Renovating a century old house - main heating appliance - stove or zero clearance fireplace?

[alexno]

Hi folks,

First post here after hours of reading.

My SO and I are planning the complete overhaul of our century-old house located in the eastern townships in Quebec, Canada. I'm looking for advice as to what type of main heating appliance we should pick, and how many BTUs we should be looking at. We have plenty of acreage with a mix of hard and soft woods that will provide more wood than I need.

The House

The renovated house will have around 2100 sf of livable areas on the first and second floors, sitting on dirt crawl spaces (ranging from 4f to 6f high). The renovations include a complete re-insulation of the exterior walls and cathedral ceilings on the second floor, with as much spray foam as we can add to the existing structure (hopefully reaching r24-28 in the walls and more in the celling). We are also thinking about spraying the basement concrete walls and dirt to add insultation and prevent dampness. We will also have a small 17x17f garage, which I plan to have insulated as much as possible to maintain heat over the winter in there.

The renovated main floor will be mostly open floor, the living room being at the center. The upper floor is composed of 3 bedrooms accessed through the main staircase that runs up from the planned living room, and another separated bedroom that will be on top of the garage.

Current and planned heating

At the moment, the house is heated with a 30 year old 37k BTU drolet stove located in the center of the house close to the staircase. It gets the job done for the mild months, but is insufficient for a drafty old house in the middle of the windy -30 winter months. We dont live there full time so it was not a worry up to now, but we are planning to move into the renovated house and need to ensure we have proper heating.

We have 2 options in front of us: A) get a new (and more powerful) stove, or B) install a zero clearance high efficiency fireplace in same room.

My thinking right now is that the zero clearance unit with forced air could help us better manage the heat and shoot it both upstairs in the bigger/remote rooms (and the one on top the garage) and to the other side of the house through a duct in the basement (kitchen and dining room). A stove would likely get the first floor and most of the second floor hot enough, but I feel it would not be as good for the more remote areas without some form of force air movement. And the living room could get a bit overheated when we have to crank it up during the coldest months.

The Questions

0.1) Is it doable to heat such a house with only one fireplace/stove, or should I start thinking about adding another stove down in the basement where the higher ceiling allows it? The basement will have electric heating anyway, but it can get costly. The rest of the house will also have electric heat as a backup/supplement

1) What do you think re: zero clearance unit vs stove in such a situation? And what amount of BTUs should we strike for?

2) I'm analyzing the possibility of keeping the fireplace/stove where the current stove is (a bit more enteally located), but it'll not be as aestheticly pleasing as it will be siting between the living and dining rooms and my SO is not into this option at all. Would putting the unit 12f from where it is currently siting, still in the central living room but a bit less centrally located, affect the heating capacity a lot? I would basically be put next to the wall shared with the garage.

3) If I go the zero clearance route, could I go for a bigger unit and shoot a bit of heat in both the garage and basement while running ducts towards more remote areas of the house? I'm not sure I would have enough control over the various outputs, sending too much heat in the garage and basement vs in the rooms where I want it. Any thoughts are welcome.

I believe that's about it. Let me know if you any additional detail, and thanks in advance for your input!

Cheers
Alex

 

[begreen]

To start with, run some heat loss calculations. This will be an entirely different house when you are done. The old Drolet might work fine with all the changes. Having proper design calculations will be important with a modern ZC to be sure it doesn't uncomfortably overheat areas.

 

[EatenByLimestone]

Agree with BG. A properly spray foamed house will be tight. 30k is likely more than you'll need.. do a heat loss calculation. You are likely to have issues getting fresh air to the stove.

 

[EbS-P]

From a cost perspective I would guess a stove is significantly cheaper. And I would spend the savings on a mini split heatpump. Nothing big nothing fancy. It’s really quite nice to have the shoulder season covered by the heatpump and have AC for the really hot days. I like the ducting idea but it just seems more complicated for bedrooms maybe if it was a larger room or two . So I vote stove.

 

[peakbagger]

If you are gutting the interior walls, the best place to IMO is to add two staggered layers of 1/2" foil faced and taped Iso board foam on the interior walls and ceilings. Packing stud cavities full of foam feels good and cuts infiltration but heat transmission through the framing starts to really be an issue as the R value of wood is lot lower than foam. Take a shot with an IR camera and you can see the framing if its not capped with foam. This also really helps places like exterior window and door headers as well as at the top and bottom plates. This means you need to extend the window jambs of if replacing windows just buy them with custom depth jambs. Then budget money for double cellular blinds with side seals. With the deeper window cavities, they can be mounted flush with the interior wall. Rather than spending premium dollars on super energy efficient windows IMO, spend it on double cellular blinds as the net gain in R value is higher. They also really cut down on radiant loss on cold night.

Be real careful keeping the roof venting system functional. If you are foaming cathedral ceilings the temptation is to go with a "cold" roof where the insulation is sprayed directly to the exterior sheathing. This can work but if you do it it has to be done out to the soffits. The other odd thing that has been found is that cold roofs still need venting at the ridge pole despite the lack of an air gap with the sheathing. Various studies of cold roofs is still finding interior moisture migration up under the sheathing to the ridge pole. If there is no venting at the ridgepole the sheathing up near the ridgepole is showing evidence of rotting on buildings with cold roofs.

Definitely you need to run heat loss calculations for the new building. If you build it tight enough to heat with 35,000 BTUs you will need forced mechanical venting with outdoor air and that system starts to become a required source of heat as air to air heat exchangers are not that efficient so supplemental heating on outdoor air is required. Most systems use an electric resistance heater running 24/7 and that adds up.

A wood stove is a lot more effective heating device as it has far more radiant surface area (four sides and top) and possibly the interior portion of the stack . A zero clearance takes up less space but its not going to be effective with radiant heating as only the front face is going to be able to radiate heat. IMHO radiant heat is lot more effective source of day to day heat. Yes you will get convective heat from air flow through vents around a ZC fire box but odds are you are going to have to fan force it. My guess is when you run the heat loss calculations you will need a bigger stove for peak winter conditions and turn down could be an issue. I would suggest looking into a stove sized for peak winter and then use a minisplit unit (or two) to supply shoulder season heating. I live down in Northern NH and I do use the air conditioning mode on occasion so that si nice bonus. I realize power is cheap in Quebec but down in NH I have solar and net metering so my mini split use is "free". If I had a forced outdoor air system it would also supply an electric heater on the outdoor air supply.

 

[alexno]

Thanks everyone for the replies.

Re heat-loss test, we will be meeting with an inspector to run an energy evaluation of the house prior to the renovations under a governmental financial assistance program, and we will run a similar test after the renovations. I'm hoping it'll cover heat-loss as it contains a blower door test to evaluate airtightness. What I'm hearing from you guys is that I would have to do the test before finalizing my choice on the stove/ZC. I'll have to confirm with the inspector if this is doable (I assume so).

@peakbagger, I'll have a look at your suggestions re: insulation and window blinds + roof insulation. I'm in discussion with the potential builders to gather their views on what to do with the cathedral ceilings. What I heard so far is that we would be preserving a space in between the exterior sheathing and insulated ceiling to keep the roof well vented, but I'll also look into the cold roof options. I'll investigate further.

I do like the idea of putting up a minisplit heatpump as it would be easier to manage heat in milder months (like right now) but also provide AC in the peak of summer. I'll look more into that. Electricity is indeed pretty cheap up here so I don't mind using more of it - and a heatpump will be way more efficient than baseboards.

As for stove VS fireplace, I gather a stove is typically better suited as a main heating appliance. I thought a ZC with forced air could better distribute heat but I gather a centrally located radiant stove could do the trick for less money.

 

[begreen]

When getting quotes on mini-split system installs, have them provide you with the heat loss calculation.

 

[peakbagger]

FYI Cold Roofs, On the video I watched from respected source, they built trial roof sections as well as forensics. I think the summary was if at all possible avoid cold roofs but if someone insists put in ventilation along the ridgepole. The ventilation is just a open pad of a plastic material that is secured under a ridge cap with the roof membrane cut back from the ridgepole.

If you do a conventional roof with an air gap make sure the area of the walls and out to the soffits are open. The gap between the top of the wall and the roof is tough on existing structures as it usually is shallow. That is high heat loss area due to the upper wall plates so the temptation is to stuff in insulation in this space cutting off air flow. There are foam channels called soffit vents that can be placed in these areas or I have seen it down with some strapping (for spacing) and isoboard foam for the bottom of the channel. This assume you have well vented soffits. If the roofing is changed make sure at the minimum that ice and water shield is run from the edge of the roof to well above the outer wall below. Ideally, go all the wall up to the ridge pole and you will never have a roof leak or ice damming unless its physically damaged (os someone blew a flashing detail.

Keep in mind most energy audits are chasing infiltration losses through air leak from outdoors. That is what a blower door does. The audits rarely actually review conductive heat losses through walls and roofs. Its just not that easy to do and reliably replicate the results. Go by a house on very cold day and the conductive heat losses will be real evident with an IR camera.

The best investment around is if you have access to the house while being built is a caulking gun and case of caulking. Head to site when the crew is gone and caulk every seam. BTW, electricians and plumber both love to screw up air barriers and create new leaks. The detailing of receptacles and switches in exterior walls are critical yet most of the time the carefully sealed outer envelope is cut to put in a box, even if they seal the front face, the holes for the cables at the back of the box let in lot of air.

 

[alexno]

Here's our most recent homemade plan, for reference.

 

[alexno]

Thanks @peekbagger, re: roof, I'll bring this up to our chosen builder and make sure we do the right thing.

Re: heat loss testing, there's a good chance the insulation will be finished during the summer months next year so it'll be difficult to test it then. What we could do is wait for colder temps before adding the stove/fireplace. The chimney will have to be put in beforehand but I guess we can pick a safe bet 6 inches insulated chimney that will not limit our choice.

Nice tip re: caulking, I'll definitely give it a try + watch for the electrical and plumbing work to ensure we avoid creating air holes around the house.

 

[Smolder]

We heat an 1880s triple brick in Ottawa, Ontario — no insulation, about the same size, but with 11’ ceilings. We heat it with an Ashford 30 from Blaze King. We load it twice a day. The only insulation is 5” of foam on the attic ceiling (under the roof) and the stone basement walls are sprayed as well. We even leave the furnace fan on for half an hour every hour to move heat.

 

[EatenByLimestone]

View attachment 285229We heat an 1880s triple brick in Ottawa, Ontario — no insulation, about the same size, but with 11’ ceilings. We heat it with an Ashford 30 from Blaze King. We load it twice a day. The only insulation is 5” of foam on the attic ceiling (under the roof) and the stone basement walls are sprayed as well. We even leave the furnace fan on for half an hour every hour to move heat.

Is that a steel roof? Looks a bit new and shiny for slate.

 

[alexno]

View attachment 285229We heat an 1880s triple brick in Ottawa, Ontario — no insulation, about the same size, but with 11’ ceilings. We heat it with an Ashford 30 from Blaze King. We load it twice a day. The only insulation is 5” of foam on the attic ceiling (under the roof) and the stone basement walls are sprayed as well. We even leave the furnace fan on for half an hour every hour to move heat.

Thanks for the comparable! Gorgeous house mate! Our stone walls were cemented at some point so we have very thick foudation walls that I'm planning to have foamed as well to make the basement a bit more insulates and airtight.
Do you have dirt floors in the basement and if yes, how did you deal with that?

How do you move air around from the stove room to heat the rest of the house? We will definitely be unable to add ducts so this is also a concern for me in designing the new place.

re: the stove, I'm on the fence with the whole cat vs non cat conversation. I was thinking on going the non-cat route but reading about the long burns you can get out of a cat, I'm more puzzled than ever. Will have to do more homework!

anyhow, thanks for jumping in Smolder.

 

[Smolder]

Thanks for the comparable! Gorgeous house mate! Our stone walls were cemented at some point so we have very thick foudation walls that I'm planning to have foamed as well to make the basement a bit more insulates and airtight.
Do you have dirt floors in the basement and if yes, how did you deal with that?

How do you move air around from the stove room to heat the rest of the house? We will definitely be unable to add ducts so this is also a concern for me in designing the new place.

re: the stove, I'm on the fence with the whole cat vs non cat conversation. I was thinking on going the non-cat route but reading about the long burns you can get out of a cat, I'm more puzzled than ever. Will have to do more homework!

anyhow, thanks for jumping in Smolder.

There were dirt floors. They were dug down, clear gravel was laid down, with drainage pipes in it, a vapor barrier was laid and then it was cemented. Peers were also added before the slab was laid to support the center of the house. The drainage pipes all run to a sump pit. A dehumidifier occasionally turns on and keeps the air dry down there which keeps the old house smell out.

Heat more or less moves by itself, transoms are over all doors and like most old homes the doors are undercut an inch and a half, which works.

We do have central air, so I just have an ecobee running the fan now and then throughout the hour.

 

[Smolder]

Is that a steel roof? Looks a bit new and shiny for slate.

Yes, just had it done, that was around sunset so it made it glint much more than it actually does. The steel shingles have a ripply texture.

 

[EatenByLimestone]

Very cool! I love all the different slate options that exist now!

 

[alexno]

Hi folks, here's an update after almost a full year of planning and renos. And a new question

The renos are currently on-going with the sprayfoam being applied everywhere today. Looking at the plans above, we decided to shift things around and add an office/guest bedroom + dedicated entrance + restroom/laundry room where the garage is located. We will end with something close to a 2500 sf fully insulated house.

Following the earlier discussions on this thread, my SO and I decided to opt for a wood stove and not for a ZC unit, which will be located at in zone B in the plans above. I'm now faced with a decision: which stove to pick.

While the stove will be located in a central location/open portion of the house, I'm still uncertain about how the heat will flow in the house (the ceilings in the living room/dining room/kitchen are low (a tad more than 7'), and I'm trying to balance out the following 2 aspects for the woodstove: (a) I want to be able to heat as much of the house as possible with the stove especially when we hit the cold Quebec winter snaps of -35C, but (b) I don't want to toast the whole family while we watch a movie in the living room where the stove will be sitting. I understand I might be looking for a unicorn here...The previous 37k BTU Drolet (steel) was in fact toasting us to a crisp 28-30C when cranked up before the renos so I'm leaning a bit more towards cast iron/soapstone stoves at the moment.

One dealer came up with the Hearthstone Heritage and Hearthstone Green Mountain 60. Wondering what Hearth.com folks think about these - I'm not sure I want to go the CAT route as we may rent the house down the road in a couple of years so ease of use could be preferable, but.

Any suggestions of stoves/sizing in our circumstances? A friend of mine acquired a Pacific Energy stove last year and I think I may have an interest there (looking at the cast iron Alderlea T5), but also interested in seeing what you guys come up with.

Also worth noting, my SO has an interest in modern-looking stoves (e.g. PE Neo) but all I could find were steel versions of these, so I'm trying to push her towards cast-iron/traditional-looking stoves...not easy to balance all of this!

Thanks folks