Looking for design advice on equipment install.

Discussion in 'General Discussions' started by OakStreetDesign, Nov 10, 2019.

  1. OakStreetDesign

    OakStreetDesign New Member

    Hello all, noob here looking for a little help. I'm a builder of nearly 30 years but a novice on geothermal. Currently building my own new house and at the point where I need professional advice.

    Underground: We've installed 5 ground loops (slinky style) approximately 65 3' loops with 6" overlap of 3/4 HDPE pipe 6' down with 6-8'between trenches. Total pipe in trenches is slightly less than 800' with probably a variance of >10% between lengths.

    Equipment: We haven't ordered it yet but considering the the Climatmaster 3 ton split unit TES038BGD00CNNS with Air Handler TAH038BGSMBS for the main part of the home and then the Climatemaster TES026BGD02CNNS 30 Seer split GSHP Unit W/internal flow control and Climatemaster TAH026CGSMBS Horizontal air handler for the new spaces. Both split units would reside in the basement where the lines enter/exit with linesets going to the air handlers.

    Ductwork is already in (we are at the sheetrock stage) and locations for the air handlers are set. I've seen pictures of some very elegant and organized piping/pump setups and am hoping those of you here could help me with a materials list/design on how mine should be configured. Questions I have are how do you control flow through the five lines/monitor outgoing and incoming temps, do you split the 5 lines between the units (3 & 2?) or combine them, do the internal pumps both operate or do you use external pumps, what should I have to take advantage of domestic water heating, and I'm sure there are a number of questions I haven't considered.

    Any help would be appreciated, if there are any of you located in the Southern/Central Connecticut area who consult on this type of work I would be more than happy to meet/work with you. This will be the last house I build for myself and I'm looking to do it right.

    Thanks in advance for your help.

    Chris
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  2. OakStreetDesign

    OakStreetDesign New Member

    I also have PEX installed in my garage slab so if there is a way to incorporate heat there in the design I would like to consider it. Will have a 4.5kwph solar system installed so the electric isn't a huge concern. Thanks!

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  3. mtrentw

    mtrentw Active Member Industry Professional Forum Leader

    I would definitely want to keep all 5 loops together. That would ensure you're not overburdening one set and that each unit would have best available water temps. Some mightrun calculations and determine lower flow through unit might impact reynolds number and reduce heat transfer efficiency if only one unit running, but I don't expect that is an issue with much larger volume and when both run, you'll get the higher flows.
    Ensure you have ball valves so you can isolate loops individually. Makes filling and flushing easier with smaller equipment than a dedicated pump cart.
    Also ensure you can isolate your manifold for troubleshooting/adjustments.
    Pressure and temperature ports at entry & exit to each of your units (pete's ports). Alternately, permanently plumb those in with 4 thermowells and 4 pressure gauges in your piping. If you're gonna geek out on the data, you may want to look at a WEL Server to monitor and log your data. Doc Jenser on this site has dozens of systems out there that are logging data.
    It seems most folks recommend going with copper when plumbing in a DSH.
    CHeck valves to prevent one unit backflowing through the other.
     
  4. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    You have radiant in your garage but not radiant in the house? Must be a car lover:D

    Kidding aside, many ways to skin a cat. Not sure if I would do 2 split units, what is wrong with a variable speed packaged unit with central ductwork, may be zoned? Also once you put in a water-water unit for your garage, I would also do all the hot water with it with the efficiency of the geo unit. You would need an indirect tank for that with a large inside heat exchanger.

    All on one loop field, with a variable, pressure regulated, circulator pump, and zone valves on each heat pump.

    Happy to help with advise. This is how I would do it, but open for any other thoughts/reasons.

    Reasoning and examples:

    https://www.groundupgeo.org/products
     
  5. wing

    wing Member

    So you have 5 tons of heating requirements via two air handlers plus a garage slab and domestic water heater.

    The ground loop is 4000 feet total of 3/4 inch HDPE slinkies and each loop penetrates the foundation wall and into the basement. The ground loop sizing is probably OK, little margin for error though. I don’t like the way the loops penetrate the foundation wall, too prone to seal failures but maybe you sealed everything up on the exterior.

    The garage slab and domestic water heater will take a water to water heat pump capability which the climate master TES does not have. I don’t count using a desuperheater as a domestic water heating strategy in a heating dominated climate.

    You are too far along to redesign your ductwork.

    My personal preference would be to have a simple single stage 5 ton water to water heat pump in your basement with a 100 gallon buffer tank. Run the heat pump load to a distribution panel with four fixed speed pumps and hydronic lines to

    1) A main floor water to air air handler
    2) The new space water to air air handler
    3) The garage slab
    4) Domestic Water heater

    Now you only need a flow center for a single 5 ton heat pump.

    There are complications like priority override for the water heater circuit but the distribution panel supplier can work this out.

    I have a very similar setup - two air handlers, radiant garage slab , water heater with the addition of in floor heating manifolds and cooling system optimized for a highly diurnal climate.

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    The hot water heater setup with 4500 watt electric element.


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    Enjoy your journey !
     
  6. OakStreetDesign

    OakStreetDesign New Member

    I may have complicated thing by adding in the garage slab (yes car lover with several classics). My thinking is I will likely handle that with an on demand propane boiler - we already have a 500 gal tank for the generator and will be doing the domestic & cooktop with gas so the marginal increase in use on those very cold snaps won't kill us.

    As for the geo - the picture I posted of the loops coming in was prior to the final 5th loop going in - there are 5 approximately 800' loops and the load on the house is based on traditional heat loss calculations where we have since gone 100% closed & open cell foam and Anderson windows with all of the energy saving coatings & films. Also, when they were here spraying the closed cell, we had them spray the foundation penetrations and having already passed a couple of heavy storms, we are leak free.

    I'm excited about this moving forward. IMG_2536.JPG
     
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    One thing to keep in mind is the reduced efficiency when using water-water with air handlers. The air handlers really don't much BTUs out if not operated at temperatures above 110F Fahrenheit, which significantly reduce your efficiency.

    I am a big fan of radiant for comfort, and it works very well when the whole house is of radiant design.
    My preference here would be a single 7 series you can zone as desired, and a small 2 ton water-water which can make all your DHW and also enough water for your radiant heat.

    What is your heat loss calculation?
     

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