Discussion in 'Maintenance and Troubleshooting' started by Di2009, Jan 12, 2009.
Would you care to elaborate on that?
I am new to this so I will do my best to provide you with the info. When i say the lines in the house are frozen i mean they have 1 1/2 thick ice all the way around the line tubes, from the outside wall to the machine, i took the cover off and the compressor is frozen and all the lines. I know that when the installers where here last time they said the line pressures where fine but the water temp was below normal. Since my post i had another installer come and look at my system to see if what he thought (second opinion). I had him unhook the aux. heat, my electric bill i got today and it was $780. So if it gets cold i will use a kerosene heater to suplement. The new guy used to install geothermal systems (not waterfurnace though)i seem confident he knew what he was doing. He said unit was installed right but thought that there was problem with the loop (not big enough). He checked my loop pumps and they were working, Water in the line was rust brown. He said the line temp was okay that there was a difference in temp between the lines, it has been pretty mild temp for a couple of days (high 30's). New guy said that the air temp coming out of the register was 104 degrees. I usually keep the house at 65 degrees and since the aux. has been unhooked house has stayed the same temp with the same amount of run time. If it gets cold im skeptical that it will keep up. I will get the unit numbers and loop info, give me a little bit.
I dont know what calculated house load is? Tonnage of unit is 5 ton, loop design is? i think your asking the layout. if not let me know, the layout is two 6 foot trenches 310 feet with 3 line in the bottom of the trench, then 2 foot of dirt with 3 more lines on top of it, then backfilled. Someone asked me to elaborate on my problems with my unit, the problem is I have lived in this house for my entire life, my parents owned it then i bought it off of them, its been in my family for over 100 years, in that time there has never been an electric/gas bill combination of over $500 dollars. I have had this unit going on two years and had electric bills from $400 to over $900. My frustration is i continue to get extremely high bills and I was sold a unit that was promised to be a maximum of $400 dollars. Even $500 dollars would be more reasonable then $900. And to top it off my original installer has given up on trying to fix my unit.
Still need more info. The 104 degrees F out of the registers, is it with or without the aux heat running? What is the return air? Usually the difference between incoming and outgoing air is around 25 degrees in 2nd stage with the aux off.
What is the temp of the incoming water and the leaving water?
If your aux is off and you get 104 degrees of the register you have an airflow problem. Check if the registers are open and if your dampers in the airducts are open.
Also turning off your aux heat should not cause the loop to freeze up unless the antifreeze is not enough.
The is a difference between ice buildup and freezing up loops. Ice build up is normal, although lines should be insulated to avoid this. With both loops freezing that means that your entering water temperature is way below freezing, which suggests that your loop cannot take up enough heat from the ground. Two trenches 310 feet long with 3 pipes at 6 and 4 ft sounds like a too short loop to me for a 5 ton system. It would explain the ice build up on the entering line and your lack of performance.
I agree that the loop seems woefully short
It sounds like a proper heat load was never done on a 100 year old house which is a disaster in the making.
Is it? I have one 250ft trench 5 feet wide with 3 pipes at 5feet/3feet.
4 ton (NDV049) Envision. Unless the sun is shining, my system is running when the temperature is below 30.... and it has been since mid-December, for the most part.
EWT seems to be just above freezing (no ice on the fittings, thermocouple placed on the fitting reads 34/35.
LWT is below freezing. (ice on the fittings)
We've had a colder-than-average winter here in Central Indiana.
All that said, I wish I had a little more loop, just for margin. If we start having more extended heating seasons... I could be in trouble.
The fact that your system is not running unless the temp is below 30 without the sun shining indicates that you have a very efficient house without much heatloss (Congrats!), but then a 4 ton system seems to be oversized. At 2.5 feet apart, the ice radius around each pipe will touch each other, making it less efficient. 1500ft of pipe at an average of 4ft all in one trench does not usually support a 4 ton load.
Either you are talking very wet land close to being a swamp, or your house is very efficient and you do not have a 4 ton load
It is possible that I do not have a 4 ton load. I have been into the aux heat once this year when the temps were in the single-digits overnight. I do have a fair amount of south-facing windows that gather any available solar heat. It seems that the upstairs zone is CONSTANTLY calling for heat, whereas 1st floor/basement zone hardly ever calls for heat. I'm thinking I may need to improve the insulation up there just a little.
As for soil, it is pretty dense clay, and is fairly wet. My sump pump at ~9ft probably pumps around 5 gallons/hour.
Maybe I will contact my installer and see if he has a manual J for my house. I came to this forum after my installation, so I didn't know to ask for it ahead of time. Something tells me they may not have one.... just a "rule of thumb" installation.
Thanks for the feedback!
sorry it took so long to respond, here is the info i have with the electric NOT hooked up unit is producing 60 degrees at the register in the floor, coming directly out of the machine i am getting a temp of 63 degrees. The return is 42 degrees at the filter. With electric hooked up unit is 64 degrees. Thermostat is set on 64 degrees. Line temp, i have no way of hooking up to the actual hook ups but i stuck a digital thermometer on the pipes one line was 22 degrees and the other was 19 degrees. I believe i stated before that the register temp was in the 100's, After i took the temps, i called the new guy, he doesn't know where i got that from. Since my last post, I have had to hook up the electric again. my house temp was around 63 degrees and couldnt keep up (running all the time). It did get 10 degrees colder outside. I have been told by my original installer that WaterFurnace will be paying me a visit to look my furnace. Got a new electric bill was $781.21
I have now been told by my old installer that keeping my house at 65 on the termostat is whats making my bill so large? any thoughts on this?
Just where does he propose you set the thermostat?
How wide were the trenches that were dug? How far apart are the 2 trenches? Our Envision Owners Manual includes a drawing (with no measurements) with 6 pipe layout in 1 trench.
If I calculate your length of pipe correctly, you have 620' x 3 pipes = 1,860' per trench x 2 trenches = 3,720' total pipe divided by 5 tons = 744'/ton.
The WF web site states "As a rule of thumb, 500-600 feet of pipe is required per ton of system capacity. A well-insulated 2,000-square-foot home would need about a three-ton system with 1,500-1,800 feet of pipe." It doesn't sat if pipe layout affects this rule of thumb.
So, maybe the loop is fine but something else is wrong? System size, air in the loop, wiring, etc.?
P.S. Regarding the thermostat setting. The installer should have entered your desired thermostat setting in his program and provided you with several sheets on system performance data. Ona has a link to her sheets that you can look at if they are still available. Ona?
Couldn't he shock the compressor by switching to A/C to heat up the loop water and get the ice out. My open system was once set with too low of a flow and the compressor had ice all over it. A few min. in cooling mode and everything melted quickly. Maybe by doing this he could get his loop water up in temp and then measure his ewt and exit wt. ??? Maybe rig the system to run in a/c with the blower off, get the loop temp up and then see how the unit performs with better ewt?
If the air returning to the system is really 42 degrees, that's the smoking gun.
It'll run 24/7, drive the loop temps well below design, and kick in aux strips to make thermostat setpoint, explaining the ~$800 electric bill
Duh, missed that in the all the numbers thrown around.
Where's that 42F return air coming from.
Sounds like a big Duct leak. And I was thinking.... is it really 42 degrees in his house! You guys probably just figured out his problem over the web after the installer had given up!
Re 42f return air;
Make sure you are not taking readings near a make up air unit.
I don't recall a description of the duct system, was it installed with the geo or existing? Old farm houses with duct systems often started with coal or oil systems that operated at hundreds of degrees. little care was given to duct design and fuel was cheap. I have seen some systems that simply take air from outside vs actual return air duct system.
Re loop length;
We go about 150 foot of trench per ton considerably north of you so it may not be undersized. Type of soil has bearing on it as well.
You certainly have a loop system that is too small. Ask the manufacturer what the minimum loop temperature their system is designed to properly operate at. As well ask what the maximum loop temperature the system is designed to operate at. You will probably have a extremely high loop temperature this summer(above 100 deg).
As previously posted find out where the 42 deg air is coming from. You probably have an ERV or outside air duct tied into your return air. You may also have a return air duct opening in the unconditioned space.(crawl, or attic?) I can tell you from experience that if your loop is frozen as you say it will probably be into April before the ground around your loop thaws out. I have seen ice around loops as much as 5 ft around.
FWIW: In Ky I size loops for a 5 ton system at: 2 trenches 400 ft 3 pipes, at 5 and 3 ft below grade. Total 6 circuits.
Min loop temp:38deg,
Max loop temp: 92 deg.
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