Pricing per ton for GSHP and air-to-water heat pump
cathydalmeida
| Posted in General Questions on
Is there a general rule of thumb for pricing of a GSHP and Air to Water heat pump for a medium sized installation of ~17 tons or 200,000 BTU/hr. $/Ton or $/BUT? What products fit this market segment?
Do you also have a general rule of thumb for an energy retrofit of a home in $/Ton or $/BTU reduced heating demand?
Is there an issue with using a GSHP in a climate where little cooling is required?
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Replies
Cathleen,
You mentioned "an energy retrofit of a home." If this is a residential application, it's highly unlikely that you need a 17-ton heat pump. That would be a very big unit.
We need to know more about your house. In general, ground-source heat pumps are quite expensive, and aren't the most cost-effective way to heat or cool a home.
For an energy retrofit project, the first order of business is usually air sealing work, followed by insulation improvements and sometimes window improvements.
If you are planning that type of work, you should be able to have someone perform a Manual J heat loss and cooling load calculation. That will allow you to size your heating system.
In most cases, you won't be using a ground-source heat pump for this type of project.
For more information, see Are Affordable Ground-Source Heat Pumps On the Horizon?
Air-to-water heat pumps are rarely used in the U.S.; until recently, there was only one major player on the market (Daikin Altherma), and evidently Daikin is no longer distributing that equipment in the U.S.
In most cases, the best type of heat pump for this application is an air-to-air heat pump -- specifically, a ductless minisplit or ducted minisplit.
Martin, Thank you for the response. It is consistent with everything I've heard and read. I appreciate the response.
Actually I do have one additional follow up question. If someone already has radiant floor heating and/or wants to install radiant floor heating what type heating technology would you use?
Cathleen,
Most radiant floor systems include a boiler. Boilers can be fueled by natural gas, propane, oil, or firewood.
A few radiant floor systems use a water heater as a heat source. Some of these installations are successful, while others are glitchy and problematic.
You might want to read this article before you specify a radiant floor system: All About Radiant Floors.
Cathleen ,
Radiant systems can be done properly and not suffer the doomsday scenario in Martins "All about radiant floors" . If designed properly with proper zoning taking SHG and the like into consideration it is the finest system available . Rooms on the south should never be zoned with Northern rooms . In a tight home or even semi tight the water temps in the floor should be well below any temp that the floor can reach while receiving sun thus it is not possible for those rooms to OVERHEAT the space . Hotter goes to colder and high goes to low and even Martin will not argue that fact , I THINK .
The title of Martin's paper should have been "ALL ABOUT CHEAP , POORLY DESIGNED RADIANT FLOORS ON A BUDGET " . I say this because every time this paper is referenced and I read it just to remind myself how bad a name creeps without proper knowledge have given radiant heat . Research " radiant ceilings " , it's been done for decades successfully and is not just for commercial apllications anymore , as if it should only have been there to begin with . Those same tubes can also handle the entire sensible load for cooling while latent can be done with a DOAS system which isn't difficult since these houses built with GBAs tolerances should not have such a high latent gain anyway . Again , this all is dependent upon the quality of the envelope .
As to your original question . That is almost impossible to answer without knowing about the things Martin has mentioned . I don't believe there is a set per ton price and I would even say that if someone is willing to giveyou that price without first performing a proper heat loss and having a good idea about the ACH in the home you should not even consider him a candidate to perform the work . 17 tons is a whole lotta energy also . I recently designed a system for a project using solar thermal with NG backup (to keep the COP of w/wHP above 4) , that home is 13,546 sf and only required a 10 ton heat pump . keep in mind that I have the NG system turn on at an outdoor temp where the HP COP would drop below 4 .
GSHP is deceiving also and can cost more than is comfortable . The pumping required to move all that fluid through the ground and transfer the required heat is huge and is not included in many contractors efficiency numbers at time of sale . Whoever thinks about GSHP systems should have a look at solar thermal DESIGNED properly taking everything into consideration . A W/W HP recieving 70* fluid has an exponentially higher COP than one receiving =<50* fluid . Low pumping costs also become possible in this way . Buried tanks become the storage for your medium , usually about 40 - 50% lower install cost . When there is no sun for an extended period it can take up to a week before the stored fluid drops 10* and enters the HP at 60* at which point you're still far better off than at 50* with GSHP . It would be a good amount of time before you get the EWT to 50* and even then you do not have that large parasitic pumping cost that goes with GSHP systems . ECM pumping is the norm in these types of systems and remember with backup when temps are very low the HP should be off line anyway . Martin also wrote "SOLAR THERMAL IS REALLY < REALLY DEAD ". Quite entertaining actually but it kinda died in the comments section after some recognizable heavy hitters starting showing up that Google really , really well . I cannot still understand what aversion there is on a site such as this to technologies that meet the definition of Passive by many published standards . Long ago this movement started because of things that were bad for the environment , now it seems common practice to put those bad things like refrigerants right in the house with the folks we began to save the planet for . What exactly is an environmentally friendly refrigerant and is there really such a thing ?
I would be happy to work alongside Martin to give you good advice as long as this does not turn into a radiant fear mongering campaign by the usual suspects . If it does go that way , feel free to PM me or email me at [email protected]
> Is there an issue with using a GSHP in a climate where little cooling is required?
This depends mostly on the costs for various energy sources you have available. http://www.eia.gov/neic/experts/heatcalc.xls will help you compare them effectively. In some parts of the country a modern heatpump (whether air-source or water source) can cost less than half what LPG does on an annual basis. In other places the energy cost differential is far less, making the added first cost for the heatpump a lot less attractive.
Costs are definitely a regional issue. I just priced a gshp, a conventional heat pump, and mini splits for my new home. After the 30% tax credit, the high end 2-stage gshp installed by a reputable company was about $1,000 more than a high seer conventional system. The mini splits were even higher. The service life of gshp should be longer than the other two as well since all the equipment is inside. I'm going with gshp.
There is a good argument that I could put half that money in equipment and the other half in shell (insulation, etc), thus reducing my load and making mini splits a better option, but frankly I'm not comfortable risking it. I'm already getting everything I can from our local trades in terms of shell. Mention exterior foam insulation around here and people look at you like you have two heads.
I'm guessing that you've got perhaps a 3500 sq. foot house, and someone used a cold climate rule of thumb of 60 BTU/sq foot and told you to get a 200 kBTU/hr heating system. That rule of thumb is based on the following
1) Avoiding calculations that require more than 1 minute or any math more complex than on multiplication.
2) For a contractor, there's rarely a penalty for oversizing a furnace. A 200 kBTU furnace is a little more expensive than a 100 kBTU furnace, but that actually means more profit for the contractor. On the other hand, if the installation is undersized, he might get a callback and have to bear some fo the cost of upgrading, and/or suffer a hit to his reputation.
3) Less insulation, worse windows, etc., than are now allowed by code.
For a GSHP, the cost is closer to proportional to size, and the initial installation and equipment cost is much higher, with the hope to save on operation cost later. That makes the sizing of the system much more important, if you don't want to waste money.
As for cold climates, it can certainly work, and in some ways, the benefit of a ground-source heat pump over an air source is more dramatic when the air is very cold. On the other hand, using the loop for cooling in the summer does help "recharge" the heat in the ground, and if you are not doing that, you need deeper and/or more wells, or larger area if you are doing a horizontal loop. That's not a problem, but it does mean you want someone you trust sizing the system, and it will make the cost a little higher.
Nobody has dared directly answer your question--I don't have any solid data or recent experience, but I'll hazard a very general guess of $15k + $5k/ton. That's going to vary widely and I put a number out mostly in hopes that others will say I'm wrong and give better guesses. But that would mean $100k for a 17 ton system. I'd guess that a good analysis of your building would show you really only need perhaps an 8 ton system, and if you spend a fraction of the money you save on a better envelope, you could get that down to 4 tons, at which point it starts to seem much more interesting. On the other hand, at that point, heating with a few minisplits also becomes feasible, and might be less expensive.
A typical code-min 2500' house would have a heat load at 0F of less than 30,000 BTU/hr. A typical older house that size might be anywhere from 30K -60K, but rarely higher.
A rule of thumb of 60BTU/hr per foot of conditioned space is ridiculous for any sized house, in any US location. Even in Fairbanks AK (where the 99% outside design temp is -41F ) even the rule-of-thumb hacks use 25BTU/hr-ft^2, or 30BTU/hr-ft^2 for new construction. It takes a VERY large and mostly UNINSULATED house to have a real heat load of 200,000 BTU/ hr, unless you literally have a number of windows wide open.
In southern New England GSHP systems tend to run between 2-6 tons, with 3-4 ton systems being pretty typical. The cost in this regiion is higher than the national average at about $9000/ton, according to the data from a Connecticut statewide rebate incentive program. Of course the $/ton increases with smaller systems- I've never seen a quote for a 2-ton system less than ~$28KUSD, and that was a handful of years ago. Even after the 30% income tax credit it's still $20K. By contrast modulating ductless mini-split systems run $3.5-4K/ton. The amount of design & engineering required to do a 2 ton GSHP system right is about the same as doing a 10 ton system, and every GSHP system is a highly customized design.
And with that customization comes design risk. It's very difficult to tell the true experts from the hacks when it comes to GSHP systems, which is one reason modulating air source heat pumps like mini-splits are more attractive once you get the load down to 3 tons or less. Air is pretty much the same in any climate, and though the absolute efficiency & capacity performance of air source heat pumps is climate dependent and has to be compensated for, There is a lot less customization & risk. With ductless heat pumps that risk is extremely low- they are well-engineered pre-packaged "system in can", with far fewer ways to screw it up (though the the more idiot-proof you make something the more creative the idiots become. :-) )
When retrofitting an older home that has a 50-60,000 BTU/hr design heat load, it's usually more effective to reduce that heat load to under 40,000 BTU/hr with retrofit air sealing & insulation, maybe even some of the windows rather than paying for the extra 1-2 tons of GSHP. Subsidies for GSHP & retrofit weatherization will skew the numbers considerably however, and it takes a sharp accounting pencil to figure out exactly where the boundaries cross. But when weighting those considerations, know this: As a general rule, building envelope efficiency provides more comfort than mechanical systems efficiency. And the lifecycle of building envelope efficiency measures is 2-4x longer than any HVAC system. When in doubt, spending the real money on lowering the load is usually going to be a better long term deal than highest efficiency systems to support that load.
Martin: Where did the rumor that Daikin is no longer selling the Altherma in the US come from?
Dana,
Q. "Where did the rumor that Daikin is no longer selling the Altherma in the U.S. come from?"
A. A quick web search has me doubting the truth of the rumor. I don't know where I heard it, so I hereby withdraw the statement as unfounded -- and await further information from anyone more knowledgeable.
Dana D said
"There is a lot less customization & risk. With ductless heat pumps that risk is extremely low- they are well-engineered pre-packaged "system in can", with far fewer ways to screw it up (though the the more idiot-proof you make something the more creative the idiots become. :-) ) - "
Well said .
Daikin Altherma is alive , well and available as far as I know .
My price for two, 2-ton gshp split systems each on separate wells including all ducting and ventilation ducting (4 bathrooms, kitchen, laundry) from who is, the best I can tell, a competent and reputable installer is $30,600. Keep in mind there is a $9,180 tax credit (not a deduction. A credit). So my net cost is $21,420. That's $5,355 a ton. My other quote from another reputable installer (geo is the majority of their biz) is about the same.
Richard,
I tried to get altherma pricing from the 4 closest dealers listed on Daikin's website. Not a single one willing to sell me a unit, no one was even willing to ballpark a price because they where too far away (closest one is an hour and a half drive) I even asked for prices on specific units (I downloaded the simulator software and it gave model numbers I would need)
C. Maglio,
That is a lower price than I have heard of in the last decade. I am curious what region you are in. At that price, it does sound like a good decision, although it's a shame you can't find people to do good work on your envelope.
Charlie,
I'm in Middle Tennessee. It does seem to be a very competitive and popular option around here.
I've talked to some very energy oriented builders and architects and the consensus is If I could even find someone to do advance framing, exterior insulation, etc they'd charge me a huge premium. Everyone is really busy around here. They are not going to re-train for one job. I am using Zip insulated sheathing. Regular Zip is popular around here and the R version works just about the same. So I'll still have a decent envelope. Certainly way better than code.