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Primary/secondary worth it?

super_snop
super_snop Member Posts: 48
Hello everyone. I’’ in the process of researching how to set up a new boiler that I will be installing after the winter time. My house is a 2 floor colonial 2200 sqr feet. Heated by an oil fired boiler supplying water to 3/4” copper fin tube baseboards. I have not had the chance to do a heat loss calc yet or measure out the radiation. Last year I did some updates to my old boiler and from research decided against cold starting. I currently run a 180 high limit, 145 low limit, with the economy feature enables on my hydrolevel 3250 plus. After running a year like that, I did not notice any ill effects from condensation or soot. Boiler was barely dirty. Just want to get my planning right for when I eventually install the new boiler. My main question is... Is a primary/secondary setup ideal for a small residential system like this? I read all kinds of mixed things. Most saying that its not necessary with 3/4” fin tubes.

Comments

  • HomerJSmith
    HomerJSmith Member Posts: 1,625
    edited December 2019
    Depends on the boiler. A Hydrostat is probably not necessary on a modern boiler.
  • hot_rod
    hot_rod Member Posts: 16,563
    Conventional oil fired cast boiler? Probably not.

    Do an analysis of the heat load and amount of heat emitters. See how low of a SWT you can run at design condition.
    If you can run low temperatures you may need a boiler return protection valve. You do not want to run extended periods with return temperature below 130F, without protection.

    This journal will take you through the steps to see what some options are.
    https://www.caleffi.com/sites/default/files/file/idronics_25_na.pdf
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    super_snop
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,730
    What's your zip code and how many gallons of oil did you burn last season, for a quick heat loss.
    The installer is the most important part of the puzzle, as is proper heat loss.
    Primary/secondary may not be necessary, but definitely protecting the boiler from low return water temperature is very important.
    steve
  • super_snop
    super_snop Member Posts: 48
    My current set up is a 20 plus year old thermodynamics steel boiler. I was specifically interested in replacing it with a cast iron weil mclain wgo. Just trying to figure out what the best option is for efficiency without going crazy. I dont make DHW with the boiler. Its just for two zones of heat. The house is definitely over radiated. Pretty much baseboard wall to wall in each room against one of the walls. Its looking like I wont be able to figure out whats best until I do the heat calc and work out the numbers.
  • super_snop
    super_snop Member Posts: 48
    > @STEVEusaPA said:
    > What's your zip code and how many gallons of oil did you burn last season, for a quick heat loss.
    > The installer is the most important part of the puzzle, as is proper heat loss.
    > Primary/secondary may not be necessary, but definitely protecting the boiler from low return water temperature is very important.

    My zip code is 11779. As far as how many gallons.. I don’t have an accurate number. I use a wood stove on and off throughout the winter so the amount of oil burned won’t be very accurate.
  • STEVEusaPA
    STEVEusaPA Member Posts: 5,730
    You'll have to do it the long way then. You may want to look at an EK.
    https://energykinetics.com/productoverview/
    steve
  • super_snop
    super_snop Member Posts: 48
    > @STEVEusaPA said:
    > You'll have to do it the long way then. You may want to look at an EK.
    > https://energykinetics.com/productoverview/


    Thanks. I will definitely look into it.
  • mattmia2
    mattmia2 Member Posts: 5,742
    If you have one loop per floor and the perimeter is all fin tube element, you will want to make sure a method to keep the output matched to each room is accounted for (one way to do it is to run plain pipe in some of the covers so that there is more and less emitter in different rooms). If it is just a loop and no bypass or other means of balancing it, the end near the boiler will have hotter water and more output per foot than the end near the return.
  • gaabbee
    gaabbee Member Posts: 43
    Hey neighbor! I'm in 11779 too. Check out slant fin's app for heat loss calculator
  • super_snop
    super_snop Member Posts: 48
    Hey buddy!! I downloaded it. Hopefully if I have a chance this wknd I can measure everything out and get a heat loss calc.
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 3,339
    Are there any rooms that are over-heated or under-heated? This is important to determine if there is too much radiation.

    You need to start with the room with the lowest temperature and get that room comfortable on the normal "coldest day of the year" (otherwise known as design temperature). Once you have that water temperature right, you can start removing sections of fin from the radiators or placing aluminum foil around the fins to block some of the heat in the warmer rooms, by trial and error, you can get a fairly well-balanced zone.

    Now set the water temperature (high limit) to the lowest water temperature that will provide the needed amount of heat. This may take some time and several cold overnights until you get it right. depending on how much "over radiation" you may be able to start at 165°F and see what the room temperature is overnight. If the room is 8° too cold, then raise the limit temperature by 8° and see if that gets you closer.
    Edward Young
    Retired HVAC Contractor from So. Jersey.
    Services first oil burner at age 16
    P/T trainer for EH-CC.org
    mattmia2super_snop
  • hot_rod
    hot_rod Member Posts: 16,563
    Most fin tube have adjustable damper fins to adjust output

    Should not need to remove fins
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    mattmia2super_snop
  • super_snop
    super_snop Member Posts: 48
    @EdTheHeaterMan makes perfect sense. The master bath and bedroom get the hottest. Right now I have 2 rooms under construction and those doors are shut so that may have something to do with it. Once I get everything set I will open all the doors and put thermometers in a few rooms. Seems like I have had pretty significant savings using the hydrolevel efficiency mode. It isnt an outdoor reset but works similar. It adjusts the high limit based on how many calls for heat and how long the call for heat is. Im really looking forward to doing a proper heat calc. My current setup seems oversized. Currently running a 1.0 nozzle and the boiler IBR rating is 149k btu. Current setup is working. Only reason I plan on swapping the boiler with a new one is because this one is 20+ years old. I’m going to be in this house for a while. I would rather be worry free. Boilers arent a problem until they are a problem. Just want to make sure whatever route I go is correct and the best for my application. I plan to do the install myself and have my tech come set up the burner with a combustion test.
  • clammy
    clammy Member Posts: 2,755
    Replace your boiler w something better then a single pass boiler for God’s sake . Take a look at buderus g115 or any three pass boiler for that matter easier to clean no combustion chamber ,easy to thoroughly clean and high eff number over single pass and better grade of cast iron and last but not least better insulation on the boiler ,leveling legs . These where the only oil boiler I installed when I did oil unless they needed a tankless .again do yourself some thing bettter then a single pass ,on a side note have your water tested for tds and if high have the system filled using de mineralized water or you may need to your boiler delimed if it starts to percolate .Three pass boilers can run lower stack temps so you should possibly have your chimney lined it would be a smart preventive measure peace and good luck clammu
    R.A. Calmbacher L.L.C. HVAC
    NJ Master HVAC Lic.
    Mahwah, NJ
    Specializing in steam and hydronic heating
    STEVEusaPA
  • super_snop
    super_snop Member Posts: 48
    Thanks clammy. I will definitely look into a 3 pass. My chimney is already lined with a 6” stainless liner.