There has been a water issue, so that needs to be solved first.

We keep a lock box connected to the water spicket outside in case there is ever a malfunction with the key pad,  so if guests can't get in, I can send them the code to the lock box to use the key.

For example, often fire damage is water damage--they put the red stuff out with wet stuff.

I have seen hot water heaters in bedroom closets but not furnaces.

In the end, water has a mind and power of it's own. 

Have you talked to a local insurance agent.If you're going to get "$750 all bills paid" for each room, why aren't you including electric, gas, water/sewer, lawn care, and cable/internet in your expenses?

Or a pipe or water heater has been leaking for weeks?

Did bubble foam test and infrared test and found nothing from gas lines to stove , or in the gas water heaters.

I can only imagine that after being under water for 5 years, its tempting and rather exciting to exit, but who knows for sure.

From some research it seems like water sensors near water appliances, quarterly inspections, water proofing under sinks are some ways.