Hello, I have a multi-part question regarding our hot water tank (50 US gal, 45,000 BTU, gas, approximately ten years old):

1) When we are using hot water regularly, it works fine. However, when we do not use it for a period of time (approx. eight hours, or more), we have only warm water. After this occurs, if we run the 'hot' (luke warm) water for awhile (load of laundry, sink full of dishes, shower or similar) and then wait a bit (thirty minutes or more), we have hot water again, until the next time we let it sit.

This seems to have only started in the last year or so.

Is there anything we can do, service or adjustment-wise, that would resolve this, or should we be replacing the hot water tank? Is there any way of knowing if this is an indication of imminent failure of the tank (leaking/flooding would be worst case, but no hot water at all would be bad as well)?

For what it is worth, there are no obvious outward indications of a problem (leaking, corrosion, etc.)

2) If we should be replacing the hwt, where is the best place to start? In general, should we start with a major retailer and use their installation services, a local contractor, or start by asking friends and co-workers for their recommendations?

Thanks very much,
Scott