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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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jonr
Senior Member
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| 24 Aug 2013 05:04 PM |
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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. One can already do that with bypass valves such that most zones always receive some flow and sizing such that the result is that loops can always absorb the entire heat output. Most zones do not need the ability to go to zero flow while other zones are calling for heat. Same with zoned air systems (although most people I know do just fine with a single thermostat zone). Smart thermostats also help. |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 10:13 AM |
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"The US average for 2-10kw roof top PV is under $5 watt."
My quarrel with your math Dana (and it is a small one) is you continue to seek out the cheapest kw while employing a more expensive per ton geo rate than the pros here say they charge. You can't have it both ways.
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 10:22 AM |
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Posted By jonr on 23 Aug 2013 03:10 PM
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.
In your example the sample would be much to small not accounting for thermal mass or wind variations. I wouldn't encourage it. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 10:52 AM |
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"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."
The electric experiment is not the only way. One could use fuel oil, gas or better yet wood (at least it won't throw away a ton of money to draw a conclusion). However there is a reason manual J has a safety margin......sometimes we see uncommon weather.
Manual J and a reputable contractor are a buyer's best insurance of sensible sizing. Remember, modestly oversized furnaces do not penalize efficiency and add little to cost. That is why geo guys need to be much better students of their AO (and why internet sizing advice is unfortunate at the very least). Until you understand that, your advice to flo jo or anyone else is of little value.
Next; we size for a percent of the load. Out of curiosity what percent of the load did you design your system for? What is your actual btu loss? Remember oversized geo's are less efficient and cost more to install (DIY or not).
Variable technology does not kill sizing debates unless you wish to install an oversized GHEX on everyjob. Most agree the loopfield is one of the most major expenses of geo installation, so would you then not size a system? Put a five ton field on every job? Even if the load is 2, 3 or 4? Wouldn't we want to know that 5 ton is enough? No sir, sizing is still in the discussion, at least amongst the pro's.
Finally did you really say "The electrical inspectors are all interested in seeing geothermal stuff, it's new to them. They saw them all."
So it is new to them and they are electrical inspectors yet some how they are qualified to rate geo performance. BULL. There are mechanical inspectors in my AO who couldn't tell you how geo works, I da#n sure wouldn't ask mr. sparky what he thinks.
As a fellow nerd I trust that when I say your comments are ignorant, you will take it literally, as uneducated, and work to learn a little more prior to taking on the mantel of geoadvisor. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 11:01 AM |
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Posted By jonr on 24 Aug 2013 05:04 PM
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.
One can already do that with bypass valves such that most zones always receive some flow and sizing such that the result is that loops can always absorb the entire heat output. Most zones do not need the ability to go to zero flow while other zones are calling for heat. Same with zoned air systems (although most people I know do just fine with a single thermostat zone). Smart thermostats also help.
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 11:02 AM |
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Posted By joe.ami on 25 Aug 2013 11:01 AM
Posted By jonr on 24 Aug 2013 05:04 PM
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.
One can already do that with bypass valves such that most zones always receive some flow and sizing such that the result is that loops can always absorb the entire heat output. Most zones do not need the ability to go to zero flow while other zones are calling for heat. Same with zoned air systems (although most people I know do just fine with a single thermostat zone). Smart thermostats also help.
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 11:03 AM |
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Hmmm sorry this didn't post with that quote:
Sometimes I don't know where to begin with you jon. Suffice it to say Doc suggests a simplified variable system. You suggest overcomplicating a system. Which has more associated maintenance: valves or storage tanks? |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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joe.ami
Veteran Member
Posts:4377
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| 25 Aug 2013 11:38 AM |
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Lest I forget:
"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."
They will all work where? There are circumstances in which each are illadvised, grossly cost ineffetive or flat out won't work.
DX is another conversation entirely and not wisely discussed interchangably in the context of watersource loop configuration.
Welcome Paul, you have much to learn. It is a curve many of us went through when we first started offering opinions here. I certainly choose my words more carefully these days selecting something like "inconsequential" as opposed to "no difference what-so-ever, or "bang for my customer's buck" (after being schooled on why there is no "ROI" in geo by a helpful blogger).
You will find your words dissected. Some just to be contrary but others are readers with selective context who wish something so and use portions of your words to support a bad plan. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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docjenser
Veteran Member
Posts:1400
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| 25 Aug 2013 05:21 PM |
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Posted By jonr on 24 Aug 2013 05:04 PM
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.
One can already do that with bypass valves such that most zones always receive some flow and sizing such that the result is that loops can always absorb the entire heat output. Most zones do not need the ability to go to zero flow while other zones are calling for heat. Same with zoned air systems (although most people I know do just fine with a single thermostat zone). Smart thermostats also help.
So why don't you show us how to do this, remember, constant flow through the heatpump, and then multiple zones after the heatpump, with multiple flow requirements! looking forward for your piping diagram!
In addition, how do you push the entire flow requirement of the heat pump trough one zone? Let me say one word: Pressure drop!
And why would you continue to feed the zones when the thermostat is satisfied, lets say in a zone with much solar gain? To make the room even hotter? |
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| www.buffalogeothermalheating.com |
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jonr
Senior Member
Posts:5341
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| 26 Aug 2013 02:47 PM |
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In addition, how do you push the entire flow requirement of the heat pump trough one zone? Evidently you didn't understand what I clearly wrote. lets say in a zone with much solar gain? Evidently you missed "Most" also.
I suggest reading Siegenthaler. |
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docjenser
Veteran Member
Posts:1400
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| 26 Aug 2013 03:47 PM |
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Posted By jonr on 26 Aug 2013 02:47 PM
In addition, how do you push the entire flow requirement of the heat pump trough one zone? Evidently you didn't understand what I clearly wrote.
lets say in a zone with much solar gain? Evidently you missed "Most" also.
I suggest reading Siegenthaler.
I did understand what you wrote, however, it is inconceivable to me why you would have constant speed pumps with bypass valves for zones, because hey are energy hogs, and why you would have flow going to zones which don't need heat, making the space uncomfortable?
And if "most" implies some and some not, how do you control the zones which do need to go to zero flow and avoid short cycling of the heatpump? Again, come up with a piping diagram which solves this elegantly and efficiently, maybe Siegenthaler has something in the sleeve I am not aware of, which you can download. Surprise me here! |
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| www.buffalogeothermalheating.com |
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Dana1
Senior Member
Posts:6991
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| 26 Aug 2013 03:51 PM |
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Posted By joe.ami on 25 Aug 2013 10:13 AM
"The US average for 2-10kw roof top PV is under $5 watt."
My quarrel with your math Dana (and it is a small one) is you continue to seek out the cheapest kw while employing a more expensive per ton geo rate than the pros here say they charge. You can't have it both ways.
I'm not having it both ways at all. Far from cherry picking, I'm using the best-available compiled data from a very nearby regional program rather than relying on anecdotal evidence or web-forum budgetary numbers from pros not working in his area. I've tried to consistently state my rationale when I throw out the
$9K/ton number, and I only apply it to the local region- not to places
100s or 1000s of miles distant. (You're what, 800 crow miles from the
Hudson? Docjenser is over 100 miles away- I'm closer to Albany or NYC than he is by half, as is all of CT.) CT is right next door,
and with hard numbers on a large sample set of real systems from a wide range of
installers, I put more weight on the CT average. It really doesn't matter what you might charge, if you're not working in his area. Find me a competent pro in Albany or Newburgh posting budgetary prices akin the numbers thrown out by pros here (or if you're willing to go there and quote the system for him) and I'll adjust my numbers. The guys who came out from Indiana to install the system in MA weren't any cheaper than the locals. (FWIW: The home owner is still OK with his choice to go with GSHP, but less than completely thrilled with the system due to oversizing and tepid hot water heating performance. Expectations too high?) The PV numbers I use do not "... seek out the cheapest..." by any
means- quite the opposite! The ~$5/watt number is the 2012 national average price paid
(before subsidies) according to Lawrence Berkeley Nat'l Lab
figure of $5.30/watt for the 2012 median price paid, on a falling trend line. Projecting the trend lines even 6-months into 2013 it probably already under $5/watt for the national average, and surely would be for a home currently being designed. It's already considerably cheaper than that in both MA and NJ, very
nearby to where this house is going in, but those states have well-developed and
competitive markets due to higher than average local subsidies. PV is
getting cheaper everywhere, and faster than most people think. Any
financial analysis would be remiss without finding the recent & real
price of rooftop PV in his part of NY, but short of that the LBNL
average is a better place holder than the lower/much-lower TX, MA, NJ
pricing (that I specifically didn't use.) With the existence proof in TX and Germany that there's room to go lower ( much lower), any financial analysis would be remiss without finding out what the real current local pricing is, and project the trends forward to the date you intend to build- it's far from a static number. Budgetary numbers I've typically used for PV in discussions nearly always get undercut by the real quoted price- to the point I feel silly suggesting $5/watt for something that probably won't get built until 2015, but I find it hard to believe prices will go up on PV, given the state of the world economy and the size of the overbuilt manufacturing base for PV, and the fat underbelly of the "soft costs" for PV in the US. If that's having it both ways, I'm not sure how. I only WISH someone within 100 miles of me were installing GSHP for $6K/ton, and I'd hope to catch wind of it if & when that happens, but it's a pure fantasy number at this point, even if it's the going rate elsewhere. And I'm not sure what it would take to push PV cost higher- given the regional push to decarbonize the grid I'd expect the soft costs to continue to come down, probably faster than the hard costs in the near term. |
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Paul_L
New Member
Posts:7
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| 26 Aug 2013 07:33 PM |
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Posted By joe.ami on 25 Aug 2013 10:52 AM
The electric experiment is not the only way. One could use fuel oil, gas or better yet wood ... However there is a reason manual J has a safety margin......sometimes we see uncommon weather.
Next; we size for a percent of the load. Out of curiosity what percent of the load did you design your system for? What is your actual btu loss?
Finally did you really say "The electrical inspectors are all interested in seeing geothermal stuff, it's new to them. They saw them all."
So it is new to them and they are electrical inspectors yet some how they are qualified to rate geo performance. BULL.
As a fellow nerd I trust that when I say your comments are ignorant, you will take it literally, as uneducated, and work to learn a little more prior to taking on the mantel of geoadvisor.
To size my system I first did a quick and dirty manual "J" approximation on a spreadsheet. Then I put 8 years worth of oil consumption and local airport degree day data into another spreadsheet. I got a heat loss of 84,000 Btu at 75° inside and -5° outside for a 35 year old 5000 sq ft ranch. (It has 2x4 walls with batts, new 1.5" insulation board outside under new plastic siding, and 12" of additional batts on top of what was there in the attic.)
Then I looked outside. I figured that I had a rectangular area 100' x 60' in back between the big trees and it might produce 55,000 Btu/hr in February. Two well drillers said I had a granite shelf 50 ft down and they wanted $30 / foot. I put 6000 ft of 3/4" HDPE in a hole 100' x 60' with 2" HDPE manifolds on the right side. The ground slopes up and to the right behind the house. The top of the pipe lattice is 42 ft above the basement floor. It kept the house warm all last winter with about 40 gallons of oil plus 75 gallons of LPG for supplementary heat and potable hot water. The year before I burned 2300 gallons of oil. I'll post more about this job when I have the time. As to the electrical inspectors and their expertise, it isn't hard to figure out that a Geothermal job has something wrong when the owner has to dig up frozen pipes, or leaking pipes, or just plain turns it off and sues the contractor and puts him out of business. Even a sparky type can figure that out. OK, fellow nerd, I'll try to learn a little more. I guess I don't know enough. All that I've done so far is acquire three PhDs from MIT, Harvard and Columbia, then rewrite the NEC for UL, then recalibrate the heat flows in the electric furnaces that heat steel ingots at the Ford strip mill in Woodhaven, MI, then re-engineer a concert hall in NY and the mercantile mart HVAC in Chicago, then, after 1965 I designed the Freon heating and cooling systems for the B707-321 series aircraft for Hamilton Standard, then the air-cycle heating and cooling for the B747-100 for Hamilton Standard. Then I wound up in engineering at PanAm for 25 years, then I played at rebuilding tug boats down in Port Bolivar, TX for 8 years, and finally retired. But you're right, I still have to learn more, and I have to keep repeating to myself that both heat and water flow downhill.
I'm definitely a nerd. |
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docjenser
Veteran Member
Posts:1400
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| 27 Aug 2013 12:50 AM |
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Posted By Paul_L on 26 Aug 2013 07:33 PM
As to the electrical inspectors and their expertise, it isn't hard to figure out that a Geothermal job has something wrong when the owner has to dig up frozen pipes, or leaking pipes, or just plain turns it off and sues the contractor and puts him out of business. Even a sparky type can figure that out.
This is when it gets fishy! As you should know (or might not), the coldest part in the loop system is the heat exchanger, being quite a few degrees colder than the rest of the loop. So if there is freezing in the loop, it is in the heat exchanger coil, stopping flow, heatpump shutting down. No more flow, the loop pipe itself cannot freeze! So if someone claims to have dug up frozen pipe, that is bull.
It is impossible to freeze a loop, since the heat exchanger will freeze before that, which will shut down the system! |
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| www.buffalogeothermalheating.com |
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docjenser
Veteran Member
Posts:1400
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| 27 Aug 2013 01:25 AM |
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Posted By Paul_L on 26 Aug 2013 07:33 PM
All that I've done so far is acquire three PhDs from MIT, Harvard and Columbia, then rewrite the NEC for UL, then recalibrate the heat flows in the electric furnaces that heat steel ingots at the Ford strip mill in Woodhaven, MI, then re-engineer a concert hall in NY and the mercantile mart HVAC in Chicago, then, after 1965 I designed the Freon heating and cooling systems for the B707-321 series aircraft for Hamilton Standard, then the air-cycle heating and cooling for the B747-100 for Hamilton Standard. Then I wound up in engineering at PanAm for 25 years, then I played at rebuilding tug boats down in Port Bolivar, TX for 8 years, and finally retired. But you're right, I still have to learn more, and I have to keep repeating to myself that both heat and water flow downhill.
I'm definitely a nerd.
And none of that would qualify you to know much about geo systems.
So tell us more about your geosystem. Why is it a mess?
And why did you design down to -5F in the hudson valley? |
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| www.buffalogeothermalheating.com |
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joe.ami
Veteran Member
Posts:4377
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| 27 Aug 2013 10:06 AM |
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Yes your pedigree is impressive Paul, but in the context of geo advisor (which is in the quote you offered) there are holes in your education. A perfect example of this is installing 7 tons of geo for an 84,000 BTU load. Those savvy in geo seldom design at 100% or more (which is exactly what you've done). Reason being, running all that extra compressor all the time to avoid a little auxiliary heat now and then actually raises operating and installation cost (of course you'll get to ignorantly brag that your auxiliary heat never comes on).
If you feel called out, you are. That is due to the following:
"Hi flojo, If you're still monitoring this thread with these nerds debating among themselves you should get back to me." "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........We should talk!"
How quaint, you criticize everyone else's knowledge and then tout your own poor design as bon fides (offering to share your poor design knowledge). Ignorance.
Later offering to share your "expertise" while criticising us " 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!"
Bang for my customers' buck is in every design, if more insulation saves them a ton of geo or if solar has a better pay back, that's what I recommend. Funny we often get criticized for offering the geo solution to everything and you criticize us for evaluating all the options......Ignorance.
And "Hi flojo. I'll try to address your original query, that of sizing a heat source in new construction." This time suggesting use of electric baseboards for a year to determine load " The electric heat experiment is the only way to discover how much heat a newly built house needs,". Very expensive ignorance.
So yes lot's of education, but since you are actively offering design assisstance why not get a little geo education first?
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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jonr
Senior Member
Posts:5341
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| 27 Aug 2013 11:05 AM |
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I'm using the best-available compiled data from a very nearby regional program I hate to think how it could be that the figures reported to the government are higher that what installers are telling customers. Maybe lots of extras being thrown in for the tax credit? |
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Dana1
Senior Member
Posts:6991
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| 27 Aug 2013 11:33 AM |
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Posted By jonr on 27 Aug 2013 11:05 AM
I'm using the best-available compiled data from a very nearby regional program
I hate to think how it could be that the figures reported to the government are higher that what installers are telling customers. Maybe lots of extras being thrown in for the tax credit?
Maybe, maybe not. A presumption of tax fraud or loading would have to be backed up. The quotes I've seen in my neighborhood are very consistent with the CT numbers, which doesn't make me think they were adding re-sodding the yard after the dig was part of the quote. Meanwhile Surfsup's PV quote in Chicago has already hit the $2/watt range (after subsidy)... Cheap PV IS coming, and it affects the financial models of where the money is best spent. |
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