Forced air furnace advice

[Matt78]

Hi all,
Was needing some advice. Has anyone ever heated their basement with a wood furnace to suplament propane furnace? I have the drolet tundra and was planning on hooking in with propane furnace ducts. But currently the ducts are duct board and flex pipe. It's to expensive right now for us to replace with metal ducting. I've had three diffrent hvac people here and all three said it would be ok to tie into duct board. Drolet says otherwise. So I was thinking could I set furnace up to just blow the hot air into the basement? Not looking to eliminate propane all together as of right now. Then as we save some pennies have the furnace tied into new duct work? Our home is a ranch style home about 1800 sq ft with the basement being same size.would enough hot air come upstairs to help with propane use. Any advice would be helpful. Thanks

 

[begreen]

Welcome! I am not following in the manual where this is prohibited. Where did you get the information that says it can't be used with your ductwork?

 

[maple1]

Not sure here what ductboard is.

Is it the material of the ducting they don't like, or the configuration of it? (size etc.)

I think there are certain types of ducting material that aren't supposed to be used with a wood furnace. (Plus I don't think flex is really highly recommended period). I have almost no experience with FHA ducting though.

 

[Matt78]

I contacted SBI. They said it needs to be a minimum 30 gauge ducting. Duct board is ducting made out of insulation wrapped in some kind of metal tape.

 

[moey]

You could add a large return nearby.

 

[maple1]

I think I would stick with what Drolet said about the duct board, over the HVAC guys. If trouble arises later, it usually comes back to following manufacturers instructions.

You would likely save some just dumping heat to the basement, but how much would depend on the house layout & how much of that heat would make it's way upstairs. Some using stoves in the basment have good results, others don't. Then again if your basement is the same size as the rest of the house, and its not insulated really good, you might save quite a bit. Any way you can run a short trunk of good duct through the floor above? Until you can re-do your ductwork?

 

[Matt78]

Well, the propane furnaces return will be next to wood furnace. It has a return run to mud room above. I was thinking I could unhook it. Then it could suck warm air from basement room. Would this be legit?

 

[DoubleB]

Any way you can run a short trunk of good duct through the floor above?

I'd look into this above. And if you are particularly fortunate, you might currently have enough first-floor registers such that you could easily disconnect one or two from propane and reconnect them to the Tundra with metal ductwork (which might not be sufficient alone, but a good start).

FWIW, I added a whole new, very simple but large enough duct system just for my Tundra because my existing metal ductwork was too close to combustibles. I used three 6x12 registers into the floor of my first level, each register supplied by 8" round metal duct. In hindsight I've measured duct pressure with one of the registers closed, and turns out I could have done just fine with installing only two of the registers.

The 2nd floor is about 10 deg cooler than the first floor in winter, which is fine with us for sleeping up there. I've tried running the LP furnace fan to circulate air through the house and even out the temperature, but all that does is make a cool 68 degree breeze coming out of the registers, and the breeze feels cooler than any heat circulation it accomplishes. Therefore, I don't know if you'll get much mileage out of this:

Then it could suck warm air from basement room. Would this be legit?

I bet you'd have to have the basement unbearably hot before that helps much.

But that's just based on my house.

 

[mustash29]

I have the Englander 28-3500 furnace. For the last 2 winters I have used it with two 4" muffin fans blowing through the air jacket and dumping the heat into my walk out basement / rec room area. This area averages 80+ but there is a fan that sucks out of the rec room and blows into the master bath through a short 6 foot duct. The bedroom stays 68-70. The air leaving the bedroom rolls down the hallway into the open foyer and living room which stays about 75 ish.

If it's below 10 or windy, we keep the oil set for backup, otherwise the Englander cooks us. We are heating an 1800 sqft split level, built in '96 with r-30 attic & r-19 walls.

Here's my thread with a bunch of pics:

https://www.hearth.com/talk/threads/englander-28-3500-furnace-install-mods.102100/

 

[brenndatomu]

I've had three diffrent hvac people here and all three said it would be ok to tie into duct board. Drolet says otherwise.

As others have said, if you have a fire, the insurance co will go by the manufacturers recommendations

So I was thinking could I set furnace up to just blow the hot air into the basement?

People are usually disappointed with the results of doing this unless you have an insulated/finished basement...and even then results can be spotty

Any advice would be helpful.

How 'bout some pics and/or drawings of your setup. Maybe we can get you pointed in the right direction to DIY this using premade duct parts from the local hardware or home store, much cheaper that way. Duct work is actually pretty simple once you see hows it's done

 

[begreen]

One option to satisfy Drolet would be do redo the plenum in metal. Transition to the ductboard after the Tundra tie in. You will want to install a backdraft damper anyway so this could kill two birds with one stone.

 

[Matt78]

Thanks for all the info guys. I'm currently on vacation in North Carolina. When I get back I'll try to post some pictures.

Begreen, the plenum is metal. They say all ducts and connections need to be 30 gauge. I really don't want to do anything to compermise the house. So I'm going to respect drolets advice.

 

[begreen]

That seems to be quite arbitrary and not correct. 30 ga is very light and thin metal. Most plenums are 24 ga with some of the lighter stuff at 26 ga. Cheap round pipe can be 28 or 26ga. 30 ga is tin foil.

 

[brenndatomu]

They say all ducts and connections need to be 30 gauge

I was gonna say, I believe all the manuals I have ever read for any wood furnaces call for all metal ducts at least on the supply side anyways.
Of all the cheap crap you can buy in the big box/home supply stores now, I don't think I have ever seen any duct metal thinner than 28 ga, and I thought that was thin, man, 30 really must be tinfoil!

I'm currently on vacation in North Carolina

Enjoy! Looks like it's gonna be a hot/humid week in Ohio this week...

 

[Matt78]

Hi all, sorry been a while. Finally getting going on the furnace install. I have a contractor helping me with some of the work. As a side job for him. He suggested running the chimney through the wood wall above concrete foundation but below the upstairs floor. This would require moving some electrical wiring. And I would need 2" to combustibles. Then need to fill that 2" with something that's not combustible. He suggested a fire retardant caulk. Or I could go through the concrete foundation. Where's I wouldn't need to move electrical wires or maintain the 2". But would be harder to do. I could add some pictures if I could figure out how to do it from my I pad. As always any info would be appreciated. Thanks

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[begreen]

If you want to run an exterior class A chimney with 2" clearances you need a wall thimble kit from the pipe mfg. That will include the spacer, flashing and trim. Here's an example for DuraTech:



Will the outside tee that this pipe runs into be high enough off the ground to allow removing the cleanout cap from the base of the tee and a brush to run up the pipe?

 

[Matt78]

 

[Matt78]

The wood you see there isn't high enough for thimble. Maybe going through the concrete is the best option. The air return will be moved. Will there be problem with the electric conduit about 12 inches from chimney? There should be enough for a clean out. May have to get it from top. There will be a chase around chimney. Thanks

 

[begreen]

It should be ok with double-wall stove pipe. Single wall connector pipe will need to be 18" from any and all combustibles including the plastic conduit. Double-wall reduces ceiling clearance to 9" and wall clearance to 6".

 

[brenndatomu]

View attachment 161025 View attachment 161026

You don't wan't to cut the rim joist. Go through the block wall, it's not that hard to do. I've done it with a long 1/4" masonry bit, hammer drill, and a 4" angle grinder with a diamond blade.
Find center, drill clear through the wall with the drill (gotta be level/straight). Draw a circle inside and out 1" bigger than a clay thimble or heavy steel pipe (well casing) that is big enough to pass the class A pipe through. Drill holes every 1" or so all around the circle inside and out. Carefully use a hammer to break out the pieces. Use the angle grinder to clean it all up. You can mortar the new thimble right into the wall then.
If the cleanout tee is below ground outside, I've seen people dig down enough to get a pan/etc. in under the tee to catch soot, then install a large enough window well to get said pan in n out, clean from the top.

 

[STIHLY DAN]

Or rent a dry core drill.

 

[brenndatomu]

Or rent a dry core drill.

Oh sure, take the easy way out...

 

[Matt78]

I should be able to get the tools at work and get started on it this week. Should of started last week when it was cooler. Lol. Oh well. I'll work through it.

Where would I get clay wall thimble? Lowes? You would mortar clay thimble in wall and mortar the class a pipe into thimble? Why not just mortar class a pipe into concrete wall?

 

[begreen]

The class A pipe can pass directly through the cement wall. Then mortar it in place. No need for a clay thimble though you may want to add an outside flashing as a storm collar if that is the weather side of the house.

 

[brenndatomu]

Where would I get clay wall thimble?

Anyplace around you that sells brick/block/concrete

Why not just mortar class a pipe into concrete wall?

You can...a thimble just leaves you options in the future. I like to leave myself options...