Living and Learning with Geo

Discussion in 'Geothermal Heat Pump Testimonials' started by ChrisJ, Feb 2, 2011.

  1. ChrisJ

    ChrisJ Active Member Forum Leader

    My wife and I both wanted geo in the new house we were building. 2000 sq ft ranch, walk out basement, drive under garage. Radiant in slab, basement and garage. We are located in Rhode Island.

    The unit is a 4 ton made by Hydro-Temp, combination unit(Hybrid), dual compressors, air main floor, priority hot water, aux hot water for radiant. Horizontal ground loop. Installer is an HVAC guy but he installs lots of Water Furnace geo's.

    We moved in to the house in March 2010. Main floor air heat had been working for a while already and working great. Nice even heat, quiet too. The DHW worked good too. 55 gal electric hot water heater, 3" insulation, breaker off. The radiant was a bit of a different story.

    There is also the same style tank for our buffer tank sending water to the floors. Hydro-Temp supplied a plumbing diagram (not very detailed). We were having our plumber do the tank hook up. Once it was up and running my wife joked with me, asking are you down there feeling the pipes again? Yes I was. Found a check valve was needed, water going wrong way.

    Easy fix. More difficult problem was radiant return was dead heading at a T. Plumbing diagram had us T the radiant return to the pipe that was returning heated water to buffer tank. If the floor was calling for heat and the tank called for re-heating, no flow in the floor, circulators ran with no water moving. Well it was March and I shut down the radiant so we could solve the problem before next winter.

    Changing the T to a venturi T was our first attempt at fixing the problem, but it didn't do anything. Called Hydro- Temp, they said take out both elec element and use those openings for re-heating water. Well I really liked the option of flipping the breaker on if the unit couldn't heat the water. That's when I discovered this forum.

    Thanks to the people, pros and homeowners, I read about using the T&P valve opening in the tank to return the heated water to the buffer tank. There is a lower pressure relief valve in the pipe already. Now the water flows to the floor when the tank is being re-heated. It has been running this way for about 4-5 weeks, so much for fixing it before winter.

    So far this winter our elec bills have seemed high, but in our old house we would spend about the same amount per month on a 10 month oil budget. The unit is much more efficient at making warm air then it is at making warm water. Air almost never goes to stage 2, but DHW always re-heats in stage 3.

    Ideal radiant tank temps, that is what I am trying to learn about. Seems like there is a lot of different opinions on that. I will continue to read and learn, living in this beautiful house my wife and I built ourselves, with a lot of help from family and friends.

    Thanks, ChrisJ
     
    Last edited: Dec 8, 2011
  2. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Welcome

    Chris: Thanks for your input on Kandk's home. What do you want to know about radiant?

    The more pipe the lower the entering water temp needed. It is all about "FLOW" as you have learned.

    Can you draw me a picture or take a photo?

    warm regards,

    Mark
     
  3. ChrisJ

    ChrisJ Active Member Forum Leader

    Delta T, Most efficient set point

    I started with 95 tank temp, return temp of 65. Room temp 65-66, basement. That's 30 delta T yes? The guy that sold us the tubing said I should have a lower delta T. I read what you wrote saying 20 to 30 is ok. My installer an I have lowered the tank temp to 89, figuring that will lower the delta T. I am just hoping to find the right temp for the HP to run most efficient.

    Water is pumped through exchanger via Bell & Gosset PL-36 booster pump, in floor water moved by Taco 007's. Buffer tank, we removed restrictive nipples.

    My system is easily adjusted with a palm pilot, pretty cool I thought. Can read 9 sensors, all the important stuff, loop, air, DHW, AUX hot water(radiant), refrigerant temps. One of the sensors quit last week, left us with no compressors briefly, flipped on the breaker for DHW my wife still had a hot shower. Anyway, still some question as to why the emergency heat strip didn't come on.

    I am going to try to attach pictures, sorry in advance I am new at this!!

    I am really enjoying this forum, you folks are great!

    Chris
     

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    Last edited: Feb 3, 2011
  4. ChrisJ

    ChrisJ Active Member Forum Leader

    Hydro-Temp 4 ton unit

    I don't have exact sizes in front of me but I know the unit has 1 small compressor for stage 1, a larger compressor for stage 2 and both run for stage 3. I have a 5KW emergency strip.

    Air heat on main level has been maintaining 68 deg. all winter on stage 1, maybe went to stage 2 for a little while when I bumped the stat to 70. Stage 2 will engage when stat is 2 deg below set temp, run for 30 min., if not satisfied goes to stage 3. Blower ramping up each time, 800cfm, 1100, 1400.

    DHW is 55 gal electric tank 3" insulation, wired in but breaker is off. Bell & Gosset pump circulates water to heat pump via 3/4" copper pipe. 120 deg set point, reheats when sensor gets to 112 deg. I think the unit runs at stage 3 for reheating water ASAP.

    Radiant in basement and garage, has it's own 55 gal elec tank wired in breaker off, as a buffer tank. 2 zones: basement area 1200' 1/2" tubing in slab, garage 600' 1/2" tubing. B & G pump to reheat water 1" copper pipe. 3/4" copper for supply and return to floor w/ Taco 007 circulators.

    In basement I keep stat at 64-65 air temp, garage 50-55 air temp. Still trying to find best tank temp for infloor to be most efficient.

    The installer makes adjustments and reads info from a Palm pilot. 9 sensors. Also tells % of run time per stage. As of two weeks ago, 78% stage 1, >1% stage 2, 21% stage 3. I said to him, "It's running like a 2 stage unit". So he set the radiant to run stage 2 max. Ok if it takes a little longer to heat radiant tank.

    Let me know what other info would help.

    Chris
     
    Last edited: Jun 28, 2011
  5. ChrisJ

    ChrisJ Active Member Forum Leader

    Bad sensor

    On 1/24/11 I could hear the big compressor trying to come on, it would run for a few seconds then off, maybe a minute later try again. The air was running fine on 1st stage, DHW pump was trying to come on with big comp. My wife got a hot shower, I just turned on the breaker for the DHW tank. Called the installer, he used the Palm to troubleshoot, PDA could not find any of the sensors (none) is what it displayed for all. Turned power off and back on, started working fine, found sensors. Of course it didn't reset when I shut the breaker before the installer came from 1.5hrs away.

    Fluke right, nope, 3 days later, same noise from compressor. 5:30am, 16"-18" of snow had just fallen. I shut the breaker, turned it back on, nothing, no heat or hot water from heat pump. I have to say my installer was great, dropped his snowblower, left the plowing to his father and drove the 1.5hrs to come diagnose prob.

    When he got here his PDA couldn't find any sensors again. Turns out the sensors are daisey chained together, he had to 1 by 1 take them out of line to find the bad one. It was the LWT sensor. System working fine now. He will install new one when it comes in. Too much technology (bells and whistles) may not be a good thing.:rolleyes:

    Chris
     
  6. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Chris

    I am just in from a road trip and missed your posts above. I do not know much about palm pilot sensors, but I am sure I can help with the radiant.

    Did anyone address why stage 2 compressor was not starting. Sounds to me as if it is getting a call to run, trying to start then going off on an internal safty. Start with the run capacitors if it is a PCS compressor.

    Back to the radiant. In slab floors make a good heat sink for the building, but you need to start them early in the heating system. Cold concrete will just eat all the BTUH you can send them untill they warm up and become part of the solution. It is difficult to get the slow and steady heat pump , and from what you type this is an bit of an extra on a water to air system, to warm up enough to counter act cold ground. I would take the buffering tank feeding the floors as high as the heat pump will allow without locking out, maybe 130*F.
     
  7. ChrisJ

    ChrisJ Active Member Forum Leader

    Hydro-Temp 4-ton

    Mark, I believe the bad sensor was causing the compressor to not come on. Since taking the sensor out everything working good, just can't tell what my LWT is, EWT was 37*, had been about 4-5* delta T. Horizontal loop, 5 trenches 200' long, 7'-8' down, 1" pipe, 20% glycol.

    Radiant works ok, I'm maintaining 65* in basement, 55* in garage. My return water is usually around 68* from basement zone, 60* from garage zone. 90* buffer tank seems to bring room temps up within a reasonable time frame, maybe an hour or two depending on outdoor temp. Your right about it being a water to air that thinks it's a water to water HP. I am realizing that it is just not as efficient a hot water maker as it is an air maker. I started heating floors up in late Oct, but was having the "flow" issue mentioned before.

    Something I have learned about my HP. When the water and air are being heated at the same time, runs both compressors, the air temp is reduced. Air temp is reduced more if buffer tank is heating compaired to when DHW tank is being heated. I am pretty sure the refidgerant lines go through water exchangers then to air exchanger.

    Maybe having buffer tank temp higher would help air temps, but at what cost$, a lot of what I have read leads me to think a high buffer tank temp will use a lot of electricity.

    People around here talk a lot about comfort level. We are comfortable. Just looking for that fine line of saving. Lower water temp, longer run times of floor circulators, but less time compressors run to meet set point.

    Maybe it's just going to take a couple of winters of data, trial and error, to figure whats going to be most efficient. Thanks for reading, I know I can be long winded.

    I was intrigued about ECM pumps after reading the article you had a link to. I think it was you. Huge savings. I only have 2 zones not 10, but I do know my B&G pumps use a good amount of elec.

    Chris
     
    Last edited: Jun 28, 2011
  8. ChrisJ

    ChrisJ Active Member Forum Leader

    Horizontal loop

    I thought I was getting an "extra loop"

    When I met with installer and loop installer (I had in my head I was getting a slinky), they told me "We need your excavator to dig 6 trenches 250' long, 8' deep", for a 5-ton unit.

    Problem was only 200' available, 250' and they are in the street. Between the two contractors they re-figured for 5 trenches 200' with 1" pipe instead of 3/4" pipe. So essentially dropping the "extra loop". I know my excavator was happy about one less trench. He was getting close to a row of apple trees that were still producing.

    I got a little reduction in price for 1 less loop. The loop is working good, EWT high 30's, LWT low 30's, just got through a cold spell, but here comes another one 10*-12*F next few nights.

    Then the loop installer told me he wanted to add a PVC drip loop. He layed PVC pipes just above, maybe 18-20", loop pipes. Said I can introduce moisture to loop field so it doesn't dry up and be less efficient years down the road.

    Anyone else do drip loops?

    Chris

    June 2011: Found out unit was reduced to 4-ton when loop field was reconfigured.
     

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    Last edited: Jun 28, 2011
  9. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    That looks like nice dirt.

    Not being a geologist from the photos it looks to be sandy. The drip loops might help.
     
  10. ChrisJ

    ChrisJ Active Member Forum Leader

    Good dirt

    The soil was good for septic system, traditional leach field. A lot of gravel, had enough for the 300' driveway. Lots of rocks for retaining walls and walkways, all from our 4 acres.

    The loop installer said hook a hose to the drip loop and let the water run for a few hours. I thought to do that this summer when the EWT got higher.

    Chris
     

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    Last edited: Mar 10, 2011
  11. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader

    Chris:

    If you do, use a rain water system to slowly drip the loop field after the thunder storm.

    Mark
     
  12. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader


    Adding water is not a common practice, some do it to settle the soil.

    It can add some benefit in sandy soil, in heavy clay not so much.
     
  13. ChrisJ

    ChrisJ Active Member Forum Leader

    The basement and garage radiant heat has been off since early April. In November when it was turned on the electric bill doubled, I was a bit bummed. Was used to $150.00 a month average since we moved in 3/2010.

    Hello Chris, now you are heating 3800sq' not 1900sq'. Can't expect to heat basement to 64*F and garage to 55-58*F for free.

    I do wish we had used more tubing in the slab, 12" spacing. Sent 95* water out to the floor most of the winter, seemed to work OK. May try 100* to start next winter. That's about the max for geo from what folks around forum have said.

    I am considering cutting the slab in front of the double sliding glass doors. We didn't put insulation between slab and foundation, my feet got really cold when I walked up to the doors. The garage doors are the same, no insulation seperating main floor from cement that goes out under doors.

    I have an electric meter in the utility room which keeps track of heatpump usage. I take daily readings. I made an excel spreadsheet that shows what the house used and what the heatpump used per month.

    ChrisJ
     

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    Last edited: Feb 28, 2013
  14. ChrisJ

    ChrisJ Active Member Forum Leader

    Summer cooling & DHW

    It's very interesting how the Hydro-Temp system works in the summer. When the stat calls for A/C, the pump for the DHW circulates water between the hot water tank and heat exchanger until the sensor on the DHW tank is satisfied, then switches to circulating the ground loop.

    I checked the EWT when system was using the ground loop, 62*F, still have no LWT sensor, installer has not replaced yet. Temp seems pretty good for early-mid summer.

    I sometimes get warm air trickling from supply vents, I think it's due to a high return that is in the attic. The duct is insulated flex line, above ceiling insulation. May have to insulate from hot attic better.

    When I talked with insulation contractors during the build, most wanted to insulate the underside of the roof. I thought it would be better to have a vented attic and insulate the ceiling. Less conditioned space.

    Just want to say thanks again to all the regulars on the forum for sharing your knowledge and experience with all of us.

    ChrisJ
     
  15. ChrisJ

    ChrisJ Active Member Forum Leader

    Radiant tank plumbing, future solar?

    I am using a 55 gal electric water heater for my buffer tank (not powered, unless I need to). Had an issue with plumbing right from the start. As it is now Infloor supply from hot at the top of the tank, return to cold at top of tank. Heat pump supply from tank drain opening, HP return into T&P hole in side of tank kind of near the top of the tank.

    Worked OK this winter, was a very mild winter. Couple of problems. I have a 30*F or so delta T, gets better with longer run times. Radiant return water going to the bottom of the tank via dip tube is about 60*-70*F. When the floor calls for heat 95* water goes out to floor, doesn't take too long before tank calls to be re-heated. HP pulls cool water from the bottom of the tank, returning it to near the top at only a few degrees warmer then the bottom of the tank. The water going out to the radiant supply quickly drops in temp down to high 70's low 80's, because the water coming from the HP shoots across the tank and right out to the floor. The tank stratification gets all goofed up. Makes for nice long run times in first and second stage (3 compressor stages) but runs until the tank is back up to 95*F.

    I think before next winter I will have HP suppy and return swapped, draw from the T&P opening near the top and return to the bottom drain. My main concern with that configuration is short cycling. Temp sensor is between insulation and tank about 1/4 of the way up from the bottom, may have to figure out a way to put it closer to 1/2 way up.

    Solar thermal DIY is something I have been reading about. Builditsolar.com has a lot of info and projects that are very doable. With my heat pump doing on demand DHW all year and radiant all winter, I thought solar could maybe take some of the stress off my compressors (dual compressor heat pump).

    Electric bill goes up about $100 a month when I turn on the radiant, so I thought that it will be a long payback if I spend 2k-3k on DIY solar, then I thought it will probably be worth it if it helps extend the life of the compressors:)

    ChrisJ
     
  16. Bergy

    Bergy Member Industry Professional Forum Leader

    Chris,

    This is how we plumb our Geo/Radiant installs. We remove the lower element and plumb that into the heat pump. The T&P valve is replaced with a 30 lb. pressure relief valve. The load side flow rate is matched to the source side flow requirements. Remember, the load side is a closed loop and should need 3 GPM/ton.

    Bergy
     

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  17. ChrisJ

    ChrisJ Active Member Forum Leader

    Thanks for the response Bergy, I like the picture, my pipes go up and across and down just like your diagram.

    The way mine is plumbed now is similar, load supply is drawing from the drain where a tee was used to still have a drain. Load and source both use 1/6 hp B&G pumps, so GPM should be close. Dip tube is still original. I have a 30lb pressure relief valve.

    I had asked the plumber if a dip tube could be added to the load return to divert the incoming water towards the middle of the tank rather then straight towards the radiant supply. He said it would have to be a 1/2" piece of pipe or tubing, hole in tank is 3/4". I just don't think that will work, going from 1" copper to 1/2" anything.

    Maybe I should concentrate on getting the delta T down on the radiant return, need more flow. 2 zones- Basement 4 300' loops 1/2" pex-al-pex, 1 taco 007 circulator. Garage is 2 300' loops, 40' of 5/8" pex-al-pex from 007 circlator to manifold. Plumber said we should take out the internal flow checks in the 007's, don't know if that will gain anything. Larger pump will use more electric.

    ChrisJ
     
    Last edited: Mar 21, 2012
  18. ACES-Energy

    ACES-Energy Member Industry Professional Forum Leader

    just be careful on flows, I have fixed a few larger jobs that tried putting a bunch of flow through some openings and than forget they were 3/4" ports...
     
  19. ChrisJ

    ChrisJ Active Member Forum Leader

    Quote from Urthbouy-
    "I find the key is the difference between optimization vs. functional... They work. Could they be optimized better? Yes."

    My system works,, could it work better?? yes.

    Aces- That's the problem with electric tanks as buffers, all the ports are 3/4" except the heating element ports.

    Manufacturer recommends tanks like this for the emergency use of the elements. How's that for confidence in their product.

    Bergy- I see in another diagram you posted, 1" pipe on Load and radiant supply & return. My load is 1",radiant is all 3/4", any gain in flow if both are into 3/4" ports?
    Also, having the Load return in the center of the top of the tank, doesn't that put lower temp water into the top of the tank where the radiant supply can draw it in, do you add a dip tube?

    Original diagram supplied by manufacturer has both load and radiant returns going into cold water port. They show the radiant return going straight through tee, load on the 90* of the tee. My plumber did the opposite load straight through of 1" pipe, radiant on the 90* of 3/4" pipe, load flow dead headed the radiant flow. That's when we seperated them into 2 loops.

    I know there are many ways to skin a cat, but with GSHP I think the margin for error is very narrow. I read about it a lot with all aspects of Geo.

    ChrisJ
     
    Last edited: Mar 23, 2012
  20. Bergy

    Bergy Member Industry Professional Forum Leader

    Chris

    The Geo supply is plumed into the center (T&P) port, sometimes this is on the side of the tank. The radiant supply comes off the "hot out" and the radiant return goes into the "cold in". We remove the dip tube, cut about 6 inches off and drill holes through the tube up to within 12 inches of the top. Not exact science... This helps increase water flow from the return.

    Bergy
     

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