raised vs dropped flue arch

[Mark-NH]

Is there a difference in the shape of the arch. I have a 2 1/2 x 4 leader drop flue pan that will need updating. I just retined my arch and added a blower so I want to keep it. Do I need to replace the pans with a drop pan or can I just swap to raised flue?

thanks in advance

[325abn]

I would think that the only thing you will need to do is add some blanket and/or brick to make-up the space under the raised flues.

[HanginAround]

I agree, should be able to build it up or add some baffles to force the gases up into your flues without too much trouble.

[brookledge]

If you do go to raised flue the best thing would be to look at someone who has a raised flue or go to a dealer and see what the arch looks llike. That way when you modify your arch you will know what you need to do.
Keith

[WF MASON]

Measure from the arch front back down the top rail the length of your syrup pan (4' ?)plus 20" more mark that, do it each side , then cut a pc of sheet metal that will fit inside the arch(29wx18l) to form a slope up to your 20" marks. Rivet or weld or shim under the top of it to hold it in place. Brick up the slope under the top rail. Top row of brick will need cut flush with top rail.

[JasonS]

I have switched from a 2x3 drop flue to a 2x4 raised flu this year and have some questions. My drop flue pan would foam like crazy, if I forgot about the defoamer it would completely boil over, even with the hood on. This new 2x4 raised flue pan doesn't seem to foam to much however when ever I open the hood sap is spitting all over the place. If I didn't have the hood I get the feeling it would be making a real mess. Is this normal or am I running the pan too deep? In the past I would run the drop flue at about 1" to 1 1/2". But I didn't have floats on that pan so it was a little difficult to regulate. This Leader raised flue has a float box and I have the sap level set so it is about 1/2 to 3/4 up the copper feed pipe.
Any Ideas??
Thanks,
Jason

[Russell Lampron]

You may want to run it a little deeper. I run mine so that the pipes on top of the flues are covered. I am assuming that that is the feed pipe that you are talking about.

Russ

[nhmaple48]

If using the same arch, did you put baffles under the flue pan to force fire up into flues?

[JasonS]

Yes, I did put baffles in, I Called leader and asked what system they recomend and I followed thier ideas.

[maple flats]

I also have raised flue. The fill pipes are 2" on mine and they rest on the top of the flues, switch a plug to reverse flow. I keep my level just about half way up on these pipes or 1"-1.25" deep. These tubes enter the evaporator so the fill box/float box combo is at the same level. This makes it easy to see the level without having to see thru all of the steam and rooling boil to determin the exact level.

[maple flats]

Also, when I bricked mine I used the ideas of some members of this forum and bricked straight up at the back of the firebox until about 6" below the pans, sloped up at about 35-40 degrees until only 1/2" below the pans. everything behind this vertical wall, slope and rearward was vermiculited to the real sloping baffle and covered with one layer of firebrick and minimally befractoried to hold the vermiculite from going up the stack. From the baffle I bricked everything for a chamber for exhaust gases to get up the stack properly. Mine is a 3x6 raised flue pan behind a 3x2 syrup pan so you will have a much shorter up high level section before the baffle. The idea is to force as much heat up into the flues as you can. I think I read somewhere for your rear section you need just slightly more square inch opening than you have at the wide end of your base stack. When you get done the exhaust will go from the firebox across the bottom of the raised flues and then loop down like a P trap on a sink and then straight up.