Clayton CF700M

mtstove

New Member
Oct 16, 2020
17
montana
Had a couple of changes that I thought warranted a further update.

Ash pan knobs might look ok but are poor in function, almost having sharp edges on their sides where you grab, which is not great being that you aren't using these knobs to pull as they were probably designed for, but rather as big thread on nuts to hold ash pan in. Not as pretty, but I found some large knobs at hardware store that are made for a more industrial purpose and are actually designed to be used in a thread-on thread-off fashion. Small detail especially since I'm not sure at this point that the ash pan set up is any easier than just removing ash directly out of fire box with ash shovel....

More importantly, I ran into a bigger issue. The incoming air damper is very crude, using coarse chimney screws as hinges. Using in conjunction with my new bi-metallic thermostat, the door stuck in the open position allowing the furnace to really get hotter than I wanted at the time. My upstairs temp reached 73 degrees, whereas my thermostat shut of my blowers. Not the end of the world, but since the furnace was putting out substantial heat and no blowers were running the air in the two eight inch plentum duct runs was basically collecting stagnant and temps got to over 200 degrees. This cause the duct tape on the two eight inch pipes to start to wrinkle/melt and of course filled the house with more fumes. The installer had used the high heat tin tape I had provided on the first few pipe connections in preparation of possible heat.

So here is my fix thus far. I removed all duct tape on the new duct connectors and replaced it with the high heat tin type. I then removed the stove pipe screws used as hinges and damper door and ever so slightly enlarged the hinge holes in the door. I then replaced the coarse screws with fine thread machine screws so my intermittent sticking problem, I believe, is solved. Then I rewired my blower motors so that both come on with 110 degree snap switch but only one cycles off when I reach my cut off temp at the upstairs thermostat. This keeps a lesser volumn air flow always flowing through the system to keep duct temps happy when the furnace snap switch is reading 110 plus. Once the temp upstairs drops enough the second fan kicks back on to create higher flow. Keep in mind that I'm still am not hooked up to the return trunk of the duct system so I'm just pulling air directly out of the downstairs room and that with only two 500 cfm blowers, that are not really big enough for the sq.ft. I'm using them in, higher flow is not really that high.

This set up is working well so far in low to mid 20 degree outside temps. Since the 2750 sqft. rated furnace is in a 3400 sqft home I'm sure I have less issue then some may have dealing with excessive heat. I am happy to say that I'm able to keep the house a comfortable 69-73 degrees without running the furnace to it's full potential so far.

I believe my next project will be to install a barometric chimney damper since my chimney draft differences are so extreme. Considering keeping the manual chimney damper in the set up as an emergency back up.
 
Last edited:

brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio
Then I rewired my blower motors so that both come on with 110 degree snap switch but only one cycles off when I reach my cut off temp at the upstairs thermostat. This keeps a lesser volumn air flow always flowing through the system to keep duct temps happy when the furnace snap switch is reading 110 plus. Once the temp upstairs drops enough the second fan kicks back on to create higher flow.
Or you could just use a standard Honeywell furnace fan control/limit switch...allows normal tstat control, unless things get too hot, at that point it closes the damper (if wired that way, and its not stuck) and kicks the fan(s) on...and they can be on high, if multi-speed. These are easily adjustable switches too...
1604942610442.png
 

mtstove

New Member
Oct 16, 2020
17
montana
Or you could just use a standard Honeywell furnace fan control/limit switch...allows normal tstat control, unless things get too hot, at that point it closes the damper (if wired that way, and its not stuck) and kicks the fan(s) on...and they can be on high, if multi-speed. These are easily adjustable switches too...
View attachment 266548
Thanks but won't work with my set up since my damper is bi-metallic and not electric.
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio
Thanks but won't work with my set up since my damper is bi-metallic and not electric.
Ok, but it would still allow normal tstat operation of the blowers...unless things get too hot, then it kicks the blowers on no matter the state of the tstat.
 
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mtstove

New Member
Oct 16, 2020
17
montana
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...
I had sent two different messages to the seller and not getting a response finally click on return product with an explanation about the missing blanket. Not a couple hours later received an email appologizing for the delay and stating they had ordered the blanket and it was being shipped to me. Now I just need to find out how it's held in place. Do they just set in place or are they installed with some type of super high temp adhesive?
 

brenndatomu

Minister of Fire
Aug 21, 2013
5,530
NE Ohio
I had sent two different messages to the seller and not getting a response finally click on return product with an explanation about the missing blanket. Not a couple hours later received an email appologizing for the delay and stating they had ordered the blanket and it was being shipped to me. Now I just need to find out how it's held in place. Do they just set in place or are they installed with some type of super high temp adhesive?
On my Drolet Tundra it was just one big sheet cut to fit each side/back...would kinda stand there on its own, but basically just sandwiched in by the firebricks then...no idea on your model though.
 

mtstove

New Member
Oct 16, 2020
17
montana
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 ;)
Finally got around check liner. Best I can tell from the clean out it measuring about 6"x6.5". Did some internet searching and they are quite proud of the flex liners. Looks like the ticket is insulated/smooth at close to 1k.
 
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brenndatomu

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

moresnow

Minister of Fire
Jan 13, 2015
1,403
Iowa
Finally got around check liner. Best I can tell from the clean out it measuring about 6"x6.5". Did some internet searching and they are quite proud of the flex liners. Looks like the ticket is insulated/smooth at close to 1k.
Hmmmmm.... Time for @bholler to render a opinion if available.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
22,565
central pa
Finally got around check liner. Best I can tell from the clean out it measuring about 6"x6.5". Did some internet searching and they are quite proud of the flex liners. Looks like the ticket is insulated/smooth at close to 1k.
I need a bit more info
 

mtstove

New Member
Oct 16, 2020
17
montana
I need a bit more info
Exterior block chimney with 6x6.5 ceramic liner roughly 2.5 stories with 8" connection inside house. Furnace has 6" single wall currently with manual damper. 2800 feet against base of Rockies with crazy sweeps in barometric pressure along with down drafts from mountains. Have manometer and barometric damper ordered.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
22,565
central pa
Exterior block chimney with 6x6.5 ceramic liner roughly 2.5 stories with 8" connection inside house. Furnace has 6" single wall currently with manual damper. 2800 feet against base of Rockies with crazy sweeps in barometric pressure along with down drafts from mountains. Have manometer and barometric damper ordered.
An insulated liner will definitely help but it won't work miracles. With those atmospheric conditions you may be fighting it no matter what you do.
 
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