Two inserts...one under performing

[jdp1152]

Haven't ever had to rely solely on wood for heat. As of right now, I'm almost completely off oil and on GSHPs. The two story portion of my house is running on the GSHPs and the single story portion is still on oil for now. Well, the oil ran out two days ago, so I figured I'd just cut off all heat since the GSHPs have too much surge for the electric generator. Figure I need to know what my capacity is in the event of power outage, which are somewhat frequent in my town.

What I've noticed is that the single story, which has historically been pretty easy to keep at 68-72 degrees with the Alterra even at single digit temps, can't get above 64. Nothing new with fuel source per se. Only feeding it kiln dried. The two story is warm...very warm. The main room with the insert is large and at 79. Connecting rooms are at 71 and coolest room upstairs is 68. That's burning less than ideal wood with a few small chunks of untreated lumber on reload

I can partition between the two inserts and it has no impact. Note, the partition is not air tight nor insulated. The only other variable is the oil boiler is in the basement below the Alterra...I've measured the temp in the room it's in before it wasn't running (54) and after it was offline (51). Actually, the bulk of the heating copper is below the two story. (50) Those temps are likely pretty accurate since my heat pump water heater beeps if it gets below 50 in that room. There are also roxul acoustical panels under the floor in the mechanical room so I'm not sure it was contributing much. Well, I think they're roxul panels, but I inherited them with home purchase in 2011.

I'm pleased at the performance of the main living space insert (hybrid fyre), but a bit surprised that the Alterra isn't giving what it once gave. Thoughts on this are appreciated. I know there are folks on here running multiple stoves/inserts and was curious to hear thoughts on the matter. Only thing I can think of is the Alterra is good at maintaining temps, but not so good at raising the temps of a cool home. The temp was 51 when I discovered the oil had run out. Got up to 63 in about two hours. Two days of 24/7 running should be enough I would think if it was capable.

 

[begreen]

It takes a lot of heat to raise the mass of the room up in temp once it's cooled down. The Alterra 1250 is not a large insert and it's flush. From the description it sounds like it needs help. Is there a block-off plate at the damper in this fireplace? If not, that could help. It's hard to do a test like this objectively because there are so many variables. Outside conditions (temp, humidity and wind) and wood are the biggest ones. I also suspect that maybe the GSHP has been assisting the Alterra.

 

[velvetfoot]

Are there fans for the inserts involved?

 

[jdp1152]

Yeah...I work in science so I've been trying to put together a test to determine the right cause. There is no block off plate for the most part. There was a heatilator box in the masonry that was cut open to 7 inches to allow the flex liner through. Insulation is on top of that and at the top of the chimney, so it's not a worst case scenario. Interior chimney....weather is warmer than has been (23 presently) when the Alterra warmed much better. 64 isn't bad, but given my basement temps and the room temp without heat, I'm trying to gauge if it's even worth putting fuel in during at outage. Ambiance is a different story. 64 is certainly more tolerable than 50s. It'd be nice to know what kinda room I had to deal with if that heatilator plenum was gone. My brother would be interested in the Alterra and I could put something else in with more heating capacity. The Alterra was chosen solely based on the heatilator box size. Kinda in a pinch at this point as I've started a remodeling project on that fireplace. Unexpected results to the first firewood heat experiment.

 

[jdp1152]

Are there fans for the inserts involved?

Yes. Both have blowers. My crossover switch covers both circuits so running on the generator isn't an issue.

 

[velvetfoot]

My insert is bigger than the Alterra and it's in an 8 year old Heatilator a36r, I believe.
Again, are you running fans for both baseline and test?
I know that inserts really benefit from fans.

edit: oops, see it now. But, still, I love the additional size of my new insert.

 

[velvetfoot]

Maybe the fan is clogged with cat hair (that would be for me).

 

[jdp1152]

It takes a lot of heat to raise the mass of the room up in temp once it's cooled down. The Alterra 1250 is not a large insert and it's flush. From the description it sounds like it needs help. Is there a block-off plate at the damper in this fireplace? If not, that could help. It's hard to do a test like this objectively because there are so many variables. Outside conditions (temp, humidity and wind) and wood are the biggest ones. I also suspect that maybe the GSHP has been assisting the Alterra.

Yeah. I think you're right about the thermal mass. No block off plate. Just a small opening through an old heatilator box with insulation on top. The plenum is filled with insulation. A bit warmer today (69) despite being more windy. Sun is assisting in getting the temp up. 64-70 would be ok in an emergency situation, particularly since the other insert does a fine job of heating the most frequented living space areas. Probably be able to get that up more with planned insulation upgrades in the next year.

 

[begreen]

Insulation upgrades sound like a good plan. Also, check for air leaks. Caulking is inexpensive and can be very effective.

 

[jdp1152]

Insulation upgrades sound like a good plan. Also, check for air leaks. Caulking is inexpensive and can be very effective.

You're preaching to the choir here. Progressively remodeling and addressing areas of concern. Seeing the floors/walls/ceilings through a thermal camera was very helpful in prioritizing the work. Need to work on better air sealing in the attic, but that's probably going to be a spring project. Just need the rest of the GSHP duct work put in and I can address the basement sill. Kinda put the cart before the horse with the install this year, but the state couldn't guarantee me the no interest heat loan would be available in 2013 (as would have it, it still is)

I think I'm going to put some diesel in the oil tank this evening to keep that side warm. Save my wood for when there is an actual power outage....though I might bring that side up to temp, cut it off, and see if the Alterra can maintain it.

 

[Grisu]

Do you have a stove/IR thermometer to check whether the insert gets up to temp? If it is running sufficiently high for at least an hour or two then yes, it may be undersized for the room which means a larger stove and/or more insulation is needed. If the temp, however, stays low I would check the wood again, burning habits, chimney draft etc.

 

[TradEddie]

Just a small opening through an old heatilator box with insulation on top. The plenum is filled with insulation.

Heatilator could be describing a wide range of designs and brands, but mine were a very effective "freeze-i-lator" when the insert wasn't running. I stuffed the chambers full of fiberglass and blocked the vents, yet that part of the exterior wall is still the coldest.

TE

 

[pdxdave]

With two stoves now you may be bringing in more outside air than before, and the pathway for the air may be on the 1st floor thus cauing it to run cooler. Same heat output from the stove, but more cool air for it to heat up.