US Stove 1537G Problems

[Snowdooer]

I have a US Stove 1537G wood furnace (119,000 Btu/hr) that is rated for heating up to 2500 Sq ft. My home is 1900 sq feet and I can't keep it heated. Most people I talk to tell me it should be cooking me out of the house. I've been on the phone with US Stove several times and they are out of suggestions for me. Here's the quick and dirty on what I have and what I have done:

The wood furnace is a parallel installation with a propane furnace. It is phyically located about 20 feet from the propane furnace, but has about 30 ft of trunk line between them. All the main trunk line in the house is 16x8 rectangular. All the return duct is 20x8 retangular. I have 60 ft of supply trunk duct running the length of my house with the individual rooms running off of them. The wood furnace has (2) 550 cfm blowers. I have attached a picture of the installation. (I changed the 8" round duct out for 16x8 retangular duct since the picture was taken.)

The furnace itself seem to be operating ok in that I can acheive a good fire with 350-450 chimney temperature and a solid draft. Although I am getting short burn times, I think that may be a result of my wood being too dry. Regardless of that, I cannot seem to get a very good plenum temperature. My limit control is set to start the blowers at 175F and shut them down at 95F. Once the blowers kick on the plenum temperature almost immediately drops down to 130F and then slowers continues to drop until it settles in around 115F. It'll stay there until the fire dies down and I need to reload wood.

I have tried adjusting the under fire air and the over fire air in differant combinations, but I can't seem to keep a higher plenum temperature. If I really let the fire rip I can get about 140F in the plenum, but the wood burns so fast I'd have to relaod the furnace every couple hours to keep it there. I've installed a chimney damper as well to help keep heat in the furnace longer. That has helped some, but even with it almost shut I can't seem to get enough heat out of the furnace.

Has anyone else seen this problem? Any suggestions? Your help is greatly appreciated.

 

[smokinj]

what kind of wood you burning

 

[Snowdooer]

Cherry and Maple. Seasoned for about 2 years.

 

[smokinj]

The install looks great i have my shut down temp set at 105 iam heating 2600 sq ft with soft maple. Hows your air flow at the vents?

 

[Snowdooer]

I get decent flow out of the vents close to the furnace and almost no flow out of the runs at the far end of the trunk.

 

[smokinj]

I get decent flow out of the vents close to the furnace and almost no flow out of the runs at the far end of the trunk.

Do you have it wire up to kick your other furance fans on at the same time as your wood furance?

 

[Snowdooer]

No I do not.

 

[smokinj]

No I do not.

ok there the problem you can do it manually at the theromstat just kick the fans on there and see what you got! then you can go from that point!

 

[Snowdooer]

I can't really do that. My wood furnace is feeding the supply duct in the opposite direction that the propane furnace is supplying it, so the two blowers will be competing against each other and I think the propane blower will win resulting in almost no flow through the wood furnace. (or am I missing something)

 

[M1sterM]

No I do not.

ok there the problem you can do it manually at the theromstat just kick the fans on there and see what you got! then you can go from that point!

x2

 

[smokinj]

I can't really do that. My wood furnace is feeding the supply duct in the opposite direction that the propane furnace is supplying it, so the two blowers will be competing against each other and I think the propane blower will win resulting in almost no flow through the wood furnace. (or am I missing something)

ok the problem is 1100 cfm is not enogh to move your heat that far so is there any way of getting the two air flow going the same?

 

[Snowdooer]

Not without major duct work changes. I was debating trying to install duct booster fans in the supply trunk to get the flow up. But even with boosting the flow I'll still have the problem of only having 115F in the plenum. I am working on producing a schematic of my installation so you can see how the two furnaces inter-relate. Hopefully that'll shed some more light on it as well.

 

[M1sterM]

I can't really do that. My wood furnace is feeding the supply duct in the opposite direction that the propane furnace is supplying it, so the two blowers will be competing against each other and I think the propane blower will win resulting in almost no flow through the wood furnace. (or am I missing something)

hmmm....so you have the wood furnace at the other end of the trunk from your propane furnace? That's no good.

They're designed to run the air into the plenum on top of the existing furnace (your propane furnace). If you're really desperate to improve matters, I'd suggest running insulated ducts from the wood furnace (but not insulated within a few feet of the wood furnace) all the way to the plenum on your propane furnace. (or move the wood furnace...).

 

[smokinj]

Not without major duct work changes. I was debating trying to install duct booster fans in the supply trunk to get the flow up. But even with boosting the flow I'll still have the problem of only having 115F in the plenum. I am working on producing a schematic of my installation so you can see how the two furnaces inter-relate. Hopefully that'll shed some more light on it as well.

Your running more like a stand a lone furance thats the way i run mine if you go back to the 2 8in ducts here is what i did http://cgi.ebay.com/8-Can-Fan-INLINE-DUCT-EXHAUST-FAN-BLOWER-HYDROPONICS_W0QQitemZ200279844457QQcmdZViewItemQQptZBI_HVAC?hash=item200279844457&_trksid=p3286.c0.m14&_trkparms=72:1205|66:2|65:12|39:1|240:1318 they are good up to 170 but will give you the cfm to heat the whole house with no problems!

 

[Snowdooer]

I hear what your saying and thought about running all new duct work, but I've already got $500 invested in this duct work project and I'm running out of cash. I can't move the wood stove unless I want a chimney running through the middle of my house, so that option is out too.

 

[Snowdooer]

I can't seem to get the schematic to load properly.

 

[Snowdooer]

Let's try this.

 

[M1sterM]

Not without major duct work changes. I was debating trying to install duct booster fans in the supply trunk to get the flow up. But even with boosting the flow I'll still have the problem of only having 115F in the plenum. I am working on producing a schematic of my installation so you can see how the two furnaces inter-relate. Hopefully that'll shed some more light on it as well.

Actually, if you put booster fans in, you'll probably get temps even lower that 115F (by pulling the air faster throught the furnace). The idea of tying in to the blower on your propane furnace is it uses additional air to move the heat at the desired speed/volume. Even if the air is onyl 90F at that point (due to mixing with the extra air the propane furnace blows), but it's moving at good speed out all the registers, you will heat the house up. Think about it...say you're moving 2500 CFM at 85-90F, and figure out how much your house holds (a 2,000 sq ft house may average about 20,000 cubic feet if it has 10 foot ceilings), you're heating all the air up in your house to 85F every ten minutes or so...

I don't think the problem is the 115F degree air, but the inability to move it effectively through your trunk. You could try closing the registers nearest the wood furnace, and see if the air moves a little further down the trunk. Also, make absolutley sure there are no leaks...get out the tape and sealant.

 

[M1sterM]

Not without major duct work changes. I was debating trying to install duct booster fans in the supply trunk to get the flow up. But even with boosting the flow I'll still have the problem of only having 115F in the plenum. I am working on producing a schematic of my installation so you can see how the two furnaces inter-relate. Hopefully that'll shed some more light on it as well.

Actually, if you put booster fans in, you'll probably get temps even lower that 115F (by pulling the air faster throught the furnace). The idea of tying in to the blower on your propane furnace is it uses additional air to move the heat at the desired speed/volume. Even if the air is onyl 90F at that point (due to mixing with the extra air the propane furnace blows), but it's moving at good speed out all the registers, you will heat the house up. Think about it...say you're moving 2500 CFM at 85-90F, and figure out how much your house holds (a 2,000 sq ft house may average about 20,000 cubic feet if it has 10 foot ceilings), you're heating all the air up in your house to 85F every ten minutes or so...

I don't think the problem is the 115F degree air, but the inability to move it effectively through your trunk. You could try closing the registers nearest the wood furnace, and see if the air moves a little further down the trunk. Also, make absolutley sure there are no leaks...get out the tape and sealant.

Have to clarify...I'm not saying the booster fans are necssarily a bad idea, but don't be suprised if it lowers the air temp (not a problem following my discussion of what the propane furnace does). Some people find them a bit noisy, but may be worth the try (and assuming you find/fix any leaks in the trunks).

On the flip side, moving more "cold" air around your firebox could make it a bit harder to keep the burn temps up (e.g. it may lower efficiency just a bit). I think there's been discussion of this effect in some of the threads about upgrading blower motors on add-on furnaces.

 

[smokinj]

no the problems is with the cfms and iam not talking about busters you need super buster back before you hit the main truck ( this buster will do 747 cfms use two and your home free that would be a total of 2594 cfms counting the 1100 on the furance

 

[Snowdooer]

Not without major duct work changes. I was debating trying to install duct booster fans in the supply trunk to get the flow up. But even with boosting the flow I'll still have the problem of only having 115F in the plenum. I am working on producing a schematic of my installation so you can see how the two furnaces inter-relate. Hopefully that'll shed some more light on it as well.

Actually, if you put booster fans in, you'll probably get temps even lower that 115F (by pulling the air faster throught the furnace). The idea of tying in to the blower on your propane furnace is it uses additional air to move the heat at the desired speed/volume. Even if the air is onyl 90F at that point (due to mixing with the extra air the propane furnace blows), but it's moving at good speed out all the registers, you will heat the house up. Think about it...say you're moving 2500 CFM at 85-90F, and figure out how much your house holds (a 2,000 sq ft house may average about 20,000 cubic feet if it has 10 foot ceilings), you're heating all the air up in your house to 85F every ten minutes or so...

I don't think the problem is the 115F degree air, but the inability to move it effectively through your trunk. You could try closing the registers nearest the wood furnace, and see if the air moves a little further down the trunk. Also, make absolutley sure there are no leaks...get out the tape and sealant.

Hmmmm. I understand what your saying. I'm just trying to think of a way I might be able to try it out without spending a few hundred on duct work.

 

[Snowdooer]

no the problems is with the cfms and iam not talking about busters you need super buster back before you hit the main truck ( this buster will do 747 cfms use two and your home free that would be a total of 2594 cfms counting the 1100 on the furance

This would certainly be a quicker and easier experiment to perform. Where would I get a booster fan of this capacity? The only ones I've seen so far have been rated at around 500 cfm for an 8" duct. I was going to buy (2) 8" round boosters and install them side by side in my supply plenum as a test before I started posting here, but thought I'd ask some questions first.

 

[smokinj]

Not without major duct work changes. I was debating trying to install duct booster fans in the supply trunk to get the flow up. But even with boosting the flow I'll still have the problem of only having 115F in the plenum. I am working on producing a schematic of my installation so you can see how the two furnaces inter-relate. Hopefully that'll shed some more light on it as well.

Actually, if you put booster fans in, you'll probably get temps even lower that 115F (by pulling the air faster throught the furnace). The idea of tying in to the blower on your propane furnace is it uses additional air to move the heat at the desired speed/volume. Even if the air is onyl 90F at that point (due to mixing with the extra air the propane furnace blows), but it's moving at good speed out all the registers, you will heat the house up. Think about it...say you're moving 2500 CFM at 85-90F, and figure out how much your house holds (a 2,000 sq ft house may average about 20,000 cubic feet if it has 10 foot ceilings), you're heating all the air up in your house to 85F every ten minutes or so...

I don't think the problem is the 115F degree air, but the inability to move it effectively through your trunk. You could try closing the registers nearest the wood furnace, and see if the air moves a little further down the trunk. Also, make absolutley sure there are no leaks...get out the tape and sealant.

Hmmmm. I understand what your saying. I'm just trying to think of a way I might be able to try it out without spending a few hundred on duct work.

I wish i had better news but with 1900 sqft you got to move more air or cut 1/2 the house off!http://cgi.ebay.com/8-Vortex-Centrifugal-Inline-Exhaust-Fan-Duct-Blower_W0QQitemZ150303656877QQcmdZViewItemQQptZHand_Tools_Gear_Equipment?hash=item150303656877&_trksid=p3286.c0.m14&_trkparms=72:1205|66:2|65:12|39:1|240:1318 This is the ones iam using gave you the wrong one before

 

[TomB]

A couple of simple suggestions about the ductwork, first, insulate the 8 inch round supplies. 8" round pipe insulation is avaliable at the sheet metal supplier. 8" insulating sleeves that slide over the pipe. You are losing a great deal of your heat in the first 10 feet of your run. Basically, your heating the furnace room. Second, where the 8" round connect to your warm air duct, replace the 8" starting collars with a take off boot that set up for the 8" inlet but give you 9" outlet, take your 90 degree elbow and adjust it so the air moves on about a 30 to 45 degree angle in to the (what we call a "scotty" take off) starting boot. The boot look just like a adjustable 90 but have a large outlet with the folding tabs. Seal the connections.

You need to make the air flow down the ductwork, not collide with inside of the duct. Right now the air flows down the 8" in to the elbows at the trunk line and is hit the top of the duct at a 90 degree angle, make the air flow gradual. The blower with work better. Also check the return air, make sure you are actually getting air returning to the system.

This a just a suggestion. I hope is may help. Be safe and well

Tom

 

[Snowdooer]

Thanks Tom,

I did verify flow through the return duct. I have already replaced the 8" round duct in the picture with 16x8 rectangular duct to get better flow. BUT, it does still enter the main duct at a 90 deg angle. I can try and build some sort of scoop to get the flow going in the correct direction out of the supply trunk. Maybe some turning vanes in the final elbow ?