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GeoThermal HVAC

11 years ago

We are getting quotes on a geothermal AC system. Are we over-reacting to our power bills?

The house is about 80 years old, with NO insulation in the crawlspace or walls. Attic had rock wool insulation, and we have started DIY adding R-19 fiberglass batts. This summer we had 1 1/2 inches of foam added in the attic -- this made a big difference in comfort but not in the bills.

We have 3 Mitsubishi Mr. Slims MXZ units (mini splits with 3 indoor air handlers each) and a 3 ton Mitsubishi for heating and cooling (these are heat pumps). We have 2 ventless gas inserts for aux heat (18k and 24k BTU).

The MXZ units are getting some age and we are having problems -- they were never installed properly and are about 8 years old. 6 of the units basically don't function. So -- I have 3 indoor units working out of 9 and the central 3 ton air handler... We made thru the summer, but won't put up with another summer.

We have also lost 3 trees in the last 5 years -- bills went up $100/month with cooling when we lost the 1st two.

July electric was $736 -- 6792 kWH (212/day)

Aug was $691 -- 6386 kWH (213/day)

Sep was $416 -- 4539 kWH (142/day)

Oct was $284 -- 2925 kWH (101/day)

Nov was $252 -- 2766 kWH (81/day)

my questions (pls help!) --

How much of the bill is from cooling (heating) -- and how much can I drop it?

How much better geothermal than heat pump?

We want to drill now for future plans - we plan to be here for 20+ years. We think we can re-arrange the MXZ heat pumps and get by upstairs if the downstairs has central Heat/AC. As this is a older home, it doesn't have any ductwork/etc.

We are getting quotes on 11 tons of vertically drilled wells -- with 5-6 tons to be used now on the bottom floor and the 5-6 other tons for the upstairs to be added at a later date when side of the building is open for a possible addition in 8-10 years time.

1st quote was for 1/2/3 speed GT (3 compressor in one box) with DSH for $45600.

2nd quote will be for two-stage 5 or 6 ton (not sure yet) unit with DSH -- don't have it yet.

Are we looking at the right things? We need A/C this summer!

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