally faster than one in steady use. Sediment settles and stays put, and the anode rod quietly does its work with nobody checking it.
Original villa installations
In the older villas the heater is often in a cupboard inside the living space, sometimes directly above another home. A properly plumbed drip pan is essential there rather than optional, and a fair number of original installations do not have one.
You find out at the worst moment
The failure almost always shows itself on the first evening of a visit. Servicing in the off season, rather than waiting, is genuinely worthwhile on a house used this way.
What is worth repairing
A thermostat, element, thermocouple or gas valve on a tank under about eight years old is usually worth fixing. A tank leaking from the body has rusted through, and above another home that is worth replacing promptly rather than watching.