grate spacing

[Brent]

More questions from the newbie with a Half Pint

Watching the burn in our half pint it seemed that after a couple hours of burning it was not as hot as a half hour after we started. I noticed there was quite a pile of ash and hot embers on top of the grate. The grate is 2" angle with the V pointed down. But there is only about 1/4" gap between the tops of the angle iron and that seems to hold too much ash and restrict the air flow.

So we put on a blower. That helped but most of the air was still blowing around the end and not up through the core of the fire. By the way we're going to tyr to gasket the door before we use the blower again. Already put gasket under the pan. Can't imagine why Leader don't mention this in the instructions.

Anyway, back the angle iron spacing. What kind of air gaps do the bigger units have?

[WESTVIRGINIAMAPLER]

I have stanard grates in my evpoatotor and the V is down just like the letter V on a piece of paper. I have probably 3/4" gaps on my grates.

[Brent]

yeh I brought my grate to work today.

Going to open up the gaps. I'll let you know how it goes.

I think they put the V points down so the bottoms stay slightly insulated and help prevent deformation. They would shed the ash better it the points were up but the the entire angle iron would be exposed to hot coals and likely get too hot.

Got to respect their years of experience a bit.

[WESTVIRGINIAMAPLER]

Brent,

Might work better if you could drill a bunch of 1/2" holes in them and close off the air on the end of the grates. With a blower and holes in them, the evap rate should definitely pick up. :)

[Brent]

I'm going to add a plate at the front and back.

Holes might be better than thinning down the angle. Give it a bit more form strength. Thanks ... I'll think about that.

Still waiting for some sunshine to turn on the flow. Rain and wet flurries coming. Daxxxxxx

[Russell Lampron]

I haven't looked at a Half Pint lately but if yours has the factory grates in it the "V" should be pointed down and the hollowed out part filled with refractory cement. The refractory cement helps control warping.

My Algier evaporator uses large cast iron grates that have 1/2" to 3/4' spaces between them and have about a 1/2' space at the lenghtwise ends for expansion when they get hot. They also have some space so thet they can expand sideways.

Russ

[Brent]

Well I spoke with Leader and they said there was no special science in the spacing they used so the grate went on a milling machine and we opened up the slots to just over 1/2".

We got more sap yesterday so we had enough for a test boil.

WOW what a difference. 90% of the ash and coals fell through. When I had the blower in the bottom door we had a fire breathing dragon. Got 9 feet of stove pipe and there was 18" for dull red "jet blast" coming out the top.
Took the blower off and we still had some dull red blast. Put the draft door back on and things got just about as hot as I wanted it.

We did put a peice of 1" angle at the front an the back where Leader had left a gap, so all the draft had to go through the grate and into the fuel.

Needless to say, so far, very pleased with the results.

Now, if we can only get more sun.

[WESTVIRGINIAMAPLER]

Brent,

Keep us posted on how the grates look after a season of boiling. One thing to remember is keep the ashes/coals on the underside cleaned out all the time to keep the underside as cool as possible and allow air to get to underside. :)

[Brent]

Looks like were pretty well done this year.

The wider grate spacing helped a lot. The finer coals and ash fell through letting the air get at the wood pretty well. We were boiling in the neigbourhood of 7-8 GPH. Did over 100 gallons a couple days in a row and we did not have very good wood. I would guess we could improve on that next year. Might get close to 10 GPH but it would take a lot of attention.

We did put on a small blower and that made a big difference. The grates did not distort at all. Next year I will put something on the door and its frame and seal the air leaks ( aka smoke leaks ) around the upper door. The blower forces the smoke out anywhere it can go.

Had a lot of fun. Got better than Vermont fancy on 90 percent of the boil. Only one small batch came out between fancy and dark amber. Don't understand for sure why but I think I let the sap sit warm too long.

[Brent]

A few people asked for more info and a picture of the mods I made to the grate in our Half Pint.

Here is a link to a picture

http://www.hhrobertsmachinery.com/grate.gif

I notice that most of the air flow was around the ends of the grate and that ash and coals had pretty much plugged up the gaps between the angle iron so I openned up the spaces between the angle iron on a milling machine. A disc grinder could accomplish the same thing and make you deaf at the same time. In the picture you will see the two smaller pieces of angle that we added to the front and back. It worked well but after we did it there was still a large gap between the gap firing door and the grate. Temporarily I put a fire brick in that gap. I will weld in another peice to prevent that before next season.

The spacing between the angle iron is now about 1/2" and I thing a bit bigger gap would be better. I am planning to open it up to more like 5/8" before the next season. We were still getting some coals sitting on top. A little poking around during firing and they fell through.

There was not warping at all. I like the suggestion to fill the V's of the angle iron. I will slice some fire brick and cement it in place. It will keep the grate a bit cooler to help avoid warping and make it easier to clean.

Now all the air from the draft box and fan is forced up through the grate, none by-passing around the ends.

Good luck to all and thanks for the comments

[Fred Henderson]

The 5/8 spaceing is not enough if you are burning hard wood, it will work fine for soft wood but got to 3/4-7/8 for hard.

[Brent]

Your comments sound like good advice. We started off burning mixed and then got almost all hardwood and the piles of coals got bigger.

Wonder if anyone from Leader reads this stuff ?

[Fred Henderson]

I have homemade angle iron grates in mine with a 5/8 spacing. Burning Tamrack they worked great but when I got onto some maple that was in the shed they were not so good coals kept building up. Before the season I burned some 1/2 holes in them and it helped but a wider space would be better.