I have a bumper crop of jalapeno hot peppers that I would like to dry in my oven. I love to roast and grind dried chiles for Chili Con Carne or Enchiladas. The correct oven temperature and drying time are the obvious questions that come to mind.
I've dried out chillies a bunch of times, both with and without a fan-assisted oven. It's much easier with a fan oven, but not impossible with a conventional oven, but it is wasteful of energy in a conventional oven as you have to leave the door cracked. That and you must have an oven that has a very low setting.
The reason that heat works is that heating air reduces its relative humidity as warmer air can contain more moisture. Once the warmer air fills with moisture it will saturate, and won't be able to accept any more, and when that happens your chillies will stop drying. A fan oven will generally cycle the air out and bring in new air which will accept more moisture, but a conventional oven won't, so you either have to crack the door or open it every 10 minutes to bring fresh air in.
All in all it takes days to dry chillies in a fan oven with it being constantly on, and it will stink up your house while doing it. A more effective way (although I've never tried it) would be to use a desiccant like silica gel (available from hobby stores) in a sealed container to dry them out.
A good way to keep dried chillies dry in a moist environment is to put them in a sealed container with a bunch of rice grains in the bottom, the rice will absorb any moisture.
When it comes to drying, air flow is actually more important than temperature. If your oven does not have a convection mode, I wouldn't even bother. Furthermore, even if your oven does have a convection mode, chances are that it cannot maintain a low enough temperature to dry the peppers without actually cooking them in the process. If you know that your oven can maintain a steady temperature of 120 degrees F or less with convection, then drying the peppers should take no more than 10 or 12 hours. This might be possible if your oven has a bread proofing mode that also supports convection. If your oven has a bread proofing mode that does not support convection, then I think the only reason you might want to use that is if you live in a particularly humid environment. Otherwise, hanging the peppers in front of a fan is probably your best bet.