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sizing geothermal HP in New York
Last Post 27 Aug 2013 11:33 AM by Dana1. 77 Replies. |
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Dana1
Senior Member
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| 16 Aug 2013 10:52 AM |
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Posted By joe.ami on 16 Aug 2013 09:38 AM
I'll agree with one thing, the comparison is silly. 25K for 4 tons is quite common around here, 3/watt not so much.
The US average for 2-10kw roof top PV is under $5 watt. (The median for sub 10kw grid tied in 2012 was $5.30/w, according to t hose tracking it at Lawrence Berkeley.) In places like CA/NJ/MA where the subsidies have attracted competition $4-4.50/watt is common, $3 after the 30% federal tax credit, in the high-2s after state & local subsidies. Third-party ownership business models (in states where regulatory agencies allow that) where the installer owns & maintains the PV and either leases the panels to the homeowner or guarantees the a lower-than-retail fixed rate for their power is also driving the installed volume up, costs down. Local regulations make or break the price & viability of PV solar. The panel cost no longer dominates the cost of the systems- inverters are still adding a large fraction of a buck a watt or so (but falling in price), racking isn't free (but also falling in price), with the rest being hand-holding & red tape jumping through multiple utility/state/local regulatory hoops, and (somewhat mysteriously) far more man-hours per kw on the installation than in Germany. In NJ the price came down dramatically when the state streamlined the permitting requirements, and in MA similar streamlining and cost cutting happens for residents in communities participating in the Solarize Mass program. Post-subsidy price points under $3/watt are becoming very common here. (I personally know two families who have hit the sub-$3/w post-subsidy for PV on their own homes in the past 18 months.) I only WISH $25K for 4 ton systems were other than a mythical creature in New England. There may have been a few of those in the mix under the CT rebate program. But with the average system size of 5.63 tons and average cost of a hair over $9K/ton, if half were cheap & easy swamp-dirt trenches at $6/ton, the rest had to all have been deep granite bores. Even the larger scale commercial sized installations avereged ~$8.7K/ton. If it can be done a whole lot cheaper, there's a clear market opportunity for installers to get into it in MA/CT. BTW: I found a really great deal down at the Wal-Mart- a 5000BTU (1465 watt) window unit for $98.99- that's only 7 cents a watt!  (With a deal like that who would ever buy PV, or GSHP?  ) |
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Dana1
Senior Member
Posts:6991
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| 16 Aug 2013 02:57 PM |
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An analyst who has sifted through more of the Lawrence Berkeley data than me pointed out in a blog just this afternoon that <10kw system installed prices in Texas averaged a pre-subsidy $3.90/watt last year! With the 30% Federal tax incentive that's a statewide AVERAGE cost of <$2.73/watt paid, when other incentives get factored in. In places with fatter local incentives somebody has probably already hit the $2/watt mark. It'll be awhile before it hits $2 without subsidy for most of us, but we're already seeing the thin edge of the wedge: At $4/watt PV already has a lifecycle per kwh levelized cost (including financing & a 15 year lifecycle on the inverter) well below the residential retail prices for electricity in NY or CA. |
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Paul_L
New Member
Posts:7
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| 20 Aug 2013 04:01 PM |
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Hi flojo,
If you're still monitoring this thread with these nerds debating among themselves you should get back to me. I'm a retired engineer / physicist in the Hudson valley. I'm almost done retrofitting a 7 tom geothermal system to my 4000 sq ft ranch. It's taken 2 years to do. The HVAC contractors up here know very little. Three of them made every mistake in the book. I had six guys bid on the job at the beginning. They each claimed 20 plus installations. The building departments of the three towns here say there are just four installations and three of them don't work. I don't know where these guys did their installations but it wasn't here.
The big problems here are poor transportation of heating oil, oil terminal monopolies, high oil price, very few LPG dealers, high electric rates, spotty gas main patterns, solid granite folded rock shelves, and confused town building departments.
We should talk!
Paul_L |
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Dana1
Senior Member
Posts:6991
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| 20 Aug 2013 06:26 PM |
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Posted By Paul_L on 20 Aug 2013 04:01 PM
Hi flojo,
If you're still monitoring this thread with these nerds debating among themselves you should get back to me. I'm a retired engineer / physicist in the Hudson valley. I'm almost done retrofitting a 7 tom geothermal system to my 4000 sq ft ranch. It's taken 2 years to do. The HVAC contractors up here know very little. Three of them made every mistake in the book. I had six guys bid on the job at the beginning. They each claimed 20 plus installations. The building departments of the three towns here say there are just four installations and three of them don't work. I don't know where these guys did their installations but it wasn't here.
The big problems here are poor transportation of heating oil, oil terminal monopolies, high oil price, very few LPG dealers, high electric rates, spotty gas main patterns, solid granite folded rock shelves, and confused town building departments.
We should talk!
Paul_L
OUCH!! That's not a very confidence inspiring local state of affairs, to say the least!?! (DIY geo- it's not for everyone, but good for you!) In my part of MA I've only personally seen a handful of geo installations. All of them were expensive by joe.ami's and docjenser's standards, but they managed to heat & cool the houses quite comfortably. One of them was installed maybe 3-4 years ago by a geo outfit from Indiana (can't remember the name of that company). They weren't the low bidder- they were the only bidder the client had any confidence in after getting into the technical weeds on it even a little bit. I was a bit surprised the would haul a crew (including the drilling rig!) 800-900 miles or so from home, but it was during the economic melt-down, local jobs might have been tough to get. Getting competent design and installation is the only way to get the real efficiency out of this stuff (at any price.) Feels like there's some room for improvement. |
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jonr
Senior Member
Posts:5341
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| 21 Aug 2013 09:46 AM |
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Sounds like a lot of reasons favoring nat gas. |
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Paul_L
New Member
Posts:7
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| 21 Aug 2013 05:23 PM |
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I said spotty natural gas main patterns and I meant it. In Dutchess county only 7,000 out of 47,000 residences have a gas main available. Most of them have hooked up. Central Hudson Gas & Electric has about 5,400 gas customers in the county. The rest of us are out of luck.
Oil gets barged up the Hudson from the pipeline heads and refineries in northern New Jersey. Most of the river frontage is railroad property. There are very few places to put tank farms so the ones here tend to become local monopolies. Take a look at google maps. There are tank farms in Newburg, Marlboro, New Hamburg, Kingston and Hudson. That covers 90 miles of the river.
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docjenser
Veteran Member
Posts:1400
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| 22 Aug 2013 04:29 PM |
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Posted By Paul_L on 20 Aug 2013 04:01 PM
... this thread with these nerds debating among themselves you should get back to me. I'm a retired engineer / physicist.....
...It's taken 2 years to do... The HVAC contractors up here know very little. Three of them made every mistake in the book. .....
The building departments of the three towns here say there are just four installations and three of them don't work.
I don't know where these guys did their installations but it wasn't here.
Paul_L
Well Paul_L, welcome to the forum. Great first post! Since you are a retired engineer/physicist, and imply that you are not a nerd, a couple questions:
Why did it take an engineer 2 year so far to retrofit its house with a geosystem? How did you know that the contractors around you know very little, and what were their mistakes they did? And what is the booK? Maybe the contractor which knew so very little could have done that much quicker?
And how does the building department knew how many systems were installed. NYS does not require permits for geothermal system, does your town requires that? And how did they know what worked and what not, and how did they determine that?
And if they did not do their installation in your location, they could not be responsible for the 3 out of 4 installs which are not suppose to be working, correct? So that is good, right?
Hopefully easy to answer questions for a retired engineer/physicist.
Many here have seen our share of installers being incompetent and not serving the customers well, but very few had a better "I know it better" entrance here in their first post!
Which reminds me of a speech Bill Gates once gave to a high school where he said "Be nice to nerds, chances are that you will be working for one soon...." Obviously, that will not be the case here, since you are retired, right? |
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Paul_L
New Member
Posts:7
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| 23 Aug 2013 04:16 AM |
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Hi docjenser, thanks for the welcome.
I didn't say I wasn't a nerd. I said you guys were. (I'm definitely a big nerd.) But you guys got off the track. Flojo originally said that he had hired some "specialist" to do an energy audit and wanted to "sound members of this forum on the appropriate sizing of the Geo HP for my type of climate". You guys were debating the relative merits of insulation vs. heat pumps vs. photovoltaic vs. everything else. Come on, give the guy some help!
You asked several questions.
1. Why did it take an engineer 2 year so far to retrofit its house with a geosystem. Because of several reasons. First, I'm lazy and inefficient and old and slow. Second, my wife had a stroke and distracted me from the task. Third, the contractors didn't show up when they said they would for appointments or to do the work. There are several more reasons but I'll leave that for now.
2. How did you know that the contractors around you know very little, and what were their mistakes they did? I knew because I studied physics. Each one of them absolutely knew that the exact way he wanted to do the job was the only way that would work. One insisted that vertical bores would work but a horizontal field would not. Another insisted that horizontal was the way to go. Another wanted direct expansion. Their mistake was in assuming that I was stupid. Those are three different topologies of heat exchangers .... they will all work. One might cost more than another but they will work.
And what is the booK? That is a rhetorical device used by people possessing the propensity to perambulate through a polysyllabic vocabulary .... in other words .... a nerd.
Maybe the contractor which knew so very little could have done that much quicker? Maybe he could have finished the job quicker and maybe it would have worked.
And how does the building department knew how many systems were installed. NYS does not require permits for geothermal system, does your town requires that? The cities of Beacon, Newburg, Poughkeepsie, and the towns of Poughkeepsie, Wappingers Falls, Fishkill, and East Fishkill all require electrical permits and inspections. The electrical inspectors are all interested in seeing geothermal stuff, it's new to them. They saw them all.
And how did they know what worked and what not, and how did they determine that? By hearing the complaints of the home owners, (and one farmer who tried to heat a barn), who got stuck.
And if they did not do their installation in your location, they could not be responsible for the 3 out of 4 installs which are not suppose to be working, correct? So that is good, right? I suppose there might be installations outside of the areas I mentioned, but those areas have 80% of the population of Dutchess and Orange counties, so there won't be too many.
My next post will try to answer flojo's original question. Someday I will post about the mess that I've got here, but today I'm too tired.
Anyway, it's nice to meet you docjenser.
Dana1, I'm surprised that you've only seen a handful of installations up your way! You must not be too near Boston. Are you out in the sticks? Fuel oil is even more expensive there than here. It all has to be barged north and east of the pipeline heads in New Jersey.
Jonr and joe.ami It's nice to meet you guys too. |
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Paul_L
New Member
Posts:7
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| 23 Aug 2013 04:49 AM |
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Hi flojo. I'll try to address your original query, that of sizing a heat source in new construction.
There are methods, like manual "J", which try to forecast the heat requirements of new construction. They work by calculating the surface area of the envelope, the heated volume, and multiply that area by measured rates of heat transfer. You need to know all the materials being used and the areas of the walls, ceilings or roof, floor or slab, windows and doors in the exterior surface. You can do it with paper and pencil or a spreadsheet or an expensive computer program.
Either way you come up with a single number and then you cross your fingers and hope. If the carpenters were sloppy or the plumber or electrician drilled some unaccounted for holes, or the insulation guys didn't fill the cavities or get the vapor barrier just right, or the guys putting on the shingles and flashing missed something or ..... or ...... You get the idea. It might not work!
You will find out how much heat you need only after you finish the envelope and the thing is weather tight. Unfortunately, you can't move in without a C of O, and you can't get a C of O without a heating system. So you have to install the heat, (and cooling), before you know how much heat you need.
I have often thought that the way to do it is to install cheap electrical resistance heat, move in, and record how much power it uses and the degree days you encounter. After one winter you will know exactly how much heat the building needs. Then you can design the permanent HVAC system to provide exactly the amount of heat you need without the expense and uncertainty associated with a careful manual "J" computation.
Cheap electric baseboards sell for about $10 per foot. Each foot uses 250 watts and delivers 850 Btu. If you do a quick manual "J" type calculation and find you need about 85000 Btu, you'll need 100 feet of baseboard distributed around the house which will cost $1000. A few thermostats and relays will add another $400 to that. Then you will have to find some cheap electric clocks ... the old fashioned kind with a plug. You wire the clocks so one runs when each thermostats call for heat. You then record how many hours the clocks run every day together with the degree days for that day. You then multiply (the hours each baseboard ran) times (its length in feet) times (.25 Kw/ft) times (electrical power x 3.412 Btuh/Kwh) for each baseboard or group on one thermostat and sum the results. A spreadsheet will do this nicely. |
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Dana1
Senior Member
Posts:6991
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| 23 Aug 2013 12:58 PM |
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Posted By Paul_L on 23 Aug 2013 04:16 AM
Dana1, I'm surprised that you've only seen a handful of installations up your way! You must not be too near Boston. Are you out in the sticks? Fuel oil is even more expensive there than here. It all has to be barged north and east of the pipeline heads in New Jersey
"The sticks" is Worcester, MA, second only to Boston in size of New England cities (and under an hour away). It's twice the size of Albany, NY. But Worcester, like Boston, is on the gas grid, and despite limited long-haul pipeline capacity and large fraction of LNG in the grid, residential retail gas on the local grid costs less than half the $/MMBTU of oil at recent prices. In a perfectly implemented GSHP system there would be an nominal operating cost advantage (but not a lifecycle cost advantge) over the (typically half-assed) gas burner implementations here. That may eventually change if gas prices soar and electricity doesn't (not likely given that about half the power on the MA grid is fueled by gas.) Were I actively seeking them out I'm sure I could make my first-person GSHP sightings would go up, but I'm not. The few that I have seen are in nearby off-the-gas-grid central MA towns, in homes of the "price is no object" extremely well-off, with one exception, and despite more conventional income that guy paid slightly more per-ton than the fat-cats did (but for a somewhat smaller system too.) In most retrofit situations I see the economics of improving the building envelope are usually more favorable than $9K/ton GSHP in the local MA subsidy climate, but not always. In other situations taking the lower efficiency of ductless air source and adding rooftop solar PV makes more sense, after all subsidies are considered, but not always. The risk factor on GSHP is usually bigger than the other options too, and even the few case where I've advised seeking out a geo contractor the homeowners have all balked, and either deferred the decision or gone another direction. |
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jonr
Senior Member
Posts:5341
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| 23 Aug 2013 03:10 PM |
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In a not yet built house, I think it is very appropriate to compare investments in more insulation to various heating systems. Designing or building it and then figuring out how much heat it needs is not going to lead to optimal results.
An interesting challenge would be to find heat load by doing measurements during a couple of nights using temporary heaters (or A/C or both), data loggers and some math to account for thermal mass, outdoor temp, wind, etc. I suspect it would be an improvement on most Manual Js and a lot cheaper than running a whole season on electric baseboards. |
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Dana1
Senior Member
Posts:6991
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| 23 Aug 2013 07:38 PM |
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All new construction benefits from iterative processes like that. The big error bars in the GSHP calc here are the actual cost and actual performance, both of which have quite a range. It's far easier to zoom in on the MMBTU/year and BTU/hr performance of the building.
A $12K/ton GSHP running at a seasonal average COP of 3 is a very different set of economics than a $6K/ton GSHP than hits 4.5, and either are real possibilities. Where it actually ends up has a real effect on where it's rational to stop on the building envelope. Based on third party examples I've seen to date I'd be loathe to presume that a random installer would hit the $6K/ton 4.5 COP mark. Penciling in the CT $9K/ton and assuming a COP of 3.5 would be more likely, unless you have tested existence proofs by the same installer along with a budgetary quote.
BeOpt is a pretty flexible tool on dealing with all the "what ifs" for the building envelope part, since it was designed specifically for cost-optimizing thermal performance of a specific design using DOE-2 as the underlying thermal performance tool. DOE-2 uses local climate data and does a reasonable job on thermal mass issues. |
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docjenser
Veteran Member
Posts:1400
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| 23 Aug 2013 09:55 PM |
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Posted By Dana1 on 23 Aug 2013 12:58 PM
the few case where I've advised seeking out a geo contractor the homeowners have all balked, and either deferred the decision or gone another direction.
Why does that not surprise me??? |
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| www.buffalogeothermalheating.com |
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docjenser
Veteran Member
Posts:1400
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| 23 Aug 2013 10:01 PM |
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Posted By jonr on 23 Aug 2013 03:10 PM
In a not yet built house, I think it is very appropriate to compare investments in more insulation to various heating systems. Designing or building it and then figuring out how much heat it needs is not going to lead to optimal results.
An interesting challenge would be to find heat load by doing measurements during a couple of nights using temporary heaters (or A/C or both), data loggers and some math to account for thermal mass, outdoor temp, wind, etc. I suspect it would be an improvement on most Manual Js and a lot cheaper than running a whole season on electric baseboards.
It is previous consumption data, see Dana's post. It is actual data , but has little room for error ("oh, we forgot to tell you that we went to Florida for 8 weeks in January, and thad the thermostat was set at 45F"). Differences in peak load can easily be covered with short term supplement heat. |
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| www.buffalogeothermalheating.com |
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jonr
Senior Member
Posts:5341
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| 23 Aug 2013 10:52 PM |
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>It is previous consumption data,
>> I am in the process of building a 5,200 sqft luxury home in the hudson valley |
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docjenser
Veteran Member
Posts:1400
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| 23 Aug 2013 11:34 PM |
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Posted By Paul_L on 23 Aug 2013 04:49 AM
Hi flojo. I'll try to address your original query, that of sizing a heat source in new construction.
There are methods, like manual "J", which try to forecast the heat requirements of new construction. They work by calculating the surface area of the envelope, the heated volume, and multiply that area by measured rates of heat transfer. You need to know all the materials being used and the areas of the walls, ceilings or roof, floor or slab, windows and doors in the exterior surface. You can do it with paper and pencil or a spreadsheet or an expensive computer program.
Either way you come up with a single number and then you cross your fingers and hope. If the carpenters were sloppy or the plumber or electrician drilled some unaccounted for holes, or the insulation guys didn't fill the cavities or get the vapor barrier just right, or the guys putting on the shingles and flashing missed something or ..... or ...... You get the idea. It might not work!
You will find out how much heat you need only after you finish the envelope and the thing is weather tight. Unfortunately, you can't move in without a C of O, and you can't get a C of O without a heating system. So you have to install the heat, (and cooling), before you know how much heat you need.
I have often thought that the way to do it is to install cheap electrical resistance heat, move in, and record how much power it uses and the degree days you encounter. After one winter you will know exactly how much heat the building needs. Then you can design the permanent HVAC system to provide exactly the amount of heat you need without the expense and uncertainty associated with a careful manual "J" computation.
Cheap electric baseboards sell for about $10 per foot. Each foot uses 250 watts and delivers 850 Btu. If you do a quick manual "J" type calculation and find you need about 85000 Btu, you'll need 100 feet of baseboard distributed around the house which will cost $1000. A few thermostats and relays will add another $400 to that. Then you will have to find some cheap electric clocks ... the old fashioned kind with a plug. You wire the clocks so one runs when each thermostats call for heat. You then record how many hours the clocks run every day together with the degree days for that day. You then multiply (the hours each baseboard ran) times (its length in feet) times (.25 Kw/ft) times (electrical power x 3.412 Btuh/Kwh) for each baseboard or group on one thermostat and sum the results. A spreadsheet will do this nicely.
The difficulties and dangers of advising and sizing a system over the internet are obvious.
So you think investing $1400 in materials, about $5000 in electricity for the season, and a significant effort to install the baseboard just to size your geosystem is the way to go?
The entire purpose of the load calculations is to be in the ball park. Heat pumps come in 1 ton increments, if you are off by one ton shifts the upfront costs slightly, as well as the balance point when the supplement heat comes on. But in most cases for lets say a 4 ton load, a 3 ton or a 5 ton would work "OK" as well. The 3 ton would run about 6-7% more efficient and is cheaper to install, but dip more into supplement heat. A 5 ton , would use less or no supplement heat, run a bit more inefficient, cycle more in 1st stage and cost more to install. Not desirable, but not catastrophic either. Still much better than a single stage fossil fuel furnace. But much better than spending $7000 or more trying to zoom in on "the best and only size".
Even lesser of an issue with the new variable speed HPs, except a bit more upfront. What would be the big deal in making it one size bigger? It would go less into supplement heat? Or worst case scenario, would cycle through 11 stages instead of 12 stages? Moving to variable speed technology will change our thinking and practice.
Can't wait for a 5 ton variable speed water to water heatpump, one size fits it all. No more buffer tank, a single variable speed circulation pump sending the load water directly from the heatpump into the zones, making the systems 15 % more efficient. And no more sizing discussions... |
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| www.buffalogeothermalheating.com |
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Paul_L
New Member
Posts:7
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| 24 Aug 2013 05:21 AM |
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Posted By docjenser on 23 Aug 2013 11:34 PM
So you think investing $1400 in materials, about $5000 in electricity for the season, and a significant effort to install the baseboard just to size your geosystem is the way to go?
The entire purpose of the load calculations is to be in the ball park. Heat pumps come in 1 ton increments, ......
Can't wait for a 5 ton variable speed water to water heatpump, ..... And no more sizing discussions...
You're right, Manual "J" just gets you into the ball park. The electric heat experiment is the only way to discover how much heat a newly built house needs, but it is too time consuming and costs too much to do. Then the incremental capacity steps negate much of the precision of the experimental data anyway.
I wanted to make sure that flojo understood that the Manual "J" study would probably contain an overstatement of the heat needs as a safety factor and would result in an oversized installation.
The variable speed water to water system would smooth out temperature excursions and improve efficiency greatly. I like that idea.
It would be a shame to see it kill these sizing debates. That would mean less entertainment for us nerds. |
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Paul_L
New Member
Posts:7
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| 24 Aug 2013 05:33 AM |
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Posted By Dana1 on 23 Aug 2013 12:58 PM
Posted By Paul_L on 23 Aug 2013 04:16 AM
Dana1, I'm surprised that you've only seen a handful of installations up your way! You must not be too near Boston. Are you out in the sticks? Fuel oil is even more expensive there than here. It all has to be barged north and east of the pipeline heads in New Jersey
"The sticks" is Worcester, MA, second only to Boston in size of New England cities (and under an hour away). It's twice the size of Albany, NY.
But Worcester, like Boston, is on the gas grid, ..... We've got a good heavy gauge gas grid here .... it feeds the IBM microprocessor fab 4 miles from my house, but it was never built out into a uniform light gauge grid so most residences and light commercial properties don't have a pipeline.
We're 60 minutes north of NYC on the Vanderbilt's excellent Hudson east shore rail line. That's just a little beyond commuting distance so I've got a dairy farm 1/4 mile away. |
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docjenser
Veteran Member
Posts:1400
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| 24 Aug 2013 12:39 PM |
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Posted By jonr on 23 Aug 2013 10:52 PM
>It is previous consumption data,
>> I am in the process of building a 5,200 sqft luxury home in the hudson valley
I was referring to Paul here who already has his house built, and suggesting the experiment. New houses are simple, since you don't have to guestimate what is in the walls. |
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| www.buffalogeothermalheating.com |
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docjenser
Veteran Member
Posts:1400
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| 24 Aug 2013 12:56 PM |
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Posted By Paul_L on 24 Aug 2013 05:21 AM
The variable speed water to water system would smooth out temperature excursions and improve efficiency greatly. I like that idea.
More importantly it would allow us, in combination with a single variable speed circulation pump, to send leaving load water directly to the zones without going through a buffer tank, gaining about 7-8 degrees. That would save equipment costs, and increase the efficiency by roughly 10-12%. |
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| www.buffalogeothermalheating.com |
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