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Questions about adding a blower to an older insert.

Post in 'Classic Wood Stove Forums (prior to approx. 1993)' started by s.recker, Aug 25, 2011.

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  1. s.recker

    s.recker New Member

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    Hello all,

    New member here. And I need some advice on adding a blower to a old Cresswood insert.

    Some background first.
    I bought my house in October of last year and it came with about 2 face cords of wood. So I burnt that plus some dead elm I cut at a friends place. The problem is that it really didn't seem to add that much heat into the house.

    The insert is on the main floor of a story and a half house in the living room. The warmest I ever had it was maybe 76 °F in the living room and the gas furnace set to 65.

    So I would like to know how much of a difference a blower would make?

    Also I was going to make my own blower using 2 muffin fans to move the air. How important is having variable speed on the blower? My plan was to have a "low" setting which would only run one fan and high would be both for a total of about 110 CFM. Do you all think this would work?


    Thanks, Scott

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  2. begreen

    begreen Mooderator Staff Member

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    I'd be careful where the blowers are placed. The old Cresswood inserts I have seen have vertical intakes alongside of the loading door. If this is the case with your stove, that area is going to get hot. There could be a fire hazard by trying to mount fans on the stove. If this is your insert design, it would be safer to place a table fan on the floor blowing toward the intake vent. but at a safe distance of at least 3 ft away.
  3. s.recker

    s.recker New Member

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    I will post a picture later after I get off from work.
  4. s.recker

    s.recker New Member

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    Here is couple of pictures of my insert.


    [​IMG]

    [​IMG]

    I don't think the fans would get to hot underneath the ash lip, I've stuck my hand in there with a good fire going and it wasn't very hot. The lip gets pretty hot next to the doors (180 degrees F maybe), but there will not be any thing touching it.
  5. begreen

    begreen Mooderator Staff Member

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    That is what I remember it looking like. I think the grilles alongside of the doors are the air jacket air intakes with the outlets at the top of the stove. It doesn't seem like mounting fans under the stove would do much. I'd try the fan blowing at those intakes first.
  6. s.recker

    s.recker New Member

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    I initially thought the same as you. So as an experiment, I stuck the output of a shopvac underneath where I am proposing adding the fans now. I blew out a lot of dust and cobwebs but near as I can tell the insert is designed for some type of fan to mounted on the very bottom. I had air coming out the top vents and the side "intake" vents.
  7. kettensäge

    kettensäge Feeling the Heat

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    You are on the right track the blower would mount at the very bottom.
    A blower will make a lot of difference, When the power goes out my surface temps run hotter than with the blower is on. I target a room temp of 74 under normal conditions. Without the blower, It slowly drops to the upper 60's with a prolonged outage. My air box never gets much above 70 or so, the incoming cool air keeps it cool. I don't believe it will be an issue. I would form a shield from sheet metal to keep the electrical parts covered and prevent damage from falling wood.
    You will use less wood. My insert is newer but simillar to yours. The fan mounts there and blows cold air into the insert jacket.
    I am playing with an idea to use 2 12v muffin fans, and a variable speed controller with a plug in wall transformer. I would install a female connetor to the airbox and connect a 12 v battery to run the fans during an outage.
    I did find nearly 200 cfm of air from 2 muffin fans is not the same as 180 cfm from the factory installed 120v squirrell cage fan, they just don't seem to be able to move air through a resistive path like the factory fan, but they are quieter. Since you have nothing now it would be a great start.
    Are there any universal or replacement 120V fans available in Lowes that would be an easy install?

    Plan on yearly cleanings as well.

    The dust and cobwebs go away quickly with regular use.

    Here is a pic of mine, airbox on the bottom blows air through the bottom opening, out the vertical side vents and out of the horizontal top vent below the built in mantle. It will blow 280 degree air when surface temps above the doors are around 450. Nice and toasty. My fan is 3 speed, 118, 140, 180 cfm. I rarely use mid or high speed. Low is plenty.

    Attached Files:

  8. begreen

    begreen Mooderator Staff Member

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    Thanks kettensäge. Good to know, I stand corrected.
  9. kettensäge

    kettensäge Feeling the Heat

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    Thank you, I've had to stand corrected here several times as well. Makes us all better off in the end.
  10. s.recker

    s.recker New Member

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    Thanks for the input, Kettensäge, you have confirmed a suspension of mine. I was worried that the muffin fans would not move enough air through the passages.

    I looked at Lowe's for a fan but they were pretty pricey and would need a fair amount of work to mount.

    I found a kit online last January that I could get to work, but it still will cost a $150.00 for kit and materials to make it work.

    Off to do sum research.
  11. kettensäge

    kettensäge Feeling the Heat

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    You could always mock up an airbox with some cardboard and tape, put the muffin fans inside and see how they will work.
    I have found running the fan at the 180 cfm setting doesn't increase the actual heat output that greatly above the lowest setting. It moves more air faster, and that air is "cooler" than on the low setting.
    You will also have increased noise at a higher setting. Another thing to consider is how much flow you can get through the insert at a given pressure. No use trying to force 180cfm through it if it will only flow 130.


    The fans are a little pricey but they will do the job. Mine still has the original fan from 1988, a new replacement is close to $200. It is a little bit of an investment but it will payback with better heat.
    Be sure to clean and lube every year.

    What were you thinking for a thermostat? Mine is a snap disc type, 100°F. It is surface mounted near to the opening for the fan. It turns on about 15 mins after I refire the stove (coals present) or about 25 mins on a cold restart.
    This allows surface temps exposed to the actual firebox to reach the low 300's and the blower to discharge 160° air when it first starts.
    Keep in mind your burn times will be shorter with a blower.


    Tons of cool stuff here. This is where I got everything for my muffin fan experiment.

    http://www.surpluscenter.com/
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