Furnace install questions

[tjcole50]

Im so back and forth its rediculous. Was very close to placing an order on an owb. Then i went back to the drolet heatmax idea. Put together some duraplus pipe and 30 degree elbows with a through wall kit total im at 2900 which is over 50% cheaper than an owb setup. I also like the idea that i dont have to worry about a boiler system if i leave for extended periods. Anyway anyone have a guide on how to get an lp furnace fan and an add on wood furnace to play nice? I would like it setup so that if the wood furnace dies out the propane can compensate and take over. Would puttinf the 2-8" air ducts higher into my plenum allow for that? If that makes sense? Also how do you get your main tstat to control the drolet furnace? Thanks

Edit forgot to add i do not currently have a cold air return. The existing lp furnace pulls off of the basement. Was like that when i moved in. Does this cause any problems with a drolet or psg caddy install?

 

[brenndatomu]

Im so back and forth its rediculous

Boy you can say that again!

2900 which is over 50% cheaper than an owb setup

I'd say a lot cheaper than 50%...I think it would be hard to do a OWB for less than 10Gs all in.

Anyway anyone have a guide on how to get an lp furnace fan and an add on wood furnace to play nice?

Only one at a time runs normally.

You will need to put anti-backdraft dampers on the LP furnace and then the Tundra too so that neither one back feeds the other. They can be manual, auto, electric, or spring operated. Manual only works if you are gonna be there to do the switch over between fuels.

I would like it setup so that if the wood furnace dies out the propane can compensate and take over.

Also how do you get your main tstat to control the drolet furnace?

The Drolet will need its own tstat. The LP tsat is just set a few degrees lower than the Drolet 'stat so that the LP will kick on when the wood runs out.
But really, if the wood 'stat is calling for heat too often then you are loosing efficiency and burn time. Ideally, over time you will learn the furnace and can control the house temp mainly by the type of wood and size of the wood load more than the tstat does. If you read the "Everything Tundra/HeatMax" thread you will see that some guys (including me this coming season) will install a temp controller in conjunction with the tstat, that takes efficiency to the next level...when the 'stat is calling for heat, the controller is keeping the furnace right in its "sweet spot" and when the 'stat is not calling for heat, well, then you are just cruising along on a nice secondary burn (or coals)

 

[brenndatomu]

Put together some duraplus pipe and 30 degree elbows with a through wall kit total im at 2900

Oh, and I would bet if you catch a Tundra on sale...and some Supervent pipe on sale...(Menards has killer sale prices on both (big heating sale here in about 3 weeks or so...typically) you could shave another $5-800 off your total install price

 

[tjcole50]

Nice! Supervent the same as duraplus stuff? I was shocked at a 30 degree elbow kit that duraplus had... i think it was 5xx$ for 2x 30 elbows seems steep. I have a good size over hang to get around

 

[brenndatomu]

Supervent the same as duraplus stuff

No, I think DP is triple wall...SV is your typical stainless class A pipe. I always have heard that class A double wall insulated pipe is the preferred pipe for wood burners

 

[tjcole50]

I have no cold air return how does an add on wood furnace perform without one?

 

[Wisneaky]

duratech and duraplus HTC is double wall. Duraplus is triple wall. All made by duravent. It's good stuff. I have the duraliner chimney liner made by them. Supervent is made by a different brand.

 

[brenndatomu]

I have no cold air return how does an add on wood furnace perform without one?

Well, if your existing furnace is set up to work like that you may get away with it but it is definitely not ideal and could cause trouble.
The issue is negative pressure. If the blower is pulling a negative pressure on the basement, it can affect your draft, which worst case scenario can make for a furnace that just doesn't burn right and could even give you smoke in the house, especially on reloads.
Now, depending on your floor plan it may not be an issue. If you have a very open floor plan, like say most split level houses do, it likely won't be an issue. But if all the air has to return through a bunch of doorways, could be trouble...wouldn't want someone closing a door when you are burning.
If you tried this and had a borderline situation then something as simple as adding some height to the chimney, or only burning when it is under XX degrees outside, or even just cutting some return air vents in could be the cure. But there is a small risk proper return air ducts would be the only solution...but I kinda doubt it would come to that.
My sister has a Tundra that is not hooked to return air ducts, it works fine but they do have pretty open floor plan ranch...and there is no door on the basement stairway

 

[DoubleB]

Anyway anyone have a guide on how to get an lp furnace fan and an add on wood furnace to play nice?

What @brenndatomu said, and see section 7.5.2 here for a generic schematic:
http://www.drolet.ca/upload/documents/manuels/45690A_10-06-2015.pdf

If you really want to make sure there is no conflict between the wood and LP furnaces, consider going with section 7.5.1, in which the Drolet ductwork is separate from the LP ductwork. At least that's why I added separate ducts for my Tundra. A bit more work, but not much, especially since I didn't have to mess with fitting in backdraft dampers. Based on my experience and depending upon your house, you could probably get by with a couple larger (6x12) supply floor registers, another couple return registers, and large enough and short ductwork.

 

[DoubleB]

a couple larger (6x12) supply floor registers, another couple return registers, and large enough and short ductwork.

And actually, it might be even simpler if you do have unrestricted air passage back to your basement such that you wouldn't even need the return registers. Two new big supply registers might be all you need to get in business separate from the LP furnace.

 

[brenndatomu]

If you really want to make sure there is no conflict between the wood and LP furnaces, consider going with section 7.5.1, in which the Drolet ductwork is separate from the LP ductwork

That's true, that is exactly what I did at my sisters place...separate supply ducts for the wood and the oil. There was no way I was gonna meet required clearances with their existing oil furnace supply ducts. Which brings up another issue, make sure you can meet the clearance requirements listed in the Tundra manual...which most fossil fuel furnace supply ducts don't

 

[JRHAWK9]

Anyway anyone have a guide on how to get an lp furnace fan and an add on wood furnace to play nice? I would like it setup so that if the wood furnace dies out the propane can compensate and take over.

-HERE'S- how I have mine set up to accomplish exactly what you want to do. It works GREAT. Both the Kuuma and LP fans can run at the same time if need be. Keep in mind they DO NOT share the same cold air though, only share the warm air supply. My Kuuma does not have a cold air attached to it, I have an open staircase in the middle of the house which acts as my cold air. I don't see much more than a 4° temperature differential between the basement, first floor and loft, so it seems I have good internal circulation.

 

[tjcole50]

I have an A-frame house living,dinign, and kitchen is all one big open space up to the loft. Stair case to the basement is dead center of the house. I cant run seperete ducts to 2 big ones. The poibt if this is ti have hest hitting the ducts like lp does (wife) required deal here. She likes the owb but likes the $ savings of a furnace.

 

[JRHAWK9]

I have an A-frame house living,dinign, and kitchen is all one big open space up to the loft. Stair case to the basement is dead center of the house. I cant run seperete ducts to 2 big ones. The poibt if this is ti have hest hitting the ducts like lp does (wife) required deal here. She likes the owb but likes the $ savings of a furnace.

sounds just like our place. We also have an A frame/log cabin type of home.

 

[tjcole50]

Wish ours was a cabin but its close. All 10 "cedar overlapped planks.the loft is huge because we dont have a typical a frame ours is pitched out instead of the roof line going to ground level. Im going to wall that waster loft off and turn it into our bedroom eventually.

 

[3fordasho]

I simply ran 2-8" ducts from the tundra to the plenum on the LP forced air furnace. As high in the plenum as possible to allow hot air movement in case of power failure.
Cold air for the tundra simply pulls from the furnace room. The LP has it's own return air ducting. The only backdraft damper I seem to need is for running a/c in the summer and for now I replace the filter in the tundra with a block off plate. As far as hot air from the tundra pushing into the cold air returns on the LP furnace - not been an issue because the hot air would have to travel down through the LP furnace and through the LP furnace filter - does not seem to want to do that naturally.

Thermostat wise the LP furnace has its thermostat, the tundra a separate one. The goal is to keep the LP furnace off so its thermostat is set a few degrees lower than the wood thermostat. On the occasion that they both would run (rarely) it worked fine in my case as the LP furnace blower is set on low for heat and does not reverse the flow thru the tundra. So in my case LP furnace takes over just fine with no additional wiring or anything else other than the LP thermostat being set a bit lower.

So the furnace mode possibilities are:

Heating -Tundra blower only - most heated air is making it to desired hot air ducting- if some is bleeding into the return air ducting of the LP furnace - it's not much and I can't perceive any detectable flow.

Heating -Tundra and LP blower running - Max heat mode - all heated air is directed to hot air ducts - in my case the LP blower does not overcome the tundra blower and cause reverse flow through the tundra

Heating -LP blower only - some hot air is reverse flowing out the filter box on the tundra. Since the goal is to keep the LP off this should be a rare occurrence but will happen when away for longer than normal - in my case the loss is into conditioned space anyway so doesn't matter.

Cooling - LP blower on high - this does cause significant cooled air coming out the filter box on the Tundra. Since the furnace room is already pretty cool (heat pump water heater in same room) I install a block off plate in place of the Tundra's filter for the cooling season.

Now with all that said - I would be concerned about both furnaces pulling return air from the furnace room - reversing the draft on the wood furnace is the possible issue. I also installed a non-closeable vent into the furnace room (in the door actually) to make sure the Tundra can't get its return air closed off from the rest of the house.

Anyway anyone have a guide on how to get an lp furnace fan and an add on wood furnace to play nice? I would like it setup so that if the wood furnace dies out the propane can compensate and take over. Would puttinf the 2-8" air ducts higher into my plenum allow for that? If that makes sense? Also how do you get your main tstat to control the drolet furnace? Thanks

Edit forgot to add i do not currently have a cold air return. The existing lp furnace pulls off of the basement. Was like that when i moved in. Does this cause any problems with a drolet or psg caddy install?

 

[Wisneaky]

-HERE'S- how I have mine set up to accomplish exactly what you want to do. It works GREAT. Both the Kuuma and LP fans can run at the same time if need be. Keep in mind they DO NOT share the same cold air though, only share the warm air supply. My Kuuma does not have a cold air attached to it, I have an open staircase in the middle of the house which acts as my cold air. I don't see much more than a 4° temperature differential between the basement, first floor and loft, so it seems I have good internal circulation.

I really like how you have yours setup. I would like to do the same to mine, but I don't understand how to wire it. What exactly would I need to do this? Can you pm me? Thank you

 

[DoubleB]

Which brings up another issue, make sure you can meet the clearance requirements listed in the Tundra manual...which most fossil fuel furnace supply ducts don't

Yes. Another prime reason I added new ductwork for the wood furnace. When I decided to have the fire inside my house instead of an OWB, I decided I would meet all manufacturer's requirements and ensure the insurance company was happy and would cover me if heaven forbid I had a housefire. If your existing LP furnace ductwork meets Drolet's requirements, you are more lucky than I am.

The poibt if this is ti have hest hitting the ducts like lp does (wife) required deal here.

I can imagine the wife's requirements may trump even the manufacturer and insurance company's requirements. Hopefully you can get a solution that all 3 can live with. For me, my wife finds the heat from the 2 Tundra registers to feel plenty warm. (Technically I have a 3rd register too but it is further away and doesn't do much, I often have it shut). Admittedly, the upstairs is a bit cooler than she prefers, but it's nice sleeping weather and we don't have a loft like you for better heat distribution.