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Natural gas line capacity for adding 85K BTU mod con radiant system?

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ekubec
ekubec Member Posts: 12
Hi, folks.

Been working on adding a mod con hydronic radiant floor system to efficiently heat key areas of my house. A 135k BTU forced air furnace currently exists. My question is: does my house have enough capacity in the natural gas line to add the HTP ELU-85WBN boiler component of the system?

Here are the current specs of the natural gas system: 1" ND pipe: about 35 feet from meter to a 1" x 1/2" x 1/2" T where the 1/2" ports serve a 135K furnace and a 55K water heater. Before that T that feeds these appliances above there is another T (1" x 1" x 1/2") and 3 x 1" right angles. From this 1" x 1" x 1/2" T, the 1/2" feeds another 20 - 22' with about 4 right angles to a 25k BTU fireplace.

I've looked at some of the natural gas capacity charts for length and size of pipe, but am not confident I know enough to make an educated guess.

Folks may question why would I want a furnace and a radiant floor system. It's a two part answer: 1) I would keep the furnace because it is already installed and would give me redundancy in the event the hydronic system fails and I need to order a part and find a service provider. I am in Denver / Front Range area where hydronic is not as common as it seems to be in the NE. 2) part is I want a radiant floor for the 'core' living area: a 'great room' that includes the living room, the breakfast nook/kitchen table, the kitchen, the foray, the dining room and the open stairs to the 2nd floor. As a side note it seems incredibly difficult to get a heat load for this 'room' as all of the above are connected with no doors.

My design principal is to keep it initially focused on the core living area. Keep head to a minimum. Use a single zone with multiple branches each with head +/- 15% for the core area. Use a combination of low temp radiators and radiant floor and some wall. Get a delta T of about 13. Make the core single zone emit about 15k BTU at 130 degrees so to give plenty of capacity to set back and keep the mod con doing both without short cycling. By using low temp radiators inline before the radiant floor (which is 1/2" pex al pex set 2 per joist bay, set in U channel aluminum with heat sink transfer grease, then "pressed" onto sub floor with 3/4 inch rigid foam and 7/16 OSB) I believe I will get enough output. If it is too much, it will bleed off to the second floor.

Comments

  • hot_rod
    hot_rod Member Posts: 22,258
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    This fellow does a good job of showing the procedure. Watch it and dump your numbers into the example.

    It is hard to blend radiant and forced air, so be sure you design the radiant to cover the load, even on design day. Really should do a room by room load calc to assure your assumptions are realistic.

    Colorado must be in the top 3 radiant markets in the US, probably 100's of radiant savy contractors in that area. I train across the US and Canada, turnout at Colorado events is always the highest. Same with hydronic specific wholesalers, dozens of them.

    Skip the heat transfer grease. Use the fins that have a tight snap fit.

    https://video.search.yahoo.com/yhs/search?fr=yhs-ima-st_mig&ei=UTF-8&hsimp=yhs-st_mig&hspart=ima&p=sizing+gas+piping&type=q3000_A1BWP_set_bcrq#id=1&vid=022ba9bf51e05c0d9976ee92a7a807bb&action=click
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    ekubec
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,622
    edited December 2022
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    No not even close. You have to measure from the meter to the furthest appliance (fireplace?). Looks like you have a 60 or 70' run but you have to add the drop to the farthest appliance to get the total run.

    Then you use that length to size all the mains.

    The branches can be sized using each branch's actual length

    Your actually undersized with what you have.

    What you have is actually too small with what is connected

    The branch that feeds the furnace and water heater should be 1" with with 3/4 to the furnace and 1/2" to the water heater

    Fireplace is ok on a 1/2" branch

    The branch to the mod con should be 1/2" if under 20'

    You probably need 1 1/4 off the meter

    if you ditch the furnace your probably ok with 1" off the meter

    In addition, the meter needs to be checked to see if it can handle the total load of 300K

    This is a guess based on the info provided but seeing that the a

    You might be able to convince the inspector that the boiler and furnace will not run at the same time. (you could electrically interlock them) but seeing that the gas line is too small.


    I will take a guess that originally the furnace and water heater existed, and the gas line was large enough and the fireplace was added, and the added length had to be in the calculations now
    ekubec
  • ekubec
    ekubec Member Posts: 12
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    Just took a look again at the meter. 5psi mean, 250 C.H.F, and 1/2" Diff. Strange. Coming off the meter to the house the pipe is 3/4, then goes into a 1" T (3/4 x 1" x 1") where one of the 1" goes into the house, and the the other 1" is plugged. Water heater, furnace and fireplace were all 'original equipment' to the house. This would seem to imply that it is even further under capacity. I looked at that video on sizing for natural gas.
  • ekubec
    ekubec Member Posts: 12
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    Colorado must be in the top 3 radiant markets in the US, probably 100's of radiant savy contractors in that area. I train across the US and Canada, turnout at Colorado events is always the highest. Same with hydronic specific wholesalers, dozens of them.


    Thanks, Hotrod. You familiar with: www.brothersplumbing.com ? They sponsored local Winter Fest event, and their website links to HTP Elite boilers, which they indicate they prefer.
  • mattmia2
    mattmia2 Member Posts: 9,747
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    I would pipe the panel radiators and radiant separately back to the boiler. You can control them as the same zone but I would supply them separately so you can control flow separately and if necessary supply the panel radiators with a higher temp. Also better control of the temp supplied to the floor.
    ekubec
  • hot_rod
    hot_rod Member Posts: 22,258
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    ekubec said:

    Colorado must be in the top 3 radiant markets in the US, probably 100's of radiant savy contractors in that area. I train across the US and Canada, turnout at Colorado events is always the highest. Same with hydronic specific wholesalers, dozens of them.


    Thanks, Hotrod. You familiar with: www.brothersplumbing.com ? They sponsored local Winter Fest event, and their website links to HTP Elite boilers, which they indicate they prefer.
    Doesn't ring a bell. I've known and worked with Advanced Hydronics in Denver for 30 years or so. Check the find a contractor list on this site.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream