Texas Heat Pump Project - Experiencing 7 years of operation

Discussion in 'Geothermal Heat Pump Testimonials' started by heatpumpproject, Oct 21, 2014.

  1. heatpumpproject

    heatpumpproject New Member

    Hi. I'm new on this forum. I found some very useful experiences from other owners or professionals dealing with ground source heat pump on this forum. Here I will share my experience in few posts. I'm real enthusiast about getting the heat from the ground, I made also a youtube video about my project, the blog and lots of other things. I'm the owner of ground source heat pump for 7 years now. I have 3 vertical geo collectors installed (2 x 60m deep, 1x100m deep). The output of my HP is about 14kW.
    In this post I will share some useful experiences related to the 7 years of operation of my ground sourced heat pump. Most wanted facts about heat pump operations:

    • Costs: In first years operating costs (heating area 150m2, good insulation, county EU Slovenia) were from 250€ to 350€ for one winter season.
    • Operation time: The heat pump was in operation 3,5 hours on average per day.
    • Geothermal collector efficiency: At the beginning of the winter season the water from the geothermal collector was about 10,5 degrees Celsius. At the end of the winter season the water from the geothermal collector was about 7 degrees Celsius.

    The pump was running very smoothly without any problems ... until. Two years ago I noticed that my heat pump runs more and more hours per day. At the end it was running almost 5 hours on average. From 3,5 hours to 5 hours ... what happened?! The winters were comparable in last years, the settings of the heat pump were the same, the geothermal collector was working O.K. So? I called the maintenance team of the producer of the heat pump. They showed up very quickly in few days. We found out an oil stain inside the heat pump below the compresor and we found out that cooling gas level is too low. After checking and screwing some pipes we added the cooling gas to the correct level. We started the machine, made some tests and ... it was running like new and it still do. The cost for the maintenance was 70€ and it was worth paying this money, because the pump will again run more efficient this winter.

    This winter 2014/2015 a have a new device and a tool in place to monitor my Heat Pump electricity consumption. It is called Efergy Energy monitor. You can track the consumption at the very moment, you can track average consumption, consumption per day or month, you can monitor costs per day, month and some other statistics and future predictions. I'm now in the testing phase and it really works fine. I can monitor my consumption either on the web via personal computer or Android phone (you can download the application on the G. Play). I already found some strange deviations and what is causing real costs. I will be able to check if the Heat Pump specifications regarding energy consumption are something you can trust. Hope you like the post ... I'll be back :)
  2. heatpumpproject

    heatpumpproject New Member

    The most fascinating part of the project for me was drilling the hole (well) for geothermal vertical collector. I have two for 60m deep and one 100m deep. The is a photo of drilling machine. More about drilling you can find here (http://heatpumpproject.blogspot.com/2007/12/drilling-hole-well-for-geothermal.html):
    [​IMG] .

    A lot of people were asking me also about detailed installation schema. You can find it here:
  3. heatpumpproject

    heatpumpproject New Member

    Installation schema you can download:

    Attached Files:

  4. engineer

    engineer Well-Known Member Industry Professional Forum Leader

    "We found out an oil stain inside the heat pump below the compresor and we found out that cooling gas level is too low."

    That suggests, beyond doubt, a refrigerant leak. I hope you fixed it.
    heatpumpproject likes this.
  5. Mark Custis

    Mark Custis Not soon. Industry Professional Forum Leader


    In the land of the blind, the one eye is king, Bruce Jogeson 1968, Athens, OH.

  6. heatpumpproject

    heatpumpproject New Member

    True, there was a refrigerant leak. The guy from the maintenance service added the refrigerant to proper level and he measured the levels after few starts and stops of the heat pump. After fixing this issue also the sound of the compressor was a bit different. It works fine now ... but I assume it might happen again, because it is hard to be 100% sure that after checking and fixing some pipes there is no more leakage.
  7. frankz

    frankz New Member

    Conspicuous by its absence is the buffer tank. Conventional wisdom says with radiant floor you need a buffer to prevent short-cycle times at mild outdoor temperatures. Do you have some adjustment to prevent this? What are your cycle times when it is say 10 degrees C outside temp? Is there a thermostatic shutoff that limits the leaving load temperature, or is it controlled entirely by the room temperature.
    heatpumpproject likes this.
  8. heatpumpproject

    heatpumpproject New Member

    True. I'm not using a buffer tank. First reason is that I have aprox. 180 square meters of radiant floor where is already relatively high capacity of water. Second reason is that the output power of my HP is a bit less than it should be for the very cold month (I have a backup 2x3kW electrical heater in the HP, but I almost didn't use it so far) ... so the system warms up quite slowly. The third reason is that additional buffer tank causes additional heat loses. And the fourth reason is that additional tank means additional money and additional point of failure. For those reasons I decided not to install the buffer tank. The HP is mostly controlled by it self (according to the return water temperature and 4 degrees Celsius difference) and it is NOT controlled by the room temperature. If it really gets to hot because of the sunny day (e.g. over 21.5 degrees) then the room thermostat switches off the HP. I'm adjusting the return water temperature on the HP 3 or 4 times per winter season, staring with 26 degrees Celsius in autumn to 30 degrees Celsius for very cold moth.

    In attachment you can see the normal operation of the HP when outside temperature is 10 degrees C.

    Attached Files:

  9. Bergy

    Bergy Member Industry Professional Forum Leader

    You need to have 3GPM/ton flowing through BOTH the Source side and the Load side of the water to water. (For closed loop)
    I've never seen a radiant system requiring that much flow. A good buffer tank will loose about 5* F/day and add YEARS to your heat pump.
    heatpumpproject likes this.
  10. heatpumpproject

    heatpumpproject New Member

    Thanks Bergy. I don't have very short cycles so I assume the impact on the heat pump should not be so bad. But maybe I'm mistaken.

    On average I have from 30minutes to 1 hour cycles. At the start of the winter the HP starts 4-5 times per day for half an hour and in extremely low temperatures HP starts 7-10 times per day. Probably the buffer tank would reduce the number of daily cycles ... but I'm not sure for how much ... maybe half?

Share This Page