The AM Forum

Does anyone have experience using a standard 120VAC light dimmer to power a blower/squirrel cage fan?  I wonder about start-up load stress and longevity.  I'm looking at 150-200 CFM size blowers - not all that big.

I use Variacs now for the rigs, but want to add a few blowers around the house to circulate warm air from the coal stove and use the cheaper, easy-to-install dimmers to ramp down the fans at times.

Anyone doing this now?

T

Coal stove!!??

My fireplace insert has two good-sized Dayton blowers in it, and came with a plug-in rheostat for fan speed control.  It worked well, but wasn't heavy duty enough - only lasted a few winters.

73, Karl

Inductive loads can be an issue with dimmers.
Do they make speed controls for over head fans?

Yeah, even a switch-type speed control would be acceptable.   If no one knows for sure, I'll do some more searching.


Just picking up a used 5-year-old Harman Mark III coal stove for a good price, good for 95,000 BTU, 550 pounds! That thing will drive me outa the living room, so gonna add ducting to push warm air into the radio room and kitchen/downstairs bedroom using the blowers. (Remember that I suck in outside for the rigs - cold)  I put the blowers right at the top of the wall/ceiling junction to access the warmest air. The cold air will circulate back along the floor. Evidently a whole house can be covered with a few well placed fans.  The upstairs naturally gets warmed via the stairway hallway, as I've found with the existing wood stove.  I'm just tired of hauling wood and restarting the fire. This coal stove should stay on for months....

T

Here's a pic of the stove and one in action:

The Dimmers are not going to work well for the motor.

Check out Ebay item  180495994633

They are $19 and work exactly like need.  You just cant use Brushless motors. Only normal Brush type.

The other option is the $7 units on ebay. They are 2.5 amp so confirm thats large enough and you will need to panel mount them and wire them up.  Just search AC motor control on ebay

I have used Variacs on Brushless motors before. It seems to never work out.  The motors run real, real hot if you try to go to low. Full blast, The motor and shaft runs cool.

I used Dayton blower in my 4-400 rig.  Its very smooth. I made a rubber gasket for it so its isolated from the chassis.  

Thanks Clark - I'm going to order two.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=180495994633&ru=http%3A%2F%2Fshop.ebay.com%3A80%2F%3F_from%3DR40%26_trksid%3Dp5197.m570.l1313%26_nkw%3D180495994633%26_sacat%3DSee-All-Categories%26_fvi%3D1&_rdc=1


The ad says:
"Will not work on induction, shaded pole, soft/slow start, or brushless type motors."

Hmmm...  I am using a common 120VAC 5" muffin fan and an unmarked  squirrel cage 120VAC blower. Not being an electric motor kinda guy, how do I know if either falls under this restricted category?

T

I doubt the muffin fan will start.  This is why They are suggesting you cant use the control on this type of fan.  Brushless motors have a low tolerance for low voltage.  What I did was to use a bypass Relay with a timer control on it. The fans come on full blast, then after 90 seconds, They go to low.  With this arrangement, i dont see why it wont work, OR, Just turn the controll all the way up to start the fans.

C

Soooo parts of your house will sound like a microwave oven cooking, Tom?

I might be making a bad decision for our house. We plan to heat with GAS. Supposedly excessive gas in storage from the Marcellus Shale....................And Rendell wants to tax the gas industry for that..............prices are down to $5.30 /mcf.

Coal is kewl.
Fred

A couple of years ago I had one of the pedestal fans in my Desk KW go up in smoke (literally).  I replaced them with a couple of larger Rotron "patriot" fans but I didn't want to run them at full speed since they produced much more air flow than the originals (or what was needed).  I bought one of the units designed for motor speed control but I still ran into problems with the fans wanting to change speed as they/the controller warmed up and the controller was creating some electrical noise.  I was lucky in my case to be able to put the two fans in series (running from 120V) and the speed is perfect at this level with very little noise.

There was an article in Electric Radio that dealt with using a motor speed controller for the blower in the Heathkit KL-1 "Chippewa" and it would be worthwhile to refer to that article for additional information.  It appeared in February and March of '98 but I am away from my ER collection right now so I don't know which installation of the article covered blower speed.

Tom,
Phelps and Sons on Rt 30 Vernon by the intersection of RT31 is by far the best place to buy coal.
There is a lot of junk coal out there that will drive you crazy. When you drop junk coal on a hard surface it has a thud sound. good hard coal has more of a ring. I burned two tons a year for many years. I had the stove in the basement that kept it in the 80s with the rest of the house in the 70s. It is very nice even heat but a bit dusty. I only had to load/shake the stove twice a day. The basement stove kept the floors nice and warm.

I've got a Gayuta Andes cylinder stove. I can't find much on the google.  any stove guru?    गुरु

..... I know coal stoves can burn wood, how can ya tell if you have a coal stove, a wood stove or a stove that can burn both?   Coal burns hotter and ya cant just burn it in anything. 


klc

I had no idea people were still burning coal, I guess I am a left coastie....

My previous house had a coal chute, last used in the twenties.  Some of the houses here in Portland still have (non-used) wood burning furnaces.

Rich

OK Clark - I can live with starting the motor on fast. I'll order those controllers. Thanks again for the info.




"I know coal stoves can burn wood, how can ya tell if you have a coal stove, a wood stove or a stove that can burn both? "

From what I know, a stove designed for coal will have a movable "grate" at the bottom to shake the ashes into the pan below to shake down. A wood stove usually needs no movable grate and will be stationary. The ashes just fall to the pan for wood. Coal produces about 8-10 times more ashes than wood, so needs to be cleaned out more often - but the coal stove will stay lite longer, like 18-24 hours on the bigger ones.

There are combo wood/coal stoves too.  I think it may be best to get one optimized for wood OR coal however.

A coal stove burns much hotter than a wood stove, so there is more stress on the firebox components, esp the grate. Easy to warp or break it with heat.  

Some coal stoves can be used for wood with slight mods. One mod is to add a steel plate to cover the grate somewhat. The info is on the web for any particular stove. There are laws against switching fuels around like that, however.

Frank - the guy included 1.5 tons of coal with the stove, so I'll be schleping this weekend with my truck... ;D

T

Coal stoves are made from cast iron.....Wood stoves can be made from steel...coal will melt steel...

From what I know, a stove designed for coal will have a movable "grate" at the bottom to shake the ashes into the pan below to shake down. A wood stove usually needs no movable grate and will be stationary.

That’s what my old man said. The stove has the revolving grates. The OM usda stoke the low pressure babies.  But he said, you better have someone look at it.

 The info is on the web for any particular stove.

Not for this baby


There are laws against switching fuels around like that, however.

So far, not in the hills of NY……. Or so I think 



The nice thing about wood, other than the woodsy sound, is that the ash is gud fer the soil. Coal ‘ash’ is good if you want to use it for a filler or as part of a road base….  Snot good to have lying around….

I use a fan to blow the heat around the cellar. I pulled out the 2KW lectric heater. Way to much juice....  Maybee I'll get the 813X813 rig going; i've not done anything with her fer 3 years.  (need a name fer her)

klc

.

If you burn quality coal you can run at about 200 degrees stack temperature and have plenty of heat.
I dumped my ash pan once or twice a week because good coal isn't full of sand. It will be fairly light colored. Dark gray means lots of dirt. Quality coal stays burning. I could go all season and maybe have it go out once or twice. Usually it was my fault being too lazy to get up early on a weekend or away from the house at feeding time.
The hardest thing to learn is how to feed the coal without filling the house full of dust. The best method if you have the time is throw a shovel of coal in and let it get going good so there is plenty of draft. Then shake it down.
Wood was a big pita.
If you get into it build a bin under a basement window then Phelps can deliver it and shoot it right into the bin. I hauled many a pickup load. 2 tons was usually 3 trips.

Nice old buzzard stove!  I'll bet that's a 90K BTU from the looks. It's almost looks bronze?

Steve, I could be wrong, but the Harman body is made from a single piece of 1/4" steel and robotically welded. The door is cast since there is no firebrick in front. I realize 2000 degrees (coal burning temp) will melt steel, but I think the body is insulated by the firebrick. The temp gauge on top varies from 200-600 degrees F according to the specs. The grate is cast iron since it is in contact with the coal, however. 

Frank, interesting about the coal quality. I thought I'd be getting away from that with the wood problems, but guess coal varies too. I didn't even look the coal over I'm getting from the guy.

The bin idea is appealing. I wonder if one could be built outside? Why does everyone put it in the cellar? Not sure if the bin has to be below ground for gravity unloading - or maybe the weather outside will keep it too moist?

T

Hi

This one works with shaded pole motors.

http://cgi.ebay.com/SmartFan-Nimbus-AC-Motor-Fan-Speed-Control-240vjw03-/180568826048?pt=LH_DefaultDomain_0&hash=item2a0abda0c0


73
Craig

Phelps coal truck has an outlet at about 5 feet so the bin needs to be below that. There is no problem keeping it outside or in the garage. I filled my bulk head hole with a dam in front of the door. Inside the stove was about 10 feet away so I just opened the basement door and shoveled it out from below the bottom step. You don't want to move it too many times if possible.
Once you get the coal going you can idle it way back and get plenty of heat. I suggest you get a CO detector if the house is tight and you use it in the living area. I stunk the house out a couple times form having the house so tight that the stove got choked out. First your head hurts from lack of O2.
My father in Law used to get coal delivered. He could do bags or loose.
Bags are easier but the cost is higher.  I liked the big stove coal the best but medium nut coal was also ok. That depends on your grate. Run the coal too hot and the cast grate will sag in time. I replaced mine once. It is good to have a spare one around. My grate failed in the middle of the winter and it took a week to get anew one.

Good info, Frank, Tnx.

Yes, the bags are easy to work with, though the initial loading and unloading makes the bin easier.  I'm thinking of what material I cud make the bin with. Pressure treated lumber or maybe there is a clever way to build a cheap concrete bin outside.  

I installed my two strategically placed blowers tonight. I have them both sucking warm air within a few inches of the ceiling and blowing it into the next rooms thru the walls. The shack now has a good breeze from the stove room. It was always cold in there cuz that room has a crawl space below. We'll see.

OK on the grate sag. I checked prices and they want $400 for the three grates this Harman requires. Hope the exisiting one lasts for a long time. The stove is so big compared to the old stove and is overkill for the room. I'm hoping to run in low most of the time.

Later -

T

Tom,
Check for air valves so you can idle it back. 25K to 30 KBTU should keep that place warm. You might consider going under the shack and adding insulation with foam over the bottom of the floor Joists. Go easy on the grate when you fire up the stove without ash on top of it. Mine is almost an inch thick and it still sagged. 4X4 posts lag bolted to 2X10s would make a nice bin with pressure treated.

OK, Frank - good info, tnx.

I did add fiberglass insulation years ago, but still is cold. I understand they cud blow in foam, but I wudn't be able to access the crawl space anymore for whatever, right?

Interesting on making an outside coal bin using 4X4 posts and 2X10 sides.   I might do that next year. I picked up 2/3's of the bagged coal today and think I'm set for the year. Got the stove and it's sitting in the garage here now. Want to build a brick pedestal for it. Have to do some reading on the web so I don't so a Three Stooges job.

I looked at the grate closely today and see an ever so slight sag in it. There's three in there and they cost $400 new total, so I'm gonna nurse these. Gonna add new door and glass gaskets and repaint it with high temp flat black. The paint is rated at 1200 degrees - I hope that's high enuff for the outside of a coal stove.  I'm taking the old wood stove to the metal yard as scrap. Maybe I can trade them for some aluminum sheet.


T

Tom you need to seal the cavity. We had the same problem at my Dad's place when we built a family room off the back of the house. We had to put plywood across the bottoms of the floor joists  to make the insulation effective. I would use 1 or 1 1/2 inch polyisocyanurate attached to the bottoms of the floor joists. It goes for about $14 for a 4X8 sheet at home chepo. I used it under all the sheetrock in the new place with an air gap between. Steve did the same thing at his place. I also used aluminum duct tape on the seams. I attached it with 3 inch deck screws with the aluminum discs you use to hold down tar paper. about .01 inch thick washer to help holding the foam up.. They are cheap and come in a nail sized box. The foam is light and easy to work with. 1 inch is R6.5 and 1 1/2 is R10.
Your grate runs the hottest when the coal first gets going since there is no ash between the fire and grate.

.

T

Instead of paint consider 'Stove Black'. Comes in various packaging and by various names. Does a good job of 'coloring' rust black and slowing down it's progress. Kinda like shoe polish for steel/cast iron stoves. Apply it every couple years where needed.

stove black works great. Kind of like VHT header paint
Rustolium makes a good product I have been spraying on the underside of my truck. It turns surface rust black. Home chepo sells it. I wouldn't use it on a hot surface though

Good suggestion, Jay. I wasn't keen on painting the stove anyway cuz of the potential problems of prepwork, break-in smell, etc.  This black stove polish looks perfect for the job. TrueValue Hardware has it:

http://www.idealtruevalue.com/servlet/the-41767/Detail

BTW, I have some brickwork the stove will sit on that needs some serious cleaning after 15 years of stove abuse.  What product or method should I use?  It's in the house over a wood floor, so sand blasting or soaking with a liquid might be a problem, unless it requires small amounts of liquid so not to drain thru the cracks. I thought some kind of acid was used with a stiff brush?

Opcom:  Thanks for the info on the various controllers. I'm still looking and deciding what to use.

T

Tom,
 LOL! Funny you should ask about this topic. I just got flamed by a couple or morons on another board regarding dimmers and inductive loads.  Suffice to say the other posters are correct here, it's not a recommended way to go.

I have often reduced/adjusted the speed of small fans and blowers with a series capacitor. They don't dissipate any significant energy and don't get the motor hot. Depending on the impedance and load of you motor you may have to try quite a few values. 300 to 600 volt, polys in the 1-2uF range, or less, usually do it the average 120 VAC muffin fan.

Thanks for the suggestion, Mark.

I will try clip leading in a few capacitor values and see if I can get the two fan speeds in the ballpark.  At full speed they are too noisy and blow too much air anyway.  Hopefully I can find lower settings that are good and will start up - and leave it alone. The variable controls will be my second choice, but will cost $50+ to do.


T

 " Nice old buzzard stove!  I'll bet that's a 90K BTU from the looks. It's almost looks bronze? "

The Gay uta-Andes apears to be cast iron. The construction has a 'firebox' base, front doors and vent and a top, all apear to be cast iron. The center, or cylinder part is sheet metal, probably steel, I donta know. Its thin compared to the casting..... The 'skirts' are removeable. They are chromed, along with the nameplate you see in the picture. The crome is showing some rust; thats the 'brass' look. The top thing is removabel, so you can put your coffee pot or frying pan on it. The thingie is just a ornament although it would help to radiate heat from the top..... 

gottra get the chimbeley sweep in to check the stack.....



klc

Oh BTW, be safe and install a CO detector down there.  Prevents the permanent nap....

73

Rich

I've played the game and puked till i bled.... just a little Code violation. Natural gas water heater vented into a unlined bric chimbley.... the brick dust, soot, bird crap buried the exhaust and nearly killed all of us. Funny how them little rules have a meaning.


klc

Be sure to post up how the series cap works.

hi Tom ... seems like the cheapie wall dimmers don't like highly inductive loads so the question becomes just how much resistive (acting) load do you put in series or parallel to tame the critters ...an experiment to try would be to put a 100 Watt incadescent lamp in parallel with the fan ... iffin I can find some time I will try ....be willing to bet ittl werk

******* ....the next day .... *******

did a quick test using a $5 rotary dial chinese dimmer .... instruction paper said incad or halogen NO motors, transformers, lids or space cadets ...40 w min load if you prease ... the resistive load is a 60 W incad bulb and I paralled 2 diff centrifugal fans and tested

fan #1 is small (approx 2 1/2 " impeller) shaded pole motor with nameplate draw of .17 Amp

fan #2 is medium size (approx 4 " impeller) shaded pole motor with nameplate draw of .37 Amp
(out of Henry 2K amp)

while running into the lamp dimmed somewhat I added the fan with clip leads and the dimmed lamp brilliance remained unchanged and either fan ran quietly at reduced speed ... connecting/unconnecting the fan did not change lamp indication ... ran this for 15 min ...dimmer box didn't even warm up any that I could tell

so I guess that it can work .... I suppose that an inductive power factor limit should be determined

Tom,

If you build an outside bin, be sure it is well covered and protected from snow/rain/ice. Back in the mid nineties, Baltimore suffered from power outages during one winter cold spell, because the giant mounds of coal for their municipal power generators froze solid. Granted it was sub zero weather.

When I was a kid, we would visit my grandparents in Queens, NY and they had a "basement" under their back porch that was actually an old coal bin, then no longer used. There was a loading chute opening outside and a small access door in the basement near the furnace, which had been replaced with a gas fired furnace. My brother an I pretended that the bin was a dungeon!

Coal bins were typically built in the basement for a lot of reasons:
Easy ramp style filling from the truck.
Close to the point of use, just across the basement.
Keeping the weather out of the coal, and keeping the operator out of the weather. Who wants to leave the house when it's -15 outside to shovel some coal into the bin? 

I ran a coal stove some years ago. Reliable and put out good heat. No problems with ash, but we burned anthracite, lump coal. Poor coal forms lots of ash and clinkers (lumps of nonburning material that can clog up the grates, black sand or some such I think that gets fuzed by the heat). A small shovel and an iron rod bent into a hook shape with abit of a point. Use the shovel to fill, and the rod to rake, bank, and break up clinkers if needed. That thing only when out once, and I was not really that reliable at filling it.  I'd usually put in a good bit before bed, bank it up and set the damper.  We didn't have a bin in that place, but would have a pile dumped in the drive and would load up a bunch of old 5-gallon pails.  Kept a pail in the room near the stove, the others could be kept anywhere with the lids on and stacked etc.  I'd have rather had a bin but it wasn't my house.

Yes an rod about 3 feet long bent into about 4 to 5 inch L is great for clearing grate. When you burn good coal you will never need it.
My first couple years I burned crap and used it every day.

OK the bin info, etc.  I guess most older stoves/furnaces were in the cellar, so a good idea to have the bin there too. In my case, the stove is on the main floor, above the celllar, so an outside bin would be the shortest trip and less gravity to fight.  Good point on the coal icing.

Well, I moved the old 400 pound stove outside and brought the new 550 pounder in and put it up on a 18" pedestal. Did it myself - with a good dolly and rolling engine hoist it was a piece of cake... ;D 

The stove itself has a blower that moves air thru the body. That, coupled with the two blowers pushing air to the adjoining rooms should be a great system. Can't wait to try it out this season.

I'll key an eye on the coal klinkers, Frank. I got the coal with the deal, so pot luck.

Think I'll make up an "L" rod like you guys suggested - thanks.

I might take a phoro of the installation once the bricks are cleaned up.

T

My coal bin was in the corner of the basement (my former QTH).  It was next to a cellar window that I could open and shovel the coal from my pickup right into the window.  In the basement, I had a opening about a foot wide going from the floor to the top of the bin with slots for several pieces of plywood with handles on 'em.  I had stops about 6" from the floor so the plywood pieces wouldn't go all the way to the floor.

When I needed coal I merely took a heavy duty plastic shovel with a square blade (slipped under the coal easy) and took some coal from the bin and put it into a special coal pail (hopper).  Then over to the stove and dumped it into the top and had another several hours of comfy heat.  Wish I had taken a pic of it  :( .  I still have the shovel and the pail. 

Oh yeah, back then we could buy bulk by weight

Al

It was a good heating system. Just a little less convenient than oil, unless you had a top of the line furnace with an auto-stoker system, which most average joes couldn't afford. I think it was the mess with the coal dust and the ashes, and the required work that made most folks go over to oil heat.

Anyone remember Blue Coal ads?

I remember fireplaces with coal  grates when I was a kid. I enjoyed watching and listening to the psychedelic blue flames that would blow out of a lump of coal as it heated up and outgassed.

And the iron poker used to punch the fire and let the ashes fall to the bottom. My first pyrotechnic experience, at pre-school age, was to stick the poker into the fire and pull it out once it got red-hot.  I never managed to set anything on fire or burn the house down.

I can still close my eyes, reminisce, and feel my face and shins scorch while my back side is freezing.

I think I found the goods for the job - these are 120VAC 2.5A  blower motor contollers for only $7 each on eBay. I ordered four and will test them out and report back.   The feedback on them is good in the ebay files.

T

http://cgi.ebay.com/Solid-State-AC-speed-Control-for-Blower-motors_W0QQitemZ140451274231QQcategoryZ71393QQcmdZViewItemQQ_trksidZp4340.m444QQ_trkparmsZalgo%3DCRX%26its%3DC%252BS%26itu%3DSI%252BUA%252BLM%252BLA%26otn%3D5%26ps%3D63%26clkid%3D5168298676862381365

vary the speed by changing the frequency.  Maybe a homebrewed amp with a fist full of FETS and a signal generator might do the trick???

Bob,
Fans will suck a lot of current at a lower frequency (Xl)

http://cgi.ebay.com/Solid-State-AC-speed-Control-for-Blower-motors_W0QQitemZ140451274231QQcategoryZ71393QQcmdZViewItemQQ_trksidZp4340.m444QQ_trkparmsZalgo%3DCRX%26its%3DC%252BS%26itu%3DSI%252BUA%252BLM%252BLA%26otn%3D5%26ps%3D63%26clkid%3D5168298676862381365

These work very well on both a blower or muffin fan.  They appear to perform much like a Variac.  One blower could be turned down very slow while the other had a minimum threshold and then slowed to a crawl.

All in all, for <$ 7 each, highly recommended as an alternative to a Variac. (Limited to 2.5A, 120AC)  I have them installed on all three related fan/blowers for the coal stove.


BTW, Jay, the stove black polish worked out FB. Looks like a new stove, tnx.

T

Fire the stove up before it gets cold. This way you can open the windows to let the smell out. Once the paint has been heated once you will be fine.