Actual savings from Geo

Singh_9

Do you have any numbers for W-W heat pumps?

singh

Doing the Math

Looking for formula to calculate actual savings when using GSHP vs. gas mod/con or oil conventional boilers. So one could compare actual dollars spent in a heating season.

I read only 20%-50% depending on many variables. And this assumes the highest COP's and EWT don't fluctuate through the heating season. No cooling.

I found this article interesting also:
http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/96/961113.html

Thanks.

Devan

nugs

Shhhh. we don't want everyone to know
Wanna see the savings for tankless water heaters?

Leo G_103

can't remeber

which manufacture of GSHP but they no longer predict savings. Seems they were out on some of them, and got sued. Be careful Devan, talk only in generalities, as you know, some people will sue at the drop of a coffee!

Leo G

Unknown

you would have to know what efficiency you would run the boiler at, and what COP the geothermal would run at, calculated out over the course of a heating season.

that's the hard part. It's pretty hard to do that even for a boiler: what is the exact efficiency at 7AM october 21st vs 2 PM January 15th? How does it average out for the overall heat load for the season?

It's even harder on a geothermal system because the type of geo, ground situation, well quality, and more all play a part in COP, in addition to massive (by our standards) COP changes based on water temperature requirements as well.

so, just like anyone who could say they had a formula for calculating payback on any heat source comparison, in the end it all depends on the quality of your assumptions. The only way I know to get assumptions that are (presumably) good are site by site with a geo pro with experience in the dirt-side system issues.

singh

Using heating degree days

or bin method times heat load and cost of fuel/electric should get an average and estimated operational cost. Just as we do for any conventional system. Than compare the two.

What I'm uncertain of is using manufacturers data on their heat pump. Their charts give a number of COP's at different EWT, you are correct, which one to chose is a guess. Without the expensive In-situ testing services, finding how a unit actually performs can be tricky. Also, is the information given including the pumping power to and from ground loop. If not how should one calculate that. And we know wire to water effciency of most wet rotor pumps are less than 30%.

It is the generalities of GSHP that in my opinion are misleading, "free heat" and "why settle for 90% when you can have 400%" , "reduced CO2 emissions". Their is a good is potential for GSHP, perhaps for larger commercial projects. The average homeowner may not fully be aware of the electrical costs associated with these units. Compare electric baseboard to GSHP and heat pumps always win out. Not so much when compared to a high-efficiency gas unit.

And inefficiencies in power generaion and transmission losses connected to those heat pumps are a whole other topic .

I'm just trying to find a way to explain all of this to a potential client , and using some numbers to back me up.

Unknown

well, the range is COP of 2 to 5. That's a pretty wide range; but up here in maine just to hit parity with oil at 85% (well controlled to actually get that 85%), you need a COP of 3 just doing basic unit and cost conversions. If you actually want payback, well, you better exceed that by a significant amount... and/or work out some kind of off-peak deal with the utility or something. the question of "how green is your power" is a big one, but up here we do have the option of buying all hydro power or hydro with "wind offset", whatever that is... but I consider hydro pretty green.

Whatever that "target" COP is, then the question is, is it a reasonable target for Geo design? That's the best I've got so far anyway... I'm confident in a COP of 3 to 4 with very low temperature design and good control, but I have no idea about ground conditions and how those effect the big picture. I leave that to the geo guys. but at a COP of 3 to 4, it is indeed only very large heat demands that make sense, typically. "Pump and Dump" geo might make better sense for those with high water recharge rates though.

Craig R Bergman

Numbers

A GeoComfort GT060 will operate as follows...

5 ton closed loop with an entering water temp of 30* @ 15 GPM. An entering air temp of 70* @ 2,100 CFM. Heat of Extraction (the free heat from the ground) 36,000 BtuH.
The TOTAL heating capacity is 50,800 BtuH @ 3.33 COP.

The following numbers will be close, but not exact.
At a 3.5 COP and an electric rate of 10 cents/kWh you would have to purchase fuel oil, for a 55% standard efficiency, at $0.64/Gal. For a 90% efficient Propane appliance the comp cost would be $0.69/Gal. For a 90% efficient Natural Gas appliance the comp cost would be $0.75/CCF.

Bergy

Craig R Bergman

The Green Argument

Singh said "And inefficiencies in power generation and transmission losses connected to those heat pumps are a whole other topic."

My clients don't care about transmission losses. They care about saving, on average, $150.00/month on their heating, cooling and hot water costs. What are the TRUE GREEN costs for Propane, Natural Gas and Fuel Oil when extraction, processing and transporting are factored in?

NRT.Rob said "the question of "how green is your power" is a big one, but up here we do have the option of buying all hydro power or hydro with "wind offset", whatever that is... but I consider hydro pretty green." and "Pump and Dump" geo might make better sense for those with high water recharge rates though."

At what cost to the environment is Hydro "green"? Dams change the eco system both upstream and downstream of them and can affect local weather patterns. Pump and Dump depletes aquifers, wasting a precious resource.

My point is, there are downsides to every energy source. We need to conserve when reasonable and use our resources responsibly. (Pump and Dump systems are not, in my opinion, a responsible use of the resource.)

Bergy

GREG LAUER

blah blah

save 15% over geo by installing a Daikin system. they can do geo also but why pay for weels you do not need?
i AM GETTING TIRED OF GREEN=GEO. It is a one trick pony and you still need electric backup in the northern states. you do not with Daikin.

Singh_9

The green argument

Craig , I do believe clients do care about transmission losses, but not sure what they can do about the state of the infrastructure. My opinion is that we as an industry should make them aware of all the variables. And that includes distribution efficiencies as well as appliance efficiency, and not quibble about the small incremental percentages over one heat source or another.

For example:

Although geo units have a high thermal effciency (COP) let's assume we have water to air unit whos Total output (at its best COP) is 48,000 btu/hr and uses 1080 watts. Divide watts into output and distribution efficiency is 44.4 btu/hr per watt.

Now let's take a 48,000 hydronic heat load that uses one standard circulator at 80 watts. Results in 600 btu/hr per watt. So hydronic can deliver the heat more effcient than a geo-air source.

How much savings in percentages does that $150.00 a month amount to including electrical use.

And has any one replaced a boiler with a water to water gshp and monitored the estimated savings, what were they?

So my quandry is how to explain this to a client, rather than handing out a glossy brochure and make a statement about how much they may save.

Singh_9

COP's

Rob, loop size, soil conditions , entering fluid temperatures , time of year, and if hydronic, leaving fluid temps all effect COP's.

So I wonder how the manufactures test their equipment and come up with a EER or COP.

Seems like fuzzy math. But you and I do need to have a basic understanding of the numbers, that's what I'm trying to work out.

Unknown

Not completely true

I have a pump and dump system. I live aside of a creek that never dries up. My soil is very porous and static level in well is the same as the creek. Unlimited water. Water is 6.2 ph, no iron and 57 degrees all year round. Use water to water with setback on buffer feeding radiant slab and underfloor. My COP is over 5 and sometimes closer to 6 and cost was no more than a good modulating boiler. I am not depleting anything. Like all things the pump and dump has its place.
The geothermal gives the biggest bang for the buck( electric wise)which means it is ideal for a grid tie PV System so even if there isnt enough sun in the winter to run it, the difference can be made up in the spring summer and fall to make the house a net zero footprint.

Unknown

Why do you need electric backup

Water to Water requires no backup. Unless im missing something?

Unknown

No one knows

what fossil fuel or electric will cost in a month much less two years. The only fuel I know for sure that will be there and be the same price is the sun. I know I can make electric from sun, maybe not enough in the winter to run the GEO but with the net metering I can bank the extra in the warm months and end up free. Taking into consideration that PV Panels should be coming down in price in a few years( many estimate 1/3 the cost)The Geo is the way to go for the best use of Pv power. Grid tie PV with Geo is the future. Thermal solar panels are great for the spring and summer to take the load off the PV but just cant produce or store enough in the winter for house heating. What will you have if you put in a modcon and gas goes to 5 or 6 a therm. So if this house has a chance at using pv panels start installing something that will not end up a dead end.

Craig R Bergman

glgto

You do not NEED electric backup in the northern states. We can size a geo system to provide 100% of the heating requirements for a home. We don't size that way for two reasons.

1) ECONOMICS. For every ton we up-size a geo system we add about 3K to 4K to the cost. If I can get a 4 ton system to handle 92~97% of the required heating I can add a 10kW strip heater as aux heat and emergency back-up. If that same 4 ton unit will handle 92~97% of the heating at DESIGN temp don't you think we will be over sized for the better part of the year?

2) Cooling. In eastern Iowa we require about twice the heating Btu's as cooling Btu's for an average home. A four ton, two stage unit will produce 70% of cooling capacity in first stage. (33,600 Btu's assuming a full 48,000 capacity)
That may well be pushing the comfort of the home where a 5 ton unit most likely would be uncomfortable.

So...stay off the bandwagon. Others will gladly pick up your customers that want Geo.

Bergy

Craig R Bergman

Tony

We normally add an electric strip to the air handler. If the compressor goes belly up they have some heat.

I would agree that your Pump and Dump set up would not deplete the resource. That's not the case around here. One utility company will not give rebates on Pump and Dump, only Pump and Re-inject systems qualify.

Bergy

Craig R Bergman

Singh

Replacing a boiler with water to water Geo would be very tricky. The best water temps we can achieve are about 120*. There are a lot a systems that would not be compatible with Geo without a source for supplemental heat.

Bergy

Unknown

oversized?

put in a buffer tank and you are never oversized. Ah, but that requires hydronics

Purposefully undersizing geo, frankly, ticks me off. Do geo or don't do geo, but don't spend the big bucks and then have to heat on straight resistance during the highest volume heating demands of the year. That's playing games.

If cooling is the issue, use two units and stage them for heating.

Unknown

I understand all that affects the numbers: there are a bunch of similar effects on boilers too, but you don't lose sleep over those

GREG LAUER

bergy

Stay on your bandwagon and be passed by newer techology. With a inverter compressor and exv supioror comfort control can be found and with over 3,000 ft of lineset there are no extra costly pumps, wells ect to drive up the electric bills. Oh they can do geo too with the inverter technology and still beat any other geo system in eff. This isnt a bandwangon it is the future of HVAC hop on or be left behind. There is a product coming that will handle a entire convienance store hvac, high and low temp refrigeration and possibly dhw all in one cascade refrigerant system and with failure rates globaly of less than one tenth of one percent I think these guys know what they are doing. Several high rise buildings around the world are equipt with Daikin VRV units and the heat recovery options only add to the eff of the system by transfering btus in the space before being rejected to the outdoor unit that also has the lowest db levels around. We still sell geo but once a customer see the savings and no well cost it is a no brainer. 120 deg disharge air has been seen consitantly in -18 deg weather in Canada. Another thing Daikin does it they do not mislead their customers on seer ratings the listed seer is the MINIMUM achived at ARI rather than the maximum so a 15 seer unit runs most of the time in the 20's. Dont be sour adapt to more than one option. Raw energy cost/savings is what Green standards should be based on and with no wells the roi is much better.

singh

To all

So I met with Architect and homeowner client today at the house. He's adding on a 20x20 addition to roughly 7500 sq ft. of living areas. Of that most of it is heated with numerous zones, combination HWBB, fan coil and radiant. There is radiant in every room of the house with supplemental as needed. All done by a local heating contractor who does not want to do any geo .

I came up with a whole house load of 195,000 btu/hr. There is a oil fired Buderus G205 there, so boiler is sized ok. But owner stated last years oil bill came in at $10,000 including DHW.

I did some back of the napkin numbers and suggested two 5 ton units to cover about 60% of the load . Factored in labor and materials and figured a savings of $3,500.00 annually at todays oil prices of $2.75 gal. Educated guess , since it seems difficult to narrow any concrete numbers. ( My reason to start the thread)

His response was to figure three 5 ton units to cover more tied into the existing boiler, and he'll bring in a solar guy to cover the increased electrical load.

There is plenty of acerage of well manicured lawn area , we are looking at horizontal loops, since an excavater will be on site to build addition. Only caveat is where the field will be is about 400' from the house.

He's also the president of a local land conservancy group, so this is real important to him. Obvious the client has the means to do this regardless of the numbers, more of a social statement it seemed.

I worry too much I guess, I suggested energy audit , but he said house is now well insulated, changing out the circs to ECM technology but he was not too concerned with that either. Only that oil will once again jump up to $150+ a barrel.

Thanks for the lively and CIVIL discussion guys!

Hey I have a kid and I need to pay for her college education one day.
So I'm going to ride the gravy train.......

Mark Custis

Singh

So build a radiant floor under the lawn and tie it to a manifold, then pump back to the house.

Darin Cook_9

Funny Isn't It?

The one true building science test offered to the customer and he refuses. The blower door test alone would quantify the ACH and come up with a much more accurate heat loss. You know - so you could figure out what you really need for equipment. Let's see how green he wants to be when it is time to take the green out of the wallet.

Darin

Cosmo_3

I love it

When someone states the obvious!!!

This thread has been very interesting and educational.

Singh- does your HM know the differences btwn horizontal and vertical loops? I have been in negotiations on a geo project that started out horizontal, however as the HM is learning some of the advantages of vertical he is considering even though it costs more.

Let's keep it going!!

Cosmo

Steve Ebels_3

Watch yourself......

Around here there is a definite uptick in the amount of GSHP work going in. The sad part of it is that a large percentage of the systems are very poorly done. I've seen them sized to A/C loads (in Michigan that's next to nothing compared with heat) Scrimpy ground loops that are short in length or not buried deep enough, undersized duct systems, you name it. The butchers are out there low bidding everything and geo is no exception.

Devan, this is a eia.gov website that gives you a direct comparison of fuel costs and allows input for local fuel pricing as well as appliance efficiency. Should allow you to go apples to apples on a comparison if the correct factors are used.

www.eia.doe.gov/neic/experts/heatcalc.xls

john g_5

driving a geo metro will def. increase you MPG and save u tons!

Cosmo_3

re-watch yourself

I have yet to install a horizontal loop system for teh main reason that this particular type of installation is EXTREMELY dependent on stable ground moisture levels and this can vary when the loop is only 5 feet deep!!

What happens when there is a drought condition, and you lose heat conductivity? Usually when I explain this the HM starts finding $ to do the vertical loops, assuming you don't hit bedrock right away!!

Cosmo

singh

That's what the existing boiler is for, back up.

As long as the geo side is not short looped, drought conditions not really a concern. This is prime farm land. Wetlands beyond. Oh did I forget to mention the grass is irrigated. Actually came on while we were talking outside, at 9 AM after it rained the night before.

Craig R Bergman

Cosmo

The easiest way to control moisture are soaker pipes attached to the down spouts, with good leaf guards on them. They are placed about a foot above the loops and protected with landscapers cloth. If you get into a drought situation a garden hose can be placed in the pipe to water your loop.

Bergy

realolman

Huh?


adding on a 20x20 addition to roughly 7500 sq ft. of living area


last years oil bill came in at $10,000


plenty of acerage of well manicured lawn area

Only that oil will once again jump up to $150+ a barrel.

where the field will be is about 400' from the house

He's also the president of a local land conservancy group

I don't know whether to laugh or cry... I am leaning toward crying.