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New Member heat loss check and design help

OliveoneOliveone Member Posts: 5
Hello this is my first post!!! Need Help to set up my radiant heat. First part is to verify the load data below. To make sure I am in the right ball park as this is my first time doing this. Below I will go over building build as to help clear up any questions before hand. Only thing that is done is the install of the pex pipe in the concrete and a small forced hot air unit to make the area warm over the past few winters. I work save money and build then do it all over again.

Building plans and permits are required here in my area. I am a DIY person within reason. I have friends that work in the trades and I help them they help me.

I live in the Kingston New York 12401 area of upstate New York. I have been working on a shop build since 2015. In 2015 I poured the 28W x 48L (1344sq ft) monolithic slab with a 2 foot by 2 foot outside edge with 5 inch the middle of the floor. Floor is about 45 yards of concert with fiber mesh. The base was 4 inches crushed stone compacted and watered a few times to make it strong. There is a vapor barrier and 2 inch xps foam under all concrete. There is a 1 foot by 1 foot square ½ inch rebar grid over the floor on 2 inch heavy metal chairs.

The 2 foot thicken edge of the concrete floor and the walls on top are insulated concrete forums with an 8 inch of concrete about 12 ¼ inchs wide. The pex pipe was started about 30 inchs in from the edge of the concrete. Pex pipe lay out is 23W x 44L (1012sq ft). Pipe was zip tied to the rebar is 4 zones of uponor pexa ½ inch heating pipe about 260-280 feet each. Wish I had just put in 5 loops but can’t change that now LOL… The outside of the slab is insulated by 3 - 6 inches of xps foam, with a horizontal piece going out 16 inches on the bottom.

The walls are ICF with 8 core 12 feet high. Openings for the walls are follows.
1. Man Doors 2 each 36 x 80 in solid wood door with double pain glass in the very top only.
2. Over head door 10’ x 10’ with a r18 rating
3. Windows are Anderson 400 series 32” x 46”

The upstairs of the building is a big gambrel roof all in one room at this time. It is 13 feet and change in the center. This is made out of 2x12 x12 on all four side of the gambrel. Roof when it is insulated will be at lest an r38 and the walls an r 21.There will be a double solid wood door out front and 6 Windows that are Anderson 400 series 32” x 46”

Currently I have a 60,000 BTU force hot air unit 96% that I use to heat the ground floor area when I am working out there and leave it about 50-55 when not working.

I have done a heat loss but not sure it has been done right. See info below.
The zone load for the ground floor is around 23,600 with a flow of 2.37 GPM of 120 water and a total of 5.4 head. The outside temp was used for Kingston NY with a 2 degree temp. The room temp was set at 70 with floor
temp at 79.
The zone load for the second floor was around 22,600 with a flow of 2.26 GPM of 120 water and a total of 3.9 head. The outside temp was used for Kingston NY with a 2 degree temp. The room temp was set at 70
with floor temp at 79.
Total heat load was 41,550 ( second floor numbers may have a gain from the down stairs as the numbers
don’t match.) Total head was 6.1.

This year I took an old 15,000 btu window AC unit put in a window and it would cool down the shop on the very hot days here in NY. I am talking about 96 outside and the room could be 76 inside. This was only used a few hours a day. I would work outside till the heat got too much then work inside for a few hours in the middle of the day.

The primary heat for the building will be radiant but will keep the force hot air for any needed increases as the slab is too big to change in a few hours time.

Can someone please double check to make sure the numbers are in the right ball park for heat loss load info?
Once the loads are verified or fixed I will be working with lots of help from you all for the right equipment and way to have it installed.

I would like to use equipment that once installed would be like my oil boiler that I can service on my own. Pellet stove for heat and oil for hot water and back up heat source. Burn less than 400 gallons of oil a year and have all service parts on hand for any break down. Boiler service man comes by every 2 year for a cleaning and check up. I do the service the other years to include pump strainer, filter and a nozzle.

I am not a heating or plumber so please help me out and teach me please!! I have spent over 500 hours reading on the right and best way to do this. Then you think you on the right path and you read something and you’re not sure. This is one of my ideas. Install a GV90+4 84,000 BTU High Efficiency Boiler (Propane) a friend has one heating his shop with radiant heat that is working good. I would use like to use 40 gallon indirect water heater for the heated floor. This way I could set the floor temp to the 120 and be done with it if I need more temp would be easy to turn up to 130 or down to 110.

Once the heat loss is verified I will move to design phase. Once the design is done I will go to 5 or 6 plumber in the area ask for the cost to install this design.

Sorry for this long book LOL I hate to write. I did not want to leave anything out !!

Can someone check the heat loss and then help with the best was to make this work.



  • Steve MinnichSteve Minnich Member Posts: 2,618
    Jason - That would be a fair amount of work for anyone to do. Based on the construction data you have and the boiler you chose, my guess is that it’s oversized. 
    Author - Hard Knocks: My Life Inside Boiler Rooms
    PHC News Columnist
    Minnich Hydronic Consulting & Design, LLC
  • OliveoneOliveone Member Posts: 5

    Yes it is an over sized unit. According to my calculations I should need about 50,000 they do have a unit that is about 55,000. If my numbers are wrong then I am short on needed btu’s. I would like to be able to have one as the primary and one as the backup. That way if one went down I would not be cold while getting it fixed. My home is heated with a pellet stove and the backup is oil heat.

    Anyone have some help here.

    Currently I am trying to get the ground floor radiant working. Second floor is about 2 year out from needing heat. Trying to confirm the load need and feet of head for the pump. The area is 28x48x12 with r21 wall and r30 ceiling with 1200 feet of ½ pipe in 4 zones with 1 inch manifoled. There is about 175 SQ ft of openings. With the load info and the feet of head needed for the pump I could start ordering parts.

    Thanks in advance

  • hot_rodhot_rod Member Posts: 14,087
    Your slab numbers look to be 17 btu/ sq ft, sounds reasonable in a well insulated building. Upstairs load looks maybe high, did you use heated space below for the calc? Windows and doors add to load, of course.
    Most load calcs have some fudge factor, 10% or more, so 50K is what I would trust.
    Keep in mind once that much mass is heated you could coast a few days of below design conditions. And you also have unit heaters?
    Probably less than 2% of the heating season are you at or below design. If the shop dropped a few degrees, would that be a big deal?
    Get one of the ECM circulators with plenty of adjustment to dial in to the actual requirements, your math looks reasonable.

    Here is some BIN data for upstate NY, showing actual hours at various temperatures.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    The magic is in hydronics, and hydronics is in me
  • Alan (California Radiant) ForbesAlan (California Radiant) Forbes Member Posts: 2,537
    edited November 24
    Let's say your longest loop is 300' and you're flowing .5 gpm/loop. The pressure drop is under 3'. Add in another foot or so for piping to and from the manifold.

    If you have 4 loops at .5gpm, that's 2gpm.

    You could use a Grundfos 15-58 at the lowest speed or a small ECM pump.

    Often wrong, never in doubt.

    Click here to learn more about this contractor.
  • ZmanZman Member Posts: 6,128
    Your comment about the boiler and indirect is confusing. Typically the boiler heats the floor directly using outdoor reset and the indirect heats the DHW indirectly in the tank. The GV-90 has always looked like a Frankenstein to me. Some folks swear by them, to me they look like an afterthought.
    What are your available fuels? Is natural gas an option?
    This sheet allows you to input your available fuel costs and make the right decision.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • OliveoneOliveone Member Posts: 5
    Thanks All for the replies. I got busy have not been online in a few days. B)

    Funny story was at the local auto shop and a new boiler tech was at the shop talking to the owner. So I asked if he did any work on the side. He said yes all the time. I was thinking great. Told him I was doing radiant he said we just did one last week. Wow so asked what type he said staple up under floor. This is the same as I will be doing upstairs in my building. I was starting to have high hopes. I asked what metal plate he used on the job. The reply was metal plates are a waste of time and money. OMG chucked out the contact number on the way out of the shop.

    Hot Rod

    The upstairs area is a gambrel roof that is 13 feet high in the center an zero on the sides. This will take a little extra heat to keep the floor warm. I did not use heated space below as this was the first time I have done a heat loss.

    The shop is the ground floor. This was sized to be heated by the radiant heat to 70. I don’t use the shop every day so the radiant would be left a little lower at like 48-50. The when I need to shop would use the force hot air unit heater to bring it up to the working temp for the time in the shop. Right now I turn up the heat ( forced hot air ) from 48-50 to 60-65 about an hour before I am going to work in the shop. I start work dress warm then remove items as the shop warms up.

    It would be no big deal if the floor dropped a few degrees.

    I started the research on the ECM circulator looks like I may try the Taco 0018e ECM High-Efficiency Circulator or a GRUNDFOS ALPHA2 15-55F. I need to read about this more before I decide. Any input ??

    Alan Forbs

    Like the pressure drop tool in the picture!!! That picture could have saved me a lot of time. This is how we learn LOL.

    Grundfos 15-58 was on the short list for possible Circulator.


    I believe that the GV can only heat to a low of 140. I would need to put in a P/S zone and mixing valve. Then try to figure that all out. I would use the indirect as a storage tank and run the water to the floor from the indirect. I could easy turn down the water temp to floor on the indirect to less than 120 in the spring and fall. I would need a second circulator, air scoop and expiation tank.

    House has oil heat and pellet stove, shop has a 500GL propane tank. Propane is cost effective and we have no Natural Gas within 14 miles of my home.


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