Controlling Convection fans

[MalcolmH]

I have a Enviro Windsor Stove that seems to push more Convection air than I would like, the stove has variable speed convection and exhaust on settings 1-5, Convection voltage is 79V-85V-90V-97V-120V accordingly, you can also shut the convection fan off and it will kick on HIGH when the stove heats up enough so it acts like a radiate heater with all that cast iron around it, nice feature. I was wondering if I could put in a 120VAC 5amp variable speed fan controller in line to the convection blower to dial it down slightly, I realize it won't kick on full High 120V now when called for but the new setting, and that if on high the stove may shut down due to HIGH Limit switch tripped if i dial it down to much obviously, so I am aware of the safety issues concerning this, just curious if anyone has tried this on a pellet stove successfully. Also don't want to hurt the control board by messing with the line voltage going to the fan but don't see how that would hurt it.

 

[Ssyko]

The only component that could be damaged would be your convection blower motor. If you dial it down to low it can overheat the motor and windings (low voltage sends the magnetic field into heuristics) and will create a resistance in the windings. And with no amp/voltage indicators it hard to tell what settings would be optimal.

 

[MalcolmH]

I'm hoping to dial it down so that the fan does still work on low/less than 79V, i realize dialling down to low or so low that it gets such a low voltage that it won't turn could be a fire hazard or detrimental to the life of the convection blower. I plan on setting the "fan controller" and hiding it behind the panels so that someone doesn't dial it down like you mentioned and burn out the motor unintentionally, or make it so that Fan HIGH won't cool the unit down enough and trip the high limit switch when ran on Heat level 5. I'll try it and run it through its heat levels over a 24hour period and see if I can find that sweet spot.

**Thanks Ssyko you've been a wealth of knowledge and assistance. If anyone can recommend a 120V fan controller that they have tried for this application please let me know, I just assumed 5amp would be on the safer side as the stove is rated at 5 Amp 575Watts, looking at a "Lutron FS-5E-WH rotary 5Amp fully variable single pole" should do the trick but we all know what assume means.

 

[Ssyko]

this is a digital (proper) speed control 20 bucks. no light dimmers. if you go below 75vac watch the temp of the motor housing with a laser type thermometer. a lil testing needed to keep from smoking your motor ( go from 85v test temp. 79v teat temp. etc.)

 

[MalcolmH]

I was looking at that one on Amazon, and good idea noting the temp at different ranges as thats probably the biggest concern, I do have a laser thermometer.

I was also looking at this one from KB Electronics, noting it has minimum speed trim pot / low speed adjustment so you can set the minimum speed so the fans don't stall, incase anyone decided to open up the stove and play with it.

KBMC-13BV

 

[Ssyko]

That looks like a winner cheaper, 2.5a (that helps protect the motor) and looks like its a lot smaller