M55 Pellet consumption impacted by pellet burning temperature?

[steveg_nh]

I have a question for all of you much smarter than me when it comes to pellet stoves (I'm very much still learning).

On my M55 insert, when really using it to heat up with 20-30 degree temps outside, I'm averaging about 2-2.5 bags per day in pellets. This is running the stove mostly on settings 3 and 4. This keeps the house around 70 degrees. I'm currently using 0 oil right now. The stove is able to carry the whole house, which is amazing to me. The stove has also been installed since mid October.

I was expecting pellet consumption around 1.5 bags/day, but not 2.5. Seems like I'm going to really go through pellets and my expected savings may not be as great as I thought over oil (still will be good though).

Anyway I happened to be talking to my dealer today, trying to get my hands on a set of service rails, and I mentioned this to her. She told me to try different pellets, and recommended a softwood pellet she has that burns very hot, specifically Okanagan Douglas Fir. She said the stove actually measures stove or burning temp and determines when to drop pellets based on temp in the pot. REALLY?

Is that really how it works? I thought it was just a set timed interval, say every 15 seconds or so, it drops a bunch of pellets. Higher heat setting means pellets drop more frequently and the blower runs higher.

Is she right? Does the temp at which one pellet burns vs another determine consumption rates? I'm burning "Maine's Choice 100% hardwood pellets" right now (made by Geneva Wood Products), as I have 1 ton of these, and then I have 3 tons of actual Geneva branded Super Premium 100% hardwood pellets. The Maine's Choice burn pretty clean and feel plenty hot to me.

So was she pulling my leg, or do I really not understand how this all works? Does a "hotter" pellet burn mean slower feeding on the stove? How does that work?

Thanks.

 

[nayslayer]

I believe if you are running in stove temp mode, there is a probe on exhaust that tells it whether to add more pellets or not. Not really temp in the pot, temp on the exhaust.

 

[Bob E]

My stove runs on timed intervals, but it is an older plain jane kind of stove. Better pellets will put out more heat for the same feed rate compared to a lesser pellet. I have some hardwood ProPellets that put out a solid 20 more at the outlet of the heat exchanger for the same feed rate compared to the Wayne Davis (WD) softwood pellets that I have. Which means I have to jump up an extra heat range or two in order to increase the feed rate and make the same amount of heat with the softwood pellets. Even though the WD's were about $0.50 cheaper per bag, they turning out to be more expensive because I have to burn them faster.
I think there is a lot of marketing involved in the hardwood vs softwood pellet debate. I think the quality of the finished pellet is going to be more important.

 

[corkman]

I believe if you are running in stove temp mode, there is a probe on exhaust that tells it whether to add more pellets or not. Not really temp in the pot, temp on the exhaust.

these are features exclusive to a Harman and would not apply to OP.he has an M55.it does sound like the dealer is under the impression he has a harman though based on the advice she gave him

 

[SmokeyTheBear]

I have a question for all of you much smarter than me when it comes to pellet stoves (I'm very much still learning).

On my M55 insert, when really using it to heat up with 20-30 degree temps outside, I'm averaging about 2-2.5 bags per day in pellets. This is running the stove mostly on settings 3 and 4. This keeps the house around 70 degrees. I'm currently using 0 oil right now. The stove is able to carry the whole house, which is amazing to me. The stove has also been installed since mid October.

I was expecting pellet consumption around 1.5 bags/day, but not 2.5. Seems like I'm going to really go through pellets and my expected savings may not be as great as I thought over oil (still will be good though).

Anyway I happened to be talking to my dealer today, trying to get my hands on a set of service rails, and I mentioned this to her. She told me to try different pellets, and recommended a softwood pellet she has that burns very hot, specifically Okanagan Douglas Fir. She said the stove actually measures stove or burning temp and determines when to drop pellets based on temp in the pot. REALLY?

Is that really how it works? I thought it was just a set timed interval, say every 15 seconds or so, it drops a bunch of pellets. Higher heat setting means pellets drop more frequently and the blower runs higher.

Is she right? Does the temp at which one pellet burns vs another determine consumption rates? I'm burning "Maine's Choice 100% hardwood pellets" right now (made by Geneva Wood Products), as I have 1 ton of these, and then I have 3 tons of actual Geneva branded Super Premium 100% hardwood pellets. The Maine's Choice burn pretty clean and feel plenty hot to me.

So was she pulling my leg, or do I really not understand how this all works? Does a "hotter" pellet burn mean slower feeding on the stove? How does that work?

Thanks.

Your stove works on a timed feed system that is set by the stoves heat range setting you told it to run at..

If your stove is on a thermostat it can run in a temperature controlled manner exactly like an oil, gas, or electric heating system because the thermostat turns it on and off or changes from pilot (low) to high (the heat range you set). That dealer was wrong.

 

[Skier76]

Can you try backing it down to 2? I noticed my GCI60 really slows down on the pellet consumptive n when I dial it back to 2. But it certainly decreases the heat output. I can un it on 2 overnight if it's around/slightly about freezing. With the temps now, it may be a bit too cool.

 

[JDenyer236]

The amount of pellets you burn really depends on the size of your house, how warm you want to keep the house, how well the house is insulated and how cold it is outside. For example I have a1400sqft house that I keep at 72 degrees. I go thru about 1 to 2 bags a day. My father in law's house is a three story 3000sqft home. They go thru 3 to 4 bags a day in the dead of winter. What size is your home and how well insulated is it? How much oil did you use during a typical winter before you had the pellet stove?

 

[AbbyCha]

Did you hook up your tstat yet? Pretty sure we're burning less with it installed. We're burning a bag or little over per day. 2200 sf.

 

[steveg_nh]

Thanks all. Great info...I told the dealer it was an M55, as I was looking for service rails, but maybe she thought it was a standard stove feature.

Our house is about 3,800 sq ft. But of that, two main areas are somewhat out of the main heating area. 700 sq ft over the garage (stays about 5 degrees cooler than the main house. And the master bedroom suite, about 300 sq ft. So about 2,800 sq ft is being heated to 70 degrees by the stove, and the garage room and MBR are around 65...To keep these temps, the stove is averaging 24 hr run time on setting 3. It's 23 degrees out right now here in southern NH, and the Tstat for the HVAC system on the wall shows 70.

House is about 18 years old, fairly tight and well built.

With the tstat, at least I'll be able to reduce output during the days we aren't home, and a bit at night too...

So maybe what I'm seeing isn't crazy, and consumption isn't really going to change with a hotter pellet.

What about lowering my feed rate trim? It's on the default of 3. Would reducing to 2 make a meaningful difference, or would the loss of flame size reduce heat output enough that I'd have to bump the stove to a higher heat setting?

 

[smwilliamson]

I have a question for all of you much smarter than me when it comes to pellet stoves (I'm very much still learning).

On my M55 insert, when really using it to heat up with 20-30 degree temps outside, I'm averaging about 2-2.5 bags per day in pellets. This is running the stove mostly on settings 3 and 4. This keeps the house around 70 degrees. I'm currently using 0 oil right now. The stove is able to carry the whole house, which is amazing to me. The stove has also been installed since mid October.

I was expecting pellet consumption around 1.5 bags/day, but not 2.5. Seems like I'm going to really go through pellets and my expected savings may not be as great as I thought over oil (still will be good though).

Anyway I happened to be talking to my dealer today, trying to get my hands on a set of service rails, and I mentioned this to her. She told me to try different pellets, and recommended a softwood pellet she has that burns very hot, specifically Okanagan Douglas Fir. She said the stove actually measures stove or burning temp and determines when to drop pellets based on temp in the pot. REALLY?

Is that really how it works? I thought it was just a set timed interval, say every 15 seconds or so, it drops a bunch of pellets. Higher heat setting means pellets drop more frequently and the blower runs higher.

Is she right? Does the temp at which one pellet burns vs another determine consumption rates? I'm burning "Maine's Choice 100% hardwood pellets" right now (made by Geneva Wood Products), as I have 1 ton of these, and then I have 3 tons of actual Geneva branded Super Premium 100% hardwood pellets. The Maine's Choice burn pretty clean and feel plenty hot to me.

So was she pulling my leg, or do I really not understand how this all works? Does a "hotter" pellet burn mean slower feeding on the stove? How does that work?

Thanks.

The stove has no idea how hot or cold it's running. There is no temp sensor anywhere on the stove. It uses limit switches to go from start up to run. If you run the stove on a thermostat you can measure the room temp and get the stove to modulate somewhat. That will help ya a little little bit but over the long term adds more savings.

All Harmans, the Enviro P3. Hearthstone, Rika, GBH pleasant hearth and most of your European models utilize thermistor probes to modulate burn time to ramp up and ramp down feed rates based upon pre programmed data points as they relate to sensors.

Rika/ Austraflamme (hearthstone too) is the only maker I know of that modulates based upon firebox data.

 

[smwilliamson]

At 2.5 bags a day in a house that big in NH you are going to go through about 6 ton a year which is roughly $1800 in pellet fuel. You live in an above average size home for NE. The average NE oil bill is $2460 annually and I would imagine your oil bill was at or near $3500-$4000 previously. So your looking again offset of about $1700, not too bad. 3.5 y ROI but I bet you thought you'd be paying off the insert quicker?

 

[RickNH]

I have a 2900 sq ft (26x36 base) house in S NH, colonial with 16 x 26 addition on the main level with a finished attic I have closed off right now. The insert is in the base house - not in the addition. the house is about 20 years old and well built. I have a t-stat connected and it is set to 65 at night and 71 day. with a 2- 2.5 degree swing. I run on Hi/Low setting #3. Right now I am using about 1 - 1.25 bags per day. Your pellet consumption sounds about right for your house and your setting. Our upstairs during these last few days has been reading 65 - 66 during the day and 63 - 65 during the night. I am burning cubex I got in Plaistow. I have had ZERO oil use this year (for house heat)! I just use the oil furnace now to heat the SW aquarium I have which is a "zone" on the oil, and have a GeoSpring hot water heater. I agree with the others that the stove does NOT adjust with the temperature ... it uses a t-stat for that.

Hope this helps.

 

[Skier76]

Rick,
Thanks for the t-stat info. Interesting that you're running one with a swing mode. I would think the high/low mode the stove has built in wouldn't require a swing since the stove won't cycle on and off.

 

[RickNH]

Rick,
Thanks for the t-stat info. Interesting that you're running one with a swing mode. I would think the high/low mode the stove has built in wouldn't require a swing since the stove won't cycle on and off.

Good point. I had it in swing mode for when it was in on/off mode when it was warmer out. I will take the swing off now since I am now running in Hi Low. Thanks for the reminder!

 

[steveg_nh]

At 2.5 bags a day in a house that big in NH you are going to go through about 6 ton a year which is roughly $1800 in pellet fuel. You live in an above average size home for NE. The average NE oil bill is $2460 annually and I would imagine your oil bill was at or near $3500-$4000 previously. So your looking again offset of about $1700, not too bad. 3.5 y ROI but I bet you thought you'd be paying off the insert quicker?

2013 I spent $4,000 in oil in total, including domestic hot water usage. In 2014, $4,700. I actually planned on a 3 year return so I'm not rushing it. Any savings to me is worth it. I just didn't plan on this level of consumption, so I only bought 4 tons.

As for the other comments about swing mode, why does it matter if you are running in Hi/Lo vs Auto/Off? My understanding is that it just allows a larger "swing" before it calls for the stove to heat up again...so it' snot always cycling. If you aren't using a swing, the stove will always be trying to maintain an exact temp, and constantly switching fro hi to lo, and back...Am I not understanding how it works?

And Rick, what is your house layout? My living room is where the stove is, and I have cathedral ceilings up to the second floor. We have a balcony that cuts the living room, meaning, the living room on the first floor is wide open to the second floor. This allows such great heat coverage to the second floor with only one 54" ceiling fan in the living room running in reverse, on medium speed. I am surprised you're only at 1-1.25 bags a day. And where in plaistow did you get Cubix?

 

[Skier76]

Good point. I had it in swing mode for when it was in on/off mode when it was warmer out. I will take the swing off now since I am now running in Hi Low. Thanks for the reminder!

Glad I could help! And now I know when I use the on/off mode for the t-stat..shoulder season. I hadn't thought of that before.

 

[RickNH]

2013 I spent $4,000 in oil in total, including domestic hot water usage. In 2014, $4,700. I actually planned on a 3 year return so I'm not rushing it. Any savings to me is worth it. I just didn't plan on this level of consumption, so I only bought 4 tons.

As for the other comments about swing mode, why does it matter if you are running in Hi/Lo vs Auto/Off? My understanding is that it just allows a larger "swing" before it calls for the stove to heat up again...so it' snot always cycling. If you aren't using a swing, the stove will always be trying to maintain an exact temp, and constantly switching fro hi to lo, and back...Am I not understanding how it works?

And Rick, what is your house layout? My living room is where the stove is, and I have cathedral ceilings up to the second floor. We have a balcony that cuts the living room, meaning, the living room on the first floor is wide open to the second floor. This allows such great heat coverage to the second floor with only one 54" ceiling fan in the living room running in reverse, on medium speed. I am surprised you're only at 1-1.25 bags a day. And where in plaistow did you get Cubix?

I have an open-concept first floor and stairs up to the second floor. kind-of a living room/kitchen "L-shape" - then a dining room off of the kitchen. I got the cubex at the Fireplace store on 125 however I just drove by the agway on 125 who had some.

I switched the swing mode to "less" so that the house will stay at a more constant temperature while in hi/lo mode.

Hope this helps!

 

[steveg_nh]

Got it thanks. I got my Genevas at Agway on 125. Maybe I should pick up more. Hmmm.

 

[chken]

I have a question for all of you much smarter than me when it comes to pellet stoves (I'm very much still learning).

On my M55 insert, when really using it to heat up with 20-30 degree temps outside, I'm averaging about 2-2.5 bags per day in pellets. This is running the stove mostly on settings 3 and 4. This keeps the house around 70 degrees. I'm currently using 0 oil right now. The stove is able to carry the whole house, which is amazing to me. The stove has also been installed since mid October.

I was expecting pellet consumption around 1.5 bags/day, but not 2.5. Seems like I'm going to really go through pellets and my expected savings may not be as great as I thought over oil (still will be good though).

Anyway I happened to be talking to my dealer today, trying to get my hands on a set of service rails, and I mentioned this to her. She told me to try different pellets, and recommended a softwood pellet she has that burns very hot, specifically Okanagan Douglas Fir. She said the stove actually measures stove or burning temp and determines when to drop pellets based on temp in the pot. REALLY?

Is that really how it works? I thought it was just a set timed interval, say every 15 seconds or so, it drops a bunch of pellets. Higher heat setting means pellets drop more frequently and the blower runs higher.

Is she right? Does the temp at which one pellet burns vs another determine consumption rates? I'm burning "Maine's Choice 100% hardwood pellets" right now (made by Geneva Wood Products), as I have 1 ton of these, and then I have 3 tons of actual Geneva branded Super Premium 100% hardwood pellets. The Maine's Choice burn pretty clean and feel plenty hot to me.

So was she pulling my leg, or do I really not understand how this all works? Does a "hotter" pellet burn mean slower feeding on the stove? How does that work?

Thanks.

2 to 2.5 bags a day is thermo equal to about 4.8 to 6 gallons of oil a day. For a 25 degree day, and a larger than avg sized home, that's not out of the ordinary. In fact, it sounds pretty good.

As for Okanagan DF pellets, they may have at best 10% more BTUs than the average pellet, but they cost a lot more than 10% more than your average pellet.

"2013 I spent $4,000 in oil in total, including domestic hot water usage. In 2014, $4,700. I actually planned on a 3 year return so I'm not rushing it. Any savings to me is worth it. I just didn't plan on this level of consumption, so I only bought 4 tons."

Assuming an average price of about $3.50 a gallon, you burned about 1150 gallons in 2013, a normal winter. Your oil use seems good for such a large home with DHW. The thermo equivalent to replace all of those 1150 gallons would be almost 10 tons of pellets However, since you are using an indirect DHW, which could easily be about 350 gallons, then perhaps your oil use for heat is only about 800 gallons. Replacing that would take about 6.5 tons. I don't think 4 tons is enough.

[edit]

So, you bought 4 tons, which might have cost anywhere from $800 to $1000, which is $3000 less than you spend on oil in a normal winter, and you expect a 3-yr breakeven? Did you spend $9000 on your stove?

 

[steveg_nh]

I actually made a mistake too in my statement on usage, but only the years. 2012 was $4,000, and 2013 was $4.700. YTD for 2014 is $4,000 and I expect another delivery in a week or two, and then December (although they'll find I've used very little oil!).

Actual gallons delivered were 1100 or so in 2012, and about 1350 in 2013. My hot water seems to use about 30-40 gallons a month, so your numbers are spot on!

My 4 tons cost me $1100. But I would need 2 more tons to get to replacement of all oil for the season, at least right? So say $1700 in pellets, vs $3250 in oil (assuming 1000 gallons for heat only as 2014 is looking like another 1300-1400 gallon oil year in total, taking out hot water use). So a savings of $1550 year I get to, assuming oil at $3.25/gallon. Over 3 years, that's $4650 in savings. I paid for the stove and install (forget about the rework I did on my hearth/fireplace to make it cosmetically how I wanted it), $4,700. Pretty darn close!

I think everything I said makes sense. Need to reread it.

 

[chken]

I actually made a mistake too in my statement on usage, but only the years. 2012 was $4,000, and 2013 was $4.700. YTD for 2014 is $4,000 and I expect another delivery in a week or two, and then December (although they'll find I've used very little oil!).

Actual gallons delivered were 1100 or so in 2012, and about 1350 in 2013. My hot water seems to use about 30-40 gallons a month, so your numbers are spot on!

My 4 tons cost me $1100. But I would need 2 more tons to get to replacement of all oil for the season, at least right? So say $1700 in pellets, vs $3250 in oil (assuming 1000 gallons for heat only as 2014 is looking like another 1300-1400 gallon oil year in total, taking out hot water use). So a savings of $1550 year I get to, assuming oil at $3.25/gallon. Over 3 years, that's $4650 in savings. I paid for the stove and install (forget about the rework I did on my hearth/fireplace to make it cosmetically how I wanted it), $4,700. Pretty darn close!

I think everything I said makes sense. Need to reread it.

I'm a little shocked that I seem to have made some pretty close guesstimates. You seem to be in good shape. 6 tons is a good starting point if you have the space to keep it. More can be kept for the following season and less can be filled by picking up 15 to 20 bags at a time at the end of the season.

So, back to your original question about your pellet usage, DF pellets may give you 10% more BTUs than your Genevas, but they cost a lot more than 10% more, unless you can get Blazers, which are DF from Oregon. Some HDs in Maine have had Blazers for $239 a ton.

After a season, you can compare your pellet use against your historical oil use to see if they match up, but you probably underestimated your needs if you thought 4 tons would be enough, as it seems 6 tons minimum is more like it.

 

[steveg_nh]

I based my 4 ton estimate on the literature of the stove and the store, targeting about 1.5 bags per day, vs 2.5.

 

[steveg_nh]

And just because I'm this much of a data geek, I've kept track of my oil usage since 2010. Here's my average daily usage by month.

 

[SmokeyTheBear]

Damn, no degree day information then or now at your location, but if you are firing it manually your usage will not match what it was when on the oil eater.

 

[steveg_nh]

Firing what manually, the pellet stove? So far, my oil burner hasn't kicked on once for hear this year, only hot water. All thermostats for the boiler are set to 55.