@Midnighter, the scenario you described is not one for which there is a simple answer. Many of the replies have dealt with aspects of it.
In terms of cleaning the flue, you should get that done now, since you're somewhat (I forget how long) new to the house. It's a safety issue. Beyond that, how frequently you get it cleaned is somewhat a factor of what type of wood you burn, how green it is (or isn't) when you burn it, and the type of fires (roaring or smoldering, large or small, etc.) you have. I'd recommend that you get it cleaned now, and then again at the start of next winter, and talk with the person that performs the task both times, to get a sense of what they find, and what they recommend. Your wife and kids live in the house, and flue cleanings aren't super expensive (relatively speaking). So while it's not always necessary to clean a flue each year, there are some good incentives for you to do so.
the smokey smell can be attributed to a number of factors. I'll try to go over some of them, but there can be others.
- as noted in some other replies, green wood will not burn as well, or as hot, as well seasoned hard wood. If you're burning that, the fire will generate more smoke (visible or not), and that can linger
- even if you use seasoned wood, that's not a cure-all for eliminating smoke. There will always be some smoke generated in any fire. You have to have a good paper/kindling startup, then some smaller sized branches, to get the fire going, and then some well seasoned wood that is also without a lot of resin, and is also well spaced appropriately to minimize smoke. To add to that, while a fire doesn't need constant adjustment, if you're trying to eliminate smoke, you do need to make small adjustments to the alignment every 10 or so minutes
- positioning of the fire is also important with regards to smoke. If you set the grate and wood toward the back of the fireplace, you will minimize the amount of smoke that may escape into the house. The flip side is that doing so reduces the amount of heat that makes it into the room, but eliminating smoke should be the higher priority
- when you get the fireplace cleaned, ask the person that performs the task if your fireplace has a smoke shelf. I'm pretty sure that would have been code in the '70s (not certain), but it would help to verify its presence. A smoke shelf helps to keep rain, cold air, and debris from the floor of your fireplace. That said, a poorly designed smoke shelf can cause more smoke to leak into your house. (In conjunction with the next point, there is some reason to have a fireplace specialist, and not a chimney cleaner check out the smoke shelf.)
- you might want to consider (assuming they are not already part of your fireplace), of having glass doors added to the fireplace. They would reduce the amount of smoke that makes it into the house. On a larger scale, they also reduce the amount of conventional heat lost through the fireplace. The downside is that if you use them while a fire is burning, you also reduce the amount of heat that makes it from the fireplace to your room
Basically, it can be complicated to resolve this issue, though also somewhat simple if one of the above actions resolves the situation. You kind of have to work through all of these things, to see if you can resolve the situation, but as also mentioned above, you may also need some professional assistance.
Keep us posted on the process/resolution.
