High heating bills with double Geothermal system running. Not seeing any my savings.

Hi, Brand new member here. I decided to join this blog based off the problems I'm having, that are similar to "Thundermustard" in a blog on this site http://www.geoexchange.org/forum/th...-winter-with-geothermal-still-not-happy.5790/. I had a general contractor install my geothermal system in our 3000 sf house last February ( House Facts*built in 1900, used to have base board heat, but was stripped of copper prior to me buying the house). I too have two goethermal systems, one for upstairs and one for downstairs. My system is a 3.5ton main floor Tetco Model#TST040B11AAANSS and 1.5ton Climate Master Model#PDW18GAADCSB upstairs unit, both sharing a 4000ft slinky loop consisting of 6 fingers burried 7' deep and around 10' between them. I'm running the racing fuel water mixture in my lines. The ductwork is brand new since the house was base board heat originally.

I had outrageous bills right from the start but did't realize it until 3 months later when I found out my first two months of geo heat were estimate readings by the electric company. $140, $120, $2043 respectively for February, March, April. I discoverd that my electric heat was kicking on every time the geothermal was running, including in cool mode. The cause was that the emergency heat circuit was jumpered off of the compressor circuit in the geo unit and not wired into the thermostat at all. I unhooked the auxillary curcuit from the air handler until I figured out my issue late this fall.
I fixed this in early November and to my disapointment my November bill was $703 and December was $835 and January will probably blow my mind. From previous conversations with my contractor I decided that my house was loosing too much heat, so I put plastic on all my windows, caulked any air leaks, and called Retrofoam to have my exterior walls injected with foam and my crawl space walls and basement rim joist spray foamed. $5000 later, I haven't really seen much improvement if any. Retrofoam is comming back out to do a thermal image of my walls. At this point, I don't know if the geo is working right or if the foam was installed poorly. I've done a lot of Google research and have talked to a few knowlegeble people, but everything seems right.
My loop is incomming at 34F and outgoing at 31F. Both Geo's are sending water to the air handlers at 120F. The main floor air handler air temp just in front of coil is 65F and 84F just after the coil. Air temp at the register is 80F. The upstairs air handler has water coming in at 100F, so a 25F drop from the geo to upstairs. (I'm going to have my wall foamed between the studs that the lines are running in to help insulate them. This is an interior wall. The upstairs air handler air temp just in front of the coil is 69F and 81F just after the coil. Air temp at register is 81F. Everything seems right, but I'm not sure what the vent air temperature should be.
I wasn't sure if my geo should be slowing the desuper heater usage down if the house was calling for heat too much. I'm also not sure if the system was sized right.

 

Going to need more information...
What is your kwh cost? 6 cents? 10 cents? 15 cents?
How much how your electric is being used by the geo systems vs the rest of the house?

The incoming loop temp looks fine. (but we have no idea where you are located) Your water delta T seems a bit low (to me).. this could be due to the water flow being too high, (would need EWP/LWP to figure that out and the temps at each geo)

 

So these are hydronic fan coils? What is the CFM of each air handler? What are the brands and models of the air handlers? Why did you go WTW vs water to air? How many geo installs did the contractor have prior to this. Can you give us some photos of the heat pumps and piping? I agree that you are either not extracting a lot of heat or your GPM might be high.

 

dgbair- It looks like with all of delivery fees and such added together I'm charged about 13.4 cents per KWh. My electric company does not give any geothermal discounts. Everything in my house is electric. In the spring months with the geo not running very much I have some energy bills in the $200 range. The geo was running during these months, but just not that often. It's important to note that electricity is about 30% more expensive in the summer too. I don't have any water pressure values, but it should be pretty low. My incomming water flows into a shared flow ceneter. The larger goe uses two pumps in series and the smaller geo uses just one pump. Maybe if they are both running I'm getting too much flow.

Joe- Hydronic fan coils.....I'm not sure. My geo recieves water from the closed loop and amplifies the heat into coolant lines (freon, water, something else...not really sure). These lines run to the air handler and flow through the coil and back to the geo. I'm not sure if this qualifies as a hydronic fan coil.

Both air handlers are Lennox. The larger air handler is model numberCB26uh-042-r-230-1 and is rated for 42,000 GTU/H. I have the fan set on medium speed and will look up the CFM later tonight. In the summer I had to rewire the fan for the highest setting since my coil kept frosting over. After I did this and left the geothermals running I never had a frost issue again. The I will have to look up the smaller air handler information later.

My contractor had installed geothermals in his last two homes and I reviewed the system in his current house before deciding to have him install mine. He uses a wholesaler in Iowa to purchase his units from, so you kind of get whatever he has at the time that works for the application. The guy in Iowa is where he gets most of the specific install information from. I've recently been in contact with him my self. He thinks that maybe the methonal mixture is freezing in the goe causing it to work too hard, maybe not enough methonal. He was going to call Tetco and find out if it has freeze protection or not. He also recommended shutting the DSH off just to see if it helps.

I will send some pictures later.

 

dgbair- I missed one of your questions. I live in lower Michigan. Also, are you looking for the loop temp at the goe. If so it should be the same as what I mentioned in my initial post, incomming 34F. Both are sending about 120F to the air handlers.

Joe- For the main floor air handler on medium speed with external static pressure of 25Pa my cfm is 1404, at 125Pa the cfm is 1192. On high speed I can reach 1540cfm at 25Pa. The upstairs air handler is model dumber CB26UH-24-R-230-1. It is set on high speed, so at 25Pa the cfm is 1074 and at 125Pa the cfm is 672.

I have some pictures of the sysem attached.

Sorry for the typos in pretty much every post. If you couldn't tell, everything I know about geothermal heating and cooling systems has been learned over the last year. Please bare with me if I missunderstand some questions or just don't understand them at all. I'm on here to learn more and hopefully get to the root of my problem. Thanks for your input so far. I look forward to your suggestions.

 

The air handlers are DX coils using refrigerant. That is why the unit frosted on medium speed.

Mark

 

Agreed Mark, Alli was mistaken about what was being sent to the air-handlers with this statement " Both Geo's are sending water to the air handlers at 120F."

That said Alli, the temperature rise from the upstairs air handler is uninspiring at best. While some of the system appears to be installed by someone who's done this before, I have a few questions about the duct work.
What does the installer say about system performance. If we were icing up stairs we might have a charge or a duct size problem.

 

Mark and Joe- To be clear, I am running refridgerant. I was incorrect with my first post. This being said, the DX coil is the correct application right? I'm not sure if I have an icing issue any more since I turned the fans up and didn't let the house get too warm before turning the cooling on. I asked my contractor to have the charge checked and he said I was likely not getting enough flow, had too much moisture in the basement (which I did), and I needed to just turn the geo on and let it keep the air at a constant temp. After my issues in the spring I never had any issue cooling. I think the ducts are ok, but I can draw up a diagram if I need to. I have two ducts in every room in my house except the kitchen and downstairs bath. Some of the runs are kind of long and I have an centeral cold air return upstairs which I had to cut 2" from every door for air flow. Down stairs I have two cold air returns, one at the front of the house and one near the back.

Joe- I checked my incoming refridgerant upstias now that I insulated what lines I could reach in the basement and its around 114F. My wall will get insulated Monday, so I expect that number to rise. I had 71F comming in to the coil and 82F going out, so a little improvement. Keep in mind that the upstairs fan is on high and downstairs is on medium.......is it better to run the fans faster to take as much heat from the system as possible, but net a lower register temp or run slower not move as much air and get a higher register temp?

Does anyone see any smoking guns with my pictures or in the description of my problem? I have seen a slight drop in electric bill (Dec. vs. Jan.) since I turned the room temp down to 71F gradually over the second week of January from 74F. January has been significantly colder than december. At the same time, for about 2 weeks total out of January I hooked my emergency circuit into my auxilary in the thermostat since the one auxillary coil could not keep the house to temp on the -8F days. Vent temp with auxillary running was about 10F higher than just geo and with auxillary and emergency running I'm around 110F. It seems like I gain 10F per electric coil of heat. FYI, I don't have auxillary heat upstairs due to the theory of hot air rising. Most of my issues are with keeping the main floor to temp and runing the electric heat too much. This system seems to be heating the air better......Maybe it is too small?

 

Heat goes to cold.

The magic is in the change of state between liquid and vapor of the refrigerant. That is what makes these systems work.

The rest is all about heat transfer. What needs to go where. Once measured and designed, the only issue is how to interface the system to the people that live in the conditioned space.

Mark

 

Do I see galvanized pipe fittings in those pictures? After ripping out all of my old galvanized house plumbing a few year back I can't believe the corrosion would be good for the anyone much less the geo unit.

 

If CFM is correct for unit size (which it appears to be) I would expect at least a 20F rise across the fan coil without auxiliary on. Never mind refrigerent line temps for now. Entering and leaving air and water are all that interest us.
Where in MI?

 

Joe- I live near Flint....AMI Contracting=Howell MI, so you are about 30minutes away. Any chance you want to visit Swartz Creek in the near future?

So in your opinion, if I am getting 20F accross the main floor air handler coil then my system is working correctly? This would then lead me to belive that I need a larger system to handle the heat loss or have less heat loss (add more insulation) to match the geo size? Based on one auxillary running I can keep temp almost to 0F on a calm day which is about 90F at the register. Maybe I just need to figure out how to have my thermostat not call for Auxillary all the time and let my geo run longer.

I don't seem to have a big issue upstiars where i'm not getting the 20F temp gain....maybe I will switch to medium speed and check the temperature gain.

Possible improvements to do in the future:
Insulate the wall between studs on upstairs hair handler refridgerant lines
Cange out any galvinized fittings for copper....or plastic?
Check line charge on upstairs refridgerant if insulation doesn't help
Slow pump speed in loop system
Add more methanol to water...maybe, if it is freezing in the goe.

Should I do any/all or are there a couple I should try first?

 

You might try reduced fan speed upstairs. You want 400 CFMish/ton. Downstairs does not appear to be overblowing.
I'm suspicious of refrigerant charge or metering problem but I don't know what I don't know based on your descriptions.
I don't bet the ponys. But I'm not afraid to come to Schwartz creek. We just want to be careful not to step on anyone's toes or void warranties.

 

Joe- I will wait until the retrofoam guys come back out Monday and I have the energy audit done next tuesday, but if I still have questions I will call AMI and ask for you. The only warranties I have are manufacture warranties, so I don't think that's going to be a problem.

In the meantime, if anyone has any other suggestions or comments feel free to speak your mind.

 

Yes I am not a Tetco or a Lennox dealer so whether I could get warranties honored I don't know. I'm not sure I know who is the Tetco distributor. But we can take a look if you like.

 

Does anyone know of a thermostat that I can adjust the temp difference between room and actual before the axillary turns on. The way I understand my current thermostat, if the geo runs too long without getting the room to temp the axillary will turn on. The auxillary will turn on sooner the next time and so on. Unless I'm wrong, it seems like I would be better off running the geo 24hours than to have my axillary turn on for 10 minutes every half hour.

I can set the thermostat to fast or slow cycle, but it delays stage one too. I think my ideal setting would be to kick on stage 1 at 1f temp difference and stage two if the temp drops to 2f difference. A I wrong?

 

Lots of thermostats permit setting by "Delta T" or difference in temperature (DT). You can arrange the "droop" (DT between stages) to where you want it.

 

Any recommendations? I dont want to over or under buy?

 

I have my clients install the Ecobee's. If you have WiFi, you can monitor operation and it will alert us to trouble. I think your system needs charging, so let me know when you'd like to get together.

 

Joe,
what model of ecobees do you recomend for my system? Im convinced I need to change thermostats and I want to do it sooner rather than later.