Clayton CF700M

mtstove

New Member
Oct 16, 2020
17
montana
I just wanted to give my experience with my new Clayton CF700M since I didn't find a ton of info on the net prior to purchase in hopes this helps someone else out. I know these furnaces are discontinued and are probalby not as many around as with some other brands and models.

As far as reference, I grew up in southern Ohio and we heated primarily with the local hard woods and Riteway stoves and the like. Many years later I now live in NW Montana and the wood of course is quite a bit different.

My house is a '79, three level, 3400 sqft home, with 2x6 on 2' centers. Not super efficient but pretty good over all. The house originally had a wood furnace and base board electric but a previous owner removed the furnace and installed a ground source heat pump. Upon purchasing the home I slowly started removing the baseboard heaters in the upper two levels and since I already had a concrete block chimney not being used, I bought a cheap, used, Suburban wood stove off Craigslist as a small backup heat source in case of power outages. I found myself firing the Suburban up when really cold temps made the geothermal want to jump into auxiliary mode to save electric.

Jump to 17 years later and my thirty year old geothermal system needs a $3500.00 part which is a whole other story. So as a quick fix, looking at single digit temps coming in a few weeks, I went on the hunt for a wood furnace to get us by. Started looking for used without much luck. Not much new out there either due to EPA in the end months of 2020 and the few nice ones I found, sadly, were out of my price range.

So in my low budget search for used furnaces and stoves I stumbled upon a refurbished CF700M, which I believe was also marketed as an Ashley AF700, built by US Stoves but has been discontinued like many wood furnaces in the recent years. After doing what reading I could, I found that they were sold at Tractor Supply retailers and the like, so this led me to believe that this was and entry level furnace. The furnace that I purchased was off Ebay! One left as I am writing this post.


I purchase it for $1350 and free shipping so I was not real worried if it failed to work well in my situation. I received it in roughly two weeks (which if pretty good shipping time in Montana) with only some minor wrinkling/bending of outer rear shell around blowing mounting area and upon removing most of the fire brick found the fire blanket slightly torn and bunched up at one side. A heads up here there is conflicting info from the manufacturer in the literature as to weather or not burn fires in it outside to burn off fumes. I attempted to do this twice with little effect partially due to no chimney/draft hooked up. I then got it in the house, assembled it, hooked it up to the chimney, and plugged it in. As I am writing this it is still not plumbed into the duct work.

First impressions were that it really didn't feel quite 550 lbs. the shipper told me it was. The blowers are made in China but seem to be fine with quiet, super smooth bearings that spin for quite a while once shut off. The fire brick, which I removed all but back wall and ceiling to help loose some weight for moving, was typical. So other than maybe being built beefier and having a larger fire box, I thought it may work.

I fired it up and in the process of figuring out my new purchase almost fumigated us all. Fumes were extreme. Upper floors were hazy looking accross the rooms. Headaches and sore throats all around and of course a lot of open doors and windows. I assume this is something all new wood burners need to be aware of, I was just not ready for the extremity especially after running a couple of burns in outside.

Once seasoned so we could stay in the house I found that I had purchased a stove that did not have any way of automatically adjusting the air intake like my prior stoves did with either a bi-metallic controlled door or blower fan. Also found I had to get this furnace super hot in order to get the blowers for the duct work to even kick on. I'm sure all of this has to do with attempting to meet EPA requirements.

I started brain storming and pulled the thermo snap switch and researched it, finding that it was set for 302 degrees! I went in town and purchased a 110 degree switch. I was recommended not to go lower in case summer temps were hot enough to make the blowers come on without the furnace being fired up. Not and issue in my cool lower level in NW Montana but something to keep in mind for those who may have a warmer environment. So now I have the blowers coming on at a more reasonable temp but I wanted to be able to shut off the blowers if I reached the called for temp in our main living area. Originally I was trying to fiqure out how to hook a typical furnace thermostate into the mix as a cut off but things get complicated switching voltages. Then with help from a electrical specialty store (Platt Electric) I figured out a good old fashioned baseboard heater thermostate would do the trick nicely and oddly enough I had a few! So now I have blowers coming on around 110 degrees and off at whatever temp I have the baseboard heater set at which will probably be the 72-73 mark.

Next I wanted to have more control over the chimney draft. Originally there was a biometric pressure damper in the chimney which I verified is still ok to do with Montana code but I decided to put a manual damper in for more control of my two plus story chimney which is located right at the base of the Rocky Mountains which can create some odd drafts believe it or not. While I had the chimney back apart I also add some cement blocks under the unit to make a little higher for slightly easier tending.

On to the next issue. Incoming air.... This unit has a manual draft door that is opened and closed by a crude turn handle. Below this adjustable door is three air openings. This door also has a small metered hole in it that is over the center opening so if the door is complete close air still enters here. Doing some research some people are putting magnets over this hole to cut of this air supply as another way to have further air control. This stove also has no grate. You build your fire directly on bricks, building your fire upside down from what I'm used to when starting one. This fire box also has a metered hole centered below the glass fire box door to, I believe, aid in keeping the glass door clean and help the burn. Then down lower yet on the unit there are two more openings of around and inch square that I believe sends air to the three air tubes on the ceiling of the burn box. These tubes look like propane grill burner tubes. So with the damper shut all the way there are four openings taking in air all the time. This being said when the damper is in the closed possition it certainly cuts back the air noticeably to the fire. I have started playing with the chimney damper and a magnet covering the damper door hole on warm days to cut things back. Above the burn box is a cavity housing three sections of large cast pipe that the smoke and heat are winding it's way through to reach the chimney. I still have not been able to figure out where the smoke actually exits the burn box to enter this area or the exact route it travels in this upper chamber.

So as to how it's working so far... It's been two weeks running, not hooked up to the duct system, burning a mix of dry, larch, birch, fir, and such. We've seen 7 degrees here at night and I'm still able to keep the central part of the middle floor in the 73 degree range. Now this it's a given, my lower level is much warmer because it's coming through a downstairs doorway and up the main hall steps and the outer middle floor bedrooms are cooler especially if doors are closed for sleeping. In warmer temps, 25-40 degrees, I'm getting up to twelve hours burn time to coals so my concern of the fire box being too small seems to be negated. Getting down to single digits it's closer to eight hour burn times. For a furnace rated for 2750 sqft, not hooked up to duct work yet, in a 3400 sqft home, I couldn't be happier!

I now have a bi-metallic thermo control assembly on order from Hitzer I plan on attempting to install to the incoming air damper door for a little further automatic control, as well as a chimney thermometer, and Koal saver shovel. I also already have the optional air return box that excepts an air filter and also aids in the hook up to my retune air trunk portion of the house duct work.

Needless to say, I'm anxous to see how much better she'll do once fully plumed in. Hope this helps anyone considering one of these units.
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Gearhead660

Feeling the Heat
Dec 20, 2018
461
Southern WI
This looks an awful lot like a Tundra...minus the automation. Check out the thread dedicated to the Tundras on this site. Once you get it all ironed out, should be a good heater for you.
 
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mtstove

New Member
Oct 16, 2020
17
montana
This looks an awful lot like a Tundra...minus the automation. Check out the thread dedicated to the Tundras on this site. Once you get it all ironed out, should be a good heater for you.
Wow. It does look an awful lot alike. I'm guessing it's like many other things. Somebody makes a decent item and doesn't have patents on every single square inch of it so the other company buys it, disassembles it, and makes one almost identical.
 

mtstove

New Member
Oct 16, 2020
17
montana
So today my bimetallic thermostat showed up! I took the time to install it and I've only had a few hours run time, but it's working like a charm! I just removed the manual adjusting handle which is basically a fancy threaded bolt and replaced it with the regular flare head bolt . Drilled two holes to mount the thermostat itself to the face of the furnace and fabricated small bracket too attached pull chain to. We will see how well it will work when temperatures start to dip again outside. Right now I'm only between 25 degrees and 35 degrees at night.
20201030_234710.jpg


One concern I do have is one of the manuel's I got off the internet showing a breakdown diagram of parts, shows the insulation blanket behind the bricks going the full height of the firebox and in the ceiling as well. I removed my brick for easier moving of the unit and found the blanket only goes up about 2 or 3 in on the sides. Couldn't remove the back or ceiling bricks easily so not sure what's there. Concerned I may need the insulation on the rest of the box as well. Being that this was a refurbished unit there's uncertainty.
 

mtstove

New Member
Oct 16, 2020
17
montana
Any tips or tricks on how to prevent excessive smoke when exiting the firebox when attempting to restock stove? I'm opening both dampers all the way for a minute or so and crack the door about half an inch to get things flowing better but still getting way too much in the house. Part of it I believe is he outside pressure right now.
 

maple1

Minister of Fire
Sep 15, 2011
10,602
Nova Scotia
Any tips or tricks on how to prevent excessive smoke when exiting the firebox when attempting to restock stove? I'm opening both dampers all the way for a minute or so and crack the door about half an inch to get things flowing better but still getting way too much in the house. Part of it I believe is he outside pressure right now.
Could be a sign of a poor drafting chimney? The basics would be, don't reload until you are down to a coal bed (coals don't have any smoke making stuff left in them), and reload it and shut the door again as fast as you can.
 
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brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio
That bimetallic tstat will work well...that's actually a time tested setup you have there as the Amish have been doing that on Caddy's for years (what the Tundra was modeled from)
As far as the smoke rollout, what is your chimney like? (Type, height, etc)
Sounds like low draft for sure...it will probably get better as the weather cools too....
 
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mtstove

New Member
Oct 16, 2020
17
montana
I'm sure it's thetemps/weather, my location, and my chimney is about a two-and-a-half story block chimney with the ceramic liner. Another big factor effecting the draft is that I'm right against the Rocky Mountains and I do mean right against! We're about 2,800 feet and the mountain just behind me is closer to 7000 . A lot of downforce winds different times in the seasons. I didn't think to open a window or door a little too which may help draft.
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio
Ok, yeah masonry chimneys tend to not perform that well with modern wood stoves...they just don't waste enough heat up the chimney to keep it warm to the top...
 
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moresnow

Minister of Fire
Jan 13, 2015
1,403
Iowa
Any tips or tricks on how to prevent excessive smoke when exiting the firebox when attempting to restock stove? I'm opening both dampers all the way for a minute or so and crack the door about half an inch to get things flowing better but still getting way too much in the house. Part of it I believe is he outside pressure right now.
What is the I.D. of your chimney liner? This may be much of your draft issue. Potentially it's oversize leading to poor draft performance. A insulated stainless flex liner matching the stove outlet should help your draft/smoke roll out issue. Something to consider as you pursue hot-rodding your setup ;)
 

mtstove

New Member
Oct 16, 2020
17
montana
Thanks for the info. I'm not sure of the ID of the chimney liner. I'll have to get up on my roof and check. Pretty good size though. Are the insulated stainless Flex liners hard to put in or very expensive? Would that accept a Chimney Cap as well?
 

SpaceBus

Minister of Fire
Nov 18, 2018
4,774
Downeast Maine
Does your chimney not have a ground level clean out? You should have a small cast iron door at the bottom of the chimney where you can run a brush up and then clean out the stuff that falls down. That will also be a location to measure the liner.
 

SpaceBus

Minister of Fire
Nov 18, 2018
4,774
Downeast Maine
Yes it does. Not sure how easily i can measure from there but I'll take a look
The liner *should* run from the floor all the way up to the top of the chimney in your application, should be an easy thing.
 

SpaceBus

Minister of Fire
Nov 18, 2018
4,774
Downeast Maine
I believe I'm also going to add a controlled fresh air intake that would end next to the stove at some point which should help
Do you have any windows or doors in the basement? Usually opening a window or door 3-6" will tell you if an outside air intake would be helpful. Still a good idea, but I think a free standing stove would see more benefit than a wood burning furnace.
 

mtstove

New Member
Oct 16, 2020
17
montana
I do have Windows and Door in the downstairs and since my post, opening those slightly does seem to help. When I first install the furnace we had single-digit temperatures and with the difference between inside and outside temperature Plus whatever the pressure was doing outside seemed to give me an extreme draft. That's what led me to install a chimney damper to help with that. I'm finding that the barometric pressure along with the temperature really fluctuate and as a result so does my draft
 

andym

Member
Feb 6, 2020
233
Hicksville, Ohio
I do have Windows and Door in the downstairs and since my post, opening those slightly does seem to help. When I first install the furnace we had single-digit temperatures and with the difference between inside and outside temperature Plus whatever the pressure was doing outside seemed to give me an extreme draft. That's what led me to install a chimney damper to help with that. I'm finding that the barometric pressure along with the temperature really fluctuate and as a result so does my draft
I love my Dwyer Mark II manometer. It is always connected so I can see at a glance how much draft I've got. My chimney is exterior so this is really nice on cold start-ups as I can tell for sure if I've got a back draft to deal with. I normally have good draft, but smoke spillage is pretty common anyway. I doubt fresh air intake will help. It's the only real complaint I have with my Heatmax 2.
 

SpaceBus

Minister of Fire
Nov 18, 2018
4,774
Downeast Maine
I think that most wood burning furnaces *require* a barometric damper on the flue, which will regulate the drat.
 

GreenmtNCfarmer

New Member
Nov 1, 2020
1
Green Mountain, NC
I just wanted to give my experience with my new Clayton CF700M since I didn't find a ton of info on the net prior to purchase in hopes this helps someone else out. I know these furnaces are discontinued and are probalby not as many around as with some other brands and models.

As far as reference, I grew up in southern Ohio and we heated primarily with the local hard woods and Riteway stoves and the like. Many years later I now live in NW Montana and the wood of course is quite a bit different.

My house is a '79, three level, 3400 sqft home, with 2x6 on 2' centers. Not super efficient but pretty good over all. The house originally had a wood furnace and base board electric but a previous owner removed the furnace and installed a ground source heat pump. Upon purchasing the home I slowly started removing the baseboard heaters in the upper two levels and since I already had a concrete block chimney not being used, I bought a cheap, used, Suburban wood stove off Craigslist as a small backup heat source in case of power outages. I found myself firing the Suburban up when really cold temps made the geothermal want to jump into auxiliary mode to save electric.

Jump to 17 years later and my thirty year old geothermal system needs a $3500.00 part which is a whole other story. So as a quick fix, looking at single digit temps coming in a few weeks, I went on the hunt for a wood furnace to get us by. Started looking for used without much luck. Not much new out there either due to EPA in the end months of 2020 and the few nice ones I found, sadly, were out of my price range.

So in my low budget search for used furnaces and stoves I stumbled upon a refurbished CF700M, which I believe was also marketed as an Ashley AF700, built by US Stoves but has been discontinued like many wood furnaces in the recent years. After doing what reading I could, I found that they were sold at Tractor Supply retailers and the like, so this led me to believe that this was and entry level furnace. The furnace that I purchased was off Ebay! One left as I am writing this post.


I purchase it for $1350 and free shipping so I was not real worried if it failed to work well in my situation. I received it in roughly two weeks (which if pretty good shipping time in Montana) with only some minor wrinkling/bending of outer rear shell around blowing mounting area and upon removing most of the fire brick found the fire blanket slightly torn and bunched up at one side. A heads up here there is conflicting info from the manufacturer in the literature as to weather or not burn fires in it outside to burn off fumes. I attempted to do this twice with little effect partially due to no chimney/draft hooked up. I then got it in the house, assembled it, hooked it up to the chimney, and plugged it in. As I am writing this it is still not plumbed into the duct work.

First impressions were that it really didn't feel quite 550 lbs. the shipper told me it was. The blowers are made in China but seem to be fine with quiet, super smooth bearings that spin for quite a while once shut off. The fire brick, which I removed all but back wall and ceiling to help loose some weight for moving, was typical. So other than maybe being built beefier and having a larger fire box, I thought it may work.

I fired it up and in the process of figuring out my new purchase almost fumigated us all. Fumes were extreme. Upper floors were hazy looking accross the rooms. Headaches and sore throats all around and of course a lot of open doors and windows. I assume this is something all new wood burners need to be aware of, I was just not ready for the extremity especially after running a couple of burns in outside.

Once seasoned so we could stay in the house I found that I had purchased a stove that did not have any way of automatically adjusting the air intake like my prior stoves did with either a bi-metallic controlled door or blower fan. Also found I had to get this furnace super hot in order to get the blowers for the duct work to even kick on. I'm sure all of this has to do with attempting to meet EPA requirements.

I started brain storming and pulled the thermo snap switch and researched it, finding that it was set for 302 degrees! I went in town and purchased a 110 degree switch. I was recommended not to go lower in case summer temps were hot enough to make the blowers come on without the furnace being fired up. Not and issue in my cool lower level in NW Montana but something to keep in mind for those who may have a warmer environment. So now I have the blowers coming on at a more reasonable temp but I wanted to be able to shut off the blowers if I reached the called for temp in our main living area. Originally I was trying to fiqure out how to hook a typical furnace thermostate into the mix as a cut off but things get complicated switching voltages. Then with help from a electrical specialty store (Platt Electric) I figured out a good old fashioned baseboard heater thermostate would do the trick nicely and oddly enough I had a few! So now I have blowers coming on around 110 degrees and off at whatever temp I have the baseboard heater set at which will probably be the 72-73 mark.

Next I wanted to have more control over the chimney draft. Originally there was a biometric pressure damper in the chimney which I verified is still ok to do with Montana code but I decided to put a manual damper in for more control of my two plus story chimney which is located right at the base of the Rocky Mountains which can create some odd drafts believe it or not. While I had the chimney back apart I also add some cement blocks under the unit to make a little higher for slightly easier tending.

On to the next issue. Incoming air.... This unit has a manual draft door that is opened and closed by a crude turn handle. Below this adjustable door is three air openings. This door also has a small metered hole in it that is over the center opening so if the door is complete close air still enters here. Doing some research some people are putting magnets over this hole to cut of this air supply as another way to have further air control. This stove also has no grate. You build your fire directly on bricks, building your fire upside down from what I'm used to when starting one. This fire box also has a metered hole centered below the glass fire box door to, I believe, aid in keeping the glass door clean and help the burn. Then down lower yet on the unit there are two more openings of around and inch square that I believe sends air to the three air tubes on the ceiling of the burn box. These tubes look like propane grill burner tubes. So with the damper shut all the way there are four openings taking in air all the time. This being said when the damper is in the closed possition it certainly cuts back the air noticeably to the fire. I have started playing with the chimney damper and a magnet covering the damper door hole on warm days to cut things back. Above the burn box is a cavity housing three sections of large cast pipe that the smoke and heat are winding it's way through to reach the chimney. I still have not been able to figure out where the smoke actually exits the burn box to enter this area or the exact route it travels in this upper chamber.

So as to how it's working so far... It's been two weeks running, not hooked up to the duct system, burning a mix of dry, larch, birch, fir, and such. We've seen 7 degrees here at night and I'm still able to keep the central part of the middle floor in the 73 degree range. Now this it's a given, my lower level is much warmer because it's coming through a downstairs doorway and up the main hall steps and the outer middle floor bedrooms are cooler especially if doors are closed for sleeping. In warmer temps, 25-40 degrees, I'm getting up to twelve hours burn time to coals so my concern of the fire box being too small seems to be negated. Getting down to single digits it's closer to eight hour burn times. For a furnace rated for 2750 sqft, not hooked up to duct work yet, in a 3400 sqft home, I couldn't be happier!

I now have a bi-metallic thermo control assembly on order from Hitzer I plan on attempting to install to the incoming air damper door for a little further automatic control, as well as a chimney thermometer, and Koal saver shovel. I also already have the optional air return box that excepts an air filter and also aids in the hook up to my retune air trunk portion of the house duct work.

Needless to say, I'm anxous to see how much better she'll do once fully plumed in. Hope this helps anyone considering one of these units. View attachment 265658 View attachment 265659 View attachment 265660


View attachment 265661
Bought the same stove. Probably from the same eBay it sounds like. Appreciate the time you put into this post. Very helpful. Right now we can't keep the blower on for a full minute. It kicks on 4 seconds. Off a minute.
 
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mtstove

New Member
Oct 16, 2020
17
montana
Mine was doing very similar unless I just had furnace roaring. That's when I started to look at the snap switch and I found it was 302 degrees! Switch that out for the hundred and ten and It was like night and day. Only about $25. The other issue you may be having and I was having as well is since I'm not hooked up to my ductwork yet it was pulling cooler air from where it is located. As soon as I cool air hits that high temp switch it's enough to cool down and kick it off. Cause of cycling. They also make an adjustable snap switch if you want to play with different settings. The 110 is working great for me though.
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio

mtstove

New Member
Oct 16, 2020
17
montana
Bought the same stove. Probably from the same eBay it sounds like. Appreciate the time you put into this post. Very helpful. Right now we can't keep the blower on for a full minute. It kicks on 4 seconds. Off a minute.
Greenmt, you may want to remove fire brick and verify there is a blanket between the bricks and inner metal fire box. Found parts diag. on line showing entire box lined with this material. I called U.S. Stove and they verified that is should have this but they no longer have the parts. I did not remove the ceiling brick or rear wall bricks due to not finding an easy way to. Mine only had the liner on approx. 2" of the bottom sides. My fear is that the metal fire box may fatique and possibly crack more readliy without this buffer to control extreme heat changes. I'm contacting seller and waiting to hear back. Plan "B" is to find bulk product to purchase and possibly install myself.
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio
If its real thin, (1/16"- 1/8" plus) search for "ceramic fiber paper" online...its commonly available on Amazon and ebay...also at supply houses for ceramic kilns, steel mills, glass manufacturing, etc, they generally have this stuff in stock, often reasonably priced too. Same for the thicker "ceramic fiber blanket", and also "ceramic fiber board", if there is one used for a baffle...(which would be superior in insulative performance to steel plate/firebricks)
FYI, I removed the ceramic fiber paper behind the bricks on one of my units in the past, in an attempt to get more heat to the house...I put it right back then because it didn't work, and having it out really screwed with the secondary burn too...
 
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