Hi Everyone, I'm brand new to this forum so I apologize, Geothermal is very new to me. I just purchased a two story zoned house 2650 square feet built in 1978. I live in central PA so temperatures can be drastic in both Summer and Winter. For Air-conditioning my second floor has its own (Carrier almost three years old) air handler and outside unit, same story for the first floor. However, when it comes to heating my house and hot water I unfortunately have oil! My heating is radiant hot water baseboards for the second floor. The first floor A/C unit has some kind of hot water coil inside it and that heats the first floor. Not a terrible set up but I do not want to pay the price of oil. Plus the 26 year old NewYorker is on its last leg I'm sure. Now onto Geothermal, I have had three different companies come out and give me quotes for Split systems due to my zoned house. The first companies quote: $38,402.00 Climatemaster Tranquility 30 series 5 Ton's- 3 ton unit for first floor(TEV038) two stage compressor and variable speed ECM motor. And a 2 ton unit for second floor (TES026) two stage compressor located in basement. One Climatemaster TAH026 2 ton air handler with variable speed blower located in the second floor attic. Two Flow centers built in the units Two auxiliary heat kits Two Bradford White 50 gal electric water heaters 3 vertical wells at 250ft. The second companies quote: 37,611.00 Climatemaster Tranquility 22 series 4 Ton's- 2 Ton unit for the first floor (TZV024) 2 stage variable speed package. And a 2 ton unit for the second floor (TES026) Split system in basement and a TAH 026 air handler in the attic. 1 Bradford white 50 gal electric water heater. Connecting De-superheater from first floor unit to my existing indirect tank. 2 Climatemaster digital thermostats 2 8kw Auxiliary heat kits 2 wells at 300ft. The third company quote: Have not received it yet, they came just yesterday. This company is going to quote me for a Carrier Geothermal system. According to their sales rep Carrier and Bosch are no longer connected at all whatsoever. I have read a lot of bad things when it comes to Bosch units. He assured me that within the last 6 years Carrier and Bosch are completely separate units. He went on to say that Carrier has a great performance series and an Infinity series that are great. He then said Carrier backs everything up with a 10 year parts and 10 year labor warranty! Plus Carrier offers a 60 month 0% interest loan, or a $1400 rebate for each unit so $2,800. The other companies have financing as well but either 1 year 0% or 97 months at 9.99%. (not so great). This Carrier option is starting to sound very appealing to me. Any insight or help would be very appreciated!
Let's be clear, I am no expert. I am in the same position as you, but I have done a fair bit of research along the way. The Tranquility 30 is a more efficient system (29.6 EER / 5.0 COP) compared to the Tranquility 22 (23.7 EER / 4.1 COP). Since the ClimateMaster quotes are about the same cost, makes more sense to me to go with the 30 model (if the 30 and 22 series are the only two options). But, I am wondering what the block heating/cooling loads per ACCA Manual J were for your site because the 1st quote is for a 3-ton unit to handle the 1st floor and the 2nd quote is for a 2-ton unit. Why? Capacity matters and too much can be a bad thing (lower actual system efficiencies, ineffective dehumidification, etc.). Also, Companies 1 and 2 are specifying 150' of vertical depth per ton of capacity, a common rule of thumb, which always makes my Spidey senses tingle in a bad way (the thermal conductivity of the ground and the grout can both have a substantial impact on the well depth; up to ±20% for each). As with the proposals that I received here in Perry County, PA, the wellfield is the least understood aspect by HVAC contractors and is, imo, one of the most important aspects. Proper design of the GSHP system, wellfield, and ductwork are all essential and then you need a quality installation (refer to ACCA's Residential Quality Installation Checklist).
That is how I felt regarding the two systems the price difference was too close to not go with the 30 series. As far as the Manual J, none of the contractors did one from what I can tell. All three took maybe two to three measurements while in the basement. My understanding with the manual J is that it takes some time...I also think most wont do a proper manual J for free in fear that you will use the info with a different company. But yes I agree too much and too little can be major issues with Geothermal. As far as the wells go I'm not sure who to trust on that part, both companies contract out with a local drilling companies that are reputable for Geothermal; however, how many wells and how deep I'm sure depend on what the HVAC companies tell them...
My assessment is that the business model is broken... you get what you pay for and with a "free" proposal, you get nothing of value. You're right, the HVAC contractors don't want to do the ACCA Manual J, S, T, D calculations to get an accurate design because they have a marginal chance of sealing the deal and they think you're going to take their work product to their competitors. But, that won't happen if they are highly qualified... AND can dazzle you with their expertise. In the end, they want to sell you a pig in a poke for $40K. Once you agree to the price by signing the contract, what's the incentive for the contractor to design the system properly? An improperly designed or installed system is not going to work well.
Just design it yourself. Let the contractor be a contractor and install your design. I had the exact same issue and decided these systems were too much money to leave to chance. I gave you the blueprint in post #2 of your "Vertical Loop Design Consideration"
I do cheer you to be critical for what you get told for some installers, you are rightful to do so. Yes, with single or even dual stage systems, an oversized system is not good. However, with variable speed, the "oversizing" is now right sizing, and a larger unit running at stage 5 instead of a smaller one at stage 7, the larger one will put out the same amount of BTUs and operate more efficient due to relatively larger heat exchangers and lower compressor speed. Thermal conductivity of the ground is relatively stable once you get into rock, usually between 1.5 and 1.9, which only, the difference is not more than 10%. The difference between 0.4 bentonite grout, and 1.6 graphite grout can be close to 90%, meaning 0.4 grout can demand almost twice as long borings. We are using 500ft in a single borehole and put up to 7 tons of heat pump capacity on it, 5 tons for space conditioning, and 2 tons for domestic hot water. We monitor every system we put in, so we have the feedback (and so has the customer) how the performance is. Full transparency. You get the best performing system money can buy, at the lowest possible cost, and we guarantee it, and we give you the means to check on us since you see the performance too, but don't bother me with your demand for ACCA Manual prior to engaging us. The variable speed technology turns the old argument about oversizing upset down. Undersizing and using supplement heat has become the new enemy, since gas and other fossil fuels will be phased out, and the heating sector will be electrified via heat pumps, and them all using supplement heat at the same time on a peak daywould collapse the grid. Speaking about ACCA manual J, which Harrisburg PA shows a design temp of 11 degrees F. How do you heat you house if it is -5F and the wind is blowing during apolar vortex? And supplement heat is not an option anymore due grid a lack of grid resilience? ACCA and ASHRAE need to adopt their seizing standard to variable speed heat pump technology, and not oversized furnaces and single stage A/C units. What ACCA manual J tells you does not fit in anymore to the needs heat pumps are serving.
Wait so if I plan to use the geothermal for hot water as well they should be adding Tonnage? If that is the case both companies did not account for that. I actually did question the one company about why he quoted 5 tons and his response was the same as what you said about the variable speed technology. What are your thoughts on the Carrier units? Do you happen to know if they have truly separated from Bosch and are now actually new Carrier units?
In general, if you want to generate hot water in the winter, it is an additional load on the loop field over and above what ever heat is pulled from the earth to produce hot forced air or water (hydronic). In the summer time, generating hot water is reducing the heat being rejected into the ground loop. So its not really a loop load during the summer in the same sense as the winter time condition. Depending on how the system is set up, you can be actively producing hot water with a dedicated gshp, have a dedicated gshp for both space heating and hot water production, or just supplementing a hot water heater by stealing extra heat pump production (desuperheater). How much of a unit size increase depends on the system setup and volume of hot water production. There should be no unit size increase if going the desuperheater route and possibly none to a small loop size increase (lots of variables here). There should be both a unit size and loop size increase for dedicated hot water production.
It seems like you're quotes are more likely to use Desuperheater and not dedicated hot water. If using geothermal as a dedicated hot water generator, a typical family of 4 uses 100 gallons of hot water daily, which would require about 58,000 BTU to heat from 50 to 120 degrees. Spread out over a full 24 hours, that's only 1/5th a ton additional load on your ground source, but the way hot water use might be more focused in mornings and evenings, you could see a 2 ton demand increase in hours of hot water use. My thought is not a huge problem for the ground source or a dedicated unit if sized properly.
Yes they do plan to use Desuperheater with an electric water heater so that makes sense now. I do have one other concern the company quoting me at 4tons only wants to do two wells at 300' would three at 200' be better? I just want to make sure that this unit will be able to keep up with the colder winter days. He told me that I should expect only a few days that the aux heat would have to run when it got very cold. Wouldn't it just be better to have either a larger unit like 3 tons or more wells to avoid that aux heat kicking on at all?
Also can anyone speak for the Carrier Infinity series? Was hoping to have some more responses from this forum.
You typically would want to do fewer wells at deeper depth for efficiency of construction and more stable ground temp over length of loop. Given 600' of bore length, I would go 2 wells at 300'. Its certainly possible to do 1 well at 600' but there maybe issues with drilling equipment at that depth plus you would probably need larger diameter loop pipe to reduce friction to lower overall pumping power while maintaining turbulent flow. I would think 3 wells at 200' would be possibly more expensive to construct and not necessarily improve system performance. Whether or not the system can keep up with a cold winter day is dependent on: 1)the unit's capacity relative to house heat loss at the design temp for your area 2)length of ground loop to be able to pull the heat needed from the ground to satisfy #1 3)flowcenter/piping/pumping arrangement to satisfy both #1 and #2 All three need to be properly sized in order to work as a system. 1 of the 3 can't be correct and still work. For example, a loop that can only pull 2 tons of heat from the ground is only going to give a 4 ton unit 2 tons of heat (it doesn't really work this way - the water temp in the loop will just drop below unit working range and stop working as the unit tries to extract 4 tons of heat). If your design temp is 11F (per docjenser above), that means that the actual outdoor temperature will only drop below that 1% of the time (for heating, design temps are the lowest 1% of historical temps; 99% temp for cooling). You might get a night at 0F (actual temp not windchill) for several hours but by the time your house catches up to that, the sun came up and the outdoor temperature rose. Heat loss isn't immediate (unless you live in an open air barn). Design temps were determined with statistical analysis based on historical weather and can be trusted for design or no HVAC equipment in the US would work (both residential or commercial).
Hello again, I have one more question about the "oversizing". As I've stated before my house is roughly 2,650sqft. The last and final contractor I've had come out to my house quoted me for 6 tons, 900ft of wells. However, when it comes to the units he only wants to install a 3 ton for the first floor and a split 2 ton for the second floor. His explanation for this is to avoid ever having to run Aux heat. He said he sees it too often that customers will complain about the higher than usual heating bills during the cold months. He would rather have too much wells for heat than run out of loop. The system he is proposing is the Carrier Infinity line. Is this oversizing necessary/better to avoid aux heat? He sent me this in an email maybe this will make more sense to you guys. "Your total heat loss for both floors and the basement is 68,500 btuh maintaining 70 degrees in the winter and the total heat gain is 46,750 to maintain 68 degrees in the summer (those were the desired temperatures you mentioned). I am not concerned about the cooling, only the heating side. As you can see, there is over a 20,000 btuh difference in system output vs. your home’s need in the dead of winter. The difference is made up with the electric auxiliary heat that is built into the system. Even without considering heating the basement at this time, there is no insulation in the floor between the basement and the first floor and therefore your basement is pulling a lot of heat from the system." Thank you again to all you professionals that take the time to help us out on this forum
