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Warehouse, RF & Solar

hot_rod
hot_rod Member Posts: 21,882
garage doors are what hit me. 10 doors at 225 square feet each R-3 at the very best for an insulated overhead door. There was only about 4 feet of insulated wall between all the OH doors.

Yes the radiant slab works great for open and closing doors as far as response when the door close, but you still need the BTUs to keep that flywheel spinning.

Good idea on the 3/4 tube so you have the ability to move some large amounts of energy if needed.

I used a 15" oc, even though the calcs showed 18".

To get 15" on a 6X6 wire mesh I put one on 12", the next on 18" across the room. It averaged to 15 and still allowed me to tie tightly to the wire.

I used a great custom manifold from www.earthlee. 2" schedule 40 so it held up well to the jobsite abuse. I used a mini tube injection method and fed that large manifold in the center of the shop with insulated 1"

Sounds like a nice project.

I also used a job service to get day laborers to help with the tube installation and tie down as I am a one man operation (was). You meet some real characters with day labor help :)

hr
Bob "hot rod" Rohr
trainer for Caleffi NA
Living the hydronic dream

Comments

  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Met with a guy

    this morning, that wants radiant floor for a warehouse. 170 ft x 80 ft. footprint. Ceiling 16 ft. It is for a garage for garbage trucks. One Bay is a service bay the rest are parking. He wants to run it on solar thermal. Wants to aim for 60 degrees tops no problem if it drops below occassionally. I recommended drainback wt flat panels. Storage in concrete pad only. 3/4 pex in slab, on 18 or 24 inch centers. There's some small offices at the end we will supplement with ductless Heat Pumps. Does anyone have suggestions,ideas or experiences to share? WW

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  • Mark Custis
    Mark Custis Member Posts: 539
    Step back and

    re-read what you wrote.

    Yes it can be done.

    You can not design it for free.

    Grab yourself say, "How long will it take me to figure this out?". Take the how long number and multiply it by your rate. With that number, then say, "I can do what you want, but to give you a realistic price that we both can live with, I need (how long times rate) as a retainer and down payment to do the design work." Then it he or she says yes, make what ever allowances to a signed contract.
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Sound advice.

    Thanks Mark. I've already been noodling with the numbers and it is too big for a one man shop like me. Heat load is 160,000 btuh design day bringing space up to 60 degrees, best case scenario which changes with infiltration every time they open a garage door.:) If an AET flat panel could give 40000 btu's a day (another optimistic wish number)that means 4 panels could provide one hour of heating on a design day. So multiply that by 24 hours and you need 96 panels. The roof space can only handle 40. At our breakfast meeting the guy was not expecting that kind of number. At least I got a free breakfast out of it. :) Folks think solar thermal is a magic roof boiler. You can't rush the sun, and some days it doesnt even come out. At best you might be able to load up the slab on nice days and coast on the thermal mass for a while, but not forever. WW

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  • hot_rod
    hot_rod Member Posts: 21,882
    the heat load for 13,600

    at a realistic 30 btu/ square foot, maybe more would be around 408,000BTU per hour?

    I did almost an identical shop for Waste Management here in Springfield a few years back. Truck repair, 10 large overhead doors, and a few office spaces. I staged two Crown gas fired 220,000 boilers.

    It struggles at design, mainly because those large overhead doors are opening and closing all day. Some times the door is opened with a truck half in and half out if the bays are full. Large air change load, watch your design calcs.

    This building does have a backup forced air heater on the fresh air make up system.

    Do they have a wash bay? Maybe chase that DHW load with the solar as it would be a year 'round load and pencil out better. Any excess solar could go into a buffer for the radiant.

    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    Actually

    did a heat load on my Watts software. Wall are R-19. Unusual for a warehouse I know. 4 inch polystyrene underneath. R-30 in the ceiling. 160,000 before you open the garage doors. D'oh! However that is where the slab heat should help. You can open and close the doors and the slab won't lose as much. It will start heating again right away, where a scorched air system will lose all of it's buoyant hot air lickety split and will have to generate a lot of capacity to replace it.

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