How Are You Running Your Pellet Boiler, Now That It's Cold Out?

[velvetfoot]

I'm not using the wood insert to see how the pellet boiler works. Quite an eye opener. I think it's been running since 6:30 this morning. Boiler temp was in the 140's for a good part of the time. The thermostats have been cycling for a good while (don't remember for how long) and buffer tank temp has slowly risen until it's getting close to topping out.

I've had the tank, zone pumps, and boiler launch all set pretty low (in vicinity of 135 or so) to maximize use of the buffer. I'm wondering if I should bump them all up.

How are you running your pellet boiler, now that it's cold out?

 

[AndrewChurchill]

I've got my buffer tank set at 180 high limit and 160 low limit.

 

[velvetfoot]

I've got my buffer tank set at 180 high limit and 160 low limit.

Thanks!

 

[SmokeEater]

I have my buffer at 185 max and 165 min. It's always that way. And the feed dial is a little over 5. Burn is about an inch back toward the auger. No unburned pellets in the ash pan.

 

[velvetfoot]

Thanks! Can't get my tank that high-good for you!

 

[heaterman]

How's it running?......about 140# per day right now.

No buffer tank in my system. No aquastat or thermostat turning the pellet boiler on/off. The thermostat connection is jumped out and it's running all the time just like the heat emitters. The burner ramps up and down according to demand from the TRV's.
It's ranging from 60% output up to 90%. (of 70,000 btu max) It will hit 100% when there is a call for DHW.

My total system capacity is right around 110 gallons as near as I can figure so there's a little more "cushion" than a normal baseboard or water to air coil forced air set up.

 

[velvetfoot]

How's it running?......about 140# per day right now.

No buffer tank in my system. No aquastat or thermostat turning the pellet boiler on/off. The thermostat connection is jumped out and it's running all the time just like the heat emitters. The burner ramps up and down according to demand from the TRV's.
It's ranging from 60% output up to 90%. (of 70,000 btu max) It will hit 100% when there is a call for DHW.

My total system capacity is right around 110 gallons as near as I can figure so there's a little more "cushion" than a normal baseboard or water to air coil forced air set up.

Do you have it rigged that way just for the cold snap?

Edit: After thinking about it a little more I think I get it. When there's no more heat call, the boiler eventually goes to Standby on its own.

 

[heaterman]

Do you have it rigged that way just for the cold snap?

Edit: After thinking about it a little more I think I get it. When there's no more heat call, the boiler eventually goes to Standby on its own.

Exactly. There is no typical wall thermostat in my house which controls the boiler. It works via its own aquastat setting and cycles off when temp overshoots.
Right now I have it set on 165* for this frigid weather we've been having and it will be running at around 60-80% otuput. It just stays on and the burner ramps up/down based on how much the TRV's are throttling.

 

[Trout]

I'm not using the wood insert to see how the pellet boiler works. Quite an eye opener. I think it's been running since 6:30 this morning. Boiler temp was in the 140's for a good part of the time. The thermostats have been cycling for a good while (don't remember for how long) and buffer tank temp has slowly risen until it's getting close to topping out.

I've had the tank, zone pumps, and boiler launch all set pretty low (in vicinity of 135 or so) to maximize use of the buffer. I'm wondering if I should bump them all up.

How are you running your pellet boiler, now that it's cold out?

 

[Trout]

No buffer in my system, but Alpha is now keeping me warm. Did have it set at the 210 output, but with the outside temp dropping to -17 and the wind howling last night, I awoke to the house temp reading 63 degrees and the Nest set to 67. I shut the boiler down and the flipped the dip switch to 260 setting, bumped the boiler temp up to 156 and watched the Alpha catch up. After several hours, the house temp climbed to 68. With the higher setting, my burns are shorter (45 to 60 mins.), but only turning on every two or three hours. Might try turning the boiler temp down to get longer burns. What do you guys think?

Trout

 

[velvetfoot]

I was thinking about it but hung in there at 10. I don't have any Alphas, but the zones and boiler pumps are eco circs which are infinitely variable-only problem is I don't know what to set it at. I tried slowing the pumps down to get the boiler temp up-just experimenting.

Turning the external temp down several degrees, as heaterman has posted, does stretch out the cycle.

I've heard that dip switch may have only a certain number of operations in it before it mechanically fails.

 

[velvetfoot]

Right now I have it set on 165* for this frigid weather

That's the internal temp, correct, and the external terminals are jumpered?

 

[heatingcostssuck]

How's it running?......about 140# per day right now.

So, about $20 bucks a day in fuel?

 

[Trout]

I was thinking about it but hung in there at 10. I don't have any Alphas, but the zones and boiler pumps are eco circs which are infinitely variable-only problem is I don't know what to set it at. I tried slowing the pumps down to get the boiler temp up-just experimenting.

Turning the external temp down several degrees, as heaterman has posted, does stretch out the cycle.

I've heard that dip switch may have only a certain number of operations in it before it mechanically fails.

Velvetfoot - Marc also told me the dip switch was not meant to be switched back and forth. Not sure what that means exactly, in terms of how many times it can be switched, and wonder if there is any way to connect an external switch to the one dip switch that has to be changed to increase or decrease the output.

Also, in addition to my Pellergy Alpha, I do run a Grundfos Alpha circulator. In milder weather it is fine on the number 1 setting, but in this cold weather I have had it on auto, which appears to increase the gals/min as well as the pressure. This seems to distribute the hot water better to the distant radiators, etc.

 

[SmokeEater]

I posted this same on the Pellet Forum. Coldest night so far since I've had the PB105. It's heating 3 floors of 1000 sq feet each. Including an uninsulated basement. Temps outside went to -24 F and the feed rate is fixed at a little more than 5. Stack temp with a magnetic thermometer about 5 feet from the outlet was about 190 degrees. That is on a small portion of single wall vent. The boiler did burn 5 bags in 24 hours. Cellar set at 78 and first floor at 71. This morning the cellar temp was actually 75 because the modine there is only a 17,000 btu unit. The first floor was at 66 because there is no reflective insulation below the radiant PEX. Soon to be fixed. Once the insulation is there I think I can lower the cellar to 55 or so and save some pellets.

 

[velvetfoot]

Not sure what that means exactly, in terms of how many times it can be switched

The number "fifteen" has been bandied about, but I wouldn't bank on it. I'm up to two now.

I forgot the WH Pellergy is named Alpha. Slowing my pumps down seems to be helping keep the boiler temps up-satisfying loads first and then storage. It sounds like you have zone valves with your Grundfos Alpha-I have 2 zone pumps, and I figured these manually adjustable pumps would do it. I think I have to do some studying to know more about what I'm doing.

 

[velvetfoot]

I posted this same on the Pellet Forum. Coldest night so far since I've had the PB105. It's heating 3 floors of 1000 sq feet each. Including an uninsulated basement. Temps outside went to -24 F and the feed rate is fixed at a little more than 5. Stack temp with a magnetic thermometer about 5 feet from the outlet was about 190 degrees. That is on a small portion of single wall vent. The boiler did burn 5 bags in 24 hours. Cellar set at 78 and first floor at 71. This morning the cellar temp was actually 75 because the modine there is only a 17,000 but unit. The first floor was at 66 because there is no reflective insulation below the radiant PEX. Soon to be fixed. Once the insulation is there I think I can lower the cellar to 55 or so and save some pellets

Sounds like you have a lot of horsepower there! Baseboard on 2nd floor? That's an interesting mix to deal with. I'm stuck with baseboards on 2 floors totaling ~2000ft2. The insulated basement is 59 when the pellet boiler is running-might be able to insulate a few more components, like how the hell to insulate the big square head plugs on an insulated tank?

 

[heaterman]

So, about $20 bucks a day in fuel?

No we are really lucky here. 140# figures out to 3.5 bags which equals a little over $11.00 for what I buy them for.
When I burn natural gas for a month of weather like this my bill will crowd $500 so pellets are even less expensive than NG.

 

[heaterman]

No buffer in my system, but Alpha is now keeping me warm. Did have it set at the 210 output, but with the outside temp dropping to -17 and the wind howling last night, I awoke to the house temp reading 63 degrees and the Nest set to 67. I shut the boiler down and the flipped the dip switch to 260 setting, bumped the boiler temp up to 156 and watched the Alpha catch up. After several hours, the house temp climbed to 68. With the higher setting, my burns are shorter (45 to 60 mins.), but only turning on every two or three hours. Might try turning the boiler temp down to get longer burns. What do you guys think?

Trout

You'll get a longer on/off cycle time if you leave the boiler on the 70,000 btu setting (210) and raise your water temp.
The only reason to bump up to the 260 setting would be if you have water temp at maximum and the boiler will not get there running at 100% output.

 

[Trout]

You'll get a longer on/off cycle time if you leave the boiler on the 70,000 btu setting (210) and raise your water temp.
The only reason to bump up to the 260 setting would be if you have water temp at maximum and the boiler will not get there running at 100% output.

As I mentioned in a previous post, my display on the boiler reads 155, but the thermometer (inside pipe) coming out the supply side is reading 165 or so. Which one do I believe as far as increasing the temp up toward the maximum of 176?
Thanks

 

[heaterman]

Use the average. The variation is caused by location of the sensors and the sensors them selves.

 

[velvetfoot]

As I said in the post below, maybe you have a thermowell in your boiler like mine, that already has two sensors in it but has room for another or maybe two, which is where I put a Ranco controller sensor.

How do you define "short cycling?"

 

[Trout]

Use the average. The variation is caused by location of the sensors and the sensors them selves.

Thanks, heaterman, I will give it a try.

 

[bdud]

Our Windhager set as 210 seems to be running great in these colder temps even on the lower water temp setting. It wanted a cleaning on Jan 5th and these are readings from then till now.
~4 days total, 57hrs running, 0.15 tons - 300lbs, 16 starts.
Daily totals, 75lbs a day (~$11 a day in pellets) I have bulk delivery so my total cost is $290 a ton, 4 starts a day, 3.5hrs run time.
About this time I also set the basement rooms to 62F as my son has moved to an upstairs bedroom, so now only heating ~2,100 sqft.
A bathroom ejector closet alarm read 48F so I opened all my doors in the basement to use the heat from the boiler area.