The water is not heated when I put my Bunn coffee maker on

i think you may have to get a new one

I don't understand the question, but here is a try.
1 - put in two pots of water.
2 - put in third pot, the water should start coming out
Allow the water to heat (thirty minutes) then put coffee in filter housing, put in one pot of water, put empty pot on warmer, close lid, wait for brew cycle, enjoy coffee.

I had the same problem. On mine (and probably yours) the problem was the seal between the (upper) plastic water reservoir and the lower (metal) heating reservoir. No replacement seal is available.

I fixed mine by coating both sides of the old seal with aquarium grade clear silicone sealer - available at pet supply stores. Just a light (1/16") coating is all that's required. Carefully re-assemble and allow the sealer to cure for 24 hours.

I did that over a year ago, and it hasn't leaked a drop ever since.

Every time I plug in my bunn coffee maker, it trips the GFI. But when I plug it into another plug in my kitchen, it will work, but it seems like the water reserve is not right. It blows too much steam and the top starts lifting up from the pressure of the steam, then it starts leaking out the top left side. Then if I pour enough water to make 10 cups, it only makes 6 or 8. The coffee maker is only 3 years old, what should I do?

before plugging in place your empty filter basket in the coffee maker and place a pot under it. Slowly pour in two pots of water using the pour pitcher. Now you can plug it in. it'll take 15 min to heat up first time . when you brew your first pot leave your water level a little short,because the water will expand (only the first time)

Please get the model and the date code from the bottom of the machine and contact customer serivce. Depending on the date code, there might be a seal kit available or the machine can be replaced at no cost if 3 years old or less. If it is over 3 years old and the seal kit isn't available, the machine will be replaced at a reduced price.

Most likely this is your heating element, but it could also be your main thermostat

You could have scale building up on the heating element and thermostat probe. try running a 1/3 white vinigar - 2/3 water mix into the brewer, let it heat up completely, then run several pots of clear water through the unit. keep pouring water through it until the vinigar smell is out of the water,

It sounds like you have a pour over model and the problem is the tank isn't full. Turn the machine off (or unplug it). Put a pot on the warmer like you are going to brew coffee. Pour clean cold water into the top until it starts coming out the sprayhead (above where the coffee grounds go). Now plug it in and turn on. Let it heat up then you can brew.

The way your machine works is that there is always about 2-1/2 pots of water in the tank. The water you pour in to make coffee is actually pushing the hot water in the tank out. So, if you don't fill the tank before using it, you may be hurting the heating element since it isn't totally submerged in water.