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Hot water boiler sizing..

ALNY
ALNY Member Posts: 37
Had a boiler working fine in a property, now flooded and needs to be replaced. The flooded boiler specs are as follows:

Weil McLain boiler model CGM-4-PI natural gas boiler.

input BTU/HR 105000  DOE heating cap 83000

NET I=B=R output is 72.2

====

I like the Burnham products, and was thinking of going with their Series 304

which matches the specs more accurately....the 304 has 105000 BTU, and 77000 Water MBH

<a href="http://www.usboiler.net/products/boilers/series-3/">http://www.usboiler.net/products/boilers/series-3/</a>



however my pockets are allowing for the Burnham 2 series...

however their  Input on the 204 is 96000, and Water MBH is 70K on the model 204.....here is a manufacturer reference:

<a href="http://www.usboiler.net/products/boilers/series-2/">http://www.usboiler.net/products/boilers/series-2/</a>



The 205 i think would be oversized, and suggestions, or info i left out, let me know....



as i would like to get some assisatance from some of the more seasoned pros in here.

Thanks.

Comments

  • SWEI
    SWEI Member Posts: 7,356
    more info

    Don't assume the old boiler was properly sized -- most aren't/



    In order to properly size the replacement, we need several pieces of information.  This starts with a heat loss calculation and an inventory of how much/many of what kind of radiation is installed as well as any issues to be addressed (rooms that are too hot or too cold.)



    Is the boiler also used for domestic hot water?
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    hope this is some help

    The domestic hot water is produced by a 50gallon water heater.

    None of the rooms were too hot or too cold.

    and i have no heat loss calc

    and there are radiant baseboard heaters in the home.



    I have more familiarity with steam systems, and know that water is a diff beast.
  • SWEI
    SWEI Member Posts: 7,356
    heat loss calc

    Still needed, but we can start with how many linear feet of baseboard and what brand/type?



    An indirect water heater will lower your DHW fuel use and/or provide more hot water.  You can add that later if you want.
  • ALNY
    ALNY Member Posts: 37
    I will get back to you

    I am not at the property as of yet, however i will be going there tomorrow, i will get all the

    linear footage of the baseboards and type..anything else you might need sinnce i will be going out there.

    i will get the heat loss cal for you as well.....is the heat loss cal something i can do?

    are there apps online that than help me with some calculations/ or do i need to hire someone?

    I really appreciate all of your help.



    Thanks.
  • SWEI
    SWEI Member Posts: 7,356
    make a sktech

    Of the room sizes, baseboard lengths, pipe routing and sizing.



    Heat loss calc tools are online, but the sketch (amended with window sizes, wall heights, etc.) is a starting point.
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    Made a diagram

    I made a diagram of what i wanted to put in there, if you could, please review it, and give me your feedback.  Thanks!

    If there is anything you would do different, let me know....if there is something you would add let me know./ or placement.



    Please note that drawing is not to scale and some of the piping has been expanded for clarification of setup....Any feedback would be highly appreciated.
  • JStar
    JStar Member Posts: 2,752
    edited January 2013
    Piping

    Things I would change...



    Move the circulator to the supply after the air scoop.

    Move the water feed into the line of the expansion tank.

    Get rid of the air vents on top. They're not necessary if you bleed the system correctly.

    The flow controls aren't required when you zone with valves.

    Install a ball valve before the air scoop, so you can bleed the system from both zones without moving hoses around.
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    thnx for suggestions

    I will omit flow valves obviously as zones would shut and stop flow.



    I have seen circ pumps both on return and supply, pros cons...better pressure on supply side i am assuming, because pump has to push into the boiler if its on the return side like i have it in my sketch. I had it on return side because of installation, and ease of changing it, as space is pretty crap to place on supply side...



    So basically by putting circ pump on supply side after scoop, and putting ball valve in front of scoop to cut off water, the city water will replace water being expelled on boiler drain over the LWCO on the supply side, and no need for individual zone flushing....is that correct?  Thanks again.
  • SWEI
    SWEI Member Posts: 7,356
    diagram

    of the near-boiler piping, and Joe gave you some good advice.  Did you get a chance to measure the baseboard and note the type?
  • ALNY
    ALNY Member Posts: 37
    first thing in the morning

    Heading out first thing in yhe morning, and will have all info for u
  • Dave H_2
    Dave H_2 Member Posts: 423
    Another drawing

    Using theFloPro Designer software.

    Once the heat loss is done, based upon the little info I have right now, your supply pipe may be smaller than 1-1/4"



    Dave H.
    Dave H
  • ALNY
    ALNY Member Posts: 37
    Two questions on your flow control diagram...

    What is the green item next to the supply line exiting the boiler?



    I see you have the city feed line tapped into the expansion tank on the supply side....i believe this is what JStar was referring to, but i will wait for him to get back to me....but i think so , since you have it plumbed on the supply side as well.



    I am leaving now for the heat loss items, and will get back to you ... much appreciated.

    I had no idea that this forum would be so helpful...



    I will take pictures of the baseboard heating, and all footage, etc. and be back by this evening.
  • ALNY
    ALNY Member Posts: 37
    FEED line into hot side

    I have always worked with steam systems, and feed line is always tapped into the return side....no danger into tapping into supply side as temps dont get hot as steam, and no cracking in hydronics, as i have seen layouts with both...feedback is appreciated.
  • Paul48
    Paul48 Member Posts: 4,492
    Steam vs Hydronic

    No aternative with steam. At least this way, if cold water is added while the boiler is running, it doesn't go directly to the boiler.
  • Dave H_2
    Dave H_2 Member Posts: 423
    Green Item

    That would be a Low Water Cut-Off here is the link http://www.taco-hvac.com/uploads/FileLibrary/100-8.1.pdf



    Dave H.
    Dave H
  • ALNY
    ALNY Member Posts: 37
    LWCO

    Thank you, your drawing much cleaner than mine....updating heat loss numbers
  • ALNY
    ALNY Member Posts: 37
    LWCO

    Thank you, your drawing much cleaner than mine....updating heat loss numbers
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    ROOM SIZES

    HERE IS THE BREAKDOWN OF THE ROOMS AND THE AMOUNT OF LINEAR FEET THAT THE PLACE CONTAINS:

    2nd floor first : This is a two story property., all baseboard heaters have 3/4 in pipe.

    There was no name that i could notice anywhere...if cheap is a brand, these looked cheap..lol.

    OVERALL HOUSE DIMENSIONS is approximately 

    I will start with second floor:



    one room 6x10': 6 feet of baseboard heating  has one window

    second room bathroom 6x8 6 feet of baseboard heating / one window

    common hallway, nothing

    third room 12x12 and 20 linear feet of baseboard one window

    4th room 30 linear feet of baseboard/ two windows

    5th room 10x10 and has 8 feet of heater, and one window.

    total linear feet for the second floor :  70 linear feet of baseboard heating.





    1st Floor:

    room one Kitchen 6x10 has 6 feet of baseboard and 1 window

    room 2 bathroom has no heating and one small window

    room 3 den area is 8x12 and only has 6 feet of baseboard two windows

    room 4 hallway area nothing

    room 5 8x15 and 8 linear feet of baseboard

    room 6 living room 35 feet of baseboard heating and two windows

    room 7 one 6 foot radiator for hallway area.



    1st Floor has 61 linear feet of baseboard heating.  The house rough dimensions

    as i didnt take them are roughly 35x20.

    Wall heights are roughly 10 feet in height.

    I took a picture of the baseboard and have included it below as could not find a manufacturer.
  • ALNY
    ALNY Member Posts: 37
    REVISED DIAGRAM

    I have revised the boiler piping based on the Burnham Manual, and

    suggestions that you guys have made in here have come up with the following diagram. Essentially the corrections that JStar recommended were a spitting image of what the Burnham manual also had as far as a setup for zoned systems.



    I would like to share, and get feed from you guys if you feel this is correct before implementation of the system..i have left the extra drainage above the zone valves in case i wanted the separate option of doing each zone separately. I was told by a guy at the supply house that bleeding the system would only be on the return side (and not as we have in here), or can it be done either way without any issues, as long as plumbing is correct?



    Also my only issue left is help with the heat loss...i have ordered this book called modern hydronics by  John Siegenthaler... i will take my time reading and interpreting it, however right now, i gotta do a crash course in hydronics...lol.



    Thank you, once agin for all of your feedback.
  • Paul48
    Paul48 Member Posts: 4,492
    edited January 2013
    Info

    Here's a link for slant/fin's heat loss calculator http://www.pvsullivan.com/Downloads.html There is no need for the expansion tank on the return as well as the supply.The boiler has its own hydronic controls and doesn't need the aquastat. I have seen aquastats placed like that on some boilers, and they have problems with temp control.

    I think you'll be suprized at what you get for a heat loss.I did your 1st floor quickly, and came up slightly over 24000 btus.
  • ALNY
    ALNY Member Posts: 37
    Aquastat

    So your saying, no expansion tanks at all for this system?



    So your saying the boiler control has a setting for a limit on temp internally (is boiler setting adjustable), and an aquastat is redundant, and would be an extra expense. Could i still setup the aquastat as a failsafe in case of factory failure?



    The original unit ratings were much higher, unless i am missing something.
  • SWEI
    SWEI Member Posts: 7,356
    edited January 2013
    baseboard load

    131 linear feet @ 600 BTU/ft = 78,600 radiation capacity (180F water, 20F ∆T.)



    Once you have your heat loss calc, the water temp gets lowered until the output matches the design load.



    Lower temps are good news -- a mod/con will be condensing most of the year.
  • Paul48
    Paul48 Member Posts: 4,492
    edited January 2013
    No

    In your diagram, you show 2 expansion tanks. The 1 on the return isn't necessary. I glanced quickly at the manual for the 3, and it says it has  a hydronic control. Look at the area...sequence of operation(page 48).As for having the aquastat as a redundant safety.....where do you stop? 2...3....10?
  • ALNY
    ALNY Member Posts: 37
    i HAVE DECIDED TO USE THE SERIES 2

    Thanks for the input Paul....I have decided to go with the Series 2, instead of the Series 3...I am not sure of the Series two has this control....if so, i will remove aquastat, no problem.....Much appreciate your help in this matter, and to all of you.
  • Paul48
    Paul48 Member Posts: 4,492
    edited January 2013
    Controls

    NORMAL OPERATION

    1. The Series 2 Boilers are equipped with an Intelligent

    Hydronic Control (control). This control replaces

    the traditional separate ignition control, high limit

    switch and circulator relay and adds energy saving

    thermal purge features. Energy is saved by starting

    the circulator and delaying the burner start when

    there is residual heat available in the boiler.

     The manual does say that some jurisdictions do require the use of an aux. limit control. I can't say whether it applies in your area.That boiler is cast iron, and requires a pypass to protect it from low return temps , and possible condensation.
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    THANKS FOR FEEDBACK..

    Yes, i am in the NYC area, and most likely they would require one, i will double check with local codes to see what they require....



     and as far as the bypass goes, would returning cold water be that it could cause issues and getting sucked up, or not realy because the cooler water will follow path of least resistance (to boiler), and the hot water will follow it into the cast iron boiler...ok so i will include a bypass...however the bypass valve, one question....



    Says to use a bypass throttle valve (mixing valve)? what are these?  can i just use a globe or ball valve, and

    whats  the recommended position to leave it in?



    I know that the pipe between the two has to be the same size, i will plumb it as shown in the figue as shown in the burnham manual, is this a system bypass, or boiler bypass....(i believe to be a boiler bypass).







    also included a page grab from burnham manual on the setup for clarification.
  • SWEI
    SWEI Member Posts: 7,356
    bypass

    Best bet would be an ESBE or Caleffi thermostatic boiler protection valve.



    No need for outdoor reset?
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    Just when i thought i had it figured out...lol

    Ok so here we go, what is an outdoor reset, and how does it work? What is its function...  Is it similar to a heat timer outdoor thermostat for steam systems?



    This is the valve that i found and would most likely purchase..

    http://www.pexsupply.com/Caleffi-521619A-1-Sweat-MixCal-3-way-Thermostatic-Mixing-Valve-w-Temp-Gauge



    Where does this mixing valve grab the cold water from?? City supply with another backflow preventer on it? or do i just tee from the original city feed after the pressure reg, and just send it to the cold side of the mixing valve....i have a 1/2" feed from the city, and 1 1/4" supply from boiler..., and then have the mix pushed into the return on the boiler?

    Would diffence in piping sizes be an issue? How would you do this? Reduce supply side to same as cold water side? And pipe to return what size?



    As far as outdoor reset, once i know what it is, i will see if i need.

    I looked up a bunch of stuff on the outdoor reset, looks good, (kinda like a heat timer for hydronics) but for now i think i will do without it...
  • SWEI
    SWEI Member Posts: 7,356
    outdoor reset

    varies the supply water temperature based on the outdoor air temp.  The intent is to deliver just the right amount of heat necessary to offset the building envelope losses.  It delivers superior comfort and efficiency.  Mod/con boilers come already equipped for it, since they can vary their output temps by design.  ORC on a conventional boiler typically requires an additional pump and often a buffer tank.
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    gotcha!

    Yeah i see the boiler protection valve is setup different than a standard mixing valve....

    the 280 thermostatic looks really good, and 140 is the standard temp it comes setup with....outdoor reset not really something i am going with.



    If the valve is open and no circulator on the return, this boiler protection valve will still work fine, correct?  i am concerned about flow from supply to bypass...and closes once it hits 140 degrees. In other words, i see they make one with a pump on it, would it be beneficial to have the pump one on my system? since circulator is on the

    supply side.



    http://www.youtube.com/watch?v=yfEyGy50P20





    i think i have nailed out most of the kinks....still any word on heat loss....i have tried some of the calculators, but seem lost on some of the R values its asking for.



    One guy stated 24000 BTU for first floor alone...after i get this done, think i will be pretty set to start threading, and soldering away!
  • ALNY
    ALNY Member Posts: 37
    edited January 2013
    HEAT LOSS CALC

    I tried a couple of different heat loss calculation programs and was not able to locate any......any suggestions on a good program?



    Surely there is a thread where this topic has been beat to death, i will see if i can locate any, but in the meantime, any assistance on how one does the subtractions,....

    Looks like the old boiler was sized by the method you used with the 600 BTU per linear foot, cause thats the size boiler in there, and it worked fine...but if it can be tweaked, all the better....
  • SWEI
    SWEI Member Posts: 7,356
    to pump or not to pump

    ThermoMix assumes you have a boiler circ already, ThermoBloc includes one.  I have not looked at the pump curves,
  • ALNY
    ALNY Member Posts: 37
    Boiler valve

    I think for now the boiler protection valve valve will have to go,..if i had the circ pump on the return looks like this boiler valve would be great...but no need for anther pump, i will just plumb them separately individually, should be fine.



    Thanks for your help on the topic....still looking at heat loss calcs,



    i did some of the heat calcs, and this is what i came up with usiing the build it solar site.

    Any feedback...on boiler size?
  • SWEI
    SWEI Member Posts: 7,356
    heat loss & boiler protection

    Boiler protection valve will work fine with the circ on the supply - it just diverts some of that hot water to the bypass leg until the boiler heats up.



    Not sure what that 23.3k heat loss is for?
  • ALNY
    ALNY Member Posts: 37
    THIS IS THE SITE I USED

    propbably inaaccurate but this is the site that i used....

    and the part your looking at is the numberrs i got from using the walls facing outside, etc, as it asked.



    http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm
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