pschuster_gw

sport court barn hvac--need suggestions

pschuster
August 26, 2013

We are building a barn in Pennsylvania which will house a sport court (think basketball, tennis, etc.) It will have a pitched roof, 35' high at the peak, 20' high at the bottom of the trusses. To protect the wood floor of this court, we will need a constant 65-70 degree temperature & humidity swings of no more than 15% (ie. about 40-55% humidity all the time). This means we will be running the hvac system at this level--and paying for it--24/7 forever.
In this context, it seemed like the additional upfront cost of geothermal would be worth it for the long-term efficiency. Dealers reported 30 EER vs. only 15 for a traditional heat pump. We also need 4-6x air exchange due to sports activity.

However, two friends who have geothermal and are knowledgable reported that while geothermal cools their house for free all summer, the cost savings in the winter have been minimal. (Which was surprising to me--we live in PA, not usually too cold here). They urged me to consider mini-splits & super high-efficiency heat pumps.

The costs of the super-efficient heat pumps (20 SEER) is $22,000 vs. only $24,000 for a 2 stage ComfortAire (30 EER) geothermal set up. Thinking costs of Mitsubishi mini-splits will be a little less, but worried they can't keep a space this big (1) warm enough & (2) circulate enough air for 4-6x exchange; & (3) regulate humidity. Also not sure where we would put the mini-split b/c can't hide it in the ceiling, as we won't be able to get to it to service it in a ceiling that high.

I would be most grateful for any guidance & input, as I'm at a standstill re: what to do.
Many thanks!

Comments (13)

  • fsq4cw

    I think your friends may be wrong on geothermal.

    I would install in-floor radiant heating and cooling with a geothermal ground source heat pump.

    Consult with professionals.

    IMPO

    SR

    Here is a link that might be useful: International Ground Source Heat Pump Association at Oklahoma State University

  • SaltiDawg

    "I would install in-floor radiant heating and cooling with a geothermal ground source heat pump."

    How does this address humidity control? Just curious.

  • ionized_gw

    "...cools their house for free...." I don't see how that can work unless they are using true geothermal to generate electricity.

    In-floor cooling will make for a very slippery, water-saturated floor.

    MIni-splits are available in different forms including air handlers that are hidden. In fact, they look pretty much like regular split units only smaller. At some point, the difference becomes semantic. What is a mini-split vs, a regular split unit? The most familiar mini-splits have no provision for ventilation. Types mounted in ceilings do.

    Is natural gas available for heat?

    If the space is going to be unoccupied for long periods, dehumidification might be more cost effective than straight cooling.

  • fsq4cw

    Humidity or latent loads are controlled by electronically monitoring temperature and humidity and keeping the temperature of the floor above the dew point, as well as integrating HRV or ERV systems for fresh air exchange.

    This should be handled as a commercial - not residential project. This type of geo-radiant configuration is commonly done in warehouses, commercial buildings, municipal garages, aircraft hangers and sports complexes.

    Geothermal is never really free, what is thought of as âÂÂfreeâ in the summertime is domestic hot water production, as the heat extracted from the envelope is transferred to the hot water tank through the desuperheater before the rest is sinked into the ground via the ground loop heat exchanger.

    SR

  • fsq4cw

    Double posted...

    SR

    This post was edited by fsq4cw on Mon, Aug 26, 13 at 20:31

  • ionized_gw

    Hot water might be a good point to make if there will be a lot of shower water used in the building in the summer. Will there be a pool that wants heating as well?

  • pschuster

    Hi everyone,
    Many thanks for the feedback. My HVAC person also suggested that there are thermostats that monitor humidity as well as temp and kick on accordingly. He thinks that the a/c can handle dehumidification but is recommending a steam humidifier for the winter.

    Seriously considered radiant heat under the floor. Concern is that b/c the floor is "floating" only a minimal amt of heat will make it up into the room. To crank the temp of the radiant high enough to heat the room may jeopardize the maple floor.

    Natural gas IS available for heat.

    Thanks, too, for the reminder that mini-splits may not address ventilation/air exchange needs. Hadn't focused on that when considering the mini-splits.

    Any other thoughts? Sounds like geothermal, if sized right, may be the way to go. Any preferences between Water Furnace Envision, Comfort Aire or ClimateMaster TE049? These are the three pieces of equipment the contractors have given me quotes on. The heat pump they are quoting is a 4 ton, 2-stage Lennox system.

  • juliekcmo

    Surprised at the load
    How large exactly is the space?
    Grade school gyms run about 30 tons once ventilation is accounted for. Your budget may be in for a bad surprise.

    You need a contractor with commercial experience to double check he load.

    Agree with previous poster regarding the space. It's most like a warehouse.

    This post was edited by juliekcmo on Mon, Aug 26, 13 at 23:31

  • fsq4cw

    Radiant can be done with virtually any type of floor. In fact the temperatures with radiant can be quite low and will not damage your maple floor. You will not have to âÂÂcrank upâ the temperature to achieve the set point. âÂÂLower temperatureâ also means âÂÂless energyâÂÂ.

    With radiant youâÂÂre heating the whole surface of the floor and on up rather than pouring hot air out of a few small openings as with forced air. Radiant heats people and things, with forced air you have to heat the whole volume of air, floor to ceiling. With radiant who cares what happens over 6 or 8 feet above the floor!

    Well pretty muchâ¦

    SR

    Here is a link that might be useful: Warmboard

  • Elmer J Fudd

    Why not a concrete floor? That would make it much cheaper and easier to deal with. You can't play tennis on a wood floor but you can play basketball on a concrete one.

  • ionized_gw

    Concrete can be pretty tough to fall down and slide on, can't it?

    Depending on where in PA you are, you might have trouble meeting the humidity range without re-heat capability. Why does it have to be that tight? Haven't modern floor manufacturing techniques made them better able to resist moisture and temp swings?

  • pschuster

    Have to have a very specific maple floor b/c it is, in fact, not a general "sports court", but a squash court. Please see great YouTube link below if you've never heard of squash (lots of people haven't). This is the video squash has submitted to be included in the 2020 Olympics. http://youtu.be/U4EnbuxUSoc

    SO, have crossed off mini-splits b/c can't add humidification and can't get adequate ventilation.

    Now just have to decide between Heat Pump & Geothermal.
    If Heat Pump--Lennox 15.5 Seer XP16 at $18,210 or 17.2 SEER XP21at $20,000? Seems like extra efficiency would be worth the extra money upfront.

    and if Geothermal--Water Furnace Envision at $40,000, Comfort Aire at $35,500, or ClimateMaster $35,800?
    Any views on quality of these different GT units?

    Also, BTW, thanks to comments on this site, have bumped insulation in the ceiling from R-30 to R-38 or maybe 45? (think I have that right--talked to the builder this morning). Many thanks!

  • fsq4cw

    If you decide to go geo and in-floor radiant, my pick would be a Nordic TF Series (Triple Function). One machine and you have it all (almost, except liquid cooling for hydronic A/C).

    Full capacity force air heating & A/C, full capacity hot water for in-floor hydronic heating and a desuperheater for domestic hot water (DHW) - ALL in 1-box, up to 6.5-ton!

    See link below and click on âÂÂdownloadsâ for complete descriptions.

    SR

    Here is a link that might be useful: Nordic Triple Function Series

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