Ryan: It looks like things are going pretty well. I noticed a couple of things looking at the chart of your boiler, so I made a couple of adjustments. You’ll notice that each time the boiler was starting, the power would go up, then fall way off, then slowly come up again. It shouldn’t do that, so I made a couple of adjustments to smooth that out. I’ll be monitoring it to see if it gets better.
Becky/Sheri: Thank you, for making those adjustments, and I was wondering about the start and stop part of the boiler, just 'felt' too extreme. Your adjustments should prove very helpful.
Ryan: Is the thermostat located directly above a section of baseboard?
Becky/Sheri: No Ryan it is in the long hallway going off the kitchen( where you come up out of the basement) , there are no baseboard heaters there.
Ryan: Okay. There is probably a thing called a heat anticipator in your thermostat that may be causing the boiler to fire for such short periods of time. Take a look at this link and let me know if this is something you guys can take a look at. See page 2 of this article for how to adjust the heat anticipator. If you are not comfortable doing this, that is fine. I can take a look at it next time I’m out.
http://homerepair.about.com/od/heatingcoolingrepair/ss/adj_anticipator.htm
Becky/Sheri: I adjusted this on our thermostat, one click towards the longer, at about 6pm....
Ryan: Great. Have you noticed any difference in the way the temperature feels? Cooler? Warmer? If you haven’t noticed a difference and/or it hasn’t bothered you, can you try moving it further toward “longer”? We’re still only getting cycles that are 20-30 minutes long. We should be aiming for about five cycles per day max. If we can’t get there with these thermostats, it might be a good idea to get new thermostats. The side effects of this short cycling are:
• Reduced Efficiency – The igniter uses quite a bit of electricity relative to the rest of the boiler. The element that gets hot draws about 700 watts of electricity (about half of a coffee pot) and is drawing that power for about five minutes each time it starts. Additionally, the heat generated by the pellets being burned isn’t all going to space heating. Instead, when the call for heat ends, it is being released as radiant heat from the boiler itself and the piping.
• Short Igniter Life – The igniter is expected to last through ~1,000 ignition cycles. At the rate your boiler is cycling, it may only last a few weeks, rather than an entire year. While it’s not an expensive part, it’s obviously not ideal.
The phenomenon we’re seeing is completely independent of the boiler; your oil boiler was most certainly cycling this often as well which means it too was operating extremely inefficiently.
Do what you can knowing you should be shooting for five or so cycles per day. If you can’t get there with the heat anticipators, plan on upgrading the thermostats. I’m happy to help in any way I can and wouldn’t hesitate to come down to help out. Just ask and I’ll be there.
Ryan: It's looking good. We're now getting cycles that are one hour or longer which has brought our cycle count down to 10-12 per day. This is a good number considering we're in the shoulder season. As it gets colder, the boiler should run for longer periods of time. We're right on track!
Becky/Sheri: We just filled our pellet hopper...and Sheri reset the hopper weight to 300 again. This is right? Sheri is wondering if you have seen anything on your end that would require another thmastat adjustment????
The temps in our home seem very steady and that is a new thing. We did not have that with our oil boiler! And we did see a big difference, starting with Sheri adjusting the downstairs thermostat, and whatever adjustments you and Sheri made after that, our home keeps improving on temp consistency.
When we filled the hopper, we did clean off the ashes on the tray.
There did seem to be a far amount, at the very end of the tray,if I were to measure the amount, I would say 1/4 of a cup. A little 'mound' of ash at he end of the tray.
Ryan: Good to hear! Resetting the hopper weight to 300 is correct. I'm not seeing anything that needs further adjustment. Everything is running perfectly!
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Optimizing Our New Boiler
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Where can all the online Kedels be seen?
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Re: Thermostat Setting
Hi Ryan,
Happy Thanksgiving to you too!
I figured you must have tweeked something this morning because it is behaving much better. It still doesn't bring the temp up to the thermostat setting though. I turned it down to 65 last night and put it back up to 75 this morning to see if it would behave differently---I'll never set it that high but I wanted to see if it behaved as it did yesterday. Sure enough, when it got to 70 in the house, the system backed off and coasted until 10:00 when I turned the thermostat back to 60. It just barely got to 71 before the set-back. It's pretty strange.
When does the circulator pump come on? The baseboard units seemed to warm up quite slowly----does the Kedel have to come up to temp before the pump starts? It took about an hour and forty minutes to bring the house up to 70 deg from 64. That may be a good reason to have a new thermostat---get the Kedel warmed up before I get up!
I tried to log into the Stoker website with no success. Is the name/password case sensitive? I tried a couple combinations but gave up. Maybe you can email the name and password.
It will be interesting to see how it handles coming back on line this evening as the house temp is falling with a cold boiler. It sure is nice being able to watch what it's doing---I'm sure it will old hat soon but it sure is captivating right now!!!
Ed
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Re: Thermostat Setting
It is strange that the thermostat seems to be off by 5 degrees or so. The circ pump comes on at 173 so yes, there will be a lag between you turning the thermostat up and heat arriving in the room. A slow reaction is what we're looking for so it doesn't overshoot when it's relatively warm out. For maximum comfort, you'll want to leave the thermostat at one setting. If you had a digital programmable thermostat, you could set the time you want the increase in temperature earlier to accommodate. Better yet, a NEST thermostat will learn how long it takes to get up to temperature in the room and create the call for heat as necessary to reach target temperature at the time you desire. http://www.revisionheat.com/renewable-heating-products/upgrade-oil-boiler/smart-controls/nest-learning-thermostat/
I'll email the login.
R
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Re: Thermostat Setting
Ryan,
I came up with an explanation of my thermostat behavior this morning as I watched my Kedel come up to temperature. When I got up this morning the house temp was 64 deg and I turned up the thermostat to 72 deg. The Kedel started out at 15% power and after 20 min or so began its increase in power as the thermostat continued to call for heat. Then, at 69 degrees or so, the thermostat stopped calling for heat. Now, the Kedel cut the circulator pump but not the power, which continued to climb for several more minutes until the high cutoff temp was reached and the power shut down. This is all taking place before I've reached my thermostat set point. What I think my T-stat is doing is giving an early signal to the boiler to cut POWER, not the circulator, so that the water temp will be decreasing as the T-stat set point is approached. By doing this the set point won't be over shot. This makes sense to me with an oil boiler which is pumping out max heat and the water reservoir is relatively large. The gun shuts down and the circulator continues moving water that is decreasing in temp. and the room temp coasts up to the set point. Does this make sense?
Is there a way to adjust the Kedel controls to reduce the power output but NOT turn off the circulator when the thermostat stops calling for heat? This would prevent the machine from shutting down prior to reaching the set point.
Ed
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Boiler Control
Ryan,
I've been thinking about how the boiler should be running to extend burn times, reducing ignitions and excessive cycling. It seems to me that the optimal run sequence would be:
1. Have the boiler come up to temperature as fast as possible because heat cannot be delivered to the home until the boiler reaches the set temp. Gradually raising the set temp will only lengthen the down time (time heat is not delivered to the home), allowing the home to get cooler. If I want a 2 degree difference between max and min temps, heat should be delivered as soon as possible after the T-stat demands heat or I'll need to reduce the max min temp difference so that the boiler will be ready to deliver heat when the difference is 2 deg (or whatever I set for a differnce).
2. Configure the burner to deliver exactly the same amount of energy to the boiler water as the distribution system delivers heat to the home. If this were in balance, the boiler would run all day on a single ignition.
If the return water temp were known, the energy output could be adjusted based on the difference between the supply and return temps (if this is allowed by the boiler controls). The greater the difference, the higher the power. As the temp difference decreases the power could be reduced until a balance was reached. When the difference in supply/return temps remains constant over time, the system is in balance and the power can be stabilized. If the stabilization power level can't be reached before the power output is at 15-20 percent, the boiler would shut down. The burn time could be extended when there is cycling of the boiler by more slowly bringing the power into balance with demand-- adjusting the power more slowly to the supply/return temp difference.
Maybe after the boiler is brought up to temp, the power could be dropped to the minimum and gradually increased from there until the balance point is reached. This would prevent the boiler from overshooting the mark during warm days, extending the burn to the max.
Can the boiler power be adjusted based on supply/return water temps?
Another way to tune the power to demand, as you suggested this morning, is to adjust power based on room temp and thermostat setting. But it seems that return water temps gives you this info without having to have a smart thermostat.
Ed
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Re: Thermostat Setting
I believe your thermostat must be out of calibration. It is not common for an analog thermostat to cut the call for heat before the temperature is reached. If it were a digital thermostat it may have the brains to do that, but being an old mercury thermostat, I think it is just out of calibration some how.
Secondly, when you have zone valves, it wouldn't make any difference whether the circ pump kept running or not because when the thermostat ends the call for heat, the zone valve closes preventing any flow to that zone. The zone valves work completely independent from the boiler. In order to achieve what you're looking for, you would need a new zone controller that allows for post purge; the controller would keep the zone valve open after telling the boiler to turn off.
Similarly, when you had the oil boiler, the circ pump was on the same control circuit as the zone valve, so as soon as the call for heat was satisfied, the pump would shut down immediately, the zone valve would close, and the burner would turn off.
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Re: Boiler Control
I appreciate that you're digging into understanding the logic behind the scenes. I'll do my best to respond without writing a book...
If the boiler operated as you have outlined above, you would get many short cycles and here is why. The radiation in your home is designed to deliver as much heat as is needed on the coldest day of the year plus a safety factor (typically 25% - 30%). This means that unless it is -25 degrees outside, your distribution will deliver more heat than is necessary to maintain or increase the temperature in the house. Hypothetical: The distribution in your home has the capacity to deliver 50,000btu. When it's -25 degrees outside, that is just the right amount of heat to raise the room temperature at a rate of 5 degrees per hour. So, knowing that, let's say it is 40 degrees outside (65 degrees warmer than what the distribution is designed for) and there is a call for heat. Because it is so much warmer outside, the house may only need 15,000 btus to warm up at a rate of 5 degrees per hour. If the boiler were to come up to temperature as quickly as possible (100% power until temperature is reached), it would be delivering 50,000btus in a hurry when you only need 15,000. This leads to lots of short cycling.
The ideal scenario would be to have the supply water temperature modulate based on room temperature. In a scenario where the boiler target was being driven by the room temperature, it would modulate power based on the difference between the "target supply temp" and the "actual supply temp", where the supply temp target would be driven by the difference between the "wanted room temp" and the "actual room temp". Let's consider another hypothetical using this theory. For this hypothetical, the supply temp has a minimum of 120 and a maximum of 180. The room is sitting at 65 degrees and you come home from work. The boiler is humming along at 120 degree supply temp and 15% power simply maintaining the 65 degrees in the house. 65 is a bit chilly in the evening, so you turn the thermostat up to 70. Now, the controller sees a 5 degree delta and increases the supply temp target from 120 to 180 instantly. Because of this change, the PID controlling the power of the boiler sees a 60 degree delta between actual and target boiler temp and ramps the power up. As the temperature of the room begins to increase, the room temp delta will diminish, driving the boiler temp target down. At some point, the room temp would reach 70 and the boiler target temp would drop to 120 again, thus leading the power back down.
The problem with this scenario is the low boiler temperatures. If the boiler operated at 120 degrees, you would likely have flue gas condensation problems because the flue gas temperature would be around 130 degrees. So, in looking at the ideal scenario and the reality that the boiler needs to stay hot in order to keep the flue gasses from condensing, the best option is to keep the boiler hot but deliver cooler water to the distribution. There are two ways of achieving this. One way is to incorporate a four way valve between the distribution and the boiler. This valve would allow the water in the distribution to completely bypass the boiler, for 100% of the water to be forced through the boiler or anywhere in between. This is quite expensive (both component cost and installation cost due to extensive re-plumbing) and requires integration with the controller and its logic which isn't available. The other option is to make sure the boiler stays hot and pulse the heat into the distribution, giving you a lower average temperature of the distribution water, which is what we are doing. Back to the first hypothetical, what we're doing is approaching the 15,000btu need from below as gently as possible. What I don't want is for it to take too long to get there resulting in an uncomfortable house. If it is taking too long to begin delivering heat and the house is cooling off too much, there are three adjustments that can be made to make the boiler react more quickly.
-You can raise the minimum performance by a few percentage points.
-You can raise the "Power Per Minute on Start" setting under PID Regulation. It is currently set to "1" meaning it will only allow the power to increase by 1% per minute after startup. It can be as high as 10 which will ramp the power quite quickly.
-The "Gain P" can be increased in the PID regulation. There are two factors determining the sensitivity of the adjustments the controller makes to the Power setting. One factor is the delta between target and actual temperature. The other factor is the time that the boiler has been away from the set point (either above or below).
The one piece that we are missing to achieve control bliss is a room temp sensor that would drive the power setting. If we had that, the power of the boiler would decrease as the room temp approached the target temp, thus leading to the pump pulsing less frequently, giving fewer and fewer shots of heat. If the room temp began to fall, the power would increase resulting in more frequent pump pulses and/or constant running if that much heat was being asked for. We are working on this solution and you'll be one of the first to get the update.
In Europe, most systems are set up to constantly circulate and the room temperature is regulated by a Thermally Regulating Valve (TRV) on each and every radiator. In very basic form, those valves simply close down, reducing flow as the room reaches the desired temperature. When the room starts to cool off, they simply open up little by little, allowing flow of hot water through the radiator. Because heating systems in the US don't have constantly circulating systems like they do in Europe, we will always be fighting the inefficiencies of stop and go type systems.
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Light Sensor Profile
Sherry: Hope you had a great holiday! I have been looking at our graphs today and the Lux seems to be all over the place. Any ideas as to why that might be?
Just wanted to touch bases with you again about the Lux profile for our boiler. When I returned home last night I checked and there was a fairly large pile of ashes on the grate where we scrape them out. We have been doing this every other day but I think this pile was the reason for the erratic Lux readings as after I scraped the profile cleared up to what it has always been. I think we will need to scrape a bit more frequently since the boiler is running longer. Will the new fan help this?
Also we did get a referral call from Scott? about the Kedel and Becky called back but only got a message machine - we are more than happy to tell everyone about our Kedel!
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Re: Light Sensor Profile
Hi Sherry. Thanksgiving was great, and I appreciate Becky sourcing a local, natural turkey for us! It was (and still is) fantastic!
You hit the nail on the head. There are four things that can cause the Lux readout from the light sensor to become erratic: Poor connection where the wires from the light sensor go into the printed circuit board, a bad light sensor, ash buildup or a dirty light sensor. The last two are the most likely. Since you don't have the compressed air blowout system, keeping the ash scraped out is very important. We're still learning what the frequency of that needs to be, so as you learn more, please post about it here.
We can also try increasing the fan speed during the cleaning cycle to see if that reduces the amount of ash building up. I turned it down pretty low because it was blowing some partially burned pellets down into the ash bin. Let's bring the fan speed during a cleaning cycle up little by little. You will need to keep an eye on the ash box to see if you are getting partially burned pellets in it.
If cleaning the ash off the burner doesn't do the trick, you can try pulling the light sensor out of the burner and wiping it off with your fingers or a cloth. It is mounted in the side of the burner and clicks in and and out very easily. If you have any more problems, let me know.
R
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Condensation
Ed: I went down to clean the ignition shelf after I returned from work today and found a small puddle of water on the floor under the pipe---water is dripping from the boiler exhaust pipe. Condensation is worse than I thought. What should I be doing? Turn off the boiler and wait for your instructions? Is it ok to continue burning as it has the past week?
Ryan: It is not a dire situation though it does need to be resolved. If it was left this way, eventually the condensate would create corrosion in the boiler, which obviously isn't a good thing. There are a few things we can do, and the first is very easy and will likely remedy the condensation. When the boiler is installed, we aim to have it running at the highest efficiency possible. Due to the extremely high efficiency of the heat exchanger, the flu gasses can sometimes be too cool, causing the moisture that is created as a result of combustion to condense in the flu. I had the same experience with my boiler.
The first step is to increase the flu gas temperature by allowing a portion of the flu gasses to bypass the third pass of the triple pass heat exchanger. This is achieved by lowering the bolts in the bypass plate that is located inside the heat exchanger. First, turn off the boiler by pressing the power button on the main screen of the controller. If the boiler was running, let it finish the cool down cycle. Once it is completely shut down, the boiler will likely still be quite warm, so you will want gloves. Remove the wing nuts from the heat exchanger cover and unplug the O2 sensor if you have one as shown in the picture. Now, the cover will lift off. Toward the back of the heat exchanger, you will see a plate with two bolts threaded into it. Turn those bolts clockwise to raise the bypass plate. If the boiler is condensing, you will want to turn the bolts so they are all the way in. This should raise the plate by 3/8" - 1/2". This adjustment will raise the flu gas temperature by about 60 degrees.
Don't fret if this doesn't completely solve the problem, as there is more that we can do. Let me know if we need to take further steps.
If you're not comfortable doing this, I'd be happy to come help out.
R
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Re: Condensation
Ryan,
I was able to turn one of the bolts but the other one is stubbornly stuck---I couldn't move it by hand and didn't have the correct socket to do the job. So, I left it with one bolt high, one low. This opens up the bypass plate about half way. Next time you're up maybe you can fix the other bolt.
I did have a scare though. While the boiler was cooling down I decided to fill the hopper. I must have somehow pushed down on the control panel with one of the bags of pellets because the screen went blank---no signs of life. I almost gave you a call but decided that since this is a computer, a cold reset might do the trick. I flipped the emergency switch off and on and it came right back to life. It's reigniting now with no harm done!
Ed
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Re: Light Sensor Profile
11/30/12/Ryan - we are still having to scrape ashes frequently, now morning and evening as the pile on the end seems to get "scrapable" in 12 hours. Can the fan still be turned up further?
Sherry
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Re: Condensation
Ryan,
The condensation has stopped since adjusting the bypass plate. I also increased the minimum power temp to 20 deg to make the fire burn hotter.
Question: Should I close down the bypass plate little by little until the condensation returns to find the optimum setting? I would like it to run as efficiently as possible. A flue temperature sensor might make this adjustment easier.
Ed
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Re: Condensation
Sorry, I meant "I also increased the minimum power to 20% to make the fire burn hotter."
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Re: Light Sensor Profile
Ryan,
My light sensor profile has been more erratic the last few days as well. I've been cleaning the burner grate twice a day. I also pulled the light sensor this morning and gave it a swipe with my fingers. The profile seems to be less erratic since.
The drop in lux occurs when pellets are fed onto the burner grate--from a brief observation of the controller monitor on the machine.
Ed
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Re: Light Sensor Profile
Ryan,
My light sensor profile has been more erratic the last few days as well. I've been cleaning the burner grate twice a day. I also pulled the light sensor this morning and gave it a swipe with my fingers. The profile seems to be less erratic since.
The drop in lux occurs when pellets are fed onto the burner grate--from a brief observation of the controller monitor on the machine.
Ed
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Re: Condensation
Great. When I was filling your boiler, I noticed due to the configuration of walls around it, that it was easiest to set the bag of pellets on top of the boiler side to dump them in rather than try to go over the top of the controller. Resetting power as you did doesn't hurt a thing. I have never gotten the blank screen, but it sounds like resetting power does the trick.
Glad to hear the condensation is solved with the bypass plate. I will bring a smoke temp sensor next time I come up. Feel free to play around with it in the meantime.
R
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Re: Light Sensor Profile
Hi Guys! While I appreciate you keeping a close eye on the light sensor, I think you'll find that you can let it go for a while between scraping the ashes. The controller is simply looking for a positive signal from the light sensor and it doesn't necessarily need to be perfect. As long as there is any amount of light, it knows there is fire. My boiler has been running for 6 days and I have burned through 200lbs of pellets and have not touched anything. I don't have the compressor clean out system so I have a nice little mound of ash towards the end of the grate, but not nearly enough to cause a problem. During our testing at the shop, we wanted to see how bad things would get before causing a problem, so we have been quite abusive with it and have yet to have a problem with ash buildup, even when the entire burner is almost completely full of ash. I'm confident you can go several days to a week, probably longer, between scraping. While the light profile will be jumpy, it won't have a negative effect until it gets bad enough to prevent lighting or until the ashes reduce air flow so much you get poor combustion.
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Ignition Faults
This morning we woke to a "cool" house. The screen on the Kedel showed we had had an ignition fault at around 4am. These are the steps I went through to get it running again - please tell me if I missed a step or should have checked something else!
First - I checked the tray where the pellets burn - it was quite full so I scraped the ashes
Second I checked the pellet supply - it was a bit low, the reading was 68 pounds and the bottom of the hopper was covered (not unusual) but I threw in a couple buckets of pellets to be sure.
At this point I tried to get the system to ignite, I had to turn the system on from the main screen, something I had never done before. I could see a glow from the ignitor attempting to ignite.
Once again ignition fault - so after searching through the menus I decided to run the auger for 6 minutes (the setting already in there) to verify that we had a fuel supply for the ignitor to ignite, and once again started the system.
This time I got ignition, still not sure what caused the failure. Over-abundance of ash? low/clogged fuel supply? Any ideas or comments greatly appreciated. We will be monitoring closely in the next few days
Becky/Sheri
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