Using Wood Pallets for Fuel - Ok?

I have never seen or used a boiler, but I am on the path to getting one. I can also get a lot of pallets for free. They will be broken down and full of nails.
If I burn these pallets in my new boiler, what happens to all the nails that were in the pallets? They end up in the ash pile when I do this in my wood burning stove. But is this okay in a boiler?

2nd question. I want to put my new boiler in the basement which has 2 - 6" daimeter holes in the walls (near the ceiling). I planned on using one hole for the stove pipe and maybe the other one could provide some outside air to the boiler.
I've just discovered that the flue on the boiler is 8" which makes me wonder if it's okay to put a reducer on the pipe so that it will go through my 6" hole in the wall. Is this a good idea? Is there another way to do this?

I have LOTS of questions. Sorry if these first 2 seem sort of stupid.

should be fine, i burned pallets allot last year. just once a month i pulled out a gallon of nails. no biggie, i figure the nails help retain the heat even. cant complain about that.

What kind of boiler are you looking to get? Some may not really like the idea of necking down the pipe as you go through the wall there... And is it the foundation wall, or a stud wall?

Burned a lot of pallets in a big boiler some time ago and when the environmental police found out they wanted to make sure the wood was not contaminated with noxious materials like lead, mercury, and the like. We had to get the suppliers to give us proof of "cleanliness" for each load shipped. Anyway, make sure you're not sending bad emissions over your neighbors way. Most pallet mills will pay a fair price for pallets that can be repaired with a board or two.

If you're looking at the EKO 25, which is the boiler that I have it's OK to reduce to 6" as long as it goes into a chimney that creates proper draft. Mine remains 8" to ceiling height and is then reduced to 6" before entering a 6" Metalbestos flue which extende 3' above the ridgeline of the house.

I mix cut up pallet wood with splits when I burn. For me, pallet wood burns too fast and hot. Since the slats are only about 3/4" thk x 8-10" long by the time you cut up the pallets to loadable/stackable pieces. The only problem I've had with the nails is allowing my ashes to cool sufficiently to dispose of ashes at the dump. Can't spread ashes full of nails on your property or all the wheeled vehicles will find them. The other downside, since I don't have storage yet, is that burn rate. Processing the pallet wood so it will fit in the door takes a fair amount of time bent over with my long bar chainsaw. Yes, and hitting nails quickly requires chain resharpening. So although it's free wood, the time spend processing equal amounts of energy in pallets vs. splitting good old oak or hickory in my experience is almost a toss up. That's why I mix it with splits. Pallet wood really adds to a good coal bed on a gasification boiler. Only headache is cutting them into processable pieces. You converging on a boiler. I'll be in and out this weekend so if you want to see a gasser drop in. Lots of Hardy boilers in our area also.

It might work fine but reducing the pipe is not code compliant in most areas. Part of the reason I went with a biomass was that the flue size was 6 inches. In the end the slight premium for a biomass was offset by the lower chimney cost.

I am hoping to get an EKO 25 or something similar in size. My exterior walls are all 8" solid concrete with 2.5" foam insulation on BOTH sides of the wall. Obviously a boiler with a 6" flue pipe would be a better fit for me, but I was just wondering whether a boiler with an 8" flue could be made to work. (code complaint or not) The existing 6" holes are what I HAVE to use. I do not have the option of enlarging the holes.

Jeff -

I feel you are painting yourself into a corner for no real reason. I think I spent 175 bucks to get my chimney core drilled. I bet for less than a couple hundred bucks you could get someone to enlarge that hole no problem.

Look around your area for "concrete cutting" I had two guys that were close by and able to do the job right quick.

JP

Jeff, Listen to JP11 on this one. You'll accomplish a couple of good things here, one, by meeting code, and two, by knowing that your boiler is set up according to the manufacturer's tested install parameters. With that said, you'll know that you can set all other adjustments according to the install directs. Example, I just installed a pellet boiler and the install directs were to have not more than 0.85" WC draft when the combustion fan was at high level. I asked the dealer if he would do that or had instrumentation that I could borrow or rent to set it up. He just said "we just set up the boilers to run and don't usually need to measure the draft". Long story, I bought a manometer and did have to work on my vent to get the suggested reading. Not sorry, because the boiler burns very very cleanly producing only a white to light grey ash in all areas.

Then you really wont be able to use a 6" hole, since you will need some triple wall piping so you dont melt/set the foam on fire.... That would be a big bummer.