geothermal

[bob hubbard]

My local supplier carries climatemaster products and im looking for some local info on payback & eer . They also gave me the name of a company that would drill & install the piping . Mine would have to be drilled since I im on a small parcel . I been told the payback is very fast . Whats the lifespan of the loop and the unit itself . Depending on what I can learn on here , I might wait and see how bad my gas bills going to be here in southern ohio . I did a load on my houses several years back and I think it was 56k heating and 29k cooling . I currentley have a 5 yr old a/s 82% gas d/f on a slab . Thanks Bh

[key]

not familiar with climate master, but if you were to search government energy web sites you might find some answers you are looking for. Ground piping has a lifespan of 50 plus years..

[heatpumpguru]

Bob,shoot me an e-mail I made a sheet for my area comparing the fuels,I can shoot it to you.

[tecman]

Bob:

I have got a few Climatemaster installs under my belt now. The unit is a great unit and should serve a long time, generally 20+ years. Advantages of having the unit live indoors, and few moving parts is a large part of the equation.

You mentioned "wells". There are two types of systems that use "wells". One is open loop, where you drill one or more water wells and use the pumped ground water for the source. The other is a closed loop utilizing "vertical loops" This uses drilled holes to contain a vertical loop of pipe which contains a coolant that is circulated for the system. The pipe is coupled to the ground with a special concrete mix that is pumped into the boles after the loop piping is inserted. The open loop systems are known to have a much higher maintanance and failure rate. This is due to the problems of poor water chemistry as well as water carried contaminents. The closed loop is a much better choice for long life and reliability.

Make sure the installer does a good review/analysis of the loop requirements.

You should be very happy with a geo system. Payback is anywhere from 5 to 15 years, depending on the energy costs, the complexity of the installation and of course the dealers final price. EERs are over 20 and you have the further comfort/efficiency advantage of never having a defrost cycle, compared to a conventional heat pump. Also make sure you get the "desuperheater" option. This will give you around 2000 btu/hr for domestic hot water, summer and winter. Best option, no matter what type of hot water heating you have today, is to add a 50 gallon hot water heater. It does not get any power hooked up to it. It is plumbed in the cold water inlet to the existing hot water heater. The heat pump will circulate through this new tank and heat it up and provide preheated water to the existing HW heater. It is the best way to extract the most "waste" heat from the geo unit, at a very reasonable cost.

paul

[Black Adder]

Check out this site: http://www.nextenergy.ca I have installed a few of their units, work real well. We use only open loop systems in my area as we are all on wells anyway.

Will have to try that set up with the Desuperheater, have always just plumbed them into the existing tank, always considered them mostly a waste of time and money. Using it as a preheater makes a lot more sense.

[Edited by Black Adder on 10-22-2005 at 01:57 AM]

[Carnak]

open loop black, you will get way more btu/ ton installed than close loop then. How warm is the well water there pushing 50F?

[Black Adder]

Wells average about 52 to 54 degrees. Get great efficiency at these temps. Just gotta watch the condition of the water or you can run into some real problems with scaleing etc.. with open loop. Well drillers are often too cheap to put a screen in the well, have seen some issues with units installed without sand filters. Always put one inline now.

[geno54]

Was wondering what most Geo guys use for valving on open loop systems. I generally use solenoid valves with a Well tank and pressure sw. operating the well pump. This type of system can be noisy at times. Have also used balancing valves with individual relays bringing on the well pump. This type of system tends to be quieter.

[Carnak]

With that warm a temp Black, you could pretty much size them for the whole heat load, the auxiliary heat would be a warning sign that they heat exchanger was scaling up!

[Black Adder]

We use slow opening solonoid valve on the outlet side of the unit. Submersable pump in 6" well casing, only issue with noise that we find is the flow valve inline, tend to make a bit of a whistleing noise when running wide open. Insulate the crap out the lines seems to help.

[heatpumpguru]

High iron in my geo well, used Richdels now use Tacos, recommend closed loop,you will not have water related problems.My ground source(water related problems only)has left my wife wondering how could I sell these things to people and stay out of jail.I tried to explain that remember when you wanted window treatments(they call them that because they cannot charge you as much if they call them curtains)and she could not used why we needed more wells,the one we have is fine.

[dakers]

Bob, look into DX Geothermal [www.amgeo.com]. They make residential systems that utilize refrigerant loops versus water loops. The loops are copper, not plastic tubing/pipe and carry a lifetime warranty. There are no water pumps and no heat exchangers to scale up, plus there is no transfer loss. This adds up to higher efficiencies [20-25% more] than water source systems. They have fewer controls and moving parts, which means less maintenance/repair costs.

[tecman]

Dakers:

I am always surprised by the claims made about direct transfer geo heat pumps. They were much more popular some years ago and have been fading away.

As to the claims of 25% higher efficiency, I believe that is way, way overstated. The only efficiency difference is the circulator power, and that is offset by the higher compressor load due to pumping losses in the long freon loops.

One often misstated point is that water based systems are less efficient due to the poor heat transfer of the buried plastic pipe. While it is true that plastic is not a great thermal conductor, it turns out that the thermal conductivity of most ground is 10 times worse than that of the plastic pipe. The dirt in contact with the pipe may transfer heat quickly to the lines, but the heat flow in the dirt to maintain the temperature is very poor. This is why so much contact surface area is needed per ton. If you have insufficient area, localized freezing or heating of the dirt in contact with the pipes, which quickly diminishes efficiencies.

Another problem related to the poor heat transfer of the ground is that it is difficult to spread the heat transfer over a long enough length of copper line containing refrigerant. The result becomes localized tenperature extremes in the loop and reduced efficiencies. It leads to what was called the "tundra effect" in some direct transfer systems, due to localized deep freezing along parts of the trench, in moderate cold periods. The water based systems are actually better matched to the heat transfer of the dirt.

The last issue is the life of the copper in the ground in some areas due to corrosion. Many times the tubing is plastic coated to protect it from corrosion, but damage to the coating in some aggressive soils can lead to short life.

If the direct transfer systems were so much better and cheaper to install, wouldn't you think there would be more of them on the market ?

paul

[dakers]

Paul,

You raise some good points that I will attempt to address.

If the DX ground loops are installed correctly, they are not in contact with dirt! All of my loop installations [pit and trench systems] are encased in screenings [crushed granite]. Vertical and diagonal loops are grouted with a thermal conductive grout. In the cooling mode, heat rejected into the Earth can cause the dirt to dry and separate from the loop leaving a void resulting in poor heat transfer. The screenings will not dry and separate from the loops resulting in better heat transfer. The additional mass also aids in the transfer process.

You are correct in stating that plastic pipe has a poor energy transfer rate. This is why water source systems require 4-5 times more loop length than DX. Longer loops require more loop field and excavating resulting in higher install costs. As far as localized freezing and heating of the Earth, it has the same effect on water source systems as it does on DX with the exception of open loop systems. But with open-loop systems, you have higher pumping costs, the water had to be filtered and treated in some cases, plus you have to dump it in an unobjectionable area.

As for loop life, I know that most plastic loops carry a 50-year warranty. However, I can not tell you how many I know of that are leaking and require continuo maintenance. Some even have water-feeding attachments on them to keep the system full of water. This leads to the transfer solution being diluted causing premature corrosion of the heat exchanger. As for the copper loops, copper is a noble metal that comes from the Earth and is the oldest metal used by man. A pH test must be performed on the soil to determine its acidity level before the system can be installed. A pH between 5.5-11.0 requires no protection, as this will not harm the copper. If it is outside this range, a cathodic protection system will protect the copper from corrosion. I have had to abandon many water loops due to leakage, but I know of only one DX system that had a loop failure. With better than a 30 year track record, I believe that speaks for itself.

As for efficiencies, I believe this to be correct. The compressors in these systems are not under anymore load than a typical system [air or water source]. The loops have been engineered with this in mind. If there were such a load on the compressor, the efficiency would drop off.

What I have a problem with is how water source manufacturers are deceiving consumers by advertising super high EER numbers. As you are aware, this is achieved by 2 speed systems and the rating is for low speed. But most consumers do not know this. When you look at the EER numbers at full capacity, they are at or below that of DX systems. Second, water source systems typically have a major drop off in heating capacity. For example, Waterfurnace's "Premier E Series Dual Capacity" 5 Ton heat pump [E060] has a cooling capacity of 60,000 Btuh and only 41,800 Btuh heating capacity. The EER is 17.0 and the COP is 3.9. That equates to 3.5 Tons of heating capacity from a 5-Ton system. American Geothermal's 5-Ton system has a heating capacity of 61,000 Btuh with a COP of 3.7. The cooling capacity is 64,000 Btuh with an EER of 16.6. This gives the Amgeo DX system 32% more heating capacity than this comparable unit. Check it out for yourself, this is directly from ARI's website.

As for DX falling off, it is all I install in terms of geothermal and I install several each year.

[tecman]

dakers:

Thanks for the reply.

The units I have installed (Climatemaster) can maintain near full capacity in heating mode. It is, of course, a function of the water loop temperature. A 3 ton will be at 33,000 BTU with a 50 deg water on a single speed system, and a COP of 3.99. As the water temp drops, the capacity and COP will go down.

Likewise on a DX system, as the exchange area cools, due to the heat extraction and heatflow of the ground, the capacity and COP will drop as well.

I believe a well designed system of either technology will perform equally. The DX has the edge on install cost, and maybe a bit on efficiency (no circulator).

As for DX falling off, there are very few mfgs today offering DX. What does that tell you ?

paul

[dakers]

As for DX falling off, there are very few mfgs today offering DX. What does that tell you?

Old dogs don't want to learn new tricks?! LOL

DX requires more work in installing the loop field since all the loops have to be brazed in while being nitrogen flowed. Allot of companies and technicians do not want to take the time to follow this step which leads to trouble. With plastic loops, you fuse the lines together and screw them to the unit...somewhat simple. That is the only draw back I have found. The pits and trenches have to be level since oil is circulating through the system. Water loops are not affected by this. Plus, water can be pumped much farther with out and problem as long as it is designed accordingly.

I agree whole-heartedly. A geothermal system of either type is preferable to air source systems in most cases.

What model of Climate Master are you installing? Open or closed loops?

Thanks Paul.

Dwayne


[Edited by dakers on 11-02-2005 at 07:39 AM]