Englander 28-3500 Add-On install thread

Hey all-I got the call Saturday that my permit is approved for the install of my add-on furnace/chimney so I got to work prepping my basement yesterday. I had to tear out two old poorly built partition walls that the previous owner had put in to divide the oil furnace off from the rest of the basement. Then I got to work on the old basement window, the opening of which can be seen covered with plastic above the wood furnace:



I'm going to set a thimble in the opening with brick and mortar, and the remaining space will be covered a louvered vent (like a gable vent) to ensure enough outside air. The vent is adjustable so I can restrict the air or close it off completely if needed. As for the chimney itself the pipe coming out of the top of the stove will be single wall black pipe which will transition to a Class A tee rather than an elbow to make the horizontal run through the thimble. The reason for this is that the top of the tee (and the horizontal run of pipe) will end up about 6" below the floor joists because the ceiling is a bit low, so even double wall stove pipe would not be permitted. Since 6" is a little close anyway I am going to install a heat shield to cover the joists over the area where the chimney pipe will pass under. This will simply be a sheet of Hardi-Board attached to the joists using non-conductive 1" spacers to provide an air gap. As you can see, heat loss shouldn't be much of an issue since I was able to locate the add-on so close to the main furnace. I'm a little worried about being able to keep moisture in the house and have looked into a duct mounted steam humidifier as the house gets pretty dry in winter as it is, so any suggestions on that would be welcome.

The furnace itself will get a few tweaks as well. After reading about the 28-3500 in various threads I found numerous recommendations regarding mounting the furnace on concrete blocks for easier loading. I'm going to buy four 12" blocks (All I have are 8") to give it an extra boost to make loading those overnight hunks of locust and oak easier on the back. Additionally I am going to mount a switch box on the side of the unit which will serve as a cutoff for the blower so that I can turn it off if need be without unplugging it. Finally, I'm still trying to figure out exactly how I'm going to do it, but I want to install some type of sheet metal housing over the blower itself so that I can direct the air through a standard furnace filter. My wife has bad allergies so I'd rather not be blowing dirty basement air through the house.

Off to the side you can see my $5 firewood rack (yard sale) and free (garbage) fire tools, but I have a still have a list of stuff to get since I'm a new woodburner and don't have all of the needed "equipment" yet. The list includes the following:

- Smoke detector (There's one near the steps on the other side of the basement, but I'd rather have another one closer)
- CO detector (Same as above)
- Fire extinguisher - Which is better suited for a wood stove related fire? CO2? Dry chemical? Plain old water? Perhaps I should just install a hose bib down there?
- Welding/foundry gloves
- Metal ash can
- Infrared thermometer

Anyway, I'm planning on updating this thread with pictures/comments as I complete the installation so that others installing a 28-3500 (or a similar add-on) can look at it and get ideas or offer suggestions. Either tomorrow or Wednesday night I plan on getting the furnace up on blocks and getting ready to run the chimney through the wall.

stee6043 said:

How far are you planning to run horizontal after your "T"? The manufacturers usually recommend a maximum of 24" of horizontal pipe in any system. If you exceed this you may not meet code since your installation would not meet manufacturer's spec. I'd recommend a 45 degree elbow for the sake of a good draft. Horizontal runs are tough on draft.

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Hart and Cooley (my chimney MFG) doesn't make a specific recommendation in the product literature, but I had planned on sloping the horizontal run 1/2" per foot so that the outside end of the pipe would end up 1 1/2" higher than the inside (36" total run), which I outlined in my permit application. I'm guessing the construction official thought it was ok since he signed off on it, but that just means I'm meeting the minimum requirement. I suppose I could go with a 30 degree elbow (H & C specifically prohibits 45 degree elbows from being used in a solid fuel application) though. I should also mention that in the original configuration the chimney will have two 90 degree bends (one off of the top of the stove, then a 36" run at 1/2" per foot slope, then one outside the house at the base) and then 21' of straight pipe to the top.

Update:

I picked up some material from Lowes today but didn't get a whole lot done. I also was able to order some Supervent parts (which I recently found out is a Selkirk brand of which Hart and Cooley-my chimney manufacturer-is a family member) through Lowes which was handy since I have a giftcard left over from our wedding. The total for a thimble, two 45 degree double wall stove pipe elbows, and an adjustable length of double wall stove pipe came to $160.00 and will be there in about a week. Now the chimney will leave the furnace at a 45 degree angle until it his the Class A adapter, then an 18" section of Class A will take it through the wall to the tee and straight up 22'. That should work better than having two 90 degree turns in the system. Tonight I worked on the ceiling protection. The closest the Class A will pass to a combustible material (the sill plate) is 6" which is three times the maximum clearance, but I still felt compelled to install a non-combustible barrier for piece of mind. Also, immediately after the Class A will be a double wall stove pipe elbow, but that will actually have 9" of clearance due to the fact that the joists sit 3" higher than the sill plate. I started my ceiling protection with the spacers which will provide the necessary air gap. I used 1.5" perforated square tubing (the kind used for hanging pipes/making shelving) which will be faced with 1/2" Durock cement board. Here are some photos of the spacer:





I figure it's not overkill to put this kind of protection over the flue since that's where most of the heat will go and because the wall and floor are concrete and I won't have to put in any effort there. The plywood backing for the main electrical panel and sub-panel on either side is far enough away to have to worry. Tomorrow I'll try to put up the other spacer so that I can start putting up the Durock. I have the concrete block to raise the furnace for easier loading but it's too damn heavy to even tilt high enough to slide the blocks under. I'll have to get some extra muscle before that happens.

stoveguy2esw said:

just a suggestion, remove the brick, the grates, and the doors before lifting the beast up onto those blocks, would lighten the load over a hundred pounds. other than that ,looks like a good plan you have im liking your "overkill" on protection. in my job i find myself working hard to talk folks out of taking shortcuts and fudging on clearances. its refreshing to look at an intended install knowing that your "fudging" is to the good side. dont forget the finished install pics, and welcome to the ESW family

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Will do on removing everything-that's a big D'oh! on my part-it's been sitting in my basement in pieces all summer and in my excitement I put it all back together after I moved it into place forgetting that I wanted to raise it up later... As far as the fire protection goes its extremely cheap insurance and assurance as far as I'm concerned. I think I spent just under $100 between the square tube, fasteners, and cement board. With all of that in place I won't think twice about getting a nice fire going before leaving the house for work or going to bed. It's also helping to put my wife at ease as it took some convincing to even get her to agree to buying the furnace. She's a country girl at heart but had a pretty suburban upbringing and just isn't used to the idea of wood heat. When I explained to her that if you really think about it, as it is right now we sleep directly above a 250 gallon tank of flammable liquid that we burn for fuel in a different kind of furnace, she started to get it. Now I'm careful to call her down to the basement once in a while to explain what I'm doing and how it far exceeds the manufacturer's specifications which helps a lot. And thanks for the welcome to the Englander family Mike-you probably don't remember but I had bugged you last winter about what to look for when buying a used 28-3500-I really admire ESW's commitment to customer service as I didn't really expect a company to be that eager to help me purchase a used stove from a third party. Needless to say that when it comes time to purchase a new stove it will be an Englander.

Gooserider said:

I agree with the prior poster on fire extinguishers, the best all around are the large dry-chem type. However there is one other aspect that I like to mention as well, which is where to put them... Remember that needing to use an extinguisher means that you are in deep doo-doo, and even the best extinguisher might not work if the fire has to much of a head start on you... IMHO it is more important to protect yourself than the house, so you want to avoid situations where you might get trapped by a fire...

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Good point-I never really thought of it in those terms. In that case I think I'm going to hang it on the wall at the top of the basement stairs. Directly behind the entrance to the basement is the door to the backyard, so I if there is ever a SHTF scenario I can chose to either run out the back or grab the extinguisher.

Cave2k said:

I have an old Englander that looks a lot like your unit (single 8" blower out) I bought a filter kit for. The kit is made by Englander takes a 10" x 20" filter and completely encompasses the blower. It worked good. The store I bought if from is closed now but they ordered it from a catalog of Englander.

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Hmmm...I'll check the catalog-Mike, do you know if its still available?

I'm almost finished with the ceiling protection-it just has to be bolted in place, but it won't happen today as in about two hours we'll be grilling and kicking back with some Oktoberfests in the parking lot of Rutgers football stadium Anyway, here are the finished "joists" which will provide the air gap/hold up the Durock:



The square tube was probably the most expensive part. I probably could have done better by going to a metal supply company rather than the hardware isle at Lowes, but the nearest metal supply place that sells to the public is an hour away and Lowes is about 20 minutes. Here is the Durock clamped in place until I have a chance to stop and get some machine screws and nuts:



As you can see here I need to space the Durock out from the tubing since the lag bolts I used don't sit flush, but now that I think about it, if I space it out with washers it will isolate the Durock itself from the supports. Once I get my infrared thermometer it will be interesting to see what the temperature differences are between the side of the board facing the chimney, the backside, the supports, and the floor joists themselves when the stove is cooking at full tilt:



I'm off to enjoy two of the three best parts of fall: football and fall beers, (the third being wood burning, but I'm not there yet).

Geez...it's been a while! That pesky thing called work got in the way of my installation and in the meantime the nights here have been dipping into the low 40s so unfortunately I've had to start burning oil, but hopefully with the three day weekend coming up I can finish before October is halfway done. Here you can see the work I've done to get the thimble set in the wall:



Starting from the top you can see the 4 1/2" air gap between the ceiling joists and the heat shield. Then from the underside of the 1/2" Durock heat shield there's an additional 4" to the Class A pipe with a 2" air gap provided by the thimble. Here's a closer look at the thimble:



My masonry skills are nothing to write home about, but it's in the there solid and I have no flammable materials within at least 10" all the way around. The black pipe adapter you can see stuck on the end of the Class A section passing through the wall will be attached to a double wall elbow with a sheet metal heat shield wrapped around it. I'm going to pick up the rest of my pipe now so hopefully I'll get a chance to post some pictures later once the wall support is on and I'm starting to run the pipe up the side of the house.

Here's today's progress (I won't get anymore time to work on it until the weekend):



It should start to go pretty quickly now-I just need to get some spacers to space the wall bands out from the wall a bit since I'm running about 3" clearance to the siding.

Outside chimney is finished It took all day, but now all I have to do is get my stove pipe connections and ductwork done and I'm in business! The first thing I did was beef up the wall brackets a bit since they seemed a little flimsy to me. I went back to Lowe's and picked up the same galvanized box channel that I used for the ceiling protection inside the basement to make a spacer bracket in order to strengthen the wall band itself as well as provide the extra spacing I wanted:



Here's a closeup of the installed bracket:



I used two wall bands and of course the wall support in what amounts to a 16 foot run up the side of the house, so that should provide all the support I need-however I need to work today on guying the top section because it extends more than 5 feet above the roofline:



Here's a view from the front of the house looking north:



From the top of the furnace the flue makes a 45 degree turn immediately, then has a run of 18" at 45 degrees where it makes another 45 degree turn into an 18" horizontal run. The horizontal run then connects to the tee for a 90 degree turn. The total length of flue inside the house plus the transition piece/tee is five feet. Once the flue makes the 90 degree turn via the tee, it is a straight vertical run for a total of 22' 6" to the top. That gives me a total flue length of 27' 6", but since I have two 90s (45+45, 90) in the system I guess my effective length is 17' 6"? In any event I went downstairs this morning as the outside temp was 38 degrees, so I was wondering if I was going to feel cold air spilling out of the opening. On the contrary I could actually feel some slight air movement into the flue. I took a tissue and dropped it in front of the opening and sucked it right into the flue! The real test will be burning of course, but I took it as an encouraging sign. Tune in next time for stove pipe, guy wires, and maybe a pic or two of a fire in the firebox!

lexybird said:

i realize you want to be up over the peak of the house ,but the flue height seems a bit overkill and very odd looking ,why so high ?

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So lexybird, how much did my wife pay you to say that? To be honest I'm wondering about it myself. The issue is not so much the peak of the roof, but rather the oil burner chimney which is within 10' of the wood burner chimney. My initial thought was to go by the 2/10 rule. The wood burner chimney is about 2' 6" above the oil burner chimney with the addition of the 18" section at the top. However, some posters said that the 2/10 rule only applies to combustibles; ie: the rule is only supposed to guard against hot embers coming out of the chimney and landing on something combustible. Some posters then said that it also applies to wind turbulence; ie: anything within 10 feet of the chimney and 2 feet of the top could cause wind turbulence that could force air down the chimney. Since I couldn't get a clear answer (the local code official didn't have an answer either), I opted on the overly cautious side. Also, the peak of the roof (well within 10') is 18', so the most I could shave off of the chimney is two feet anyway.

lexybird said:

seems you may want to contact your nearest airport and notify them theres a potential risk to low flying planes in the area directly above your house lol

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Ha! Good one... Well, I actually took the advice of you and Gooserider and subtracted one three foot length from the chimney. After some careful measuring with the aid of a level taped to a 10' 2x4 I found that the peak of the roof didn't come up as high on the stack as I thought. With the chimney three feet shorter it looks a lot better and only protrudes 5' above the at the point which it passes. The cap is still 3' above the peak and draft hasn't been affected at all as far as I can tell. Once I got the ductwork done I fired it up with some newspaper and pallet wood. Once it got going I put in a big piece of locust I'd been saving just for this occasion. It's been cruising since 8:00 and the house is currently a toasty 77 degrees. Here's a shot of the finished ductwork and the furnace lifted about 10" for easier loading:



And a closeup of the locust and oak cocktail I fed it about an hour ago:



And finally the coup de grace-my new digital indoor/outdoor thermometer. I never would have kept the house this warm with oil-the $$$ would be flying out the window!



This thread is by no means finished, but my install pretty much is save for the outside air vent cover, guy wires, and some other miscellaneous stuff. Special thanks to Mike from hearth.com for selling me this beast used at a great price, Mike from Englander for giving me tips on what to look for when buying a used 28-3500, Marty from Lowe's for all of the Selkirk special orders, and the entire crew at hearth.com-without which I'd still be paying for oil.

kieth4548 said:

Nice install. can I make a sugestion. I have the same unit. I have my furnace guy hook mine into the furnace since it was new and I didn't want to void my warranty. Make a filter back that covers the back of the blower motor and have two 6" lines going fom the filter box to the cold air return of your furnace. I thought is you av 12" of cold air feeding the blower and 8" of heat leaving so you are not choking the blower for air. It makes a big difference in keeping the air moving in your home. It will aslo eliminate any cold/hot spots in the house. My house is comfortable and even all winter. Good luck on your unit.

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I actually can't tap into my cold air return because the clean side is so close to the furnace. My wife's allergies were acting up quite a bit because of the unfiltered air though. I ended up going to Tractor Supply Company to buy their "universal filter box" which is actually made by United States Stove Company for their add-on furnaces. The 28-3500 is just a hair wider than the USSC units, so I had to modify the brackets in order to make it fit, but it wasn't a big deal. Now I can use a standard 16" x 20" 3M filter just like my oil furnace. It still draws from the basement, but the filter has made a big difference in the amount of tissues my wife uses in a day

kieth4548 said:

Curious question, how are you going to get to clean out the chimney? Looks like your T is close to the ground and how will you get a ladder to the top. I clean mine out about once or every other month. Just curious.

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Unfortunately I'll have to clean from the roof. The pitch isn't bad though, so it's doable.

whankin2 said:

This is a great thread b/c my setup is looking to be almost exactly as yours. Favor I ask is if you could please snap some pics from the side of your setup so that I can get an idea of the angle you used for the stovepipe to ClassA chimney pipe. I need to use this angle as well running the classA pipe into my house, since my ceiling will be closer to the pipe for code purposes. Please send if possible, and I will send pics of my setup as well. What do you plan to do (or have done) with your return air? Have you connected it w/ the return of your main furnace, or is it drawing from the room?

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As requested:



What you see there is all double wall stove pipe. It's Selkirk pipe (two 45 degree elbows and an adjustable straight length), special ordered from Lowes. The double wall feeds into a stove pipe to Class A adapter with a collar over it. Above the horizontal run of pipe is the Durock heat shield spaced four and a half inches from the ceiling. Hope that helps-if you run into any problems PM me.