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Old 03-28-18, 07:31 AM   #1
stevehull
Steve Hull
 
Join Date: Dec 2012
Location: hilly, tree covered Arcadia, OK USA
Posts: 829
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Default need advice from group

Looking forward to your wisdom and experience. People who have installed are especially welcome.

Time for me to heat and cool shop with a minisplit. Shop is 40 x 60 and built with SIPS (structual insulated panel system). Both roof (R 30) and walls (R 20) are SIPS. Thus, it is very efficient and has low infiltration.

With no supplimental conditioning, shop may drop to 40 F in winter and in summer rarely goes above 85F (central Oklahoma)

I currently use a 1 ton geothermal heat pump - almost 30 years old for some HVAC. But the COP is poor (maybe 2.5) and a low SEER (13-12).

There is an office, separate enclosed in the 40 x 60, of about 250 sq ft. I currently use a 120 V electric resistance heater to keep it warm in winter as it is located on the cold NE part of the building.

I am thinking that a 24 K BTU (2 tonn) will do well for shop interior and 1 ton for office (likely oversize). A standard manual J calls for a bit more, but moisture control is more important than narrow temp control.

Why change now? My livestock feed business has rapidly expanded (feed stored in shop) and feed needs controlled temps- especially in summer. Secondly, I also use the office for business meetings and feel that it does not do me good encouraging energy efficiency in a hot summer office!

One central outside condenser and two wall mounted (small one in office) distribution units, larger one in main shop area, are anticipated

I will install myself and have a HVAC contractor on board who will "sign off" on install for any potential warrantee issues.

Now, what brand, model, specs do you recommend? I am very impressed with these units with high COP and SEER.

Your collective wisdom is FAR better that me starting fresh.

Thanks in advance.

Steve

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consulting on geothermal heating/cooling & rational energy use since 1990

Last edited by stevehull; 03-28-18 at 07:38 AM.. Reason: typos
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