My house was built in the 70s, and ever since October of this year, when the sun shines on the roof, I get a smell in the kitchen and dining room like wet wood or maybe fuel oil. I have had the furnace, hot water heater and stove checked.

If the sun does not come out, there is no smell and it goes away once the sun goes down. Anyone have any ideas as to what might be causing this problem?

It is hard to pinpoint the exact cause of an odor like this, and I know how frustrating it is trying to eliminate the problem. Performing research on this topic, I would suggest starting with a professional mold inspection starting in your attic.

The sun hitting the roof could be heating up the attic air space, throwing off the smell, especially if it is caused by a roof leak and the wood is drying during the warmth of daylight.

Like troubleshooting any other mystery like this, if no mold or leaks were found, you would need to keep going down the list of potential culprits: proper sewer vent evacuation; HVAC/Heating system issues, including duct work; outside air being pulled through crawl space, etc. Good luck and please let us know what you find out.