Just started comparing add-on furnaces

[Danno77]

I'm just starting to compare add-on wood furnaces. Install will be easy enough, already have the details worked out for a new insulated 6" flex liner, but a little worried that the run will be a little long (>30ft) but I've seen woodstoves with 35 foot runs before, just wasn't sure about such a large firebox mating up with that long of a run for that far.

There are a lot more options than I figured there would be, and a lot of specs to examine when I compare them. geesh, who knew it could be this complicated.

Currently, I have a 100,000BTU gas that is 92% efficient and it can't keep up when it's windy and cold (test this week was 40mph gusts when temp was in single digits; results had house hold around 66 degrees with wood stove cranked and a number of electric heaters running throughout the 3500ish sq ft house.) The attic and wood stove room aren't ducted, so the furnace wouldn't heat them no matter what.

Let's just assume that I'm gonna heat 2500-3000ish with this furnace.
it's triple wythe soft brick with lath and plaster right on the brick inside. It's 2 stories with a finished attic on the top of that. it's 150yr old, and I'm working hard to restore the 150 year old windows to their former glory with hand made wooden storm windows.

here are a few of the choices I've run accross:

Vogelzang 2500
--------------
115,000BTUs
24" logs
? cu ft
1100CFM blower
$1200
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_1036726_1036726

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USSC 1537G
--------------
119,000BTUs
26" logs
? cu ft
twin 500cfm blowers (1100)
$1300
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200395370_200395370

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FC500
------------
100,000BTUs
22" logs
5cu ft
1150-->1500-->1800CFM blower
$1799
http://www.woodheatpro.com/fc500.aspx

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USSC 1400
------------
114,000BTUs
26" logs
? cu ft
twin 550CFM blower(total 1100CFM)
$1964 (manufacturer) probably cheaper at store ~$1400 or so
http://www.usstove.com/proddetail.php?prod=1400

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Ashley 1602R
------------
135,000BTUs
28" logs
? cu ft
1,100-->1,250-->1,400 CFM blower
$1900
http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200362036_200362036

Comments? suggestions? man, with one of these giong I'd be sure to go through 10 cords of wood at my place. I better decide soon what to get in case I have to process that much for next year...

 

[JustWood]

You get what you pay for when it comes to furnaces.
If your going to spend 2K, I wood recomend a Yukon or Woodchuck.

 

[stee6043]

You have more than 100,000btu/hr heat loss with 2500-3000 square feet of space? This is a tremendous load. I don't think any of the furnaces you mention above will handle this kind of load consistently, especially if you are planning to use 6" flex pipe for your connection.

I personally think your money will be better spent stopping the heat from leaving your house first.

 

[smokinj]

You have more than 100,000btu/hr heat loss with 2500-3000 square feet of space? This is a tremendous load. I don't think any of the furnaces you mention above will handle this kind of load consistently, especially if you are planning to use 6" flex pipe for your connection.

I personally think your money will be better spent stopping the heat from leaving your house first.

+1 the 135k maybe but at that price there's better out there

 

[Danno77]

I personally think your money will be better spent stopping the heat from leaving your house first.

I'm open to any suggestions you have there. Attic insulation is done, and I'm working on the windows, any other ideas? I hear garbage about people insulating their inside walls with styrofoam board, but they surely don't have their original trim because adding another inch to my walls just wouldn't work with the historic trim without major modifications around windows and doors.

There are no voids to fill in the walls, as it's just plaster and lath right on the brick.

I've been meaning to insulate down in the basement, I have some of the insulation to strap up into the joists, so hopefully that helps.

The window restoring process is slow, but rewarding. the few that I've done are dramatically nicer than the drafty ones I haven't, but I put plastic up on the unrestored ones and it really seems to help. Don't even try to convince me to get new windows, the data is out on that and it's a sham. I'm not paying for new vinyl windows every 10-25 years for 7 - 7ft tall windows and 6 - 5ft windows.

at any rate, I was thinking that 100K BTU furnace (actually putting out 92K, right?) sounds like a reasonably sized furnace for a house of that size and age. I have 10ft ceilings on the first floor, but only 8.5 on the second and 8 on the third.

 

[smokinj]

I personally think your money will be better spent stopping the heat from leaving your house first.

I'm open to any suggestions you have there. Attic insulation is done, and I'm working on the windows, any other ideas? I hear garbage about people insulating their inside walls with styrofoam board, but they surely don't have their original trim because adding another inch to my walls just wouldn't work with the historic trim without major modifications around windows and doors.

There are no voids to fill in the walls, as it's just plaster and lath right on the brick.

I've been meaning to insulate down in the basement, I have some of the insulation to strap up into the joists, so hopefully that helps.

The window restoring process is slow, but rewarding. the few that I've done are dramatically nicer than the drafty ones I haven't, but I put plastic up on the unrestored ones and it really seems to help. Don't even try to convince me to get new windows, the data is out on that and it's a sham. I'm not paying for new vinyl windows every 10-25 years for 7 - 7ft tall windows and 6 - 5ft windows.

at any rate, I was thinking that 100K BTU furnace (actually putting out 92K, right?) sounds like a reasonably sized furnace for a house of that size and age. I have 10ft ceilings on the first floor, but only 8.5 on the second and 8 on the third.

100k sounds small, I have 119k on 2600 sq ft heavy insultion and wished I would have gone bigger

 

[Danno77]

maybe I'm wrong, maybe it's a 125,000 furnace, but somehow I've got it stuck in my head that it's 100K. I'm pretty sure about the 92% efficiency rating though.... I'm on my way home for lunch, so I'll dbl check.

I figured that since the current furnace is good enough to heat the place to 70 degrees all winter (except for a handful of VERY FRIGID days) then a wood furnace rated a little higher than 92% of 100K/125K (92K/115K) should be able to do the same.

 

[Danno77]

right on the sticker it says "Input: 100,000btus" "output: 93,000btus". i guess I figured that something above 110K should do the job even better than my furnace, and I wouldn't need to run it hard except in the most extreme temps.

Is there a different liner I should be considering? I'm open to it. it's an interior brick chimney with no existing liner. it's been a while since I've looked at the math, but I think it can't handle anything bigger than a 6" after you get insulation on it.

 

[stee6043]

I personally think your money will be better spent stopping the heat from leaving your house first.

I'm open to any suggestions you have there. Attic insulation is done, and I'm working on the windows, any other ideas? I hear garbage about people insulating their inside walls with styrofoam board, but they surely don't have their original trim because adding another inch to my walls just wouldn't work with the historic trim without major modifications around windows and doors.

There are no voids to fill in the walls, as it's just plaster and lath right on the brick.

I've been meaning to insulate down in the basement, I have some of the insulation to strap up into the joists, so hopefully that helps.

The window restoring process is slow, but rewarding. the few that I've done are dramatically nicer than the drafty ones I haven't, but I put plastic up on the unrestored ones and it really seems to help. Don't even try to convince me to get new windows, the data is out on that and it's a sham. I'm not paying for new vinyl windows every 10-25 years for 7 - 7ft tall windows and 6 - 5ft windows.

at any rate, I was thinking that 100K BTU furnace (actually putting out 92K, right?) sounds like a reasonably sized furnace for a house of that size and age. I have 10ft ceilings on the first floor, but only 8.5 on the second and 8 on the third.

I've read varying opinions on sealing up older homes. One thing that seems to be common is the basement. Particularly, the outside edges. Lots of people spray foam around the rim joist to prevent drafts. My home has R30 insulation shoved in every joist bay for about 12" back. From there work your way up. An HVAC contractor can do a smoke test, or thermal imaging, and really give you a good idea of where your heat is getting out.

Old or new, your house is bleeding BTU's somewhere. I heat 3200 square feet in a home built in 2003. My NG furnace is 90,000 btu and even on the coldest of cold days it ran less than 40 minutes per hour. My average heat load is roughly 20,000 btu per hour in winter with my peak being approx 50k-55kbtu/hr on a VERY cold day (-20 at night, -5 during the day).

Do you have someone local that could do a thermal scan of your house? Again....I think it would be money well spent.

 

[Danno77]

I've read varying opinions on sealing up older homes. One thing that seems to be common is the basement. Particularly, the outside edges. Lots of people spray foam around the rim joist to prevent drafts. My home has R30 insulation shoved in every joist bay for about 12" back. From there work your way up. An HVAC contractor can do a smoke test, or thermal imaging, and really give you a good idea of where your heat is getting out.

Old or new, your house is bleeding BTU's somewhere. I heat 3200 square feet in a home built in 2003. My NG furnace is 90,000 btu and even on the coldest of cold days it ran less than 40 minutes per hour. My average heat load is roughly 20,000 btu per hour in winter with my peak being approx 50k-55kbtu/hr on a VERY cold day (-20 at night, -5 during the day).

Do you have someone local that could do a thermal scan of your house? Again....I think it would be money well spent.

I don't have rim joists, those are what you get when you have a wood framed house on a foundation. I have joists embedded in 2ft(?) of fieldstone and mortar where it meets the three layers of brick. I do agree that the basement could use some work, but you have to be very careful about how you mess with fieldstone basement walls. they need to be breathable, so covering them with foam insulation is a no-no.

 

[blades]

Pyro, your place built 2003 his place over 100 years old no comparison possible. completely different construction practices.
Danno, I used to have a shop, which is still standing that was built the same way as yours. Man, those walls in the winter would just suck the heat right out, reverse in the summer. 800 sq ft, 14ft ceilings, $5-600/mo. utility bills year round. There are firms that specialize in acquiring old interior moldings and such or duplication of same. The only way you are going to beat this is to insulate by installing new walls inside over the the existing and using a sprayed on foam prior to new dry wall or plaster and lathe ( to keep original appearance inside). It will not be cheap. Most all your original molding will still work if it is removed very carefully, because you will be shrinking the interior dimensions a couple inches. In fact the inside room walls adjoining the outside walls will have to be trimmed back a shade, the outside ones will remain the same length. Yes the window casings will have to be reconstructed for the added depth the actual surface moldings will remain the same. The interior sill ledge will change depth wise, but that is not a huge problem. Nor is staining it to match as there are firms that can create a stain for you to do that. Over all it can be done in a fashion that you could almost not tell anything was changed. Just requires Time, Cash and Sweat Equity. The bad news is that unless you are planning on staying there a very long time you will never achieve payback. Self satisfaction, yes.

 

[lexybird]

i would get an american made englander furnace over those lighter weight chinese models mentioned ,mine performs great and easily heats my 2,000 sq ft home i nthe coldest january nights ,its heavy duty super easy to regulate and i can get overnight burns easy (id avoid furnaces with forced draft blower becuase they eat wood ) .if you can afford it (another grand)the PSG caddie would really be your best option it is EPA certified and offers long clean burns the others dont

heres a link to lowes site
http://www.lowes.com/lowes/lkn?action=productDetail&productId=213081-76845-50-SHW35&lpage=none

 

[blades]

Danno77 your comment on the windows while perhaps true of the vinyl replacement units, does not hold true for all the types out there. Replacement sash only systems are available both in double and triple glazing made from real wood, also in fiberglass ( fiberglass units are almost the same expansion/contraction ratio as wood ones. Vinyl not even close) I would stlll recommend the storms as you are doing. I have done two homes in the past 15 years on the first (1800 sq ft ranch late 50's build) the improvements were sill insulation in basement, attic insulation, window sash replacements (wood framed) double glazed/ argon injected, and alum. storms all around. Next step would have been foam insulation injection on exterior walls sadly there was a major life change before that was possible. Outcome was a 33% reduction in utility usage, although due to the meteoric rise in utility rates no dollar savings ,per say, were realized. 2nd home (2000 sq ft ranch, 1960 build), where I am now all the aforementioned plus new 92% gas furnace & 13 seer ac-central, new gas hot water heater, (50gal), wood stove and a wood furnace ( which supply 90% of the heat) The wood furnace at present just heats the basement as this place is still a work in progress, even so utility usage has been reduced 80% over previous tenants and during my duration here 50% since acquisition. I have 3 doors to replace, an exterior wall ( back wall of garage) to rebuild/insulate. Both homes are all brick exteriors with minimum or no insulation in the exterior walls (just wasn't done in those days). So this place is another candidate for the foam insulation injection system.

 

[semlin]

guys, the insulation advice is nice but he came asking about boiler options. please consider that some big old house owners are coming here because they have done some math and figured out that a wood boiler will give more bang for the buck than insulating beyond the obvious steps they have likely already taken.

for big old houses, the reality is that getting a big wood boiler instead of a slightly smaller one may be much more cost effective than trying to insulate, especially if you are on a budget and can't do both. i have similar problems: big house, lots of big vintage single paned windows and 6" wide walls filled with powdered gypsum of unknown r value and unknown void locations. it is completely cost prohibitive for me to have storm windows made so I am also making them myself one at a time and expect to be done in three years or so. in the meantime, a little math shows that even the raw cost of lumber and glass might be better spent on a wood boiler in terms of recovery time.

and as for retrofitting, even assuming it didn't devalue the house or trap moisture, the cost of stripping down, spray foaming, strapping, drywalling, rewiring and then custom milling vintage trim for an entire big old house would cover the cost of installing a couple of garns without breaking a sweat.

 

[blades]

Danno77, I would suggest upping your sights on the wood furnace to the $2g plus range, the $1000-1500 or so units are very hard to control and fairly inefficient ( yes I have one, it will be replaced shortly) You might want to wait a bit as the new emission testing has not been applied to alot of the add-on wood furnaces as yet. What ever you do make sure it has the secondary burn system and a substantial heat exhanger system both contribute to the overall efficiency of the unit. I have seen a Caddy unit which looked pretty good but have no hands on experience with it. There is a firm here in Wisconsin ( around the middle of the state) that builds a seconday burn wood furnace also, the name escapes me at present, but they have been around a quite awhile ( longer than most). They do have a web sight. They are low key advertisement wise Comparable to the Caddy and similar units. (perhaps Meyer? not sure)

 

[Danno77]

i would get an american made englander furnace over those lighter weight chinese models mentioned

Do you work for englander or something? DBL check the stoves I posted and let me know which one is chinese.

 

[lexybird]

i would get an american made englander furnace over those lighter weight chinese models mentioned

Do you work for englander or something? DBL check the stoves I posted and let me know which one is chinese.

nope ,i just happen to like mine for the money ,now as far as the chinese stoves im just stating a fact ,to my knowledge ~the fire chief is the only one thats american made of those listed .hard ot believe but the us stoves and vogelzangs are made in china.sorry just trying to help yo u make an educated choice bro

 

[kieth4548]

I have an englander 28-3500 furnace add-on. I heat a 3000sqft house with it and I love it. When I get this the stove cranking it will burn you out of the house (no pun attended). We are opening windows at times to let out some of the heat out. I don't use a lot of wood from what people have told me. I use about 5 quards a season. This last week it got close to the single digits and our house stayed at 75 degress no trouble.

http://englandsstoveworks.com/28-3500.html

I bought mine at my local lumber yard and had them deliver it right next to my door.

 

[laynes69]

We have a 150+ year old 2400 square foot victorian with 10' ceilings. We have the same cubic feet as a 3000 square foot home with 8' ceilings. Our old hotblast did a better job at keeping up with the temperatures than our caddy does now. But I had the 1500 hotblast jacket modified to accept a series install, and could fill it every 3 to 4 hours. The caddy is a fine unit, but with that much square footage and heat loss you will need a larger furnace. We can keep our house at 70-72 with outside temps around 10-15 degrees. We have quite a bit heat loss around the base of the walls and foundation. I need to figure out a way to stop those leaks and things will be better with us. If I had to do it again, I would have installed the Max caddy, its around 3200 but is built the same as the caddy, and has the clean burning technology that the caddy has. It meets canadian clean air standards, but not yet the epa standards which are basically the same thing. I would put the money down and get something thats efficient. I don't regret our decision on the caddy but our house is almost too much. If our house was new, the caddy wouldn't be a problem. If you get a standard furnace, I would expect you to see at least 10 cords a year trying to heat a house like that. Look into the max caddy.

 

[freeburn]

Danno77, I would suggest upping your sights on the wood furnace to the $2g plus range, the $1000-1500 or so units are very hard to control and fairly inefficient ( yes I have one, it will be replaced shortly) You might want to wait a bit as the new emission testing has not been applied to alot of the add-on wood furnaces as yet. What ever you do make sure it has the secondary burn system and a substantial heat exhanger system both contribute to the overall efficiency of the unit. I have seen a Caddy unit which looked pretty good but have no hands on experience with it. There is a firm here in Wisconsin ( around the middle of the state) that builds a seconday burn wood furnace also, the name escapes me at present, but they have been around a quite awhile ( longer than most). They do have a web sight. They are low key advertisement wise Comparable to the Caddy and similar units. (perhaps Meyer? not sure)

Are you talking about the Energy King out of Eau Claire or Woodchuck out of Dorchester now distributed by Meyer Manufacturing (Woodchuck as of the last I checked was not EPA cert, no tax credit)? Wouldn't rule out the new one from Blaze King either, it's got a catalytic converter in it. It's called APEX something or other.

 

[Danno77]

i would get an american made englander furnace over those lighter weight chinese models mentioned

Do you work for englander or something? DBL check the stoves I posted and let me know which one is chinese.

nope ,i just happen to like mine for the money ,now as far as the chinese stoves im just stating a fact ,to my knowledge ~the fire chief is the only one thats american made of those listed .hard ot believe but the us stoves and vogelzangs are made in china.sorry just trying to help yo u make an educated choice bro

well, from my sig I'm sure you can see I don't mind the englander made stoves, but this USSC stuff is news to me. I'm not surprised by the VZs being Chinese made, but after looking at the USSC stoves they appeared to me (not super experienced, I'll admit) to be well made.

Anyway, the FireChief stoves are easy to get ahold of as I live 2 miles away from a store that sells them. That makes them slightly more appealing than having to go to Lowes and order one (they don't carry any stoves in the closest store ~40 mins away).

thanks for the info, all. i'm gonna keep looking a these, but I do have some more questions. Like how much of a difference does the CFMs make in a house, like is there a max to how much air you want to move past any stove of a particular size? Like do you end up just blowing more "warm" air when you have 1800CFMs past a 115,000BTU stove, where as a 1100CFMblower past a similarly sized stove would work just as well because the air would be hotter, even though there is less of it? (does that question even make sense?)

 

[freeburn]

Keep in mind, the biggest thing in installing an add-on furnace is your ductwork. Your cold air has to be as large or even larger than where your warm air is coming out otherwise it starves the blower. Same can be said of the warm air side, it must not be made to force an elephant into a straw. In short, the blower fan is only as good as it's installation and with an add-on, that can be somewhat challenging to do. That's why the Englander and I believe the fire chief too, to some extent, follow the principle that the onboard blower is not designed to use for the whole house, but is more the heat source which is pumped into the warm air plenum which is then distributed with the existing blower on your gas furnace. Now some, like myself, are able to use just the existing blower on the add-on to do both. The air gently blows out of the vents and doesn't heat up the house so fast. In colder weather sometimes I turn on the blower via T-stat, or when the warm air plenum gets hot enough it will set off the fan limit switch inside the gas furnace automatically. Hope this helps. . . and doesn't confuse you more.

 

[smokinj]

i would get an american made englander furnace over those lighter weight chinese models mentioned

Do you work for englander or something? DBL check the stoves I posted and let me know which one is chinese.

nope ,i just happen to like mine for the money ,now as far as the chinese stoves im just stating a fact ,to my knowledge ~the fire chief is the only one thats american made of those listed .hard ot believe but the us stoves and vogelzangs are made in china.sorry just trying to help yo u make an educated choice bro

well, from my sig I'm sure you can see I don't mind the englander made stoves, but this USSC stuff is news to me. I'm not surprised by the VZs being Chinese made, but after looking at the USSC stoves they appeared to me (not super experienced, I'll admit) to be well made.

Anyway, the FireChief stoves are easy to get ahold of as I live 2 miles away from a store that sells them. That makes them slightly more appealing than having to go to Lowes and order one (they don't carry any stoves in the closest store ~40 mins away).

thanks for the info, all. i'm gonna keep looking a these, but I do have some more questions. Like how much of a difference does the CFMs make in a house, like is there a max to how much air you want to move past any stove of a particular size? Like do you end up just blowing more "warm" air when you have 1800CFMs past a 115,000BTU stove, where as a 1100CFMblower past a similarly sized stove would work just as well because the air would be hotter, even though there is less of it? (does that question even make sense?)

if your adding the wood furnace to your existing furnace its not a huge deal because your using the fans from it as well

 

[Danno77]

no, that's not too confusing and helps a little, cause it means I don't have to worry as much about those CFM ratings as I was. My current furnace (as best as I can tell from the crappy manual and online searches) has a blower rated at 2000cfms.

It might also be important to note that the furnace is 3 years old and some of the ductwork was redone at that time. it seems to be pretty balanced in terms of return air vents, etc.

 

[Lifted4x4Astro]

I have a USSC 1537G and I will tell you now that it won't heat your house on the coldest days. I bought the 1537G because it was cheap and oil was too expensive. My house is around 1800 sf and the furnace keeps the basement hot too so add about 500 sf. Our house was built in the late 1800's and has all new windows and some of the rooms have been remodeled. Downstairs ceilings are 9' and upstairs are 8'. My attic only has a couple inches of insulation. Normally the 1537G keeps the house at 72-73 pretty easily. We only suffer on the windiest days. I burn through about 8 cord and use less than 50 gallons of oil per year. House is never less than 64*F.

For a house your size, I would look at a 1602M furnace if you go USSC.