My oven seems to take a really long time to preheat -- about 20 minutes to reach 350 Fahrenheit. Is that how long it is supposed to take? Thanks

If oven is electric pleace check that the heating elements are ok, could be that only one or two elements could be the only heaters hence luck power to maintain temparature when open or gets too slow to preheat.

if it is an electronic timer temp controller you might want to check it

The thermostat and control will have to be replaced

More than likely, its your oven thermometer thats taking a half hour to read correctly. The oven is probably getting there sooner. If you had a digital thermometer, the read would come quicker. So save your money,nothing wrong with your stove.

you may want to check your broil element
turn the unit on and wait a few minutes
see if you can feel the heat from the upper broiler elemnet
some model use both elements to preheat
i dont have your productiuon number so i cannot be sure with your model
anyway
14-20 mins is the industry standard for a 350 preheat...

Are you checking with a store bought thermometer or your recipe. If it is your recipe then ur thermostat might need a calibration or need to be changed completely if it is really off by more than 100 degrees. If it is 99 or less a simple calibration may just do it. If you have a steady hand. With your thermometer inside the oven and the door closed set at 350. Then take the oven knob off and take a small flat screw driver (really small). And insert it in the valve part where the knob was. With a flash light u can see the small screw. Turn it a hair at a time (1-2mm). Wait 20 minutes and see if the temp does rise. If not turn another hair. Repeat until 350 is reached. You must wait the 20-30 minutes for it to reach the temp. If all else fails changing the thermostat would be next. I do not recommend u do this alone. approx cost is: $400 - 500 front access, 500 - 600 rear access Good luck.

possible thermostat is sticking

most ovens take 15-25 min to preheat.

To preheat oven just select the temp you intend to cook at and wait until the red light goes out,it is then preheated
Then you can put your food in and carrying on cooking.
Yes you do put it on fan symbol, but make sure it is on the right one , as some ovens have fan only as well as fan and heat.
Plz rate this solution.
thanks.

Hello. I am a Viking factory trained tech. and that is actually a normal preheat time.
Now if it undercooks that is another problem.
You may need your thermostat calibrated or replaced. If you think you are up to calibrating it yourself let me know. If it is the kind that doesn't have any white silicone in the center of the knob stem then it is quit a pain in the neck, but if it does have the silcone then it is a lot easier.