If your new country was in the Bakersfield area, would you head out and grab some acreage or just grab a few blocks of downtown.

Hummm....I am conveniently close to the intersection of two major transportation roads(no isolation ship policies here),have enough acreage to go vegetarian(with a seemingly endless supply of free-range protein~ snails)... there would have to be a no growth policy until the neighbors houses come up for sale..I'll have to get back to you on the name.

 Nice one Sage.  I think you've got your national mascot right there.  :)

Anglo, sorry to jump threads on you, but I'm always up for a question.  I'm getting back to posting this thread every wednesday so even if the topic isn't home repair related, you can always ask a question here. 

 Thanks Tom, I replaced a thermostat on my house in the Rosedale area about a month ago.  This is my old house and the renter said everything about the AC/Heater worked until late evening or morning.  We have the house back now and that problem is the same.  The heater seems to work normally during the day but when it gets cold [when you neeed it] the fan works and comes on automatically but there is no heat.  Seems like the cooler weather prevents the gas valve from operating or a loose connection becomes looser with the drop in temperature.  I fix most things myself but this is really bugging me.  Brand new thermostat by the way.  It's about 15 yrs. old dual pak, roof mounted.

 Anglo, my first question, and this may seem dumb, but since it's an electronic thermostat, are you sure that it isn't realted to a clock function on the stat?  I'm sure you've tried to manually crank the temp using the stat controls at night, but you gotta ask.

Another issue could be the thermocoupling if you have a standing pilot light.  If the thermocoupling isn't right in the pilot, the temp difference could be what is causing the heater to not come on.

So if you rule that out too, I might think about testing your gas pressure to make sure your lines constricting at night wouldn't drop the pressure below operable levels or like you said, something with a sticky valve.  Rule out the pressure issue first since there's no good way (that I know of) to crack open those controllers so you'd just need to pop for a new one.  They're cheap, but not so cheap that you want to put one on if you don't need it.

 The gas pressure is something I never would have thought of. There is also a LOPI gas fireplace in the living room that we have had a hard time keeping the pilot lit.  I will get the pressure checked first.  I actually put the old thermostat back in and the same thing happened.  At the time replacing that seemed the easiest, cheapest and most likely fix.  It has an auto pilot [the dual pak] so I'm not sure if the thermocouple scenario applies.  I will let you know about the gas pressure. 

 Thanks, Anglo.  You usually don't see it on gas lines as they don't corrode as easily but if you've got a pressure issue all over, any blockage combined with constricting pipes might do it.

It won't happen with the new codes though.  I just ran a new line for a house with two gas fireplaces, a stove and a tankless water heater.  The city asked for a 1 1/2 inch line until the first split.

 Something else just occured to me: do you have a dirtleg on the incoming line?  If you go out by the meter there ought to be a 6 in. or so long pipe coming down off the line.  Usually at the first bend after the meter they'll put in a tee rather than an L.  If you don't have one, you may just have some junk built up in the line.

 Tom, I gave up on my heating problems and called a pro.  It ended up being the igniter on the heater [roof mounted].  I don't know why it worked only when warm during the day but that was the fix.  Thanks for your effort.