Replythey do BUT the ground temp is much colder in the winter and warmer in the summer at shallow depths... some do it to get around well permittingOriginally Posted by ga-hvac-tech
Professional Member*
Interesting link.
Do folks bury ground horizontal loops with the coil method... had not read much about that.
Most of what I hear in my area: Contractors do wells. Generally one 150-200' deep well per ton. Problem is... it requires lots of permitting (multiple agencies have to approve it) and is expensive. Kinda leaves geo not cost effective when one has to go through all that.
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Professional Member*
they do BUT the ground temp is much colder in the winter and warmer in the summer at shallow depths... some do it to get around well permitting
Professional Member*
[QUOTE=ga-hvac-tech;11796192]yes and no. you dont constantly have heated water running through the comparitively short wells with DX and they dont store heat (or lack of). So while the ground will heat up, its ok bc the superior heat transfer can deal with it. Its designed so the rate of heat dispersion (sp?) of the earth is equal or greater than the rate of input.
Professional Member*
[QUOTE=Gross;11796272]THX for the answer on the other post.
Seems to me if one shut off the water pump between cycles of the geo unit... and made the loop large enough... one would over-come this issue.
Thoughts?
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Professional Member*
[QUOTE=ga-hvac-tech;11796372]again, sort of. the pumps usually do shut off between cycles but hot moves to cold...so the water temp is still evenly dispersed...
bigger field means a bigger pump which means more energy draw...
This is why no watersource mfr's put the pump inside the cabinet...it would hurt their EERs and COPs too much.
Professional Member*
[QUOTE=Gross;11796412]THX 'Gross' (screen name) for the input, it is much appreciated.
I have some things I need to do today... may get back to you this evening.
Can you send along a PM with a few links I can read for more education? I think the mods would take them down from a public thread. THX!
GA
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Professional Member*
[QUOTE=ga-hvac-tech;11796032]JP...
I was talking to someone a week or so ago... they said something about the ground getting heat-soaked or cold soaked. What that means is; after years, the efficiency just goes down. I can understand this, makes good sense.
Any of the geo contractors know if wells get heat soaked?
I have never heard of heat/cold soaked before. I have some systems out that are 20+ yrs and had no problem. I even have a 3 ton system on a 2.5 ton loop that is working fine, it is also over 20 yrs old. In this area we do 200' wells, around 75' we hit some kind of water, may not be good enough for drinking but it still makes a good heat transfer when the end of a loop is hanging in water. On the newer systems we add an extra loop which doesn't add much cost but keeps loop temps more stable.
I too am looking at building a house in a few yrs with geo and solar mix so I find these threads very interesting.
Professional Member
I know DX geothermal exists and have been used and in theory should perform better. But because someone installed them in the 1970's and got away with it doesn't make them legal today. At least where I live they are not legal.
Even if they were legal, would you install thousands of feet of refrigerant pipe in a building when it is not accessible and you hope there never will be a leak? Why would you do that in the ground when in addition there is a chance to break the pipe when installing, assuming it is some rigid pipe. And who pays for thousands of pounds of refrigerant?
I'm not saying they are not a good idea nor hat they are not allowed anywhere. I'm just pointing out some issues they will introduce. and the fact that everybody (besides some you may know) uses water/glycol should tell that I'm not the only one sharing that concern.
Professional Member*
again, youre ignorant to what youre talking about. I, as well as other members of this site, install them currently. I put in two last week. There isn't thousands of feet of pipe or thousands of pounds of refrigerant. Its more like 10-25 lbs, depending on the system. Youre passing judgement on something you obviously know nothing about. As far as breaking a pipe, who pays for the well pipe to be replaced when a hdpe pipe breaks?
Professional Member
A horizontal system is only a few deep in the ground. In winter it cools down quickly since no heat will travel to it from above. you will have large dT between summer/winter. If in winter you have 32°F water instead of 50°F water your heatpump works much harder using more energy and wearing more. You also can get below the HP rated temperature. In addition you need a lot of space as soon as you apply it to more than a home. It is cheaper than vertical well, but the fact that almost everyone bites the bullet and pays for vertical wells should tell you
We own one of the horizontal systems. Beside the engineers making many mistakes, the inherent disadvantages of horizontal made it so much worse.
Professional Member
Unless I misunderstand, a closed loop system would be placing a HX in the pond or stream. The loop from HX to HP is closed, the stream flowing around it would be open.
Professional Member
I thought that was going to be the angle you took.A horizontal system is only a few deep in the ground. In winter it cools down quickly since no heat will travel to it from above. you will have large dT between summer/winter. If in winter you have 32°F water instead of 50°F water your heatpump works much harder using more energy and wearing more. You also can get below the HP rated temperature. In addition you need a lot of space as soon as you apply it to more than a home. It is cheaper than vertical well, but the fact that almost everyone bites the bullet and pays for vertical wells should tell you
We own one of the horizontal systems. Beside the engineers making many mistakes, the inherent disadvantages of horizontal made it so much worse.
So, vertical wells are the 'only' way to go, then? No way to make a hoizontal field work by depth or sizing?
Professional Member
Gross,
Got any info you would be willing to PM me on these systems?
My dad was talking about these a few years back, before he got sick and passed.
Professional Member
you can make it work. but you have to live with the fact that the water temperatures are further away from where you want them with the energy/wear penalty. If you dig deeper or make the field larger you can get close in performance to vertical field. but then you spend more money and saving money is the whole point of a horizontal field.
Most applications also would run out of space with horizontal fields. Space already is an issue with vertical fields in cities, unless you have a farm for your commercial building, I don't see horizontal fields working well. I'm not even talking about retrofit.
Again, I'm not saying it is not possible, I'm just making the case that there is a reason why almost everyone uses a vertical field. To each his own, I'm not telling you what you should do. Maybe I should start by saying: "this is what I would do... ". Is there a chance that in 1 out of 100 applications a horizontal field is more economical on the long run, sure... . but most people installing horizontal fields do it because of upfront savings, not operating savings.
This all requires some good soil analysis and someone designing who has experience with that. It is not rocket science, but requires consideration. I'm not an expert in this and don't claim to be one. I have a bit experience with it.
Professional Member
I'm not claiming to be an expert and you have experience in that, it seems and where you live they seem legal. I just wonder how you have so much less pipe length than with a water-based system? the main bottle-neck is soil conductivity and you need long pipe-runs to have enough surface.
Regarding leaks, HDPE is more flexible and less likely to break. What pipe material do you use, copper? It also will require quite some refrigeration knowledge since you basically create an evaporator/condenser. Most contractors wouldn't be able to do that since most systems basically get designed by the refrigeration system manufacturer (incl. pipes between condenser/evaporator).
Regarding leaks, besides HDPE less likely to break, the refrigerant is under higher pressure and would leak out sooner. With a water or even glycol system I could live with a tiny leak for a long time by re-filling.
I'm not trying to argue, I'm curious about this since I had researched on that a while ago and had concluded in my area it isn't worth pursuing. It is a similar issue with in building WSHP or VRF systems where with a VRF system I get more efficiency, but the potential of refrigerant in the building. Obviously I can route pipes so that I can fix them, which is hard in the ground.
when you use refrigerant geo systems, do you can simultaneously heat and cool? unless you run separate loops, I don't see how that works.
Again, not trying to argue and I admit you likely have more knowledge than I do. But I think I raise some good points to consider and would be happy to learn more about. .
Professional Member
Are there many Geo thermal systems being installed in the south? I did a little research and found that there are only a couple of aquifers in Georgia. I attended a RSES meeting that gave a presentation of Geo Thermal systems. Are there any technicians near Georgia (or nearby states) who has installed one or do any type of maintenance on one?
Professional Member*
Last time I went to the home show at the Cobb Galleria center... Water Furnace had a booth with folks from a few geo contractors in the area. They are here... just not advertized much. Look up my Email in my profile and send me an Email... and I will send you the names of two I have info for.
GA-HVAC-Tech
Your comfort, Your way, Everyday!
GA's basic rules of home heating and AC upgrades:
*Installation is more important than the brand of equipment
*The duct system keeps the house comfortable; the equipment only heats and cools (and dehumidifies)
*The value of comfort, over the long term; leave economic choices behind!
Choose your contractor wisely!
Regular Guest
It can be done, but it is also can be intensive to monitor all of the specifics of performance. We have done this with solar thermal panels on one of our geo houses. This scenario is only enabled when they are in the heating season and when the DHW tank is satisfied. We have 120 gallons of domestic storage and have a bottom of tank high limit of 150 degrees. After high limit has been reached, and the solar panels are warm enough, the solar pump is activated along with the diverter valve and geo-ground loop pump.
What we have seen through logging the temperatures of the ground-loop supply and return lines, is that this is having quite an effect on the return temperature of the fluid from the loop field thereby boosting the COP quite high. The energy used to deposit the BTUs to the ground loop is much less than the actual energy deposited.
The panels will run for a long time when they are heating 55 degree water. It has worked quite well, but of course if you have a high water table, it will not work. I have not spent too much time tracking everything on the logs since there is so much information to look at. The controls are quite intensive with radiant heating, radiant cooling, solar, geo, IAQ, etc. No time to look at the logs at this point.
We have also worked with an engineering team for a large geo project that was going to use heat accumulators with solar. They never received the grant, but it has been done quite successfully in the past. It is really a matter of cost/benefit ratio with many, many engineering problems to solve. Hope this helps out some.
Professional Member*
To me the reason to dump the solar heat into the ground is to keep the glycol from boiling too much. Otherwise it will need to be replaced every couple of years. We have installed a number of systems and the clients always want more solar heat than can be absorbed during the summer. You an always use a drainback solar system if you don't want to dump the heat.
Most of the GSHP installs we have done over the years have been wells, 200-250'/ton and MINIMUM of 12' apart. It all depends on the soil conditions but better to be safe than sorry. We have done a few lake systems where the piping was laid out like a slinky and weighed down with a steel grid and cement blocks. It was always HDPE or PEX. The only problems we ever had was with horizontal piping which seldom measured up.
Regular Guest
Geo exchange still works best when the seasonal heating load and seasonal cooling load are roughly comparable. If the imbalance between them is significant and there's no significant water flow across the loop field, accumulation happens.
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