My Geo does not do as promised!!

Daniel, I have an Envision 5 ton system with 5-150 deep bore holes. I live in north east Indiana. My system runs on first or second stage most of the time. I have a large house about 4,700 square foot 1,900, of which is a finished partially exposed basement. I have not been on electric heat once this winter. We have had -19 deg F temps this winter, the system ran most of the day on 2nd stage but it was able to keep up. Most of the time, it will cycle between first and second stage. I don't know what my EWT is because I haven't checked it this winter.

It is okay for the system to run 24/7 if your loop is sized properly it can handle it and that is where most of your savings come from. We keep our thermostat set at 73 deg F. We are a family of 5 - 2 teenagers and one who will turn 13 this year, we use a lot of hot water. Our total electric bill was $448 last month - more importantly we used a total of 4,848 KWH which is an average of $.0925 per KWH. (We have friends with smaller houes whose gas bill is over $400 not to mention their electric bill and they have their thermostat set at 67 deg F.)

I would look to your insulation and make sure that your home is tight. If your dealer based his load calculation on a certain insulation value and it isn't there then you will not be able to maintain your temp without electric backup.

 

Probably both.


But at this point it would cost less to make your house better insulated and less drafty.

 

benjie, welcome to the forums. would you start your own thread so that we can keep the discussions separate.

Thanks

 

It is possible when they joined all your circuit piping they got some piping crossed. This could render one of the circuit loops disabled. It has been an unusually cold winter. However, a vertical runing that low is a little suspicious. Closed loop is still more efficient than open loop because of the electricity required to get the open loop water to the geo unit. 1.5 to 2 horse power pump very typical. Still alot of available heat energy at low loop temps. Even thought geothermal units have long run times they are still producing over 3 watts of useable heat energy for every watt you pay for. In most new systems 4-5.

 

My unit has had a problem since it was installed. I have it posted here under low circulating temps. We have an FHP 4 ton closed loop system installed in a new home that has high cathedral ceilings and 2700sf. The system runs off 4-150ft wells that were bored into 60ft sand and 90ft hard clay. We have an extremely tight insulated home with closed foam wall insulation and high efficiency windows, etc... This is our 2nd winter in the home and our system was icing up and shutting down leaving exclusive electric heat. Our entering temps would get down to around 27-28F before shutting down. Finally, a week ago they came out and replaced the antifreeze as it was tested to be only good to 29F, thus causing things to slush up and cause low pressure error. Since replacing the antifreeze the unit has not shut down. The lowest EWT=27.5F after running cont for 10+hours. The thermostat will call for aux heat if longer run times regardless, so we disconnected the Aux to avoid this. The system maintains a temp of 70F unless extreme coldness (<0F) ensues and then we may lose a degree or two over night. According to the installation manual on our unit, the system should operate down to 25F Ewt. We are getting on average 20F of heat increase from return air which is a little better than expected according to the operation manual. I was convinced and still to an extent that our field is undersized as we are pushing the limits of our loop with regards to the EWT being low. I would have them check to see what your %antifreeze as this is quick and easy. Otherwise, it sounds like you have more short loop symptoms (undersized or not flowing the entire loop). I feel for ya about the frustration of spending $$$$ a system like this and then have it cost you more money (high electric bills). Hope some of this helps and good luck.

 

Your vertical bores

If the first 60 ' is in dry sand you will, in effect, only have a 90' bore. Dry sand does nothing for heat transfer. Remember how hot the sand is at the beach and how cool it is just an inch or so below the surface?? If this IS the case, the loop field is 240' short. (Assuming 150' per ton is the required depth in your area) Also, did your contractor grout the bore holes shut?

Bergy

 

Does it seem ironic to anyone else that every single post I've seen with unhappy customers has a system with the exact same number of loops as the tonage of their equipment? If I were buying and heard someone say "one loop per ton", I'd run the other way.

This is a bummer, I hope you guys get your systems figured out. This is a great starting point. I would also check to see what the holes were grouted with - as Bergy said... You can also access your well report (from domestic water well). It should tell you what the soil conditions are at various depths. This could be helpful.

 

One loop per ton is the standard design. It is the short length of the loops that causes problems.

Installing more than one loop per ton can lead to lower flows in each loop which can lead to insufficient turbulence in the loops which can cause lower heat transfer capabilities.

We always do one loop per ton. We just make sure that our loops are long enough to do the job.

 

new geo system

You guys with 4 or 5 ton systems must have huge houses. We installed a 3.5 ton in my 2000 square ft. house and even at -20 the backup fuel oil never came on.I've just got a pump and dump system that routes the water to my pond.I'm in west central ohio.The people that installed mine have over 400 units installed and none have over a 4 ton unit.He told me that was overkill.My electric bill went up about 90 bucks,but we had an increase anyhow,so i'm not exactly sure how much was the geo.

 

Or houses that have a huge heat loss, like mine.

 

I have a huge thread at hvac-talk.com over my system in a new home with a 4 ton system and the usual 150 ft per ton. I've had them tell me I need to rule out the house because they say I have plenty of loop. The EWT of these units should not go below freezing and I don't care what they say and how well they work, my opinion. I have little evidence to prove this but being a licensed water operator and having some training in water wells I came up with my theory. In a closed loop system if you run LWT temps in the low 20s which is what my system has done as well as yours you will start to develop ice around the shrinking grout in the well. Once this starts it will make matters worse and will never melt until the cooling season. My well driller also told me that this happens and he's seen it. If this is the case than why are they letting the well temperatures get so low?

After much research I've concluded that they just don't know what will happen from drilling into the ground and there are so many unforeseen variables that if one variable is bad it won't make enough of a noticeable difference but when a couple happen it all goes south. I.e. if the well is in the saturated ground (aquifer) and there is good water flow across the well the water will remove the cold. If not you may be keeping the cold in the area of the well and at a breaking point, the point where ice forms, you will loose your ability to extract heat.

The law should be that if the EWT temps fall too low they should come back and add another well!!! If the HP can only produce 4 ton than at full bore forever you should never go below freezing. If your HP runs 24/7 and why not and who cares about the house it should never stop producing the same heat and it should never lower the temperature in the wells to a point where the wells loose function ability.

Take the water well for instance. We drill a well and then we pump water out at the pumping rate we want. We then continue to monitor the water level draw down and if the water level falls below a safe point we either pump less or drill more. If we need 100GPM and we get 100 GPM for 1 hour and then have to shut off the pump for an hour we sure don't consider that we have a 100GPM well. Isn't this what the GT industry is doing? They give you a 4 ton unit and then tell you that the unit can't produce the same heat at lower EWT and then tell you the house is using too much heat.

This is nuts and in my home they've made me scared to go into the attic because the heat will be on too much.

I think my wells are frozen and too bad for me. The well driller thinks we used to much heat in November and the problem has only gotten worse.

john

 

How deep are the holes?

75 feet or 150 feet?

 

I'm familiar with the monster thread at HVAC-Talk

A few weeks ago here or at GBT it was decided that ice around loop pipes is OK - little or no loss in conductivity or heat transfer. Many systems run with EWT at or near 30 in late winter.

Many systems seem to run OK a bit below freezing, especially on the leaving water side. If ice were a serious problem, it would begin on the leaving side and spread, slowly at first, and then rapidly throughout a system. Manufacturers provide performance tables for entering water done to 20, so subfreezing operation is within design limits.

If ice were such a system killer, even systems normally operating in the mid 30s would be doomed during a cold snap. That doesn't happen.

It may be tempting to think of this as akin to an iced evaporator in a summertime airhandler, and the image of very white ice formed on a cold surface in free air leads one to assume it provides very good insulation, but ice formed away from air does not entrain bubbles so its heat transfer capability remains OK.

 

Hey John, welcome to a friendlier forum.

It seems like you posted on the other forum that your EWT's climbed into the 40's during a not so cold spell. If this did in fact happen, then whatever ice you had around your loops had to be melted. Remember that the deep earth temp in your area is around 50°. This heat will migrate to your cold loops as long as you are not taking the heat out faster than the heat can migrate.

Those guys who maintain that your loop length is OK are just loony in my opinion.

 

Heat goes to cold

is the rule.

 

Update

I called my installer and told him I wasn't happy because of my way higher than promised electric bills. He said that me and 3 other people he installed for last summer all have too low EWT's. He said he thought the drillers must have hit sand which would mean that I would need more wells, but he ask the drillers and they said no sand, just shale..... He said he doesnt want to come out and put more wells in and get the same result again. He said if the wells were hooked up wrong I would have bigger probs than I have now, he said he is not blowing me off and he will fix my problem but he needed a couple days research it more. I think he will fix it and make it better but I wish he could do it faster, electric aint cheap.