another secondary tube furnace retrofit

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lexybird

Minister of Fire
Nov 9, 2008
596
northwestern PA.
Ive been doing a lot of searching lately and i think i have figured out the basic concept of what i aim to do to get more efficency and heat out of my addon furnace ,it is th englander 28-3500 .First let me say I love the furnace lots of heat burns nice for us good economical choice ,but i have since got a englander nc13 for my shop and i am realizing theres lots of advantages on it .id like to apply that new secondary burn technology to my furnace to improve burn times and reduce my wood consumption .I have heard reports of people who have seen 15-25% less wood use by adding these on various non epa models .that could mean 1-2 cords less sawing splitting stacking etc..trust me I have reservations of cutting a hole in the back of my new air tight stove but as an experianced tool and die maker for the last 13+ years and my tinkering ocd i cant help but have these insane thoughts roam in my head .my plan is to use black pipe mainly 3/4 inner diameter ,I know stainless is better for heat transfer but im on a budget and i feel that changing 30$ worth of steel pipe every few years wont be a big deal .the stove is already pretty well setup so my idea is to run the tubes dow nthe angled baffle support rails and make a square loop at the baffle edge approx 14 inch wide and 25 inch long and have it tee into one pipe in back of the stove and out the back using washer and nut principle and on bot hsides to tighten and the use of chimeny cement .i plan to use staggered size and locations for the exit holes ranging from.125-187 in diameter approx 1 inch apart and pitched toward the center of the firebox,if routed right and from what ive seen others do this should give me enough freeair space to heat before it exits the holes int ofirey flames ..my first plan was to cut another hole i nthe air jacket sheet metal and run it through and out the back maybe 6 inches leading to a gate valve for adjustment ,then i read most people have them wide open anyways and if a chimney fire broke out i think the extingusher in the box would kill the secondary gassifcation immediatly anyhow .so i get the idea to angle the exit pipe 90 out the firebox in to the jacket and seal it back up wit hscrews this way it can get a good jump on heating the air due ot the air jacket being 50 degrees hotter than outside air and the advantage of the blower will push a draft into it onyl when the box temps are at 190 degrees and it will kick off once it cools which will stop the secondaries air over the coals resulting in better burntimes i think using the furnace's existing blower setup would be an advantage for this.any opinions guys ?
 
You may want to run this buy the guys over in the Boiler Forum.
 
lexy:

A shame your thread got subverted... maybe start a new one while this one is headed elsewhere?

Unless you've locked in on your secondary plan, consider using plumbing copper to 'frame in' your idea.

Cheap, available, easy to work with... and replaceable when it craps out after two seasons.

Peter B.

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Peter B. said:
lexy:

Unless you've locked in on your secondary plan, consider using plumbing copper to 'frame in' your idea.

Cheap, available, easy to work with... and replaceable when it craps out after two seasons.

Peter B.

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......Except I don't think copper would even last 2 weeks in that application. You would get some pretty blue and green flames coming out around the burn tube jets, though....;)
 
And as far as doing that to your furnace, I don't see a problem as long as you could restore it to original if it didn't work (would require welding, but do-able).
 
Jimbob said:
And as far as doing that to your furnace, I don't see a problem as long as you could restore it to original if it didn't work (would require welding, but do-able).

exactly i figured worse case scenerio if it didnt work as expected I could put a plug in it and weld it up
I feel pretty confident it will perform close to the way i intend .by accounts of others doing this mod i see no reason why it would not work in my case.
 
Jimbob said:
Peter B. said:
lexy:

Unless you've locked in on your secondary plan, consider using plumbing copper to 'frame in' your idea.

Cheap, available, easy to work with... and replaceable when it craps out after two seasons.

Peter B.

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......Except I don't think copper would even last 2 weeks in that application. You would get some pretty blue and green flames coming out around the burn tube jets, though....;)

Three (3) weeks and counting...

Peter B.

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I'll be doing mine soon. But I already have the opening at the rear of the firebox on my furnace. I plan on running 1x3 rectangular tubing, with some 1/4 wall 1 1/2 od for the burn tubes. I figure the first tube at the rear of the firebox will not be drilled, so It will help preaheat the air. Have the plans in my head. If it doesn't work, I will remove a couple welds and out it comes. Right back to factory.
 
yeah there needs to be preheated air supply before the holes are exposed for sure , thats why i think my idea shouldnt need a bunch of fancy leads and such ,the air its getting wil l already be contained in the furnace air jacket and it will be around 50 or so degrees warmer than the outside air then i wil lhave a straight piece the na tee and some burner pipe length before the tubes and that should allow it time to heat up inside the firebox good before the air is emmited out the angled holes toward the end
 
Lexybird - Thought I'd resurrect this old post and see if you ever attempted to install the secondary tubes? Anyone know if England add-on is supposed to be adding burn tubes in the future design? Any of the guys from ESW willing to share? What is the ETA of the EPA, if any?
 
no i decided it would be best to not void the warranty and cause possible leak issues ,surely it would hurt the resale value too so i n the end ill probably get a couple more heating seasons out of this unit ..then switch to the PSG caddy when the economy picks back up and funds allow
 
I know the fund thing is rough. We waited until my wife became a nurse, which I bought the same unit I eyed on display for 2 years. You have until next year to qualify for the tax credit. Of couse if you don't have it you don't have it, but for us we will be seeing 600.00 from the tax credit from the furnace. Something to consider. I will sell my old furnace this winter when all other furnaces sell out.
 
Slowzuki- Assuming you have the ESW add-on, would be interested in seeing your design. I was thinking of running a pipe through from the lower draft up through the floor of the firebox (remove some firebrick) and run the pipe up the back and over the top toward the door that way you can still control your upper air and air wash in the door. (Not sure if there is room for this through the firebrick). The bottom pipe would have to be the exact length of the ashpan on the bottom so that the pipe would hit the front of the ash door when it closes and could be regulated with the spin draft. Not sure if that would work or not, but at least it wouldn't be modifying the stove at all. I'm interested in seeing your design.
 
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