Hot Blast - Larger Blower Unit

[CCS621]

Greetings,
I have a 1300 series Hot Blast wood furnace that I have had for 20 years. We recently had to put an addition on the house and I was thinking about putting a larger blower unit on it to move more air thru the duct-work. Anyone have any experience with this type of modification? Thanks.

 

[matt701]

I had this blower hooked up on mine for about a year before switching to to a series install with the main furnace. The bigger blower really helped moved the air, even on low speed. I had a switch on it for on/off and low/high. I still have it if interested
matt

 

[CCS621]

Thanks Matt, but I already have one that was given to me. I was asking if any one here had used a larger one like yours and if it performed any better than the smaller factory provided blower that came with the furnace. Just looking for input before I modify the heater box. thanks, Rob.

 

[Moddoo]

My furnace also has a large blower unit like the one pictured.
It's a 1/3 hp maybe 12" diameter. Low and high are nice to have also.
It works much better than the stock double toy fans that came with it.

 

[CCS621]

Thanks, than it should work much better than the single factory blower that my older unit has.

 

[matt701]

It will definately work better than the original blower that you were using. Mine had 2 original blowers on the back and the bigger one pushed a lot more air, even on low speed. The little ones don't do well with any kind of resistance from the ductwork you hook it to.

 

[MNtrees]

Hi, I would like to see how it hook up with two switches. can you send the info?

Thx,
Patrick

 

[bohawg1]

yes

im interested in this thread myself as i do have the hotblast with the two litttle blowers. I do also have a larger blower like you have and you would swith over to hit if no options for series? Let me know , you get air out of the floor vents but not alot of forced air.

 

[matt701]

The blower would have to be a 2 speed blower to have the switch on it. If you have more than 2 (3 with a ground) wires going to the blower, you would hook power to the different wires for different fan speeds. If you have a one speed blower, you might be able to install a rheostat, kinda like a dimmer switch to adjust the speed you want the blower to run. I couldnt fit the blower in the back, so I put 2 steel plates over those holes. If you take out the little blowers, you can see in enough to see where there's a good spot to put another hole for the bigger blower. If I remember right, there's about 13 inches of open space all the way around the bottom of the hotlast, so you could put the new blower by the bottom on either side. i used a drill and saber saw, but tin shears works a lot better. Hope this helps.

 

[CCS621]

Well I installed the larger blower last night and what a difference. Purchased a On-Off-On toggle switch from Home Depot and hooked up the low speed and high speed motor windings. I had to enlarge the blower hole on the furnace from 9-1/2" wide x 5" high to 13-1/4" wide x 8-1/2" high. Even with the furnace on low burn and the fan on high it kept the house at 76 degrees (30 degrees outside). That is the warmest its been since we enlarged the house to 3000 sqft. Keeping in mind that this furnace is only rated to keep a 1300 sqft house warm I am very happy that we didn't't buy a larger furnace. Another plus is the new blower runs quieter than the stock unit. Wish I did this a couple years ago!

 

[matt701]

Thats great news! I don't know why the hotblasts don't just come with larger blowers in them. With more airflow, I'll bet you'll burn the same or less wood heating a larger space now. Do you have pics?

 

[CCS621]

<a href="http://s232.photobucket.com/albums/ee95/ZZRRob/?action=view&current=WoodFurnace002.jpg" target="_blank"><img src="http://i232.photobucket.com/albums/ee95/ZZRRob/WoodFurnace002.jpg" border="0" alt="Photobucket"></a>

<a href="http://s232.photobucket.com/albums/ee95/ZZRRob/?action=view&current=WoodFurnace004.jpg" target="_blank"><img src="http://i232.photobucket.com/albums/ee95/ZZRRob/WoodFurnace004.jpg" border="0" alt="Photobucket"></a>

 

[matt701]

Good looking install! Are you finding that even on low speed, it will blow more air than the little blowers it came with? Do you have it hooked to the limit switch?

 

[MNtrees]

Good looking install! Are you finding that even on low speed, it will blow more air than the little blowers it came with? Do you have it hooked to the limit switch?

Same question with Matt, picture showed the wire plug to outlet, not hook up to fan/limit control box. Do you have to turn it on manually?

 

[laynes69]

Wire the blower into the limit on the back of the furnace. That way it will only run when you have warm air. You will notice alot better airflow also if you can tie that blower into the cold air return. Looks good. Forgot to add, I added a 3rd 8" duct inbetween the 2 to help with more heat flow. Its amazing how much more heat can be pulled from the units. If I were you, I would close the door damper, and remove the rear plug from the furnace. Let that air help with secondary combustion at the baffle. I then control my heat output with the ashpan damper, not the door. Alot cleaner burn, way more heat.

 

[MNtrees]

Wire the blower into the limit on the back of the furnace. That way it will only run when you have warm air. You will notice alot better airflow also if you can tie that blower into the cold air return. Looks good. Forgot to add, I added a 3rd 8" duct inbetween the 2 to help with more heat flow. Its amazing how much more heat can be pulled from the units. If I were you, I would close the door damper, and remove the rear plug from the furnace. Let that air help with secondary combustion at the baffle. I then control my heat output with the ashpan damper, not the door. Alot cleaner burn, way more heat.

Thanks for the tips!

 

[CCS621]

Thought about the return air but didn't want to invest in duct work for this 20 year old unit and then possibly not be able to use it on a new large unit. I have an open stairwell with a half door that provides plenty of return air (sort of a central return). I blocked off the door damper long ago because just like the limiter heat switch it became inaccurate after years of cycling on & off. The spring steel looses its temper and stops working as designed. Replaced them before and only got 1-2 years out of new one. As for the use of the limiter switch, once the temp stays below 50 this unit is on all the time, thus no need for it to turn of. In my opinion it is engineered in reverse. I don't want my furnace (in the basement) telling me when it is going to turn on and turn off, that should be decided by a thermostat or myself which is in the living area. If and when I get a new larger unit I plan on installing a control for fan speed in the living area coupled with a thermostat and ducted return air.

laynes69-Great idea about the 3rd vent in between the original 2. I might try that, how do you regulate the air thru the rear plug where you would normally put an air injector? Or is it even neccessary? Thanks, Rob.

 

[laynes69]

I don't. I do have the rear draft inducer, but I don't use it. Our unit is 20 years old. I rebuilt mine last year. I understand your ideas about how it should work with the blower, but it cannot go into idle and burn cleanly. Thats where gasification boilers have the advantage. I know when the blower starts to kick off its about time for more wood. Think of it as an alarm, that way it doesn't go out. You talk about investing ductwork around a 20 year unit, I did. I reducted my whole home, with supplys and returns around the woodfurnace. I use my LP furnaces blower only, which has 2 leads on the r and g of the circuit board. By me running series, I eliminated the need to have dampers in the system. We have a 2400 sf home, w/10 foot ceilings. Its about 150 years old, but pretty tight. When its 20 out, I can have it 80 in the whole house within minutes. Our never goes out during the winter, 24/7.
The draft inducer makes people think that you can keep a house at a set temp with a furnace. Yeah right, those woodfurnaces need to dump the heat from the unit, or they will overheat quickly. I would think hard about the return. You can always use the ducting for a new furnace, just replacing a few pieces down the road.

 

[matt701]

If you're happy with it and it's heating your house fine, I can see not investing more money. Let it keep saving you money and save that money until you get a new furnace if you ever need one. I wouldn't have changed mine into series if it worked well the other way. On the topic of savings though, you would save some money only running the blower when the furnace was hot enough instead of all the time, but that could be negated by the more frequent start up draw. Now that mine is heating the whole house nicely, I'm not spending any more on it. I already bought a ton of 8" ducting, an extra blower, limit switches, you name it. I think my wife's happy I'm done messing with ours as I always seem to get blood everywhere working with ductwork haha. Happy Thanksgiving.

 

[CowboyAndy]

Another thing to check is to see if you can adjust the pulley if it is a belt drive. Mine has an expandable pulley (for lack of a better term) that you can open up to make the diameter smaller reducing the speed of the blower.