South Carolina Loop temps vary wildly and other questions.

Discussion in 'Maintenance and Troubleshooting' started by Liquorman1, Mar 28, 2019.

  1. Liquorman1

    Liquorman1 New Member

    Long time lurker, first time poster.

    Unit: WaterFurnace series 7, 3t , 29102 zip code (hot humid climate), with desuperheater, with 4 zones. Closed vertical loop system with 4 100-125ft wells (driller didn’t want to droll through The aquifer in case any leaks ever happened, tied into a manifold that runs underneath the slab of my house approx 2ft underground, brined with antifreeze.

    House: New construction, 9 inches open cell spray foam gable and roof deck, 3.5 inches closed cell spray foam in exterior walls, except behind the tub/shower combo and a garden tub in the master, where they put the pink stuff . I kept a close eye on the contractor//construction, and built this house for efficiency. 2950 sq ft, manual J Called for 2.28 tons, but series 7 smallest is a 3T, thius my sizing (variable speed mAkes it irrelevant anyway) System is sized for cooling (as per my climate) with no AUX heat at all.

    I got a certified WaterFurnace dealer that installs many systems to install my unit, (from over an hour away) since the closest installers were morons and boasted of having Installed ONE in the past year, insisting on a open loop system, which I specifically said I didn’t want, then them berating me for losing efficiency with closed loop even though my water quality would have made the system suffer /rant over
    The WaterFurnace Dealer seemed knowledgeable, through, and (most) of his workers were excellent to work with. 52k for the whole system/loops/ductwork and everything installed (which I thought was high, but no way in hell I was getting the morons to do it)

    1. This morning our unit was on and using aurora I saw loop temp at 62, this evening loop temp is at 75.1. Pics to confirm.
    From lurking this forum I’m assuming this isn’t normal. Bad sensor? Loop field plumbed wrong? Pipes to manifold not deep enough and not enough flow?

    2. I read in another post docjensen said series 7 needed a variable speed loop pump. They only installed a single speed loop pump. I’m assuming their is no harm but to my efficiency, but just checking.

    3. The unit always comes on in h-6, then ramps itself down. Is this normal? I would figure it would come on in h-1 and ramp itself up.

    4. Dehumidification and tight house. While this isn’t exactly the forum for this, what is the upper limit of humidity a house should have before we get problems in the wall cavity? I’ve noticed condensation in the windows on cop mornings. Series 7 does not support dehumidification in heating mode, except with an advanced Honeywell thermostat that runs heating and cooling mode simultaneously (something like that) to dehumidify the house. My humidity has been running in the high 60’s to as high as 75%. I have taken to running the fart fan in the bathroom during showers to expel some of the steam, was wondering what else I might do to decrease the humidity in my house. Current humidity outside pic for reference.

    Sorry for the essay, I tried to give all relevant information to achieve the best answer to my queries. Thanks in advance for the help/advice.
     

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  2. ChrisJ

    ChrisJ Active Member Forum Leader

    Hello and welcome,

    You will have to use a portable dehumidifier or 2 to get the RH closer to 50%. New homes usually have high humidity, especially when they are sealed tight with spray foam. You might try running all "fart fans" for extended times.

    Do you have a ERV or HRV? Energy Recovery Ventilator. When you said fart fan, that made me wonder if you have an ERV and the boost is the fart fan.

    The swing in loop temps could just be the difference between in use and idle loops.
     
  3. Liquorman1

    Liquorman1 New Member

    No ERV or HRV.
    We also don’t have an air exchanger. We have a 3 year old and a dog, so the outside door gets opened often enough for the exchange of air (per the WaterFurnace dealer). How critical is it to keep RH ~50%, and how critical is It that I do have an hrv/erv/air exchange in the house?
     
  4. ChrisJ

    ChrisJ Active Member Forum Leader

    When you stay in the 65-70% range too long mold can develop, which can aggravate allergies. Absolutely run the bath fans when showering and for 1/2 hour or so after. I would suggest running the bath fans and if you have a range hood that vents outside, turn them all on for a few hours to see if the RH comes down.

    Without the balanced ventilation of an ERV you are left with what is known as exhaust only ventilation, using the bath fans (fart fans LOL). Fresh air gets drawn in through the small voids here and there in the house envelope. The Relative Humidity outside is higher at low temps, when that air comes in and warms up the RH of the air now is much lower, so don't be too concerned about 83% RH outside at 40*F.

    I was in a similar situation 8-9 years ago, we built the house during a wet year, so a lot of rain on the framing and subfloor. Then the basement cement takes a long time to cure, there is still a lot of moisture coming out of the cement, for a year or more I was told. We had plaster walls done throughout the house too. It was a year or so before I even realized RH was high all the time. Started using a dehumidifier constantly. Now we have to us it during spring and fall since we aren't using a/c and there is no cold dry air like winter.

    You will have it tougher being in the hot humid SC climate.

    Check out GreenBuildingAdvisor, I have learned a lot about building science reading articles on that site.
     
  5. geoxne

    geoxne Active Member Forum Leader

    ChrisJ is correct, the loop temperature is not valid unless the pump is running. The temperature sensor is inside the unit and will approach ambient temperature over time when it is not running.
     
  6. Liquorman1

    Liquorman1 New Member

    I read some on green building advisor as I was building, I guess I will have to dig deeper.
    Unfortunately, my contractor had 0 experience with tight building or geothermal, I was on my own. The good part, he was the only one who would work with me to do it, although I had to do most of it myself.

    I will turn on the “bath fans” and see if that helps.

    Any thoughts on the unit coming on in h-6 and then ramping down? Is that normal?

    Also, the question about variable speed circ. Pump. My pump pic is attached for reference, how much would I save by having a variable speed pump (would it be enough to switch it out) and will they last as long a single speed pump. With my unit being oversized, it has stayed/potentially will stay in low more often, so will the savings be even more under those circumstances?
     

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  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    It is normal for the 7 series to go to stage 6 on start up. It starts in stage 1 and revs up to stage 6 to circulate enough oil through the compressor. It will do so every 30 minutes for 1 minute or 2 if you are running below stage 6, and then go back to whatever the thermostat calls for.

    You do have the wrong circulation pump for a 7 series. The 7 series needs a variable speed pump, and the aurora controls in the 7 series were developed to control variable speed circulation pumps. The 7 series runs about 6,000 hours per year, compared to a dual stage which runs about 2,500 hours/year.

    In my humble opinion no geo system should come with a 26-116, which is a very inefficient circulation pump.
    6,000 hours x 385 watts = 2,310 kwh/year for a 26-116

    6,000 hours x 60 watts = 360 kWh/year for a Grundfos 32-140 variable speed pump.

    The difference is about 1,950 kwh/year, about $220/year at 11 cents/kwh.

    equally important, the extra 1,950 kwh/year will end up as heat in your loop, increasing your loop temperatures. Good for heat dominated climate, bad for cooling dominated climate.

    Now your heat pump will also run less efficient....
     
  8. arkie6

    arkie6 Active Member Forum Leader

    Regarding your bath fans, since you don't have an ERV or HRV, I would install occupancy sensors with time delay on your bath fans. These sense motion and turn the fan on whenever someone enters the room and keep running a user adjustable amount of time after the person leaves the room, i.e. 15 minutes or so, which insures smells and excess moisture from showers are removed. You can buy these at home improvement centers or on Amazon for ~$20.

    If the bathroom exhaust fans or clothes dryer are exhausting air from the home, where is the outside makeup air coming from?
     
  9. mtrentw

    mtrentw Active Member Industry Professional Forum Leader

    The wild loop temperature swings may be an illusion. It wouldnt surprise me if the temperature drifted up to 75 while the unit wasn't running thus the sensor rises to room temperature?
     
  10. ChrisJ

    ChrisJ Active Member Forum Leader

    It comes from the thousands of tiny gaps through out the house.

    I did a quick search "exhaust only ventilation" here is one Q & A thread. https://www.greenbuildingadvisor.co...sive-make-up-air-for-exhaust-only-ventilation.

    A passive inlet let's you decide where the make up air comes from.
     
  11. arkie6

    arkie6 Active Member Forum Leader

    The question was primarily intended to be rhetorical. A 4" diameter filtered passive air inlet is what I have on our house to help balance air pressure inside when exhaust fans are running.
     
  12. ChrisJ

    ChrisJ Active Member Forum Leader

    My apologies Arkie, my reply was aimed towards the OP.

    The 4" inlet, where did you locate it? Do you temper it somehow?
     
  13. arkie6

    arkie6 Active Member Forum Leader

    No problem. The climate is relatively mild around here, but I did temper it somewhat. The house is on a slab and the central HVAC return plenum is ~12' from the edge of the house where the heat pump is located. A 4" thin wall PVC pipe was installed from the plenum to the heat pump for the refrigerant and control lines to the air handler. This is under the slab and slopes down to the unit. I ran another 4" PVC pipe next to that one for the fresh air intake. Since it is under the slab in the back fill, it will be somewhat tempered (our deep soil temp is ~62F here). I put a 4" PVC turned down elbow with filter material and metal screen over the end to keep dust, pollen, and critters out. The end of the elbow is ~4" above the ground.
     
  14. Liquorman1

    Liquorman1 New Member

    Update: I got the WaterFurnace installer to replace the 26-116 pump with a 32-140, at their expense since it was their oversight to start with. I can’t say oversight, I think they just stick the cheaper pump and hope no one notices.

    Is it normal to have entering air temp and exiting air temp of the system within a degree of each other when the system is operating in low speed? See picture.

    Also, I finally figured out how to turn on the dehumidify function on the unit.
    From what I’ve read it’s normal for the unit to cycle to 9, leave the fan speed at 3-4 to pull the water out of the air. I initially set the set-point at 50%, but a week later it still hasn’t reached it and the unit pretty much stays on c-9 to keep pulling water out of the house (the house is still new). I live in the hot humid south, and it’s cheaper than running a dehumidifier and the air conditioner, which must be done since I spray foamed everything and made the house so tight. My question: what would be a good humidity set point for my area, and is it normal to stay in c-9 for extended periods (more expensive than previously being in c-3 all day) and will it harm the VS compressor running flat out so much?

    Last pic to demonstrate the difference between before dehumidify option and after. I turned it on Wednesday.
     

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  15. geoxne

    geoxne Active Member Forum Leader

    NO!!! Something is not right.

    First you have to understand, the return air temperature assumed and reported by Symphony is the temperature reading at the MasterStat. The actual entering air may be quite different and for diagnosis should be measured in the return air plenum just before the unit. The leaving air sensor is between the air coil and the blower wheel. This most accurately represents the air temperature coming off the aircoil. Also, remember any recorded temperatures should be taken after the unit has been running for 10 minutes or more for accurate steady state temperatures.

    Dependent on fan speed settings the EAT and LAT difference (DeltaT) should be around 10F to 20F in cooling for a Series7. So what could be the matter?
    -Sensors could be wrong.
    -Unit is pulling in 90F air from an unconditioned space. Maybe that zone you have set to 85F or attic?
    -Fan speeds set too high (high fan speeds will also reduce the ability to dehumidify)
    -Or last suspect, unit is not performing to specifications.

    Verify EAT and LAT at the unit with a digital cooking thermometer, after the unit has been running and has reached steady state. Report to your installer along with Compressor, Fan speed and time recorded. They should be able to see and compare online with your Symphony system to help diagnose.
     
  16. Grant Brooks

    Grant Brooks New Member


    So I know I am a little slow to this reply but I was having some of the same issues described in this thread with humidity due to negative pressure in the house from the Heat & AC plus exhaust fans running and makeup air being sucked through outlets and lights. I did very similar to what Arkie did and put a 4" air intake on the outside of the house, cut a 4" hole in the return air side of the HVAC and attached it that way. This allows the Geo unit to condition (heat, cool, dehumidify, filter) that air before it is dumped into the home. This has solved literally every humidity issue that I was seeing. With out this 4" fresh air intake on very hot and humid day where the AC would run a lot I would come home to all of the light fixture sweating and dripping on the floor. Also, even with a stand alone dehumidifier the house would always be between 58% - 68% humidity. I have not had this dehumidifier on at all (unplugged) and the house maintains around 48% - 54% humidity. With all this being said as well, the house smell has improved greatly as well. No more stale air and I can tell that it is easier to breathe. If you have any more questions please feel free to reach out.
     

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