Hi, Looking for some professionals to make me feel better about this equipment size and proposal. House is 2 story 1960 square feet with a full unfinished basement. Load calcs are cooling load for the Main/Basement is 30,960 btu. Heating load for the Main/Basement is 34,608 btu. Cooling load for the Upper Level is 9,360 btu and the heating is 8,112 btu. The loop has been designed to where both units will be slaved off the same loop. Horizontal loop field will contain (4) 600' pipes connected to a maniford. Units have been designed as : Unit 1: Main & Lower Levels- Install a Waterfurnace75 series model NVV036A111CTR0KN nominal 3 ton Geothermal Heat Pump. The unit has a variable capacity scroll compressor, variable speed fan, hot water assist, 10 KW electric heat and uses R410A refrigerant. A programmable color touch screen thermostat is included with energy monitoring capabilities. Unit 2: Upper Level- Install a Waterfurnace Envision series model NDZ022A10AC nominal 2 ton split-system Geothermal heat Pump with a matching variable speed fan/coil unit with 10 KW electric heat. The Geothermal unit has a scroll compressor and uses R410A refrigerant. It will be located in the Basement with Unit 1. The fan/coil unit will be located in the attic to supply air to the Upper Level. A programmable thermostat is included. I am not questioning cost here just trying to make sure the right size equipment has been quoted. Any suggestions would be appreciated. Thanks in advance,
Personally, I have to be dragged, kicking and screaming, into proposing more than one system, ESPECIALLY for a house with such modest total loads. While I'm looking forward to my first true variable speed WaterFurnace 7 series project, know that the premium for that series is quite high and they are quite new to the market. I'm a big advocate of zoning, particularly with pricey geo systems (wholesale cost of a moderate SEER air source heat pump tends to be half that of a premium geo system, making it harder to make the case for zoning, but for geo it is a no-brainer if duct chase issues can be worked out) My own home, 3500 SF conditioned, has 3 stories and 4 zones all working off a single 3 ton WaterFurnace Envision series 2 stage geo heat pump. Load is about 30k, summer and winter. Operating cost averages about $30 per month. Your project might well perform satisfactorily with a similar arrangement. If there is an attic above the 2nd story and ductwork is located therein, look hard at applying sprayfoam and thus bringing the attic into the thermal and pressure envelope of the home. Duct losses, both by leakage and conduction, are virtually zeroed out by this approach. With foam total tonnage required could conceivably drop to just two (a series 5 026 system, possibly equipped with modest (3-5 kw) heat strips for use just a few hours just a few days per year. Know that is conjecture...don't hold me to it. Loop might drop to 3@ 600', but err on the side of abundant caution, particularly in the case of horizontal loops. Be sure the loop design accounts for soil conditions during a very hot and dry spell...there is no such thing as an "auxiliary cooling strip (in other words, backup extra capacity for cooling loads...) I offer remote consulting service to out of state clients attempting to work through options and alternatives, bid evaluations, teleconferences, 2nd opinion load calculations, etc. I doubt I've fulfilled your request to be made to feel better about the proposed equipment...oops! Sorry about that!
Thanks Engineer, A little more information on my house. The upstairs is somewhat of a loft, which includes 2 bedrooms, a bathroom, and a breezeway that looks over into the family room. The main unit is a Lennox Propane pulse furnace (Propance and being 16 years old is the reason for replacement) and the upstairs unit is the traditional heat pump. Not sure if this is able to be zonned, but I am not versed in zoning. The WaterFurnace series 7 is a little pricey, but that is fine as I am always looking for the best I can get. The 7 series being new does concern me a little, but I understand that WaterFurnace does extensive testing of it's components before they put them in the market (so I am told). Thanks again,
How heavy you load (how big the equipment you select) depends among other things on where you live and kwh cost of electricity. My gut is you have a proposal for 2 more tons of equipment than you need.
Live in South Carolina: Summers are hot and humid - 90 to 95 degree days. Winters are fairly mild, but we do have 15 to 20 degree nights, but on average upper 20's.to lower 30's. I average about 51 KWH/Day in the Summer and 36 KWH/Day in the winter. I use Propane only for heating and spend about 1500 a year. Propane on average is ~3.00 a gallon. Electric rate is .13 cents per KWH. Hope this helps.
Shouldn't a 3 or 4 ton 7-series with a nice intellizone zoning system being able to superbly manage the whole thing, without the need for another heat pump? Keep it elegantly simple!
