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Geo Outlook article "Designing for Efficiency and Longevity" by Ed Lohrenz

  • 1.  Geo Outlook article "Designing for Efficiency and Longevity" by Ed Lohrenz

    Posted 09-12-2018 11:50
    This was an excellent article and I was glad to see it in the Outlook. The arguments and points Ed made need to be widely shared and understood in our industry if we're going to get past some of the 'horror stories' and negative rep that geothermal has for some consumers. There are some great explanations about what design affects and why it is critical, and more so than for some of the other common types of heating and cooling systems, because other manufacturers have taken many of those design decisions away from the installing contractors. Ed said, "Designing a GHSP system requires attention to more details than an ordinary HVAC system since the designer and contractor are not connecting to a common energy source such as a gas pipeline or electric grid, that someone else has designed and maintains... The designer is designing and building the energy source for the system."

    Great work in this issue overall.

    Jacquelyn Scherer
    Geo Designer
    The Janes Company
    Mukilteo, WA

  • 2.  RE: Geo Outlook article "Designing for Efficiency and Longevity" by Ed Lohrenz

    Posted 08-02-2019 17:01
    Nice article Ed. I am in a more balanced area and the temps around here are a little more forgiving. I still do believe a little more loop in most situations can keep the loop temp a little higher therefore a better performing unit. Only problem I see is the Manual J or heat loss. A bad habit started when software was rare difficult, time consuming and expensive for the common HVAC company. The term that is used is "rule of thumb". I do not agree with it nor do I use it. Figuring out a loop is not like figuring out the circumference of a circle, 
    2πR  is a constant. In my Geographic area you could go 5 miles and not have the same geology ... better known as dirt. Yet many a recomendation by someone who wants to sell a box will tell the unwitting contractor "X amount of well bore per ton and you will be fine". The dirt has no constant only a value.
    The contractor sells the job. He is the one with the responsibility of comming up with the facts and has to use them correctly to determine that loop size. No one thinks about 10-20yrs down the road, most don't understand the payback period let alone the degredation of the temperature in the earth from being used and not enough time to renew it. Drillers can be a good resource that is easily tapped to help with the loop sizing. They possess a Vast knowledge of what dirt they find in a particular area.
    HVAC guys are used to 400CFM/ton for a heat pump, 300' horizontal pipe /ton, 3 gallons per minute, 1/4" to a foot for drainaige, all these rules of thumb.
    The heat exchange in that pipe matters! In my time I noticed an open well is the least expensive most consistant temperature, those units if the water is good seem to last way longer in the 25-30+ age units with loops that have been properly sized have resonse of maybe 20+ years but units with a per ton sized loop seem to go bad in 15-18 yrs. So it brings you back to the original hoot and hollar of the steadiest temperature supplied makes the unit very happy.
    I agree with Ed performance is great and there are ways to massage your particular situation but in the real world installers rarely take the time.

    Pete Prydybasz

    PSP Consulting
    Mohnton PA