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Tekmar 260

Sweet_2
Sweet_2 Member Posts: 143
Just installed Tekmar 260 on on/off boiler with with hot water baseboard heat convectors. Sure is a cool control , one thing Im curious about. AT preset boiler minimum temp 140 is condensation going to be an area of concern. Thanks

Comments

  • Ted_9
    Ted_9 Member Posts: 1,718


    No it is not a problem. That is where we set it. As long as you have everything set and installed properly. All of the sensors in the right place etc.

    If it makes you feel better, call Tekmar on Monday.

    PATRIOT HEATING & COOLING, INC.

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  • hr
    hr Member Posts: 6,106
    Depends on where

    you have that return sensor mounted :) If in fact it is at the boiler return piping connection, sounds like it is doing it's job and protecting your heat source.

    Assuming you have a non condensing boiler?

    hot rod

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  • Sweet_2
    Sweet_2 Member Posts: 143


    The sensor is located on supply side per installation manual. This is a single stage 80% cast iron boiler. Seems by the control display that boiler on temp is actually 130 degrees 10degrees below boiler minimum setting. Just worried about 110 degree water condensating.Ofcourse this is at a very mild 50-55 degree outdoor temp.
  • hr
    hr Member Posts: 6,106
    I think

    on that control the minimum boiler return temperature is set by using the boiler target temperature. The boiler min is the lowest water temperature the control uses as a Boil TRG number. I think this is how the return is protected. You may have to boost the target temperature up.

    Although I don't have a 260 manual in front of me :)
    I have this control on my own boiler so the programming is vaguely familiar.

    It takes a few read throughs to get the hang of tekmarezze, but I think you need to do some more adjusting to assure that boiler "sees" at least 130- 140° at the return taps at any load condition, any outdoor temperature.

    With that type of boiler you do have a bottom side limit in regards to return temperatures. Just the nature of the beast :)

    It won't tolerate 110° return temperature very well, very long.

    hot rod

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  • Jeffrey Campbell
    Jeffrey Campbell Member Posts: 51
    Tekmar

    Also, one more thing to think about with the 140 degree boiler minimum and the 130 actual return, is the differential. I think the diffential works even with the boiler min. So if your diffential is 20 degrees then you will have a 10 degree differtial above and below the set target temp(in your case boiler min.) You might want to change a 10-15 differtial? You as might want to look at time delay for boiler fire. If the boiler takes longer to fire(safty checks) than the control anticipates the temperature will drop lower than you desire. Tekmar controls are amazing! They have many adjustements for all applications. Good Luck Jeffrey Campbell
  • hydronicsmike
    hydronicsmike Member Posts: 855
    Excellent Rad!!

    Only very good replies here. If you're still concerned or have questions, call me at 250-545-7749, Ext. 214.

    Regards,

    Mike

    www.tekmarcontrols.com
  • Neil_5
    Neil_5 Member Posts: 179
    What Problem(s) ?

    Hot Rod:

    Having a return temp lower than 130* actually causes what type/kind of damage(s)to the boiler?

    I read everywhere regarding low return temp is a no-no, but I would like to know what kind of problems develop because of the low temp.

    Also, this low temp return rule: does this apply all the time, meaning: most of the time my circulator is on and no fire. Does the low return temp rule applies to this situation as well or only when the boiler fires up?

    Thanks,
    Neil
  • hr
    hr Member Posts: 6,106
    This article tells more about return protection

    http://www.pmengineer.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2732,90176,00.html

    Basically a low return temperature may cause the boiler to sweat (condense). Just like the water that pours from your cars exhaust pipe when you first start. Waters of combustion is what you are seeing.

    This moisture (water) can cause the sections to start rusting and corroding. The water may drip on the burner tubes and cause incomplete combustion. Burner tubes may rust, corrode and start to plug, again causing incomplete combustion. Incomplete combustion can lead to CO issues, of course.

    You may get corrosion in the divertor hood and flue piping. Any or all these are possible if the boiler is allowed to run for extended periods under low temperature conditions.

    Short cycling a boiler can cause the same symptons.

    Avoid both it at all costs. Or buy a boiler built to handle, and take advantage of, the condensing mode :)

    hot rod

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  • Sweet_2
    Sweet_2 Member Posts: 143
    Good stuff Guys What a web

    Simply Rad Your right the differential is indeed 10 above 10 below. Ive adjusted boiler min. to 150 , seeing boiler on at 140ish boiler off 155-160 Ill play with it a little more just waiting for design temp.What a cool control. Hydronicsmike , appreciate the number Ill call tommorrow.
  • Empire_2
    Empire_2 Member Posts: 2,343
    Tekmarcontrols.com.

    Everything to help you out. Great web sight.
  • Neil_5
    Neil_5 Member Posts: 179
    Great Info

    Thanks Hot Rod:

    Since low water return is so important, why dont all boilers have this protection? cost?

    With the Tekmar control, 140 is the boiler min, and with the diff. the control can wait for the water supply to be 125-130 before firing, which would make the return Temp in the low 120's depending on conditions. Would it then make sense to have the min boiler temp set at say 150?

    Neil

  • hr
    hr Member Posts: 6,106
    good question, Neil

    some boilers do come with protection. Viessmann simply uses a non adjustable 150° aquastat to fire the boiler pump. Simple and fairly effective.

    Burnham Revolution, and Weil GV Gold addressed this years ago with intergral mix devices.

    Radiant floor heat with conventional boiler has really brought this important need to the forefront.

    Dozens, if not hundreds of regular non condensing boilers have been hooked to low temperature radiant without this protection. I'd be willing to bet it is still going on :)

    The smaller HX boilers and the drive to lowest supply temperatures installations should be a wake up call for boiler manufactures.

    I suspect when the warranty cost overide the cost of shipping boilers with some sort of return protection, they will be standard equipment, from the factory :)

    hot rod

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  • hydronicsmike
    hydronicsmike Member Posts: 855
    To my knowledge...

    Condensation only becomes an issue if it occurs over a longer period of time. So when the Control fires the Boiler below the minimum because of its Automatically Adjusted Differential that is based on the Load to Minimize Boiler Short Cycling, the Control keeps the Boiler on until it is by the same half Differential above the Minimum if that is what the Target was. Then any Condensation that would occur while below the Minimum would burn off and doesn't pose a thread. Really, any Cold Start Boiler will condense during initial start up.

    But let the Boiler guys assure you that as well. Am sure I got Glen with Burnham and Noel at SlantFin behind this.

    So in my opinion, the Boiler Minimum can stay at the default of 140°F. But at the same time, Boiler Protection through a Mixing Device is always desirable. I personally would even use it on a Baseboard or Radiator System. Sure, Mixing costs a few extra Dollars to install, but if it makes the Boiler last soo much longer, I think it is definitely worth it. Would you agree?

    Mixing will also protect your Cast iron Sections from Thermal Shock. That alone makes Mixing very attractive to a lot of guys who have had to replace sections in the past. let alone the additional Benefits of increased Comfort level (Temperature Swings and Expansion Noises) and Potential Energy Savings.

    Best Regards,

    Mike
  • hydronicsmike
    hydronicsmike Member Posts: 855
    Thank you very much!

    Your feedback is very much appreciated.

    Mike
  • Sweet_2
    Sweet_2 Member Posts: 143
    Mixing Valve

    My next step is primary secondary ,do you find this to be advantagous gas consumption wise. Or will the primary circuit be fighting against the Tekmar control. By prim second The way Ive piped consists of 4 zones copntrolled by zone valves so the secondary pump will supply all 4 zones. Seems to me after reading a couple of Dans books to truly get primary secondary I need to revamp using zone circs which would be anice addition to the control. Thanks Gurus.
  • Ron Schroeder_4
    Ron Schroeder_4 Member Posts: 46


    Hi Sweet,

    You also have to look at your delta T in your heating loop. If your temperature drop from supply to return is large, you will need a higher boiler minimum temp than if the temperature drop is low.

    It also depends on fuel type. With 20% excess air, oil flue gas will begin to condense at a return water temp of about 115 degrees, propane at about 123 degrees and nat. gas at about 128 degrees. Combustion air humidity will effect the condensation temperature by about +/- 3 degrees from 0% to 100% relative humidity.

    Ron
  • hydronicsmike
    hydronicsmike Member Posts: 855
    Fuel Savings

    Although I am very confident that it should lower the fuel consumption a little bit, I don't know if it is negligible or makes enough of a difference in a residential application if it saves you another 5-10 bucks a month. But if a system water requirement could ever be below a Boilers minimum of 140°F, the Mixing Device would use less of the 140°F Water as the System requires lower water temperatures. Therefore, I would expect a Boiler to fire less if less of the 140°F from the Boiler is used to lower the Water Temp on the System side. Hope this makes sense.

    The more crucial benefit I would expect to see in overall comfort level by minimizing those temperature swings and expansion noises that are usually created by too high supply water temperatures to a system (IE Baseboard/Fin Tube Convectors, Staple Up with Heat Transfer Plates).

    Another benefit would be that through a Mixing Device, the Boiler Minimum Return Water Temperature is always ensured.

    What if a Baseboard System has a very small load because the Heatloss of the Building is low at a given time, a Conventional Boiler shouldn't operate below 140°F, but the Baseboard could get away with running on maybe 90-100°F Water Temp? In this case, the thermostats would naturally call for a shorter period of time and then be off for a longer period of time as the overshooting in the Room temp may be experienced. Then the Boiler is shut off and remains somewhat warm inside (insulated jacket), while the water out in the system may cool off to maybe even room temp (70°F?) because of no flow. If the Boiler is still too hot (maybe 160°F when operated on a Boiler Differential), would it be a problem to return 70°F to it? Not too sure if it could create Thermal Shock or what the Boiler Manufacturers would think of this, but in my opinion, Boiler Sections don’t crack because of poor quality Boilers, they crack because the Boiler is abused and Mixing will not allow that to happen. Just a thought and would appreciate some feedback from Noel or Glenn on this if they see this post. When it comes to protecting the Boilers, always consult with the Boiler Manufacturer.

    Please never hesitate to call me at 250-545-7749, Ext. 214, should I be able to help you with anything.

    Best Regards,

    Mike

    www.tekmarcontrols.com.
  • Neil_5
    Neil_5 Member Posts: 179
    with constant circulation

    or lets say >85% circulation, at any given time, would the supply and return temp be the same or very close? For eg.

    Say the supply temp (boiler target) is 150* and the boiler is off, but STAT is calling for heat and circulator is on, 15 mins later supply temp is at 135*, because the water has been circulating for the pass 15 mins, I would guess that the supply and return would be at 135*, would it? Therefore when the control fires the boiler at say 135*, the return temp is already at 135* and there for no condensation problem? Am I correct?

    Neil
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