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Buderus 2107 Logamatic Control

The 2107 is a great addition to your Buderus boiler, but the settings need to be adjusted for your home and system. The control comes out of the box set up for a typical German system and almost never works properly on a American heating system without adjustments. Your installer should program the control as part of the boiler installation. If they are unable or unwilling to do so, find someone who can.

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  • Heather_4
    Heather_4 Member Posts: 5

    Hi There, We had the Buderus 4 section boiler and 36 gal DHW installed last week. Unfortunatlty, the technician has been zero help in programming the logamatic control. Is a ref point of 167 (factory standard) best for everyone? If yes, why and if no, how do we figure out what it should be? Once the ref point is established will it control the temperature in the heating space? We like it to be at around 65 degrees early am and from around 4-10. We're just confused about the premise of the system. My mind is having a hard time wrapping around what we do with our current thermostat etc etc. Any help would be greatly appreciated.
    Regards, Heather
  • D107
    D107 Member Posts: 1,798
    depends on climate, night setback etc.

    HO here. Family house had a buderus and logamatic installed. We found it far better to learn to program it ourselves than to rely on the oil company's service dept to deal with it.

    House is in Long Island NY, and 167 reference temp works fine. The only shortcoming I've found with the 2107 is that since it has no morning boost, if you have more than a 3-4 degree night setback, it will take a relatively long time to reach your day temp. I recall the recommendation from Buderus that if this is being run by a thermostat attached to the system and your night temp desired t-stat setting is 65 degrees, you should set the logamatic night setting for 67 for a quicker recovery in the morning. Of course you can also start the day setting a little earlier. Added: If it wasn't for the fact that my mother who lives there requires 75 degree day temps with a 7 degree night setback, the factory settings probably would have been fine.

    Here are comments I received from Joe @ Buderus:

    "The Offset mostly affects the starting temperature of the curve. If the outdoor temperature is mild and more water temperature is needed, then the “Offset” is raised. The “BLDG RESP” is how quickly the control will respond to the outdoor temperature. I recommended this setting be changed from #2 to #1 since most people are not use to a slow response of outdoor reset. The “Day” and “Night” settings are values used to help determine the heating curve. The Day and Night Settings have more effect on the curve it is colder outside and less on mild outdoor temperatures. The “Ref Temp” raises the entire curve through out mild or cold outdoor temperatures."

    You might want to go to the Buderus site forum and present your questions there as well.

    Good luck,

  • Heather_4
    Heather_4 Member Posts: 5

    Hi David

    Thank you for your response. This will assist us with determing the best set up values based on our indvidual needs. I find that as American I want to control the temperature, becuase this is how I have lived forever. We are learning to change our mind set to allow this outdoor reset technology to enter our lives.

    Thanks again, and yes we will check out the Buderus help forum.
  • D107
    D107 Member Posts: 1,798
    Read your post again

    and as a homeowner I do understand about trying to adjust to the big change from just having a thermostat. The T-stat should activate the circulators which get the heat to your radiators, but the 2107 turns the boiler on and off to maintain a certain water temperature. Your temp requirements are a little unusual in that you want a 65 degree day temp in two different blocks of time, then presumably a lower temp at night and during the afternoon until 4pm. A programmable t-stat can easily set up those blocks of time, but with the 2107 you would have to create a custom program of day and night settings which the manual can help you do.

    I hope you received both the owners' AND service manuals when you had the unit installed, since both are really necessary. And of course TGO is right--if you CAN find someone who knows how to set up your system so much the better, then you can later tweak it on your own. It depends on how tech-oriented you are.

    One of the things I have learned from the Wall is that if you setback too much for any amount of time, it will take a while for not only the air temperature to rise when the heat comes back, but even longer for the furnishings, walls, etc. so that you might still feel cold even if room thermometer says you've reached the desired level.


  • psd_3
    psd_3 Member Posts: 86
    logamatic 2107

    Hi Heather,

    First off, let me congratulate you for owning an excellent system.

    I too have a Buderus with a 2107 and it took a little getting used to before I had it set to our liking.

    David makes some excellent points with respect to T-Stat setback and outdoor reset control. If you use night time setback on the 2107, then I would strongly recommend keeping your T-stats at a fixed temperature. If you don't use night time setback on the 2107, then I would recommend using only a few degree differential on your T-stats ... we use 64F at night and when we are at work and 67F when at home (~45 minutes before we arrive). Too much T-stat setback creates problems with recovery and drafts creating comfort issues and not really saving money. With a 7 degree setback, we were having to heat to 69F and weren't as comfortable as when using a T-stat setting of 67F with a 3 degree setback.

    I also had to play with the Ref Temp and the Offset on the 2107 to compensate for our particular situation. In my case I lowered the Ref Temp and increased the Offset to flatten out the heating curve a bit. This gave us better heating response during the shoulder months (Oct, Nov, March and April), allowing for a quicker recovery in milder weather.

    With a Ref Temp of 167F and a Max temp of 195F I also found some odd behavior on really cold days (-5F or below). I found that the differential would errode to only 7 degrees causing the burner to short cycle. Lowering the Ref Temp and increasing the Offset helped by pushing this point of issue out to below -20F (far and few between even for those of us in northern New England).
  • Heather_4
    Heather_4 Member Posts: 5

    Hi Sid

    Thank you very much for responding. It is helpful to read what other's have gone through in order to get to the correct heating curve for their particular situation.
    Creating a custom program was easy but I don't know what to set the T-Stat at? Day temp is 65 starting at 4 am and turns off 7 am to a temp of 63, day turns on again at 4pm and off at 10 pm. As you stated in your post, if we are using night set back, which we are, set the T-Stat to a fixed temp. We had it set at 80 degrees and found that it was about 70 degrees in the heating space. Is it safe to assume that the ref temp / heating curve created this 70 degree temp, even though day temp is at 65 on the Logamatic Control?
  • psd_3
    psd_3 Member Posts: 86

    Hi Heather,

    I assume you mean that the T-stat was set to 80F.

    If so, this will keep that T-stat zone in constant circulation until 80F is attained ... which would be "never" in your case. It also says that your heating curve had a bit of margin above 65F for that day, and that's why you reached 70F.

    With your system, the T-stat only determines if the circulator pump for the zone is on/off, and the Logamatic determines how much heat is available from the boiler ... i.e., based on the core temp it's trying to maintain as a heat source/sump.

    During the day, you want the boiler to maintain sufficient core temperature so the zones will be satisfied, and thus achieving your T-stat setting. In fact, you want this to be balanced just right so that on any given day the T-stats are statisfied, but not with a lot of extra margin. The outdoor reset control in combination with the programmed heating curve is responsible for maintaining this day-day balance over the course of the heating season. The combination of the programmed Ref Temp and the Offset determine the heating curve characteristics.

    Ideally at night and during "away" periods, you want the T-stats not to be statified and your heating zones will run in constant circulation. This is achieved by the night time setback of the Logamatic. In night mode, the Logamatic automatically lowers the boiler core temperature so that the system can no longer meet the demand of the heating zones. The ambient temperature of the dwelling drops to the point where the boiler can again maintain the heat loss. However, this is now at a lower temp than the T-stat setting so the zones are constantly circulating (i.e., the T-stat is always requesting more heat relative to the 65F setting).

    So ... in your case, if you want 65F during the time that you are home, set the T-Stats for 65F and leave them fixed there. Then program the heating curve parameters so that you achieve and maintain 65F when in day mode. You will need to calculate the correct Ref Temp in order to maintain your desired temperature on the target day (I believe it corresponds to a day that is 14F but my memory my be incorrect so check your Logamatic manual for this). If you find that you are not maintaining temperature during the coldest days of the heating season, then adjust the Ref Temp up slightly. If you need a bit more output/response from the system on all days, then you can adjust the offset up slightly. Make small adjustments to one parameter at a time and observe the response over the course of a few days.

    By the way, I have found that adjusting the day temperature setting on the Logamatic is simply another (and more convient) way of controlling the heating curve offset.

    Hope this helps!
  • D107
    D107 Member Posts: 1,798

    Hi sid--your info is very helpful. I just wanted to address a possible discrepancy between some of your comments and what Joe at Buderus stated in the quote I have earlier in the thread.

    Your comment:
    "If you find that you are not maintaining temperature during the coldest days of the heating season, then adjust the Ref Temp up slightly. If you need a bit more output/response from the system on all days, then you can adjust the offset up slightly. Make small adjustments to one parameter at a time and observe the response over the course of a few days.

    ....I have found that adjusting the day temperature setting on the Logamatic is simply another (and more convient) way of controlling the heating curve offset."

    As far as I understood it, Joe was saying that the REF temp adjusts the entire curve, the day/night temp gives more or less heat in more severe cold, and the offset adjusts the curve for the milder temperatures. Perhaps your experience differs. Obviously these parameters can interact with each other. So as I understand Joe, If you were at design temperature outside and the heat was inadequate, you might first try raising the day temp, but then if that didn't work you'd have to raise the REF temp.


  • psd_3
    psd_3 Member Posts: 86
    Re: Correction ...

    Hi David,

    I checked the Logamatic 2107 service manual to see if my memory had failed me since it's been a few years since I've dabbled with my control settings.

    From the 2107 service manual, which also correlates with my own experiences:

    The "REF TEMP" controls the slope of the heating curve and determines cold weather performance of the system. In simple terms, it determines the relationship of boiler core temperature to outside temperature ... or in other words, the day-day dynamics of the supply/demand relationship based on seasonal temperature changes.

    The "OFFSET" is used to vertically shift the entire heating curve up/down. It raises/lowers the boiler temperature by a fixed amount (2-3 degrees F) per unit change of "OFFSET". From my experience, it is used as a means to fine tune (calibrate) the output of the system to your individual situation like expected recovery rate.

    The "DAY TEMP" and "NIGHT TEMP" settings are not well described relative to their effects on the heating curve characteristics, but from my experiences they act like an offset control. You can observe this by looking at their effects on the reported heating curve data points for 50F, 32F and 14F (refer to "Display of Heating Curves"). These controls are used to adjust the system output to your demand (heat loss). In other words, they are used as a means to match the system's ability to meet the demand of your zones based on your expected comfort level ... by perhaps satisfying your T-Stat settings when in "DAY MODE". This is a point of debate, because some will argue that constant circulation is "always" better than on/off, even in "DAY MODE" ... but this is where a BFU (remote room sensor) really works better than a simple T-Stat.

    I do agree that the 2107 provides multiple means to a reasonable end with its various settings.
  • toolman_tim
    toolman_tim Member Posts: 8
    Next Question

    Ok, so does it seem odd that our week old system used 1/4 of oil? I contacted the tech and he indicated that the gauge on the tank is not the best way to judge performance. He also, indicated that it will take about one to two tanks of oil before we see any real efficieny. This does not seem "right" to me, considering night time temp is 63 and day time temp is 65. I am starting to lose hope in this tech. I feel as I am the only one who cares about the performance of the boiler they installed last week. Any thoughts?
  • D107
    D107 Member Posts: 1,798
    you should post your city and state

    and you might get a response from a wall tech or someone who knows one in your area. And go to the 'find a professional' link on this site and punch in your zip code and see who's in your area. We have no idea if a proper heat loss calculation was done in the first place to make sure the boiler was sized correctly, or if the install was done correctly or if the burner has been tuned properly. You should post some pictures. That will give people some idea.

    1/4 tank (275 gallon?) is about 69 gallons, which is about 10 gallons a day for 7 days. That would be quite high for the NY area, but not necessarily if you live in a very cold climate. The tech's comment about needing more time to see improved efficiency doesn't make sense to me.

    The Wall can be of great help but there's no substitute for getting at least a consult from a pro, and remove some of the guesswork here.

  • psd_3
    psd_3 Member Posts: 86
    Next question -

    Hi Heather,

    Can you provide some additional specs about your situation?

    What type burner is on your Buderus?

    Do you know how the tech has it configured ... nozzle size, pump pressure? I am looking for an approx. Gal/Hr rating for fuel consumption based on your burner set up.

    The 2107 provides a reading indicating how many hours your burner has run. You can get this by turning the blue dial on the front of the 2107. It will also show boiler temp, outside temp, and DHW temp by turning the dial. How may hours are being reported by the 2107 and how many days of operation does this cover?

    What was the calculated heat loss for your home? How big is your house sq-ft and where are you located?

    What size oil tank do you have 275gal, 333gal, other?

    I agree that using a 1/4 of a tank seems like a lot for a week ... assuming a typical 275gal tank. I am located in northern NE and only use 450gals per year (~25-30gals/week in peak January) ... which equates to 1/10 of a 275 gals tank. I have a G115/34 (5 section) and my heat loss was calculated at ~75K BTUs for a -20F design day ... but I tend to run well under this because of life style changes ... kids gone, both working, don't use some sections of our home regularly, etc. I agree that the tank gauges are not accurate and mine will show about 1/8 of tank consumed in a week when it is near full.

    I don't think that there is any "break in" period for these systems ... so I don't understand what the tech is getting at by his comments regarding waiting?? To really see the savings, I do agree that you will need to look over a longer period which includes periods of milder weather. However, you should already be seeing a noticable improvement over your "old" system. All things being equal between indoor temperature settings for the same outside temperature, I would expect a noticable decrease in oil consumption 10-30%.
  • psd_3
    psd_3 Member Posts: 86
    A couple of more questions -

    Here are a couple of more questions to add to those in my previous post -

    Did the tech leave a slip showing the combustion parameters following the install? If so, what are the readings listed for C02(%), Stack Temp., Efficiency, Draft at breach, and CO?

    Do you know what the configuration of your adjustable baffles are (inside the boiler)? These baffles enable some control over the stack temperature. This question is important only if the stack temp was higher than expected >>350F.

    What is your typical hot water usage? Do you fill large items like a spa/jacuzzi?

    I regularly use the hours reading as an indication of how much fuel I've used between fill ups. Once you know the burn rate of your burner, this is a fairly accurate way to estimate/confirm usage. My burner is set to ~ 1GPH based on a nozzle size (.85gph) and pump pressure 145psi. If you have a G115/28 (4 section), then I would guess you are at .8GPH based on Buderus's burner specifications for that model.

    In order to burn 1/4 of a 275gal tank in 7 days your hour reading would be approximately 78hrs. Note that I used 250gals instead of 275gals, since a 275gal tank is really never filled to 275gals.
  • Heather_4
    Heather_4 Member Posts: 5
    06078 CT Looking for Qualified Burderus Tech

    Sid -
    Again, thank you kindly for assisting me with this.
    Buderus Type = G115/28 4 section with X120 32 gal DHW.
    Burner =Riello high efficeny flame retention burner. I contacted the tech to ask him what size nozzle and the pump pressure. He indicated, "I don't know that was 70 nozzles ago." He thinks he installed .65 nozzle with 140 PSI but don't quote him on it.
    The reading indicates 36 hours run over a nine day period.
    He did not calculate the heat loss for our home. When I asked him stated that he replaced old boiler with a comperable size. The SQ of the house is 1700, 1951 construction with 21 windows, seven rooms, and about R12 in the attic.
    Oil Tank = 275 gallons.
    I did ask him if he wrote down the combustion parameters and he indciated no I did not. I don't remember what they are.
    Baffles - He said he left them at factory setting which is all the way closed.
    DHW water usage = minimal, we are a family of two with one bathroom.
    Sid - Having said the above, I am concerned about the service and compentancy of this Tech!
    I would love a second opinion and am willing to pay BUT I would prefer to know that the next Tech is qualified to assist with our particlar sitatuion.
  • Sid_4
    Sid_4 Member Posts: 1
    Re: Looking for qualified Buderus Tech ...

    Hi Heather,

    Your information was helpful ...

    Let's start with the facts-

    Buderus specifies a Riello 40-F3 for the G115/28. If the tech installed a stock configuration from Buderus then the specified nozzle and pump pressure would have been .65GPH @ 145 PSI with an equivalent firing rate of .80GPH. This pretty much agrees with his response to you ... and there would have been little reason for him to change this configuration.

    And now for some analysis-

    Given that this information is correct, then in 9 days your burner ran for 36 hours burning .80GPH ... for a total of 28.8 gallons of fuel ... which equates to 3.2G per day. 28.8Gals is approx 1/10 of a 275Gal tank and not 1/4 as your guage was suggesting. I assume that your tank was filled on day 1 of the install and the guage was at full? Do you have any prior experience with this tank, or is it also new? If new, then how many gallons were delivered at the first fill?

    Your system has an advertised NET output rating of 85,000 BTUs/Hr (fact). So at an average of 4Hrs/day of run time, you used 340,000 BTUs/day, or 14,167BTUs/hr. This may be a little optimistic since there are other considerations relative to the advertised NET rating (like optimal burner settings, or additional losses). In any case, this seems like a very good number ... but without doing a complete heat loss analysis, is still subjective.

    And now some areas where things could be improved -

    1) The tech should know the equipment he/she is installing and should have done a comprehensive heat loss analysis before recommending a system for your application.

    2) The tech should have done a complete combustion analysis as part of the install, and then left you with the results for your records and/or to furnish to the building inspector if an inspection was required.

    Now for some recommendations -

    1) Be careful not to burn a bridge with the tech/company that did the install because you may forfeit your rights to a labor/performance guarantee/warantee (typically a year on installations, but sometimes more).

    2) Be careful not to let others touch/adjust or system because you may forfeit your rights to the installation guarantee/warantee.

    3) It is still within your rights to request the results of a combustion analysis for your records and for inpection/safety reasons. Your building inspector may be able to support your position on this by requesting that you provide one for his/her records. Personally I would want to know that my system was operating within safe parameters for things like Carbon Monoxide (CO) or smoke reading.

    4) Have your tank filled at ~1/3 of a tank and record the hours on your 2107 on the day of a fill up. Compare this to the amount that was delivered to refill your tank. Use this number along with the number of days between fill ups to figure your fuel usage and BTUs delivered. Use the hours readings on your 2107 to better understand your tank guage accuracy. I can estimate delivery amounts within about 5% using this approach.

    5) Do a heat loss analysis for yourself by using information suggested from this site (Slant Fin software), or others like Crown or other HVAC manufactures. Also, understand that these programs are targeting a near worst case "design day" and not an average winter day. You will generally find a significant safety margin between the two.

    Please let me know how you make out
  • psd_3
    psd_3 Member Posts: 86
    Don't overlook the good too ...

    Your system is built with some of the best components available today ... and also some of the most affordable in this league. I assume that this recommendation came from the company that did the install? If so, kudos to them!

    Perhaps your system was a bit over-sized as a result of not doing a proper heat loss analysis, but fortunately the Logamatic 2107 helps to compensate for some of the negative effects of over-sizing. Again, using the Logamatic was a wise choice/recommendation for max. efficiency and to provide flexibility for your needs going forward.

    Based on the hours of run time from your 2107 in conjunction with your firing rate and NET BTU output, I don't see anything alarming with your fuel usage over the first 9 days (explained more in the previous post). This does raise some question with the fuel consumption reported based on your guage reading. Here the tech might have been more correct than not by recommending a longer study period ... not by suggesting that performance/efficiency would improve with age, but by allowing the tank guage inaccuracy to be averaged out over a larger swing of the guage range ... and then verified by the actual refill amount over a few deliveries. Keep your delivery tickets and make a habit of writing the change in 2107 hours on each ticket at the time of delivery, this will allow you to better predict usage. Over time the 2107 hours reading will also allow you to get a better handle on what your guage is really indicating.
  • albandjann1725849
    albandjann1725849 Member Posts: 19
    BuderusTemperature Setting

    If someone could help, I'd appreciate it. We have a 4 yr old Buderus//Logamatic 2107 and though we have several zones in our house, we're really never able to get the temperature in two of our rooms on the second floor to maintain a temp of at least 70 degrees. A service man adjusted the boiler temp to 163 degrees which seems very high to me, not to mention that since we use oil heat for energy, we're consuming way too much oil. Outside of a total redesign, we'll explore options but what should be the standard setting for the boiler temp? And, does adjusting it up produce- outside of hotter water out of the faucet, a warmer room? Thanks!

  • psd_3
    psd_3 Member Posts: 86
    Maintaining temperature ...

    Hi Ed,

    There are many factors here that could be at play ...

    Boiler sizing ... is it sufficient for your heat loss?

    The amount of BTUs sourced by your emitters (radiatiors, etc) on the 2nd floor ... are they sufficient?

    The boiler/Logamatic 2107 settings (REF TEMP, OFFSET, DAY TEMP) used to control your specific heating curve for a given outside temperature.

    Is your outside temperature registering correctly on the 2107 allowing for proper adapation of your heating curve?

    Where are you located, and is it abnormally cold when this situation occurs ... or are you always having issues maintaining temp in these rooms?

    I'm not sure which parameter the technician adjusted on your 2107 ... perhaps the REF TEMP?

    Can you describe your system and situation with a bit more detail including details about your heat loss analysis, your system configuration (boiler model/burner model), the size of the rooms, the type and amount of radiation used to heat these rooms?
  • albandjann1725849
    albandjann1725849 Member Posts: 19


    You raise some good points especially the one about outside temp. When a serviceman, not from the company that installed the unit, came to look at it; he said he couldn't find or locate a wire leading to the outside at all. So, if he's right, then I suppose it's not taking outside temp into consideration and I believe the setting is for manual vs. auto but I'll have to check. We have forced hot air via oil and I should know what the system is referred to, hydro heating? but I don't. There are seven zones and each zone has it's own pump/generator/whatever it's called- to heat each zone. To your question, I don't believe the heat source is sufficient for the two rooms. Up in the attic there's one of the units and from one unit, it then has, for lack of a better term, it branches off to 4 different vents- 3 bedrooms and a bathroom- which to me, seems like a bad design- the service man halfway closed one of the vents from the attic, to force more air,(vents located in ceiling 15 feet or so above the floor of the room), into two of the other rooms but it's still not really sufficient. We're in Boston- so yes, it's cold but no different than most of the country is during the winter. I'd also say that yes, cooling of those rooms is inadaquate especially during the hot days of August. The boiler system is a buderus and it's four years old, so it should be a decent system, (have to check on the model number) Thanks for your insights to this. I'm trying to figure out if running at a constant 160 degrees is just consuming more oil/energy then necessary. Thanks

  • psd_3
    psd_3 Member Posts: 86
    Logamatic mode manual/auto?


    I'm not familar with your heating system type. Sounds like it is a hydronic system (boiler with circulators) but then with some sort of heat exchanger to adapt to forced air with registers for heating and cooling??

    Are you saying that your Logamatic 2107 is being used in manual mode at a fixed temperature of 163F? If so, that is a waste of a great piece of equipment! You could have used an inexpensive aguastat for this application instead of a sophisticated unit with outdoor reset control.

    We still need to get to the root of your problem though. Seems like your heating zones are not well sized and/or balanced ... but without knowing more about heat loss requirements and your actual system, I still need to question your entire configuration.

  • Ed_58
    Ed_58 Member Posts: 1
    Logamatic mode manual/auto?


    Yes; you pretty much described our system- boiler with circulators- hydronic forced warm air- 8 independent zones- All I can tell you is the exchanger provides forced hot air and central a.c. in the summer. I think what I need to do is find a local service company that really understands this system and can help troubleshoot the problem and the inefficiencies of this set up.

This discussion has been closed.