Maryland Looking for advise on two competitive quotes (with different install approaches...)

New member to the forum here, but I’ve been reading the community’s posts extensively for the last few weeks ever since the wife and I began gaining quotes for geothermal HVAC upgrade for our aging standard equipment. We have weeded down a number of quotes down to two established geothermal companies in the area, but we’re stuck on best way forward. We’re hoping you can help us across the finish line.

My apologies for the wall of text coming.

Home details: 25 miles NE of Baltimore, MD. 2003 build. Above grade: 4385 sq ft (5632 sq ft including finished basement), 6” external walls, double pane windows, R-30 attic insulation, probably Rockwool on exterior walls, 9’ ceilings throughout home, 18’ vaulted ceiling in living room with a large amount of north-facing windows, and vaulted ceiling in the bedroom. The home currently maintains temperature well - with the exception of the west-facing bedroom that appears to take a lot of thermal loading in the summer months and is a few degs hotter during the afternoon.

Current equipment: Installed 2003, 1st Floor/Basement: 5 ton conventional AC/Natural Gas Furnace (in basement). 2nd Floor: 3 tons (or 3.5) AC/Natural Gas Furnace (in attic). Current energy cost is approx. $0.13/Kwh; natural gas: approx. $1.30-$1.50/therm. Water heating costs ~$30/month (natural gas + powered exhaust). We currently offset the temperature in the 1st/2nd floor 5-8 degs during the days/nights to primarily condition the floor we’re on.

Quotes: Both companies are geothermal installers primarily; IGSHPA accredited; and have been in business for 20+ years. From what I’ve read in the forums, both quotes seem fair-to-good given the system size. Both companies have good online ratings overall.

- Company 1:

• 8-tons installed; 160ft/ton vertical loop; 4 bores @ 320’, 1.25” pipe, grouted
• System 1 (1st floor/basement): Waterfurnace 5-series, 5-ton dual capacity unit (NDV064); Intellistart; ECM fan; 10 kW aux electric heat
• System 2 (2nd floor): Waterfurnace 5-series, 3-ton split unit (NDZ038); Intellistart; matching Water Furnace high efficiency air handler; 10 kW aux electric heat.
• Additional: Advanced Aurora Control System; Performance Monitoring, Energy Monitoring, Refrigeration Monitoring, flow center, thermostats, Symphony Aurora Weblink, and water alarm
• Cost: $56,000 installed gross (pre-tax incentives); free 12-months same as cash (no origination fees)

• Geolink summary: Heating Load - 73,600 Btuh, Cooling Load - 48,800 Btuh. Internal Gains - 13,205 Btuh. Colling Temp Dif - 17 degs. Winter design - 13 degs. Summer Design - 94 degs. Heating Setpoint - 70 degs. Cooling Setpoint - 72 degs.
• Geolink projects zero (0) Aux heat usage, high speed cooling, or high speed heating annually.
• Geolink projects 84% geo run time on hottest days annually, with ~10-12k of geo air Btuh’s availabile over the Load Space Btuh calculation. Coldest days are 94% run time and ~4k Btuh available over the load calculation.

• Option: Upgrade 5-series, 5-ton NDV064 to 7-series: $4,900 extra
• Option: WaterFurnace Desuperheater with 50-gallon storage tank- $2,000 extra

• Company measured the square footage of the home before the quote. I did not see the sales rep measure windows specifically, but he may have accounted for them. He indicated he calculated a Manual-J to inform his 8-ton quote.
• The sales rep noted he sizes systems to run on the low compressor setting at all times possible; he also prefers aux electric heat vs fossil fuel aux/emergency heat as it was more cost effective. He asserted this sizing and aux setup would provide the best RoI over the long term, despite potentially needing a larger system to start. He also noted running in a lower compressor setting would reduce wear and tear on equipment over time.

- Company 2:

• 7-tons installed; 160ft/ton vertical loop; 3 bores, 1,120 ft. of vertical bore, 1.25” pipe, grouted
• System 1 (1st floor/basement): Waterfurnace 5-series, 4-ton split unit (NDZ049); matching A-coil; Rheem 96% gas furnace; variable speed blower; 2 speed burner.
• System 2 (2nd floor): Waterfurnace 5-series 3-ton split unit (NDZ038). 2 Speed compressor with matching A-coil; Rheem 96% gas furnace; variable speed blower, 2 speed burner.
• Additions: Performance & Refrigerant Packages on both. Programmable thermostats
• Cost: $46,900 installed gross (pre-tax incentives); 12-months same as cash (5.5% origination fee - $2,600)

• Geolink Summary: Heating Load - 77,108 Btuh, Cooling Load - 81,080 Btuh, Internal Gains - 13,834 Btuh. Cooling Temp Dif - 20 degs. Winter design - 13 degs. Summer Design - 94 degs. Heating Setpoint - 70 degs. Cooling Setpoint - 75 degs.
• Geolink projects zero (0) Aux heat usage or high speed heating annually. 7% high speed cooling run time. (7% annual basically equals the hours in the top two temp bins)
• Coldest days are 100% run time. Geoair vs load Btuh are essentially the same in the coldest two bins (7 degs/1 deg; 13 hrs/1hr annually).
• Geolink projects 100% geo run time on hottest days annually (top two bins –92 degs & 97 degs; 72 & 6 hrs/yr). 2nd bin (92 degs) geo air Btuh is equal to load Btuh (~71k). Hottest bin (97 deg, 6 hrs annually) geo air is approx. 13.1k Btuh lower (in the red) than load Btuh.
  • The owner indicated his calculations are very conservative. He noted my high cooling load Manual –J calculation is due, in part, due to the large bay of windows in my living room.
  • I do believe Company 2’s Cooling Load Btuh calculation is conservative. Our living room currently has no issue maintaining temp at 70 degs (50% run time even with the 2nd floor temp at 77 degs) in the summer on our 5-ton, even without any blinds on the window.
  • The only issue we currently have with temp control is our master the bedroom, which runs on the 3-ton system. Even running full-time, the MBR reaches 76 degs during the hottest days of the year. It and doesn’t cool down to 71-72 until 9-10pm. The 1st HVAC use limited impact on MBR temp.

• Option: Install Waterfurnace 5-series dual capacity unit (NDV049) with 10kh aux electric heat for system 1 and Waterfurnace (NDZ038) matching air handler 5kh aux electric heat for system 2 - $4,400 extra
• Option: Hot water assist with 50-gallon storage tank- $1,900 extra

• Company owner visited twice. He took detailed measurements of the home, including window sizing, during the second visit to inform the manual-J calculations. Owner indicated the initial HVAC was oversized, which is why he recommended 7-tons.
• He quoted for a split system with natural gas aux heat; he believed this provided the best up-front cost vs. lifetime system cost given utility costs in our area.
• I have an appointment this week to run through some different system scenarios (8 vs. 7 tons, lower cooling set point, deeper wells) with him to assure we can meet our performance objectives.

I take it that many in the form do not find Geolink especially trustworthy. That said, from what I can decipher from the software both recommended systems seem viable. Company 1, as they indicated, is leaving headspace in the system to minimize usage costs (at a cost to us of $6.5k additional post-tax incentive). Company 2 appears to be tailoring a system to achieve a better install price point, with greater annual utility costs (~$150 +/- over Company 2). We initially were leaning towards Company 2’s recommended install as it would leave us with money to possibly use to do a solar install in a year or two. However, a number of questions are giving us pause the decision; this is where we're hoping you can come to our rescue.

Questions:
1) Do you believe 7-tons will be undersized for our home?
2) Do you find notable cost/performance benefit by digging deeper wells vs. adding an additional ton of capacity. On the whole, if we needed to drill company 2’s 7-ton recommendation to 180-200’/ton vs. the current 160’ quoted would we save enough to justify not simply purchasing an 8-ton to start?
3) Do you forsee any performance or reliability issues with mixing a Waterfurnce split with non-WF air handler (Rheem in this case)?
4) Should we be worried with Company 2’s Geolink calculations on the hottest/coldest days? Do you believe cooling performance will be as potentially problematic as calculated if our 2nd’ floor cooling will remain on a 3-ton between our current system & both company offers?
5) If you believe an 8-ton approach is advisable, would you recommend a 5/3-ton setup, which currently match our home, or would an 4/4 setup provide better cooling performance giving the thermal loading we’re currently experiencing in our MBR?
6) Do you find the DSH+tank worth it in more mild climates? Also, do you see any performance risks for running DSH+tank on a split system with natural gas aux? The install price is quite significant given the limited RoI (~$100/yr). We are not inclined to make the purchase if it takes 20 yrs to buy back the difference.
7) From left field… Do you see any developments in the industry that will drive down costs enough to compensate for the loss of the tax credit at the end of 2021? (Can we wait until our current systems die and not pay substantially more than with the current credits?)
8) Is there anything we’re missing and should have asked?

Thank you so much if you’ve made it to this point in the post! We thought we could work through the different options ourselves, but we simply don’t have enough experience to fully appreciate the differences between systems and any risks we might be incurring by committing to one company/approach over the other. We don’t want to spend more than necessary, but we will spend more money if we need to in order to ensure we’re not another geothermal install horror story.

 

I live in the VA Outer Banks and I have 220" vertical bores per ton. My well driller said his goal was a minimum of 175' per ton but the loop pipes came 220' - 225' long so since I was also the builder he gave me the max per loop.

 

1) It would be best to have a Manual J load calculation done, broken down at least by the two zones. Then you can assess the sizing of the heat pumps based on the load for the zone the heat pump is serving.
2) Normally the ground loop is sized to have a min/max EWT of 30/90. The industry has settled on that as a good cost/performance point. The chosen heat pump and the house loads will determine how deep the loop needs to go to meet the water temp targets. An oversized loop can save a little money, because the minimum EWT will be higher. With a higher EWT, the efficiency will be slightly higher and the heat pump can output a little more heat in the dead of winter.
3) A split unit is going to be less efficient than a packaged unit. Pairing it with a fossil-fuel furnace will likely reduce the efficiency a little further as compared to using an air handler. At the prices you posted, heating with natural gas will only cost about 50% more than geo (that's $15.29 vs $10.89 per million BTU, assuming an installed COP of 3.5). I'd look closely at the cost of geo versus going with gas.
4) Something is off on those geolink reports, unless there's a typo. #1 says cooling setpoint of 72 and a cooling temperature difference of 17. That implies a design temp of 89, which seems low. #2 says cooling setpoint of 75 and a temp diff of 20. That implies a design temp of 95, which sounds more reasonable. The reports must be run with the correct loads, design temps, and temperature differences, or they are useless.
5) See what a load calculation indicates for the two zones. I find that my upstairs bedrooms require more peak cooling than my load calculation would indicate. Heat rises and the heat from the roof soaks through, I guess.
6) Savings of only $100/yr on DHW sounds low by at least 2X. The DSH is supposed to save 65% or more on hot water.
7) Geo is low volume and that has to drive prices upwards. I don't see that changing much anytime soon.

I'm not sure about the logic of installing a two-stage 5 Series that's so large it never runs in high stage. If you look at the Waterfurnace submittal data, there is only a small difference in heating COP between low and high stage, so the savings should be small. You could ask the dealer to run a Geolink report to model that for you. The 7 series has 12 stages and modulates down to 20% capacity, so that would be the way to go if you want to take advantage of lower stages of operation.

Whatever you do make sure the dealer installs an efficient pumping solution. Get variable speed pumps if you can.

I would get the monitoring options, Symphony, and AWL. I like being able to see what's going on.

My dealer told me today the water alarm is no longer available, but you could probably find another water sensor that would work if that's true.

 

Can't give you any advise regarding the installers.

Just a few thoughts.


None of the numbers really matter, it comes down to what good of a system someone builds you. For example, none of the borehole lengths matter, since you don't know what grout they are using. Highly conductive graphite grout can make a borehole half the length perform better than another borehole using just bentonite.

Here is what I like if this is my home:

7 series heat pumps. Tough to oversize the 7 series, it simply finds it sweet spots, and it does not matter if it is stage 7, 9, 10, or 12 on the coldest days of the year.
Monitoring via symphony.
Dedicated hot water heat pumps (little 2 tons making all your hot water with the efficiency of the geo system).
Variable speed ECM pumps.
No constant speed pumps.
No split unit if possible.

 

Deuce, SShaw, docjenser -- Thanks so much for taking the time to respond. I appreciate the suggestions and the additional 'behind the curtain' details (pump specifications, etc.) that I should keep an eye on to ensure I'm not sacrificing efficiency elsewhere in the system. It gives me a few pointed questions I can present to both companies. The way they respond might be the item that helps us make a final decision.

On the reports, no typos in the original entry. Company 1 -min/max geo extreme temp = 34.3/85, geo temp min-max: 30-85; Company 2 - min/max geo extreme temp = 37/94.1, geo temp min-max: 28-95. I'll see if the company will confirm and re-run their numbers. Your observation reinforced my concern their original projection had typos, or had some questionable entries (85 max temp, 48k cooling load only).

I definitely will ask the companies to break out the Manual-J calculation by floor. That should alleviate our concerns by responding to our concerns with some specific figures vs. running the house as one system.

Looks like journey will continue for us. Admittedly we're still on the fence; the relative cost and complexity vs. conventional HVAC systems is definitely making it intimidating to take the leap. Hopefully over the next meeting or two we have with Company 1 and 2 we can be comfortable with one of their recommendation and find a sweet spot for efficiency, install cost, and break even point/RoI.

Admittedly, however, if the post-tax incentive break-even period is much more than 12 years we might stick with our current systems and instead pursue solar panels + a future conventional HVAC replacements as needed as this approach seems to be less complicated and have less risk than geothermal with an extended break-even period. Given your experience with the technology, and professionally in the field, are we being overly simplistic in our thinking? Are there any important items we should be considering/accounting for that might make a longer break-even period geothermal install still make sense? We recognize this is not an apples-to-apples comparison. We do, however, want to try to rational and data-grounded in our calculus.

 

Geolink is fine, it provides people with assurance and has good safety margins built in to always design a good system. However, you have to be careful not to fall for the illusion of precision.
You are glowing a bit too much on the load numbers and the resulting performance number, keep in mind they are a guesstimate only. No need to re-run the numbers.

A few additional things. I would n0t in a world maintain 2 gas furnaces as backup/supplement heat which should never turn on in the first place. Electric strip heat is much better solution. I cannot understand why a dual stage packaged unit with electric strip heat backup is more expensive. Maybe there is something out of my view in regards to the way the house is constructed, and the ductwork needs to run.

I am however pretty certain that a single family house in Baltimore climate will not have a higher cooling peak load than heating peak load. Installer 1 loads look very much on target.
My question is whether a 5 ton 7 series with zoning between upstairs and downstairs would be a good design solution for you. You could direct the 5 ton cooling to the upstairs, and in the winter 5.5 tons of heating towards the downstairs. Add a 2 ton w-w unit and a tank for your domestic hot water, and you are good to go. It will reduce your needed loop field size since you are taking heat out of the loop in the summer

Save a borehole or two, save one heat pump, save the fossil fuel backups.

Geo can be simple.

PS: geo temp min-max: 30-85 and 28-95 are simply the ranges set in the software, to what range you want the loop field to be within. It is just a setting.

 

On the reports... Just so there's no confusion, I was referring to the "Heating Temp Diff" and "Cooling Temp Diff" values, not the loop water temps. These parameters must be set to the difference between the local outdoor design temp and the desired indoor thermostat set point. The temperature differences between indoor and outdoor determine the heating and cooling loads, so these values need to be correct and need to match the numbers used in the load calculation for the report to be valid.

The cooling design temp for Baltimore is 94 degrees and the first report is using a "cooling temp difference" of 17 degrees, so the reported run times, etc., will correspond to a thermostat setting of (94-17) = 77, not the 72 degrees indicated. If you intend to set the thermostat to 77 , then the report doesn't need to be re-run. If you intend to use 72, then the report will not be correct and should be re-run.

As docjenser indicated, this type of modeling tool won't exactly predict performance, but I believe it is useful to compare between system alternatives.

 

docjenser -- Thanks for the alternate design concept. I did ask both companies if alternate approaches, including zoning/re-ducting, might result in a system that performs better and/or costs less. Both said no. Your concept gives me something specific to ask about. Based on our home layout (fairly open floor print), my gut read is that our floor plan does not easily support getting a supply and return trunk into the attic where all of our second floor ducting is currently -- at least not without driving the cost substantially. I'm definitely going to ask though - I'd love to get to a 7-series zoned setup if we can swing it at/near our current quotes.

On the split unit/fossel fuel approach - Company 2 did say they were getting some deals on WF split systems (not available with packaged) that let them pass on some cost savings vs. packaged unit; that plus what I'm assuming is a lower non-WF air handler/furnace cost is driving the cost delta as far as I can tell. Given that the systems should not (or only rarely) require aux heat, I'd definitely prefer packaged system+electric aux for the basement/1st floor if I can get it at the same cost. I assumed I was stuck with a split system, with attic air handler, for the 2nd floor, and split unit in the basement with the pumps. Given the discussion, however, you've got me wondering is it possible to run a supply & return pipe to/from the attic to the pumps in the basement to feed a 5 series indoor or outdoor packaged system; if it is possible, would this approach be inadvisable from a cost or loss in energy efficiency (below a split system)?

I'm immensely grateful for the effort the community has put into this forum, and the time you're spending to try to help this aspiring novice out. I feel like I've been taking an intro-to-intermediate college class on HVAC while diving into the forum and these discussions. Anyone who does this work professionally, effectively, and at a fair cost deserve praise as it is legitimately building science.

Wondering out loud - have any of the prolific forum supporters ever considered starting a consulting business. I can't imaging I'm the only person that would think about paying an independent subject matter expert to help evaluate with system designs/proposals and possibly act as a buyers agent.

 

That is what I meant when I said there might be something out of my view in terms of ductwork routing. I too have an extra packaged unit in my attic for that reason, that ductwork run in a 100+ year hour house form the basement (floor -1 to the attic floor +4) was cost prohibitive.
Now, if you can run an insulated refrigerant line set to the attic, you can run an insulated source water line to the attic, although the diameter of the line is slightly larger.
Do you have your current gas consumption (assuming is it is gas, for the last 24 months), so we can get down to the actual heating loads of the house, which is actual data. Your annual electricity consumption showing every month and seeing how much the summer consumption is increasing would help too, but in Baltimore climate, you are still be heating dominated. You can usually download that data from the utility website. Post it here, and we can quickly run an "insanity" check. It
Your installers seem to be good and experienced, I am sure either one is doing a good job for you. One wonders why they measure windows or sqf, which don't really mean much for heat loss or gain, if they have access to consumption data, match it with the weather data for that area, and you know within 5% what your heating loads are.
Could you also post your geo-link report so we know what their input is. Like how much hot water usage, and how much internal gains do they assume, etc....