JillF
New Member
Posts:26
 |
| 04 Jan 2009 01:26 PM |
|
I've posted about the problems I've had with my geothermal system. In sum: very expensive to run, even keeping the house at only 63 degrees. I have two 4-ton Water Furnace Envision series units in a two-zone set up, 765 feet of vertical loop, a 2,300 sf house located in New Jersey. I just looked up my heat load numbers and I'm posting them below, wondering if I've got the right size system for my job. Here are the numbers from the Manual J. calcs:
Htg Load Btuh: 64053.... Clg Load Btuh: 44621.... Htg AVF cfm: 1900.... Clfg AVF cfm: 1900. Thanks for any help! |
|
|
|
|
|
|
engineer
Veteran Member
Posts:2749
|
| 04 Jan 2009 01:40 PM |
|
Appears underlooped - but we need temperature of water going into each unit (EWT)
If EWT is 30-35 or higher, then I wonder about significant air leakage or heat transfer from / to ductwork and unconditioned spaces. What is temperature of air coming out of registers for both systems when running and house is 63? |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
JillF
New Member
Posts:26
|
| 04 Jan 2009 01:47 PM |
|
I am hoping to get the EWT measured this week -- I don't have a way to do so myself. Meanwhile, I have a red airflow light on one of the units now, so that may indicate a different problem. I agree that the system is underlooped. I am in the process of trying to get the installer to take responsibility for this. It's very hard to do. Thank you for your help. |
|
|
|
|
Palace Geothermal
Veteran Member
Posts:1609
|
| 04 Jan 2009 07:35 PM |
|
Jill, can you measure the air temp in the unit by the air filter and the air temp coming out of the registers? You can buy a digital thermometer at most stores. |
|
Dewayne Dean
<br>www.PalaceGeothermal.com<br>Why settle for 90% when you can have 400%<br>We heat and cool with dirt!<br>visit- http://welserver.com/WEL0114/- to see my system |
|
|
JillF
New Member
Posts:26
|
| 04 Jan 2009 08:04 PM |
|
Thanks. I'll try to do this. Good idea. |
|
|
|
|
engineer
Veteran Member
Posts:2749
|
| 04 Jan 2009 09:27 PM |
|
Jill,
Tape that same kind of thermometer's probe end to a metal part where water enters each unit and then a rag over both and you should be able to report EWT. |
|
Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
|
|
|
JillF
New Member
Posts:26
|
| 05 Jan 2009 10:07 AM |
|
Thank you for the instructions. A geo company is coming out today to take readings anyway because I have a red light on indicating an air flow problem. So I'll probably just get the numbers from them this time around. But it's good to know I can do it myself, and I'll have the company also show me how. Will post numbers later to see if they're in the ballpark. |
|
|
|
|
conniepangan
Basic Member
Posts:112
|
| 05 Jan 2009 10:22 AM |
|
Jill, what part of New Jersey are you? I just had my geo installed last November here in Essex (Oranges area). What company did you used? I have 3-ton 450' closed loop with less than 2000 SF. |
|
|
|
|
JillF
New Member
Posts:26
|
| 05 Jan 2009 10:26 AM |
|
Hi Connie,
I'd rather not name the company, because I'm posting a lot about how it might have done quite a bad job for me. When I know for sure if the problem I'm having is a poorly designed system or another issue in my house, I'll talk more openly about the installer. Just want to give him the benefit of the doubt until I know for sure. Hope that's ok. Meantime, are you happy with your system? Are you elec bills reasonable? Hope so. |
|
|
|
|
conniepangan
Basic Member
Posts:112
|
| 05 Jan 2009 10:45 AM |
|
Hi Jill! that's ok. The contractor/ installer who did our house was our company's contractor who has been doing few geothermal. I chose him because I know he'll keep his good standing in our office and it's easier to contact him if there is any problem.
Anyway, as for the electric bill, the first official electric bill as of November was about $277 (We have PSEG that combines gas and electric [ $39 for gas + $277 for electric = $315). We had oil heat in the past and spent around close to $2000 for the winter.
He adjusted our thermostat from comfort level to economy level so we'll see if the bill will be better this time which I doubt it because of the cold weather we had for weeks. I guess we can still save money if the average is around $200 for the winter. I will keep you posted. The next reading will be today so our next bill will arrive next week.
I am happy with the cleanliness and comfort plus not dealing with boiler and dryness of heat. I just hope the electric bill will get better.
|
|
|
|
|
JillF
New Member
Posts:26
|
| 05 Jan 2009 10:50 AM |
|
Your elec bill sounds like it's in the ballpark. Right now, we're paying between $300-$400/month for our geothermal heat -- and only keeping our house, which is 2,300 sf, at 63 degrees. Not a good thing, after having invested so much in the system. I believe our installer did not give us enough loop. If that's not the problem, then we'll have to look at the overall energy efficiency of our doors, windows, insulation, etc. But as you can imagine, it's very disappointing to make a huge investment in geothermal and still be shocked by the monthly billls coming in. |
|
|
|
|
conniepangan
Basic Member
Posts:112
|
| 05 Jan 2009 11:04 AM |
|
I understand your disappointment. When I did a research on this more than a year ago, it supposed to promise comfort and great savings which is not happening yet 100%. My house is less than 2000 sf (that's including finished basement)with 450' vertical closed loop installed under our driveway because we didn't have enough yard. It is a huge investment for us too (more than 30K).
You're right, the key is right installation. I thought the heat loss for exsting windows and doors is already calculated prior to determining the tonnage required?
Hope the problem will be resolve soon. |
|
|
|
|
JillF
New Member
Posts:26
|
| 05 Jan 2009 11:12 AM |
|
This is an issue for us right now: we thought that the heat loss and overall energy efficiency of the home were taken into consideration by the installer prior to designing the system. Apparently, that's true only to a certain extent. Disappointing again. |
|
|
|
|
conniepangan
Basic Member
Posts:112
|
| 05 Jan 2009 11:21 AM |
|
How many floors do you have? and how many zones?
Do you have an auxilliary/ back up heat wired to your thermostat? I think the reason (on our part) why our bills spiked is because we have that auxilliary heat coming on most of the times especially when the weather is in the lower 20's and much more we had one day when it was in the 18 degrees. I noticed that the unit didn't stop at all running the whole night. I noticed 2nd Floor thermostat (bedrooms) auxilliary heat doesn't come on, just the 1st floor because of the big windows and big area it has to heat including basement.
Today is about 40's so it should get better. |
|
|
|
|
JillF
New Member
Posts:26
|
| 05 Jan 2009 11:24 AM |
|
We have one floor, divided into two zones. Our aux heat option is turned off at the moment, so that we can better monitor the performance of the geo. We're having our loop temps taken today by an independent geo contractor who is working with us and Water Furnace to figure out what's going on. Amazing how much you learn about this stuff, although it would have been nice to know before we bought the system. |
|
|
|
|
conniepangan
Basic Member
Posts:112
|
| 05 Jan 2009 11:34 AM |
|
So true! let's keep each other posted and keep learning this geothermal stuff. I know it should serve well as long as the problem get solved. I researched this long time ago and heard nothing but praise so hopefully we can attest to this too in the future. |
|
|
|
|
cnygeo
Basic Member
Posts:170
|
| 05 Jan 2009 11:42 AM |
|
As others have said, that heating load sounds very high for a house that size, but with all that glass...
If we assume that load is close (big assumption), then here's a rough guesstimate of your heating kWh based on degree days for Trenton:
Assumptions: 9degF design temp, 3.5 average COP
|
degree days |
heating kWh |
| September |
80 |
167 |
| October |
311 |
651 |
| November |
573 |
1200 |
| December |
831 |
1739 |
| January |
874 |
1830 |
| February |
928 |
1943 |
| March |
698 |
1461 |
| April |
392 |
820 |
| May |
193 |
405 |
| Total |
4880 |
10216 |
Obviously this is pretty sketchy, but it does show that if your design load is truly 64,000btu/hr, you'll have some hefty bills even if the heat pump is working well.
You'd be using about 1200 gallons of oil per year at this load.
Posted By JillF on 01/04/2009 1:26 PM
I've posted about the problems I've had with my geothermal system. In sum: very expensive to run, even keeping the house at only 63 degrees. I have two 4-ton Water Furnace Envision series units in a two-zone set up, 765 feet of vertical loop, a 2,300 sf house located in New Jersey. I just looked up my heat load numbers and I'm posting them below, wondering if I've got the right size system for my job. Here are the numbers from the Manual J. calcs:
Htg Load Btuh: 64053.... Clg Load Btuh: 44621.... Htg AVF cfm: 1900.... Clfg AVF cfm: 1900. Thanks for any help! |
|
|
|
|
Green_Giant
New Member
Posts:8
|
| 05 Jan 2009 03:49 PM |
|
Without having all the details of the site and load calcs, it looks like your loops could be undersized. On average it's about 150' per ton when doing vertical bore. However, depending on the soil conditions this can vary. If it is a very rocky region, it is possible that less depth is required for the loops.
You mentioned about possibly needing to do upgrades to help system perform better, before you do this take a look at the Manual J. The manual J should have been calculated for existing conditions. So if you have no insulation in exterior walls, and/or old single pane windows in the house, this should have been accounted for in the load calculation. If you don't have it already, try to get a detailed version of the manual J calculations for your house. On here you wopuld be able to see what was inputted for your house in terms of insulation, walls, windows, doors, orientation. If anything, doing upgrades should help with the energy efficiency of the house, but this should not be the cause of the system not performing correctly.
Another important thing to look at is the sizing of the duct system. It might be possible that the ducts were not sized correctly.
You may also want to look at what the design temperature was for the system. You mention that you keep your house at 63, the system may have been designed for around 68-70 degrees which is a common number used when designing geothermal systems. Although, if they knew you like to keep your house at 63, that number should have been used in load calcs. However, this should really affect your cooling, since for heating the system would have less work to do, as suppose to going to 70 degrees.
Good luck on your system anaylsis. |
|
|
|
|
RayTy
New Member
Posts:4
|
| 06 Jan 2009 04:52 PM |
|
Jill, Connie,
After reading through our thread I have a question regarding the loop itself. Since it is a vertical loop, did you use a standard 20% solids grout with silica? or did you use an enhanced grout? The enhanced grouts allow for less total feet drilled but still supply the required transfer.
Just curious
Ray
|
|
|
|
|
conniepangan
Basic Member
Posts:112
|
| 06 Jan 2009 05:13 PM |
|
Ray, are you talking about the grout around the pipes penetrating from the exterior to the wall inside the house? |
|
|
|
|