New Construction HVAC decisions. Geothermal vs. alternatives with upgraded envelope.

[Kubota L39]

We currently have a wood Fireplace (zero clearance, outside air intake, can heat our home if the powers out), but my wife and I have decided we will have a gas fireplace in the new home. As much as we love the wood fire, we're tired of the mess & commitment required. Also, we're retired and plan more travel - we need something that can "do it's own thing".
Just looked at off-peak electric rates - if we can get by with a gas fireplace for back-up. A ground source heatpump might be back in play. Off peak rate is 1/2 our .14kwh regular rate. Or approx $615 annually vs $1230 at regular rate (and COP of 3).
But still have to consider lots more upfront costs.

I should add - we're going one level on a heated slab - that's non-negotiable, so it would mean a outdoor wood boiler if we went the wood route.

 

[Sigarms]

As a side note, how much heat can you get from your mini-split when it gets this cold 2 miles from our building site?
Cold, but no cigar: Cotton again hits 56 below, missing state record | Duluth News Tribune

Using a record low for a cold temp is kind of misleading when sizing for HVAC equipment.

Looks to be that Deluth does not average below 0 degrees Farenhiet duing the winter months. I know of some single zone mini split heat pump systems that could give you 33,000 BTU/h of heat at -15 degree F outside air temp while maintaining 70 inside.

Not as bad as you think I'm guessing.

 

[BitChin1]

I'm a little late to your post here (been following it over on GreenBuildingAdvisor though) - I have a Bosch Ground source system installed in late 2012 (new house build) - it has never worked quite like we expected but today the evaporator coil is being replaced (under warranty) due to having a coolant leak, so hopefully this will change shortly. I am located in central KS with ~ 4600HDD's (so a bit warmer than you). My house ~ 1900 sqft along with full walkout basement and a 600sqft loft with 28' vaulted ceilings. We are a total electric with ~ .13c/kwh electricity. My avg bill for last 6 years is $240/month with highest single bill of $337. Lowest bill was $186. My key to heating/cooling with a partially working Heatpump has been that we really rarely need it! (that also can help explain why it took so long for the HVAC contractor to figure out the issues). Along with being in a CZ4A area we also built our house very tight and moderate r-value (SIPs 24 walls 40 roof).

Would I use a ground source heatpump again? NO. The key reason being it was fairly expensive (open loop, 2 zone 3T system was ~ $22,000) and has been complex to operate and debug. I have had to replace the pump for the desuperheater and the valve that controls water flow along with R410 refills and now finally a coil.
Would I use SIP's again? NO - again expensive and too much foam, but I would focus on a solution that seals the house very tightly (including blower door to verify) and then go for a Whole wall r-value of 25+ in my area (probably a little more for yours).

As for you contractor doing the load calcs - I did my own and then argued (debated) for a couple rounds on my my #'s made sense - his initial approach/proposal was for a 6 T system and was a little concerned that it might not be enough! We went with 3T as it was the smallest they made at the time (I really only need 2T, but it has 2 speeds along with variable fan speed).

Anyway I suggest you focus on making the HVAC minimally necessary and look at other options before settling on Ground source - (that said your quotes don't seem out of line based on my experience but I think you could get a lower cost solution)

 

[Kubota L39]

Using a record low for a cold temp is kind of misleading when sizing for HVAC equipment.

Looks to be that Deluth does not average below 0 degrees Farenhiet duing the winter months. I know of some single zone mini split heat pump systems that could give you 33,000 BTU/h of heat at -15 degree F outside air temp while maintaining 70 inside.

Not as bad as you think I'm guessing.

I was making a joke but we did have 2 weeks with nightly lows around -30 or less. We have a Fujitsu Halcyon mini split heat pump - it's great for AC & a little heat spring and fall before turning on the floor heat. I wouldn't consider it for a main heat source in my climate, and our radiant floor rules it out in any case.

Done with my hijack- sorry...

 

[Sigarms]

I was making a joke but we did have 2 weeks with nightly lows around -30 or less. We have a Fujitsu Halcyon mini split heat pump - it's great for AC & a little heat spring and fall before turning on the floor heat. I wouldn't consider it for a main heat source in my climate, and our radiant floor rules it out in any case.

Fujitsu has 3 different models for single zone, one to one systems for example, and each system having a diffrent maximum heating capacity, some down to as low as -15 degree Farenhiet. Each model different model does have a different cost associated with it, primarily being the heating capacity. The issue IMO is that HVAC contractors do a crappy job of explaining what they're selling and why they're offering it. Numerous times I'll be asked to handle a phone call from a contractor with questions on mini splits only to be informed that the only thing the contractor is interested in is SEER rating. When it comes to a mini split system, SEER rating really the last thing you need to be looking at.

That said, would I rely on a mini split system only for heating if I lived in Minnesota? Heck NO! That said, would I ever live in Minnesota? HECK NO! :laughing:

Use to live in upstate Maine as well as upstate NY (around between Syracuse and Watertown), so I do speak from some good personal experience IMO LOL

With the OP being in PA, would feel more than comforatable with a mini split for heating only needs though.

 

[kenmac]

I have no idea what the temps are in Minnesota, but If the temps are no lower than -20 , I would have no issues with a mini VRF for heat.

 

[DKCDKC]

I put in a 1.5 ton Wood Furnace Geothermal in my 2,900 sq ft rancher in 2001. Never regretted it. Could have used a bit more capacity since we added windows after the calculations, but it generally does the job. We have an average $160 monthly power bill for this all-electric house and can't complain. We have a small Irish wood stove in the center of the house for use on really cold days or for ambience. Wood is free for me because I have an 80 acre woodlot and a couple guys who pay me in split firewood for wood they cut for themselves - 1 to 4 ratio. I imagine the compressor on this old heat pump will conk out in the next five years and I plan to replace it. One of the big things I really like about geo is not the lower cost - and it is a bit complicated - but it is totally quiet. Inside or out, I cannot tell when the system is running. I got so tired in other houses of that outside unit running all the time. Overall I remain a fan.

 

[Kubota L39]

I put in a 1.5 ton Wood Furnace Geothermal in my 2,900 sq ft rancher in 2001. Never regretted it. Could have used a bit more capacity since we added windows after the calculations, but it generally does the job. We have an average $160 monthly power bill for this all-electric house and can't complain. We have a small Irish wood stove in the center of the house for use on really cold days or for ambience. Wood is free for me because I have an 80 acre woodlot and a couple guys who pay me in split firewood for wood they cut for themselves - 1 to 4 ratio. I imagine the compressor on this old heat pump will conk out in the next five years and I plan to replace it. One of the big things I really like about geo is not the lower cost - and it is a bit complicated - but it is totally quiet. Inside or out, I cannot tell when the system is running. I got so tired in other houses of that outside unit running all the time. Overall I remain a fan.

I'm assuming Water Furnace Brand Geothermal - not Geothermal from a wood furnace:ashamed:

 

[DKCDKC]

I'm assuming Water Furnace Brand Geothermal - not Geothermal from a wood furnace:ashamed:

Yup. Freudian slip there. Do use wood, but it's a Water Furnace. And we now have multiple dealers around to shop for service - big change since 2000.

 

[MGH PA]

Thanks everyone. So much to digest. I'm still not sold on the up front investment. It also appears it's not recommended to zone individual rooms with the 5 series since it's not variable speed system.

Does anyone have a recommendation on a DIY load calc software?