Need help deciding to buy a Charmaster or another add-on wood furnace (forced air)

[ChrisDIY]

Hello All!

I am new to this forum and I was referred from another forum I use. My wife and I purchased a foreclosure in 2005. This home is on a wooded parcel approximately 15 acres and home size now is a little less than 4,000 sq. feet. The house currently has no fireplace or anything wood burning. We have been looking at various types and have narrowed it down to possibly a Charmaster wood furnace. The home was built in two phases. The north original home is 1-1/2 story with a new 2.5 ton heat pump, using a new Rinnai hydronic air-handler. The second add-on part of the house (south) is larger and is a two story design and has the existing 3 ton heat pump with resistive heat and has no return plenum, only closet it is in. Not sure if this even acceptable and of course the temps are uneven (another subject unless this should be corrected). The two parts of the house are connected by a short 6 foot hallway on both the first and second floors. The home from what I am being told had a corn cob stove in the basement and I am planning on using this hole in the rim joist to enlarge for chimney. After talking to the people at Charmaster a few times they insist that their unit can supply heat to both units.

What I need help with initially is where to find "slip-in" backdraft dampers that will protect the existing hydronic coil and evaporator coils? The unit with the hydronic coil sits about at the 20% mark in the main trunk line so I am thinking I will need two dampers one on each side of the vertical plenum. There is a Wye immediately in the plenum above the cased coil which would keep a vertical air flow style damper from working. The second unit which only has a 12 x 16 supply plenum would require a vertical air flow dampers since all the remaining ducts are within the second floor joist space, and I was trying not to remove any walls/ceilings, or disassemble the plenums/ducts unless absolutely necessary.

Installation will also call for a split of the supply from the Charmaster. What is a good source for planning the duct sizing and design? The supply would need to branch one to the south and one to the north. The north would then need to split and go around the plenum of the hydronic air-handler. AS far as return the hydronic air-handler has a return plenum, not optimal, with ducts located central to that portion of the house at about 9 feet from the floor. However there is no ceiling above until you reach the ceiling for second floor attic type area (pitched ceilings, 4' side walls). These return ducts are about 10-15 feet from main entry foyer which has a two story ceiling. So I would only be able to provide return air from one side of the house but passively more.

Hopefully, I haven’t started off with a whammy!

Please let me know what additional details I need to give. I do have a photo blog to reference if it doesn't violate forum.

Thanks!

Chris

 

[ChrisDIY]

North unit is in the basement. South unit is on the first floor in foyer closet. Return grille is in the floor above and connects to ceiling of closet. South portion of house is on a crawl space.

Is there an easier way?

 

[ChrisDIY]

The house project can be viewed here: ChrisDIY vs. the Ranch

See posts: #2, #41, #51, #124, and #243

Thanks!

 

[lampmfg]

Do some research on the Kuuma VaporFire furnace line at www.lamppakuuma.com.

This is the #1 Forced Air Wood Furnace in the world!!
Independently tested by Intertek:

.45 Gr/Hr. Emmission
99.4% Combustion Efficiency
99% Smokeless Burns
84% Overall Efficiency


https://www.hearth.com/econtent/index.php/forums/viewthread/28964/

 

[ChrisDIY]

Thanks for the reply. Our home has two heat pump furnaces. The maximum cfm of the VaporFire 100 is only 1,500 cfm. Is that going to be enough to distribute air to all this home's vents? Also, the supply and return plenums for the side of the house with the basement are situated in a manner which would allow installation of the wood furnace immediately below as in your instructions, however this will cause us to have to install a chimney with a 10-15 feet horizontal run to the nearest outside wall. Can this be done, especially without a chimney blower?

Most units we have looked at we were considering placing around the recommended clearances of 10"-12" from the outside basement wall and have the chimney exit through the hole used for the previous owners corn stove. I am sure modification of this hole will be needed. You can see photos in the link I provided above. In this location additional duct/plenum length will be added to the existing, how can I calculate the minimum required cfm for house? Current furnaces are around 1,200 each.

 

[ChrisDIY]

Post #42 picture shows location of return grill for portion of the house that has unit in the basement.

 

[laynes69]

Your setup sounds confusing. Two completely seperate zones, 2 heat pumps? I think tryin to do it with a single forced air woodfurnace will be difficult? I would look into a gasification boiler where separate zones and heat exchangers can be plumbed. This will allow control via thermostats to a precise temperature in the home. It may cost more, but it sounds like you have already tackled some large projects. Also adding storage will allow for fewer fires in between.

 

[ChrisDIY]

Thanks Laynes69

If you look at the photos on my blog you can see what I am trying to overcome. The house was built in two phases, as a result two units. I don't know the PO's situation but it seems the add on was an afterthought. All things being perfect both units would be side by side in the basement with proper duct work. Oh, well...

When we moved in, the north portion had an AC condenser unit running as a heat pump, with resistance heat. Changed it to a brand new Goodman heat pump with Rinnai hydronic coil. So adding boiler won't work.

Just looking at all these trees, my electric and propane bill...

 

[laynes69]

I don't have much time to read the whole blog there, but skimmed through it. I would get a heat loss calculation done on the home to see where it stands. As far as furnaces are concerned, the Max Caddy made by PSG is the largest clean burning furnace on the market. We have the little brother the Caddy and it's a well built furnace. If I have it right, there are 2 sets of ductwork correct? If so it will make things difficult. Maybe incorporating a couple stoves in the design of the home may be a better option. Just a few things to think about. No doubt you can heat with wood, it's just deciding the way to go. What's important is cutting and splitting now, you will need to get ahead so you have seasoned wood.

 

[ChrisDIY]

Charmaster suggested using un-split logs. That was one of my reasons for trying to get this worked out on feasibility. I found Manual J software online and was going to complete it this week. I do know the first phase part of the house is size correctly. The add-on is in need of a correct calc.

It would be awesome to heat all winter with wood, but partly would be great and I think it's worth a try. Two wood furnaces are out of budget. The second half of the house has only a crawlspace so both units would still be in the same basement.

 

[laynes69]

Not two furnaces, but a couple wood stoves. If both units are close to each other, then a single woodfurnace may work. Rounds take longer to season than splits. I would guess they recommend rounds because it extends the burn times. Our old furnace almost needed rounds to burn overnight, which the new I prefer splits.

 

[mikefrommaine]

Thanks Laynes69


When we moved in, the north portion had an AC condenser unit running as a heat pump, with resistance heat. Changed it to a brand new Goodman heat pump with Rinnai hydronic coil. So adding boiler won't work.

Just looking at all these trees, my electric and propane bill...

I'm not clear why a boiler feeding hydronic coils wouldn't work. What is feeding the rinnai coil, a hot water tank? Maybe you could use a heat exchanger to heat the water tank.

A boiler seems like an easier way to go to me.

 

[ChrisDIY]

Thanks Laynes69


When we moved in, the north portion had an AC condenser unit running as a heat pump, with resistance heat. Changed it to a brand new Goodman heat pump with Rinnai hydronic coil. So adding boiler won't work.

Just looking at all these trees, my electric and propane bill...

I'm not clear why a boiler feeding hydronic coils wouldn't work. What is feeding the rinnai coil, a hot water tank? Maybe you could use a heat exchanger to heat the water tank.

A boiler seems like an easier way to go to me.

Hydronic coil is being fed by our Rinnai tankless water heater. We already put in a new unit with this form of back-up heat BEFORE we learned about the wood furnace/boiler. Not enough research...

Our first choice was a soapstone wood stove/bakeoven in the kitchen but it needed a support structure that would cost as much as the stove itself. So we started looking into other ideas. The idea of wood central heat is enticing, and I only learned about it in the last month.

This unit only weighs 2,600 lbs. and may not require a support structure but won't heat too far beyond the kitchen and eat in dining area. The other realization about getting heat to the other side of the house is the requirement to cut a rather large hole in both rim joists.

Heating the whole house with wood is fading...

 

[ChrisDIY]

OK, moving to another plan. I was wondering can this be done, sketch isn't to scale but just for reference. The one problem we have to overcome is the lack of a proper return vent on the second HVAC unit. Picture here: HVAC unit is in the closet in the picture on the right. You can see return vents in floor and wall in the lower right corner of the picture. What I want to do is create a column from the floor (closet ceiling) to the second story ceiling and enclose a return plenum AND the wood stove chimney. Can I place the return plenum duct above the wood stove location? Goal will be to build this entire structure out of non-combustible materials. If we proceed with this I will probably include two PVC pipes the terminate in attic and capped off for a "new variable speed" type furnace just in case. Since the furnace pipe is PVC does this have to be "walled" off inside the column? I'd assume PVC can melt? Is there a non-combustible replacement?