125 degrees....that was the temperature of the water going into my geothermal heat pumps last night. No wonder our system is shutting down. It's never really worked...first they said it was the duct work, then lack of vents, and our R50 insulation in the attic was not enough. It's amazing what happens when you add COOLANT !!! Yes... no coolant in the system. It took many visits from Planet Geothermal and over 9 months to figure out why our system would not cool or heat our brand new home. Now it only barely works....well they're 3 tons short, we had to hire a professional for $700 to do a proper heat load calculation. We have a 3 ton and 5 ton unit, tranquility 27 split hooked in series. Yes, series not parallel as designed by the manufacturer and our installer REFUSED to change it (along with the damper installed backwards, and the filter that is 1/2 inch to large) It's sad when a housewife knows more than Dave, our GeoThermal contracted specialist. What do you do with loops at 110 - 125 degrees?? A. abandon system and put in all new conventional high efficient system. B. tear out poor duct system and replace with hard duct instead of flex tubing (that looks like spiderman's hideout) and hope that fixes it. C. Spend $11,000 for a cooling tower and then redo duct work. D. Add a conventional 4 ton unit to the house, sparingly use GeoThermal and hope the loop temp drops in the winter. while redoing all duct work. E. B C and D (est. $25,000) (ie adding loops is not possible, the lava we are on (that Planet Geothermal said would be no problem) was so hard to drill that his drillers will not come back. Any ideas, comments, leads to someone who could help would be appreciated. If we don't resolve this soon, we'll be moving into our in-laws home. Thanks!
Geothermal Nightmare Sorry to hear about your troubles. Did they say why changing the ductwork would improve the loop temperatures? I could understand increasing the ductwork to allow for larger units and to correct the flex ductwork, but I don't see how that would lower your condenser water temperature. The high water temperatures indicate that something in the geothermal loop is not correct. Do you have any details on it? I am assuming from your message it is a closed-loop vertical bore system. Did they explain the number of bores, the depth of each bore, the distance between bores, the type of pipe installed in the bore (material and diameter), the type of ground encountered (I assume it is rock), whether the field is series or parallel, and if parallel whether it is direct or reverse return. Also, do you have any temperature and pressure gages installed on the loop or heat pumps. When diagnosing the problem it is useful to know the temperature change across the heat pump(s) and the system pressure change.
I'm not sure I understand the problem; you’re saying you have 125 degrees water entering the geo system? From where? A close loop system? Geo systems can't operate at anything higher then 80 degrees F, if this is indeed a closed loop system I would say your ground loops are way too small, you extracted all the available cold from the ground and there nothing left to get. First off, turn that system off, your just risking doing more damage to it and it's not giving you any benefit anyway. The duct work has nothing to do with the water temp; I haven’t a clue what this guy is taking about. Second, get a different installer, if the original installer screwed up the system this bad, what makes you think he can fix it? If this is a close loop, I would say you have to greatly expand the size of your ground loops, try to not disturb what you have so far and add additional loops. C. Spend $11,000 for a cooling tower and then redo duct work. What the hell is a cooling tower? You have a house or a Nuke Plant? What state is this place anyway? My next question would be if you have cold winters, what do you do when the undersized loop extracts all the warmth out of the ground? Install a Heating tower? D. Add a conventional 4 ton unit to the house, sparingly use GeoThermal and hope the loop temp drops in the winter. while redoing all duct work. The loop temp will drop in the winter and the system will work perfectly fine... until you extract all of the heat out of the ground and you have the same problem in the winter as you did in the winter, frozen ground and no way to extract any more heat from it. Since summer isn't half over, I would say it will not take more than half the winter before you have no heat. This would greatly depand on where you live, since I have no referance, I'm assuming you live someplace with true winters, than someplace like South Florida, Texas and California where the winters are cool, not cold. We really need more information before helping you further. If its is a horizonal closed loop system, and your area has an extended drought, the solution could be as simple as turning on the splinkers for a few days over the location of the closed loops. When the ground is unusually dry, it don't allow for good thermal transfer between the ground and the ground loop, thus it's not cooling the water entering the ground from the system.
Geothermal Nightmare @TechGromit I agree the water temperature is too high. Most heat pumps will continue to function until somewhere in the 100F-135F region in cooling depending on the particular model in question. At that point a pressure switch will stop the unit. However, both the capacity and EER will drop off at the higher temperatures. This may be where the undersizing she mentioned comes in to play. A 5 ton unit sized for 80F water delivers about 3.5 tons at 110F as it is harder to exhaust heat into water that is already hot. They may be trying to add larger units to work with the higher water temperatures. The cooling tower would be a secondary heat rejection system. They are used in commercial applications when geothermal's initial cost is too expensive or when a loop is incorrectly sized. I am not sure why that would be considered for a residential application. I suspect that the loop is either incorrect or air locked. I am hoping her reply will provide more insight into the problem.
3 out of 4 contractors said the duct work is horrible. It's all flex tube with twist and turns. According to the thermostat (evolution by Bryant) there is too much static pressure and other resistant so the airhandlers often "stagedown" (air filters are changed every 4 weeks - recommeded every 3 months) Two of the A/C contractors said we are loosing at least 30 percent in air flow in the attic. This means the units must work harder to cool the home. It won't directly cool the loops, but it's one of the reasons we were told they became hot in the first place. That and we are 3 tons short so once again our units are working over time - they never get a break. It's 105-115 here in St. George. If we add a conventional unit - we still have to redo the duct work. We have 8 wells 200ft deep - 70 feet through lava - basalt at each well. Aprox 10 feet between each well. Pipe is 1 inch with heavy black insulation. Our Geo Thermal guy, connected the loops 2 ft under ground, it was supposed to be 4 ft. 4 loops are under the driveway, 4 in the front yard (not landscaped). It is a one loop system- the water flows through the wells, to the 5 ton unit(water going in is now at 97 - 110) - then the 10degree hotter water goes to the 3 ton unit. and the water comes out at 110-127.2 degrees the water then flows back out to the wells. The units shut off at the higher temps. Mornings are better, afternoons are hot. **The units are hooked up incorrectly. Our first step will be to plumb the 3&5 ton units parallel so each gets the same temp water from the wells. Temps: We take temps manually. I use 2 thermometers to verify temps. No pressure gages. Nothing extra installed, no flow adjusters, no ball valve. We live in a small town outside St. George, UT -2 hours north of Las Vegas we are about 10 degress cooler than them. Mild winters- no snow that sticks. Original GeoThermal Contractor abandoned us. We are on our own, with only 1 other guy who does geothermal in the area. He's not surprised we are having problems he's had to play clean up to our Geo guy before. I'd rather have more than one expert opinion on the best way to correct our system. We will have paid over 65,000 for our a/c system by the time we're done correcting this, I'm sick. The system was supposed to save us money.
St. George? That's really not helpful, St. George, UT? GA? KS? ME? MN? MO? SC? WV? AK? DE? The ground loops sound big enough, but I'm not an expert. I'm still wondering if you have Winters or not.
We live in a small town outside St. George, UT -2 hours north of Las Vegas we are about 10 degress cooler than them. Mild winters- no snow that sticks.
Geothermal Nightmare @homemom The wells are closer together than I expected. Normal spacing is 20' although sometimes bores are closer if space is limited. Additional heat exchanger is then used to offset the heat interference between the bores. Is it possible to see the color of the pipe at any place? I am trying to confirm that HDPE was used for the loop field since that affects the heat transfer. The heat pumps do need to be in parallel. The only times that we normally install in series is in open-well systems and when the operation of the units is always opposed (i.e. unit 1 always in cooling while unit 2 is heating). A loop field in series, where the output of one well is the input of the next, seems unusual when there are that many bores. It is possible that the units are in series, but the field is in parallel. The pump required to operate with that much pipe friction in series would be large. Even without fitting losses, you would be well over 100 ft-Hd at the lowest flow rate the units could run at. Do you know what type of pump is installed? The reason I bring all this up is that is the system is in parallel, it may be air locked. Essentially in very tall systems air bubbles can gather and prevent flow through one or more circuits. The field would operate as if it were missing several of the bores and the water temperature would climb until the capacity of the units matched (or the units failed). This is normally prevented by flowing water at high velocity through an air separator during the final portion of installation. If this were the case, the solution would be simple - just re-purge the system. It is a common problem when an installation is done by an inexperienced contractor. It can also develop in the summer since heated pipes expand and if the loop is not pressurized and the pump is air-cooled, air may be pulled into the system. Of course the ductwork would still need correcting. Pressure measurements would be useful as it could confirm that the field is not leaking and give a rough idea of the flow through it. It could also confirm if the system is under enough pressure.
I can e-mail pics of the unit/pump. The pump model is BGM-236 by flow center. You can e-mail me at [email:1aez4jsz]grafchiropractic@hotmail.com[/email:1aez4jsz] (it's a junk mail account). I'm not sure what HDPE is, I'm still learning - more than I ever want to know - about GeoThermal. The tubing that is at the pump & units is SURELINE 1" made by goodyear. I don't know if that was used for the wells. Corretion: The loops finger out -my husband believes - so you have one output that T's out to all 8 wells, then they gather together at another T and go through the house floor trusses to the garage where the 3 & 5 ton units are located. (sorry for the error) I can ask our Geo's son who helped put the system in - we are still on speaking terms, he no longer works for his dad and he thinks "we got screwed". sorry for the vent... I'll ask him for more information Anything else we should ask him regarding the system? I'm grateful for you insight Thanks .. homemom
Geothermal Nightmare I'm familiar with the pump since we've used them before. They use 2 B&G circulator pumps. The loop field is parallel as you mentioned. With that pump kit it wouldn't function with the loop in series. When you put the heat pumps in parallel, make sure you install check valves to keep the water from reversing direction. The first thing I would look into is the air locking issue as it is the most probable and the easiest/least expensive to fix. If your new contractor is not already familiar with the process I would find another since air purging is part of the standard installation process. The connections for purging are on the pump kit (the valves at the top). If that is not the issue, I would check the pressure of the loops. It should be at least 20 psig for the pumps to work properly. If you hear odd bubble sounds from the pump, the pressure is too low. HDPE is shorthand for high density polyethylene and that is the standard pipe type for this application. It should be black. Alternately, if the pipe is polybutylene it will be either dark gray and dark blue. That is acceptable too. You want to make sure it is not PVC which will be light gray or white depending on the "Schedule" of it. PVC isn't suitable for geothermal applications and can have many problems at the temperatures you are reporting. I would ask for an "as-built" sketch of your loop field. You will want to verify that it is either close-coupled or reverse return. The reason this is important is to make sure each bore gets the correct flow since you don't want all the water going down just one bore. If the system is direct return it could explain your situation although it will be harder to correct. It would be useful to know what they filled the bore with in addition to the pipe (i.e. did they use grout and what type). Not to worry about the venting since your frustration is justified. Hopefully this can be resolved in a way that doesn't cause too many more problems.
@MutchGeothermal.... I'm following you mostly.. could you explain "close-coupled or reverse return" and . "direct return" Which is better? Opinions...welcome - If we take off our bonus room 800sq ft (over the garage, and only hand stacked insulation) from the 3 ton. Leave the 3 ton solely for the basement which should be fairly low load. Would that help the system run less and help cool the loops? - If not this summer, next? Our plan at this point is to add 3 or possibly 4 tons conventional cooling with heat strip if the system will handle it, zone the system to provide 2 tons cooling to the bonus room and 2 tons to the kitchen/familyroom area. kind of "piggyback" the system - have 2 thermastats that control the 2 types of A/C in the same high load area. The idea is that the system SHOULD function 8 months on the GeoThermal only - except for the bonus room. If the Geo Thermal starts to heat up we can call on the conventional to help with the load in part of the house....It's just someones idea, but so far it's the best we have. Adding loops or more GeoThermal is just not feasible at this point. Thanks
Geothermal Nightmare The difference between the types is how the connections to each bore are made and the spacing between the tees. These connections are commonly called the header system. Since the bores are spaced apart, the tees can either be bunch closed together with different pipe lengths leading to the bores or they can be evenly spaced 20 ft apart with the same amount of pipe leading to each bore. If the tees are bunched together (spaced 3-24" apart), this is considered "close coupled" and it is not as important whether it is direct or reverse. Assuming they are not close coupled, it becomes significant on how the header is connected. Ideally each bore needs to have a similar flow rate and all of them must receive enough flow to be turbulent in order for heat transfer to work. Water, like electricity, takes the path of least resistance. Neglecting the effects of pipe size, more water will flow through a path that involves 20 ft of header pipe than 300 ft. A proper design attempts to keep the pressure drop across the header similar for all branches. In a direct return system, the first connection to a bore is the quickest connection back into the home and the last connection to a bore is the longest connection back to the house. This creates the situation where much more water will travel through the first bore than the last. In some situations it makes it impossible to purge the system of air since the last bores do not receive enough flow to get the water to travel 2 ft/sec. A reverse return system corrects for this by making the last connected bore the quickest connection back to the house. I understand that this is rather complex to explain in words. If I can find my old power point regarding it, I will send a PDF that illustrates the idea. Most residential designs are close coupled, but it merits looking into.
Two systems using the same duct work? I'm not sure this would work too well, since each systems is designed for a specific amount of air flow thru ducts of a set size. Two systems operating thru the same duct work is going to limit the air flow for both systems. (if they are on at the same time) I guess this could work if you turn one system off and the other on in a juggling act, but don't run them at the same time. The whole point of Geo is to have lower operating costs, there should be no need to get another system to "help" geothermal along. Poor installers give geo a bad name, you'll tell your friends about your horror experience and they will stay far away from Geo. but in reality a properly sized, designed, installed systems will yield you far lower heating bills than any other type of system. I read that some people have a $150 a month total utilities bill for 3,000 sq ft houses.
fixes I agree, the first thing to do would be to get the heat pumps in parallel w/check & balancing valves then give the loops a really good flush (min 2 hours in either direction) there is a very good chance that there is an air lock in one or most likely more of the loops. The amount and depth of the loops sounds fine, basalt is one of the best materials for energy transfer. Good luck.
