Hello - New guy here to the forums...looking around here for some time and the information has been very useful. I have three quotes to install a full Geo system in my house. House information: 2100 sq. ft. 2 story colonial built in the middle of a farm field. Built in 2001 2.5 car attached garage Standard 2x4 construction Propane heat ($2.10 per gallon now....crazy!!!) (propane is costing about $3k annually) Propane heated hot water 3 ton AC Unit. Contractor #1 Measured the whole house and windows. Uses GeoComfort systems Calculated Design Heating Load - 63,888 btu/hr Calculated Design Cooling Load - 42,973 btu/hr Quoting a GeoComfort GXT 4ton Compass Series Contractor #2 Measured some of the house Asked many questions about the home Did not provide the calculated heating load Quoting Water Furnace Series 5 2-Stage 4ton Contractor #3 Did not measure the home Asked many questions about the home Did not provide what he used for calculations Quoting ClimateMaster 2 stage 5 ton heat pump. All contractors came back with a horizontal loop field (I am on 5 acres). 10kw heat strip. I am trying to figure out if the 5 ton is too big for what is needed. Contractor #3 stated that the calculations were on the border between 4 and 5 ton and the 5 ton would be more cost efficient. Thoughts?? Input??? Questions??
Thoughts: If actually have a 64K load, you'd burn closer to $3,500/yr in propane or $4,200 if the water heater is propane as well. So yes a 5 ton is too big and a 4 ton might be. Attack the envelope first. See where you can cut load in the house. Ask to see monitored performance of the bidders' systems to demonstrate predicted outcomes. Check references on all installers. Call if you want another opinion.
Lets see, If you used $3K of propane, at $2.10, burning equals about 1800 gallons. Than you take about 300 gallon away for a 2 people household for hot water, leaving 1500 gallons for heating. Assuming Lansing, MI weather data, and a thermostat setting of 70F, you are looking at a heat loss of roughly 44,000 BTU heat loss at 1F design temp (which is the 97%) percentile. You are max a 4 ton, and if you give us more info (people in household, actual gallons used last winter, thermostat setting etc), we can zoom this in and might get down to a 3 ton, but a 4 ton would be well sized in my book.
