Posted By docjenser on 25 Jan 2012 01:50 AM
They certainly maintain the responsibility to the customer. Loop installer can provide a fantastic service to HVAC companies (and their customers) who are not that familiar with the geothermal concept yet. Because they have the experience, they actually lessen the risk to the contractor and the customer. Keep in mind, most of the install and design deficiencies come from the loopfield. The heatpumps themselves are very forgiving and operate through an extended range of conditions. So there is nothing wrong to have an experienced loop installer helping some freshmen to make the transition to geo, or to provide their service to geo companies who want to do only the inside work. Plus, it is even more common for vertical loopfields. Most installer sub vertical loopfields out to drillers. Same concept.

We sub out the excavation and the drilling, but do the fusing and all horizontal pipe ourself. We have also been hired as subs for HVAC companies who wanted to do the inside only.

This is the first I've ever heard of this being done on here over 4 1/2 yrs! I knew that most if not all HVAC contractors would contract out the digging for the trenches and for the wells because that equpt is very expensive. Had no idea that the HVAC contractor would completely contract out the actual install of the piping( the MAIN part of geo). If I remember right, the OP said his was done this way and he had to go back to the contractor that installed the loop field. Why is the OP having to go back to this contractor instead of the HVAC contractor that installed the unit? I personally don't see why it's done this way in the first place. If the HVAC contractor doesn't understand geo, they shouldn't be in the business in the first place. All this does is increase the cost alot for the HVAC cont. which of course is passed onto the customer.

There is nothing wrong with it. I know contractors 60 miles away in Rochester NY who are using loop installers for over 30 years, who has a solid reputation and installs great systems. He just decided that digging and getting dirty in the trench is nothing for him, or is not worth for him. That does not mean that he does not understand geo.

I decided that I don't want to run a drill operation and drill my own loopfields. Others here have a rig. Same thing, just a different threshold. Yes, an experienced contractor will save you much money and hassle, even if his initial estimate is not the cheapest, since he knows what is involved. But I think we had that discussion already.

I agree with Doc here. In my area, there are just a couple loop installers who do the dirty work for most of the HVAC contractors in the area. This allows the HVAC companies to stick to what they're good at.

Perhaps look at it this way. The loop installers are specialists at that aspect of the system. Most HVAC contractors only sell a handful of geothermal systems per year while the loop subcontractors might do dozens or hundreds of installs. The subs are more experienced and should do a better job installing the critical ground loops.

That said, the HVAC contractor is responsible for the *entire job* since they're subbing out the loop field (and taking a percentage of the cost). The homeowner should never have to resort to tracking down the loop installer. The HVAC contractor needs to know enough to test and maintain and troubleshoot the ground loops once installed and ensure that the entire system is working up to spec.

Tinoue,

Thank you for pointing out the prime contractor-sub contractor relationship. It is a very simple concept that eludes alot of people.

Eric

Unfortunately, after a week, I still do not have any additional informaiton regarding my loop line. The company that installed the loop line is refusing to give the company that installed the climatemaster the specifics regarding loop design and diameter of pipes used. The ClimateMaster installer stated I needed to go back to my contractor who built the hosue in order to get the information. I do not like where this is going is all I can say. The ClimateMaster installer has the distributor and a ClimateMaster rep ready to meet the loop installers at my house whenever. They feel, based on the numbers I gave them and input from their own technicians the loop field is too small. My builder did have another company come out to check to make sure the everything was configured correctly on the climatemaster. One thing he noticed was the fact it was calling for auxillary heat but my heat strips were never igniting. After 30 minutes of analyzing the issue, the damper was not wired correctly. So this entire winter the geo was never able to ignite the heat strips when the tstat was calling for it. He took another reading of my water temperature and agreed it was too cold. It was under 29 and he added more water to the lines to increase the pressure. He suggested I turn the geo off for a couple of days to allow heat to build up around the lines. He feels that since the geo has been running this entire time the loop field has to be stripped of most of its energy and to allow it to rest for a few days. Any suggestions on how to engage the loop installer in order to get the required information out of them? At this point, I have called my contractor to put pressure on him, hopefully this works. It appears as if he is dodging this problem knowing he will ultimately add additional length of loop. Very frustrating to say the least.

I am so sorry to hear the way this is going for you. Sounds to me like they are circleing the wagons and denying info for outside scrutiny. My advice is to get tough now not later. Follow the money to the builder and make him hold all the subs responsible for providing data. For the looper not to be forthcoming smells like deception, or bad money between the hvac and or the builder.
Eric

If your system was designed for auxilliary contribution and auxilliary was not functional, it could easily account for loop temps slightly out of design parameters.
You don't need ground loop design info, you need balance point and air side design info. If you are indeed running around balance point then all may be well now that auxilliary works.
Anyone who comments that you need to turn the geo off for a few days to get the heat energy back around the loops (especially if you are still in the high 20's with no aux contribution) has an alarming lack of understanding of how loops work.

Again, do not assume there is a problem simply because temps are below 30F.

The OP HVAC contractor should get outta of the business with geo and stick with ASHP!! I know HVAV contractors have to have a lic but if they do geo on the side, do they have to take any kind of tests, a different lic?
Also, the HVAC guys on here that said they always hire outside loop installers. Doesn't that add thousands of extra bucks to the home owner costs? The outside contractor marks it up to the HVAC guy and then he marks it up for the home owner. Typically, these mark ups are in the 40-50% range. So if it would have cost 3 grand for the ground loop, by the time it gets back to the home owner, it could reach up to 12 grand total. I know the markups are usually in that range. That's just business. If I'm wrong,  explain how much extra the home owner would end up paying.

Posted By robinnc on 29 Jan 2012 11:13 PM
The OP HVAC contractor should get outta of the business with geo and stick with ASHP!! I know HVAV contractors have to have a lic but if they do geo on the side, do they have to take any kind of tests, a different lic?
Also, the HVAC guys on here that said they always hire outside loop installers. Doesn't that add thousands of extra bucks to the home owner costs? The outside contractor marks it up to the HVAC guy and then he marks it up for the home owner. Typically, these mark ups are in the 40-50% range. So if it would have cost 3 grand for the ground loop, by the time it gets back to the home owner, it could reach up to 12 grand total. I know the markups are usually in that range. That's just business. If I'm wrong,  explain how much extra the home owner would end up paying.

Where is the difference. Subs are entitled to make a profit, so are geo companies who install the loops themselves. We explained multiple times here to you the finances and the economics, Please stop jumping on every posting where you suspect there is some price gauging ongoing, just because someone handles its business different.

Posted By OhioBuckeye on 28 Jan 2012 12:40 AM
Unfortunately, after a week, I still do not have any additional informaiton regarding my loop line. The company that installed the loop line is refusing to give the company that installed the climatemaster the specifics regarding loop design and diameter of pipes used. The ClimateMaster installer stated I needed to go back to my contractor who built the hosue in order to get the information. I do not like where this is going is all I can say. The ClimateMaster installer has the distributor and a ClimateMaster rep ready to meet the loop installers at my house whenever. They feel, based on the numbers I gave them and input from their own technicians the loop field is too small. My builder did have another company come out to check to make sure the everything was configured correctly on the climatemaster. One thing he noticed was the fact it was calling for auxillary heat but my heat strips were never igniting. After 30 minutes of analyzing the issue, the damper was not wired correctly. So this entire winter the geo was never able to ignite the heat strips when the tstat was calling for it. He took another reading of my water temperature and agreed it was too cold. It was under 29 and he added more water to the lines to increase the pressure. He suggested I turn the geo off for a couple of days to allow heat to build up around the lines. He feels that since the geo has been running this entire time the loop field has to be stripped of most of its energy and to allow it to rest for a few days. Any suggestions on how to engage the loop installer in order to get the required information out of them? At this point, I have called my contractor to put pressure on him, hopefully this works. It appears as if he is dodging this problem knowing he will ultimately add additional length of loop. Very frustrating to say the least.

So there was a thermostat/zone issue. Loop temps in the upper 20s are not making a geosystem fail. Stay away from the installer who suggested that all the loop heat is gone and you should shut it off for a couple weeks. He must have a complete lack of understanding of geo systems.
Most of our loops run in the low 30s by now, some fresh ones in the upper 20s. Totally OK. Let them run!
Watch your system in the next days and let us know how things are going with the fixed wiring.

Posted By robinnc on 29 Jan 2012 11:13 PM
The OP HVAC contractor should get outta of the business with geo and stick with ASHP!! I know HVAV contractors have to have a lic but if they do geo on the side, do they have to take any kind of tests, a different lic?
Also, the HVAC guys on here that said they always hire outside loop installers. Doesn't that add thousands of extra bucks to the home owner costs? The outside contractor marks it up to the HVAC guy and then he marks it up for the home owner. Typically, these mark ups are in the 40-50% range. So if it would have cost 3 grand for the ground loop, by the time it gets back to the home owner, it could reach up to 12 grand total. I know the markups are usually in that range. That's just business. If I'm wrong,  explain how much extra the home owner would end up paying.

  I am truly growing weary of your repeated rants.  This is a forum designed to help people understand geothermal and it's application,  not demand side economics 101.  I am sorry that geo is not affordable in your location, but your "chicken little" routine about crooked contractors is tree day old fish at this point.

  Might I suggest you get some training and start a reputable business in your area and show "these crooks" a thing or two.

Eric

Posted By docjenser on 30 Jan 2012 04:00 AM
So there was a thermostat/zone issue. Loop temps in the upper 20s are not making a geosystem fail. Stay away from the installer who suggested that all the loop heat is gone and you should shut it off for a couple weeks. He must have a complete lack of understanding of geo systems.
Most of our loops run in the low 30s by now, some fresh ones in the upper 20s. Totally OK. Let them run!
Watch your system in the next days and let us know how things are going with the fixed wiring.

I'm surprised by the repeated assertion that the installer who suggested a ground loop recovery period is incompetent. In fact, the advice it totally sound.

The only thing that matters to the performance/output of the GSHP is the temperature of the loop fluid that is delivered to the heat exchanger. These systems have their rated output typically assuming a temperature in the high 40's. If the loop field is delivering temperatures in the mid 20's to the system, the system will be delivering about 25% less heat to the house, shifting the balance point of the house/GSHP system to a higher temperature. But, since it's still cold out, the heating demands remain high and the system will run longer and longer, further depressing the loop field temperature and the system output.

This cycle continues until the balance is struck between the amount of energy the loop is extracting from the ground matches the far-field ground energy transfer rate - that is, the ground can keep up with the heat demands. It's all physics and rates of energy transfer. If the ground loop area is too small, the ground cannot supply energy at the rate of extraction. Same thing if the loop isn't thermally connected to the ground or the thermal conductivity of the surrounding ground isn't sufficient.

Turning the system off for a while is *GOOD ADVICE*, especially if the ground around the loop has frozen, which it has in this case since the incoming water temperatures are below freezing. It might take a week or two for the ground to thaw out and the ice to melt and bring the entering water back into the mid 30's. This will allow the system to deliver about 20% more heat to the house, which is substantial. Telling the OP that it's fine to run a GS heat pump and keep reducing the ground temperature to this extent shows a lack of understanding of the physics. If you're going to let your ground temp drop that low, you may as well just get an air source heat pump. Commercial scale GSHP systems are meticulously simulated/designed to maintain a EWT in a range that keeps them operating at high efficiency and with sufficient capacity for years. This includes minimum(winter) and maximum (summer) allowed ground/EWT temperatures. This often is a fairly narrow range, certainly not allowing EWT's below freezing.

Ultimately, the OP will have to monitor the system and determine the run time fraction that allows their system to run without excessively reducing the ground temperature.

Here's a highly relevant paper: http://talon.stockton.edu/eyos/energy_studies/content/docs/proceedings/SCHON.PDF

From the introduction: "Sizing the ground heat exchanger is one of the most important tasks in the design of a geothermal heat pump (GHP) system. Undersizing the heat exchanger can result in poor operating efficiency, reduced comfort, and nuisance heat pump lockouts on safety controls, while an oversized heat exchanger increases the installation cost of the system."

Another reference:

http://www.carb-swa.com/articles/advanced%20systems%20research/InField%20PerformanceTestingofGSHP_updated%2011_11_2010.pdf

Nice articles.... I wonder if they every did a update on the SCHON.PDF article using newer software? It's quite surprising to me that the loop field calculations varied this much between different software packages.

tino,
We design loops not around the coolest physics, but the best economics. Sure it's great to have loops that never plunge below 50 or 40 or 30F, but the price to do that may be 5 figures as the ground loops may have to be quadrupled or quintupled.

We find it is far more cost effective for our consumers to employ some auxiliary heat than to do all the work with geo. This is true in deep winter when our EWT is near 30. In other words an extra $50-$100/yr to operate vs an extra 5-10 grand in loops. In commercial/industrial with huge loads the economics may be different.

Industry standard for resi loop design is 30-90F. If some one disables their auxilliary heat, they could easily go below 30 if supplemental heat was designed in but not activated.

An HVAC contractor who (with the knowledge that aux heat was disabled) is alarmed by low EWT and suggests that one needs to turn off their heat pump (presumably then heating the home on electric auxilliary) for awhile to boost efficiency is a dumba&@. Unless of course you think advice to drop the COP from 2+ to 1 for weeks is "sound". BTW might this be the same contractor who screwed up the aux. heat to begin with?

Rob,
Just because I sub stuff out does not mean it costs more. A loop installer that also digs septic systems or drills water wells divvies the equipment cost across several more jobs than I have. He also buys pipe and fittings and tools in much greater volume than I.
While I appreciate your desire to learn, pulling numbers from a hat (i.e. paraphrased " loops that are 3k would now be marked up to 10k 'cause that's business") shows a lack of understanding about business and suggests a bent towards the sensational.
I've told you what we charge for systems as has DOC. He should be cheaper according to your theory because he installs his own loops right?
Actually, I charge a little less, because my cost of doing business is lower here (than most anywhere out East) and we put less pipe in the ground due to a different soil type.

WP, Rob hasn't even priced geo in his area, so he doesn't know if they are crooked.

OP,
Again, the important questions are air side. What is the balance point? What pct of the load was your system designed to handle? Loop driller may very likely have done many more jobs than your HVAC guy and may be uncommunicative because HVAC guy is trying to blame him for poor performance.

Joe, I agree with the spirit of what you're saying - you have to balance the economics of implementation with long term operational costs. In order to do that, you design for some auxiliary heat. If you read my post, you'll see that I am not endorsing "the coolest physics" - on the contrary, I suggested bringing the field back up to the 30's - in line with what most of you have said is a normal operating range for these systems.

What I object to are the several posts in which some attack the contractor's suggestion of letting the field recover. In the original note, I didn't see an indication that this was in lieu of fixing the aux heat, it was just to give the field a chance to recover a bit, which, in principle, is totally valid. Hopefully that wouldn't take weeks, which I agree would be stupid and uneconomical.

Ideally, now that the aux heat is working, the loop field will come back to normal with a reasonable duty cycle.

As I understand it, these discussions are opportunities for both contractors and homeowners to learn. In order to do that, some of us present a bit of theory in order to provide an opportunity for people to understand what's really going on. Then we balance that with practical considerations to keep things real. When discussions degenerate to name calling, nobody wins.

Posted By tinoue on 30 Jan 2012 07:07 AM
I'm surprised by the repeated assertion that the installer who suggested a ground loop recovery period is incompetent. In fact, the advice it totally sound.

The only thing that matters to the performance/output of the GSHP is the temperature of the loop fluid that is delivered to the heat exchanger. These systems have their rated output typically assuming a temperature in the high 40's. If the loop field is delivering temperatures in the mid 20's to the system, the system will be delivering about 25% less heat to the house, shifting the balance point of the house/GSHP system to a higher temperature. But, since it's still cold out, the heating demands remain high and the system will run longer and longer, further depressing the loop field temperature and the system output.

This is not true,Geothermal units are rated in as follows:
Entering water temperatures Full Load: 32°F heating / 77°F cooling.
Entering water temperatures Part Load: 41°F heating / 68°F cooling.
The performance is influenced by many other factors, such as flow, air flow, entering air temperature, moisture content of the air, desuperheater run time and domestic hot water temperature. It is not just loop temperature. Let me read through the highly relevant papers you cited and get back to you.

PS: Here is already a quote out of the paper:"However these results hold for this case only - a residential application with a 1.5 ton heat pump in a cooling-dominated climate".

Over the weekend, I did turn the geo off and allowed the emergency heat backup to run. In reading everyone's post I see there is a good discussion if allowing the loop field to recover a few days is a good idea. I definatley find all of this interesting. Luckily, Dayton is coming into a mild spell for the next week so hopefully I will not be putting too much strain on the system. A friend of my contractors who designs owns a geo company called me tonight and spoke to me concerning my 4 ton unit and the loop field. Since I am having issues, he is going to come in and perform another manual j calculation and also then determine how large the loop the field should be. Once this has been calculated we will then have a meeting with the installer of the loop field to determine if the right size was installed. He also wants to meet me here at the house to determine if the furnace was installed incorrectly. Based on the information I gave him he already identified one issue, I have the Aprilaire Model 500 for a home that is finished at 3100 sq feet but including the basement is sitting over 5600. He stated the 500 model is undersized especially if there is a lot of wood in the house. We basically only have hard wood floors throughout the house.

Operating an alternative heating system with a COP of 1.0 so that the loop can "recover" boosting COP from, say, 2.5 to 3.0 is, to put it gently, asinine, ranking up there with the idea of walking to work to give my car's engine a day off.

I earlier called out the 27 EWT as a likely problem, but that was in the context of recent mild winter weather. The COP difference arising from a drop in EWT from 30 to 25 is minimal, and one certainly needn't fear the supposed loss of thermal conductivity associated with frozen groundwater around loops.

Confusion arises over the thermal conductivity of frozen water. Frost and snow form in air and have crystals separated by air pockets (white color is a clue) and insulate fairly well. Solid ice, formed without significant entrained air as would be the case underground, conducts fairly well.

What's not commonly appreciated is how slow heat moves within the earth.  Loop capacity needs to be designed such that it has occasional opportunity to 'relax' during the peak of winter and summer months.  I.e., in winter, the rate of heat removal from the earth is often less than the rate of heat able to move in to replace what's been extracted near the loop.

Here's an illustration from last winter, where at the beginning of Feb. outside air temps plunged to the low 20s (very cold for a Dallas climate).  The red line is the amount of heat extracted from the earth for the day.  The blue line shows end-of-day Entering Water Temp (EWT).



Taking a look at Jan 23 - 26, you can see that the heat can move through the earth into the loop at about 250 KBTU/day.  EWT stays constant at about this heat removal rate.

Then from the 26th through the 31st, the loop gets opportunity to 'relax.'  Heat extraction from the earth is far less than about 250 KBTU/day, and therefore EWT moves favorably toward steady state undisturbed down deep earth temp (68° for my location).

Then on Feb. 1st, outside air plunges, forcing heat extraction from the earth to about 550 KBTU/day in order to satisfy the (same) thermostat setpoints.  Since replacement heat can't move through the earth fast enough, EWT drops from 67.5° to 61° in a short few day time span.

Then, starting Feb. 5th, outside temp is much warmer, the loop gets a chance to 'relax' because less heat is being extracted from the earth, and EWT thus warms up.

The point here is that every loop has a steady state heat extraction capability, where EWT doesn't change appreciably.  The loop illustrated here is designed at around 250 KBTU/day.  This steady state capacity depends on the loop length, loop pipe diameter, type of soil the loop is in, and how thermally 'connected' the loop is to the earth (this loop is surrounded by Bentonite grout).

Go beyond the steady state loop heat extraction capability, then EWT will drop over time.  If the loop isn't designed properly (i.e. undersized), EWT will drop faster than you want over time, and eventually get too cold before the winter season is over.  The only way to get the loop to perform again is to give it a chance to 'relax' - i.e. time for the earth's heat to migrate toward the loop to replace what already's been removed.

Best regards,

Bill

Posted By robinnc on 29 Jan 2012 11:13 PM
The OP HVAC contractor should get outta of the business with geo and stick with ASHP!! I know HVAV contractors have to have a lic but if they do geo on the side, do they have to take any kind of tests, a different lic?
Also, the HVAC guys on here that said they always hire outside loop installers. Doesn't that add thousands of extra bucks to the home owner costs? The outside contractor marks it up to the HVAC guy and then he marks it up for the home owner. Typically, these mark ups are in the 40-50% range. So if it would have cost 3 grand for the ground loop, by the time it gets back to the home owner, it could reach up to 12 grand total. I know the markups are usually in that range. That's just business. If I'm wrong,  explain how much extra the home owner would end up paying.

rob,

I am with Eric.... you clearly don't know what you are talking about.