How do you define "short cycling?"

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Trout

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Dec 9, 2013
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Southern MaineAxe
Hi, I have a Pellergy Alpha (read Windhager 260) pellet boiler. I live in Maine, in an 1860's Victorian house of approximately 3000 sq.ft. I have one zone with 10 large cast iron radiators, with approximately 140 gallons of water in the system. I have no buffer tank. My Alpha is set at 70% and is cycling on about 5 to 6 times per day and runs for about 1 to 2 hrs. per cycle, depending on the the thermostat setting and outside temperature. I don't know if this is good or bad, but it works for me and my wife loves the heat. How about yours?
 
That sounds fine to me. I'd define short cycling as when the pump turns on for a minute, then off for a few, then on, etc. Short timescales like that. Usually a problem when the heat source is massively oversized to the load. Think of a 200K btu/hr oil boiler kicking on for a minute or two to heat a small load.....so it is one for a minute or two....then off for a couple....then on....then off.

Running for an hour or two is great.
 
That sounds fine to me. I'd define short cycling as when the pump turns on for a minute, then off for a few, then on, etc. Short timescales like that. Usually a problem when the heat source is massively oversized to the load. Think of a 200K btu/hr oil boiler kicking on for a minute or two to heat a small load.....so it is one for a minute or two....then off for a couple....then on....then off.

Running for an hour or two is great.

Thanks bpirger, I am pleased with the long burns. I would be interested in what other pellet boiler owners, with and without buffer tanks, are experiencing.
 
sounds fine to me too, especially with the mild temps we've been having. The large mass of your heating system helps and it sounds like the boiler was sized properly too. The best sound you will hear with a system like that is the sound of the oil truck driving right on by!
 
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What do you mean when you say you have it set at 70% ?

5-6 times per day sounds pretty good to me too, especially since it hasn't been that cold.

I've been getting about 2 hours run time to charge a 110 gallon buffer tank but it is a smaller model, set at the lower output. You might be able to fool around with the temperature settings as heaterman outlined in a previous thread. I have my boiler internal temp at 176 and external temp at 172. The boiler modulates down to 30% and stays there for a while as the temp goes up slowly-in my case, a lot of times to 181. This makes for a longer run and if a zone comes on the boiler feeds it and the temp in the boiler goes down again. It might not be as vigorous though in keeping the high temp if you need it. Maybe for your style of lower temp heat emitters it would be a natural, but I'm no expert.
 
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What do you mean when you say you have it set at 70% ?

5-6 times per day sounds pretty good to me too, especially since it hasn't been that cold.

Agreed, it has not been that cold yet with the exception of the the few days in Nov. You can see how mine ran on that cold night... it was on all night and most of the day, then it got warmer and started cycling again. No buffer tank here, radiant floor. Wait till the cold comes and then you will get a good idea.
16NOV2014graph.jpg
 
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The data is fun, a great excuse to sit and play with excel... but then again when it comes to playing with excel who needs an excuse? ;)

For the record, I don't have the remote control option for the boiler, apparently if you are in the EU it comes with, here you have to shell out another $800. For what I use it for getting the data via a CF card is fine. I'm looking at a thermostat that would allow remote control... and it's a lot less then $800
 
What do you mean when you say you have it set at 70% ?

5-6 times per day sounds pretty good to me too, especially since it hasn't been that cold.

I've been getting about 2 hours run time to charge a 110 gallon buffer tank but it is a smaller model, set at the lower output. You might be able to fool around with the temperature settings as heaterman outlined in a previous thread. I have my boiler internal temp at 176 and external temp at 172. The boiler modulates down to 30% and stays there for a while as the temp goes up slowly-in my case, a lot of times to 181. This makes for a longer run and if a zone comes on the boiler feeds it and the temp in the boiler goes down again. It might not be as vigorous though in keeping the high temp if you need it. Maybe for your style of lower temp heat emitters it would be a natural, but I'm no expert.

velvetfoot - As I mentioned, I have an Alpha/Windhager 260, but have it set to the 210 output. When the temps get to zero or so and the north wind is blowing, I will probably need to set it back to full power.
 
The data is fun, a great excuse to sit and play with excel... but then again when it comes to playing with excel who needs an excuse? ;)

For the record, I don't have the remote control option for the boiler, apparently if you are in the EU it comes with, here you have to shell out another $800. For what I use it for getting the data via a CF card is fine. I'm looking at a thermostat that would allow remote control... and it's a lot less then $800


CaptainK, I have a Nest thermostat and it can be controlled remotely, etc. It also supposedly checks the temp in your area and makes adjustments re on/off cycles. Finally, it has a radiant/radiator setting that supposedly adjusts when to turn on and off based on your heating system. I can say that with my radiators, the Nest is doing a nice job shutting off before temp is actually reached because the big rads will keep giving off heat and coast up to set temp and not overshoot the set temperature.
 
CaptainK, I have a Nest thermostat and it can be controlled remotely, etc. It also supposedly checks the temp in your area and makes adjustments re on/off cycles. Finally, it has a radiant/radiator setting that supposedly adjusts when to turn on and off based on your heating system. I can say that with my radiators, the Nest is doing a nice job shutting off before temp is actually reached because the big rads will keep giving off heat and coast up to set temp and not overshoot the set temperature.

Thanks! I was torn between the Nest and the Ecobee, Right now looking at the Ecobee due to the extra sensor and the fact that you can program it. It appears the Nest "learns" as you go. But I don't want it to learn a schedule there is always someone home so the heat is set to a constant temp. Do you have a "C' wire or is it run on batteries? How long did it take for it to learn your overshoot times?
 
Thanks! I was torn between the Nest and the Ecobee, Right now looking at the Ecobee due to the extra sensor and the fact that you can program it. It appears the Nest "learns" as you go. But I don't want it to learn a schedule there is always someone home so the heat is set to a constant temp. Do you have a "C' wire or is it run on batteries? How long did it take for it to learn your overshoot times?

No c wire, just red and white! It does have a battery which charges from the main power of my system. You can shut the auto learn off and program it yourself. Like you, there is always someone home and because of the nature of our house and heating system, we usually leave the thermostat set to one temperature. I have, on occasion, scheduled it to drop down a degree or two at night, but usually, I just turn it down. You are probably aware that there is a blog on radiant heat, on the Nest web site. Also, there is a community support forum on their site with many people discussing different applications and wiring, etc. Finally, I believe it only took about a week, more or less, for it to learn my system. Good luck!
 
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I have two Ecobees, not the latest. Like them a lot. Seem to anticipate well, but I haven't paid much attention. It has a c wire.
 
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Thank you to all for the great information. :)
 
I turned on my Windhager set as a 210E, on Nov 1st, 120 gallon buffer tank, 6 zones incl hot water, ~2,400 sqft, as of Dec 31st these are my numbers between these dates.
Operating hours, 482 hrs
Pellet consumption, 1.1 tons
Boiler starts, 242

So using these numbers over ~61 days, ~4 boiler starts a day, ~2 hour run for each start.
I set my buffer tank aquastat temp high enough so if one zone is still on, the boiler will not turn off.
Seems pretty good figures.
 
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...
~2,400 sqft,
Operating hours, 482 hrs
Pellet consumption, 1.1 tons

So using these numbers over ~61 days, ~4 boiler starts a day, ~2 hour run for each start.
I set my buffer tank aquastat temp high enough so if one zone is still on, the boiler will not turn off.
Seems pretty good figures.

And an average of 0.045lbs/sqft/day... That's pretty impressive...
 
And an average of 0.045lbs/sqft/day... That's pretty impressive...
I also have a Harman pellet insert that is on a timer to go on for 2 hrs in the morning and occasionally for an hour in the evening. My wife and son like to sit in front of it before work. I limited its use as it not as efficient as the boiler and I would rather not have to feed or clean it if I don't have to. I have set that levels baseboard heating to come on earlier and hang just a degree lower so the heating during that time is hopefully shared.
 
According to Marc, if you're achieving a run/start ratio of over 1.7 you're doing very well. I have 85 gallons of storage on a Windhager 150E and my ratio is consistently in the 2 range. A bit higher during cold temps that require longer runs - a bit less in mild temps when all it's mostly doing is recharging the storage.
 
The one I just cleaned, (running 2000 sf ranch house, forced air coil, DHW, and one panel radiator) has run 1400 hours, 600 starts, 40 gallon buffer tank, 3 tons consumed. fired it up in july, so nearly half of the days it has been running have been summer hours, doing DHW only.

k
 
Shotgun replies to a few of these posts........

5-6 burner cycles per day is excellent. We use a number of 1 start/stop cycle per hour as our maximum design. Less is better. Much depends on the systems type. High mass systems like CI rads are great. Interfacing with a low mass system like baseboard or forced air requires thermal storage to get below 1 start/stop per hour.

Regarding Nest/Ecobee etc. Be aware that these are power stealing devices. In other words they scavenge a little of the 24V power from whatever device they are conntected to. Many times they do not "play well" with other devices in the system like circuit boards on furnaces, zones valves etc. In cases like that a resistor must be added across the R and C sides of the 24V circuit or you will burn stuff out. This is always the case with a 2 wire system using a power stealing stat of any kind.

Trout.......what water temp are you maintaining in your system when the boiler is running?
 
Shotgun replies to a few of these posts........

5-6 burner cycles per day is excellent. We use a number of 1 start/stop cycle per hour as our maximum design. Less is better. Much depends on the systems type. High mass systems like CI rads are great. Interfacing with a low mass system like baseboard or forced air requires thermal storage to get below 1 start/stop per hour.

Regarding Nest/Ecobee etc. Be aware that these are power stealing devices. In other words they scavenge a little of the 24V power from whatever device they are conntected to. Many times they do not "play well" with other devices in the system like circuit boards on furnaces, zones valves etc. In cases like that a resistor must be added across the R and C sides of the 24V circuit or you will burn stuff out. This is always the case with a 2 wire system using a power stealing stat of any kind.

Trout.......what water temp are you maintaining in your system when the boiler is running?


Heaterman - It depends on what you believe! The display on the Alpha/Windhager reads 155 before the secondary circulator kicks on and drops temp to 145. The temp reading coming out the supply reads about 10 degrees higher, about 165. Thoughts? So far, I have had no difficulties with the Nest. Does this become an issue over time?
 
The temp reading coming out the supply reads about 10 degrees higher, about 165.
I put the sensor for a Ranco controller in the same thermowell as the BioWin uses for its boiler temperature; they're still not exactly in agreement. There's a lot of room in that thermowell; things can get a little loosey-goosey, if you ask me.

I've been getting 3 and sometimes 4 hour run times lately. Cooler weather, still using wood insert a lot, and new buffer tank control strategy.
 
Heaterman - It depends on what you believe! The display on the Alpha/Windhager reads 155 before the secondary circulator kicks on and drops temp to 145. The temp reading coming out the supply reads about 10 degrees higher, about 165. Thoughts? So far, I have had no difficulties with the Nest. Does this become an issue over time?

The difference in temp readings is simply a matter of sensing location. The display is reading water temp at a location in the pressure vessel and your supply sensor is probably out in/on the piping itself. ?

In all the cases where we have had problems with power stealing T-stats (not just Nest/Ecobee) it can take a while for it to create problems. Nest of course denies any issues whatsoever but if you do a little digging you can find reports of problems.

One system we had problems with, burned out 2 Taco zone valves before we figured out the issue with the Nest connected to each.
John Barba from Taco finally came up with this info on making the Nest (or similar) work with a 2 wire set up.

Heard back from Tech Services - the 3rd wire appears to be the key. Nest doesn't do a very good job of explaining that, I don't think. Without a 3rd wire you'll need to use a220ohm, 5 watt resistor (per NEST) and place across w/y & c on the zone valve. Hope that helps!

Hat tip to John!
 
The difference in temp readings is simply a matter of sensing location. The display is reading water temp at a location in the pressure vessel and your supply sensor is probably out in/on the piping itself. ?

In all the cases where we have had problems with power stealing T-stats (not just Nest/Ecobee) it can take a while for it to create problems. Nest of course denies any issues whatsoever but if you do a little digging you can find reports of problems.

One system we had problems with, burned out 2 Taco zone valves before we figured out the issue with the Nest connected to each.
John Barba from Taco finally came up with this info on making the Nest (or similar) work with a 2 wire set up.

Heard back from Tech Services - the 3rd wire appears to be the key. Nest doesn't do a very good job of explaining that, I don't think. Without a 3rd wire you'll need to use a220ohm, 5 watt resistor (per NEST) and place across w/y & c on the zone valve. Hope that helps!

Hat tip to John!

Ran the new thermostat wire today! Ready for new Ecobee... :) Took some time to get the wire down stairs and some blood was spilled, but I'll survive.
 
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