Washington New GSHP s 3 stage and very happy

Discussion in 'Geothermal Heat Pump Testimonials' started by rbento, Jan 15, 2020.

  1. rbento

    rbento New Member

    My DIY GSHP s build

    I live just outside of Seattle in Washington State. My home is 25 yrs old, 4800 sq ft, two story, mostly open between floors. 9.5 acres of lowland, water table looks like 6’ My test hole indicated 52 deg at 6’

    My build is two GSHP units. 1-6T and 1-3.5T. I went with two units because I don’t have the electrical infrastructure to support a single unit with electric back up AUX. I went with MHP brand for several reasons. 1. A lot of other, more complex systems could not be purchased as a DIY. 2. Many reviews on other systems had a lot of customer service issues. 3. unfortunately the few professionals I had spoken to were not very "professional" 4. A friend of mine has a Geocool that works fine and I think it is made the same as the MHP

    10 horizontal straight loops, 600’ ea. totaling 6,000 feet of ¾” 4710 hdpe buried 6’ in 3,000’ of trench. Right at 6’. I went with the 4710 since heard it was a little more resilient to rocks. The slight additional cost is cheap insurance.

    The manifold is homemade and resides in the crawl space. It has 20 ports with 20 - 1” valves with 1 ¼” pipe to the flow center. I used PVC for all of the plumbing, Why PVC? First off, I did not know any better. Second, I have lived on a well system for more than 30 years, all PVC @ 40-60 PSI, constant pounding on and off, never a single failure. Third, so far I am not running any corrosive antifreeze, only pure H2O because my EWT, as far as I can tell, will never drop below 44 deg... currently looking into adding antifreese

    My flow center is a Geo Pulse Twin I had special build with 4 Wilo Star variable speed pumps. I could not be happier with this unit. After some trial and error I have the pumps set at their lowest settings of 140W each and have the best results in terms of Delta T about 10 deg. PSI is 7.5 – 10 It varies when I turn on both the 3.5 and 6 for stage 3… only 7.5 for stage 1 and 2 on the 6T

    In December of 2019 I was only about 75% complete with the build although I was up and running on the 6T unit and had been through a cold snap of 17 deg outside temp at my home. The performance was what I would expect, max temp inside was 66 deg when the outside was 17 deg. My EWT is usually around 49 deg but it did dip down to 44 deg during the cold snap. The EWT quickly recovered when the cold went away. I believe the water around the loops was the reason for the quick recovery.

    UPDATE. As of Jan 2019 I am running both the 3.5T and the 6T on a single plenum and it is working better than expected. I have plenty of CFM and as much as 103 deg at the registers. I installed a couple of relays so I can run a single thermostat and have 3 stages heat and 2 stages cool.

    When doing the math on the energy savings, So far I can see about $300.00 savings per month compared to the propane furnace I had previously.
    The house is always warm and I won’t be worrying about $$ for the propane any longer

    I could not be happier with my Geothermal System.

    I am new to using forums but I think I will post parts of my build in other posts where some of the details should be… I hope. I also still have some tweaking to do so I will be asking questions as well

    Great Forum
     
  2. mrpac

    mrpac Member

    Wow, sounds like you are adventurous to take on a project like that. Awesome.

    MHP sounds interesting, I did some research after reading Dave's post yesterday. It sounds like it is out of Miami, not too convenient for us Canucks north of the border.

    I have a Climatemaster Tranquility 27, and have always wondered what I will do if/when I experience hard decisions- although things work well to date.

    I like the idea of purchasing direct from the manufacturer - if someone already has a geobed and flowcenter, why not buy it direct and plumb it in? Seems like the only company out there that does this -

    I hope that the company eventually has a Canadian Rep.

    Bring on the success stories!
     
  3. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    10 degrees delta indicates relatively low flow, given your system design, and also the 103 F indicates a 30+F delta over the air coil, also suggesting a low flow. Also you seem to indicate that you are using 640 watts pumping power no matter if you are running in first, second or third stage.
    None of that is the end of the world, but some of those datapoint suggest that the system is not running optimal.
     
  4. wing

    wing Member

    For sure you need to add antifreeze to the supply loop.

    If EWT was down to 44 degrees then LWT may have been 36 to 34 degrees - dangerously close to freezing.

    I thought same as you, plenty of loop, wet ground, so EWT and LWT can never approach freezing ? But I see this morning I am down to 38 degrees EWT with a LWT of 31. Not bad but I really thought I would never go under 40 degrees EWT in the geo loop.

    And if you are going to run air conditioning in the summer, you will need anti freeze on the load side as well.
     
  5. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    With a flow around 1.5 gym/ton and no antifreeze, you would see freezing coils around 38-39F LWT. Keep in mind that in order to cool down the water to 38F, the coil actually has to be much colder, like 32 or below. Which also means tyou will have some ice built up on the inside of the coil. Ice no is an insulator and will not allow for a good heat exchange, refrigerant will not heat up enough by the water, meaning it will get colder, and LWT will get actually warmer. However, in reality your coil is freezing shut soon pr later. 38F is usually the magic LWT when open loop systems will start freezing....

    Not sure if mrpac needs antifreeze on the load side when he has two heat pumps on a plenum and talks about CFMs....:confused:
     
  6. rbento

    rbento New Member

    So sorry for the late response... I don't check in daily but will try to do better. At this point, I must apologize, I am still learning the terminology and how the science works so thank you for your input and patience.

    Let me clarify my flow center fist. I have 4 pumps. 2 on each heat pump. When a heat pump comes on it turns on a pair of pumps so 1st and 2nd stage is on the 6T unit. When the Aux (3rd stage) kicks in it triggers the other two pumps that are controlled by the 3.5T. Since it is a "TWIN" flow center it shares a common return line to the 10 loops. So when the 6T is on low, 140W per pump, the pressure gauge indicates 7.5 PSI. When the 3.5T starts (stage 3 AUX) then the same gauge on the 6T goes up to 10 PSI. BTW the pressure gauge is located on the EW side of the 6T. I have no gauges on the 3.5T
    I am measuring the EWT with a infra red temp gun directly in the flow center water and I am measuring the EWT at the in side of the 6T with a dial temp gauge in the brass el hose fitting.

    Point taken on the antifreeze... maybe I was just being hopeful :) I certainly don't want things freezing and having to tell my wife that our (my) system broke. At one point I saw the LWT around 34 deg I turned up the 6T pumps one click to give me 10 PSI in an effort to increase the LWT to 36 deg. thinking the extra flow would mitigate freezing.

    I still would like to understand more about the flow rate and is the term Delta T the difference between EWT and LWT? like I think it is. Also I am using a PSI gauge and I don't know how to figure the GPM that seems to be common in conversations.
     
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    Your temps will decrease over the heating season. If your LWT is 34 now, it might be 28F in a couple of month. You need antifreeze in your loop.
     
  8. rbento

    rbento New Member

    UPDATE: I took your (forum) advice about the antifreeze. Today I flushed the system with new clean water and added 30 gallons of methanol, 16% .. so far so good. I did notice a drop in pump pressure at the entry water port so I kicked up the Wilo pumps to the #2 settings. It's early in the season for us in Seattle but will be keeping an eye on it...
    great "peace of mind" that antifreeze, Thanks
     

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