GSHP Open Source GPM
Last Post 13 Nov 2014 08:25 AM by jonr. 158 Replies.
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noobooUser is Offline
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15 Mar 2014 07:35 PM
I'll look for a paddle wheel flow meter...in the meantime...

Please stay with me for some more detail:

After the GSHP was running, and shut down without an error showing, but still calling for heat, the outside pump was circulating for 10 minutes or more,

the outflow did not change temperature and was very close to freezing, with frost in bands on the HX.

I have a gate valve and boiler drain after the HX. With the gate valve closed, pressure at the boiler drain is 12psi. With the gate valve open, pressure is negative. So, I have throttled the gate valve to 2psi. My flow is at least 7 gpm (measured with a bucket at the HX) with the piping open at the discharge side of the HX.

Looking at the outflow (injection well) there is flow as the water level came up and out of the well casing when the pump was on.

Sorry for the ramble, but any bets to place here? The month here is March, frozen ground and pipes is possible. I have plugged in the heat wire on the pipe leaving the house.


Bill NeukranzUser is Offline
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17 Mar 2014 10:02 AM
Posted By nooboo on 14 Mar 2014 11:18 PM
Please help with a good setup for measuring flow and temp:

... before I pull the pump...on the discharge side of my open loop, I want to install pressure gauge(s) to measure psi and temo so then check pump flow.

Is there a link that I might refer to? All help appreciated.



I use the WEL ( http://www.welserver.com ) for flow, temperature and pressure monitoring.

See this example for flow and temperature monitoring: http://www.welserver.com/WEL0640 .

Temp monitoring is the easiest and it can be done post-geo system installation.  Just a few dollars for sensors and some wiring, beyond installing the fundamental WEL unit.

Flow measurement is easy to implement at any time too (just another pulse counting input as far as the WEL is concerned).  But, it's expensive to do any time after the geo system is implemented.  Installing flow sensors post geo install requires opening up the geo closed-loop water lines, inserting the flow sensors (not difficult), and then running through the loop purge process (requires some machinery, time and expertise).

Pressure measurement is straight forward, using industry standard 0-10V, or 20-400ma sensors, but, these are not inexpensive sensors.  Plus, our experience has shown that with pressure sensors you now have to deal with opening up the refrigerant line to install (or using slip over Schrader (sp?) fittings, associated with the significant possibility of leaks.  For residential units we're just not supportive of hooking up refrigerant pressure sensors.

Hope this helps.

Best regards,

Bill


Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
noobooUser is Offline
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17 Mar 2014 11:27 PM
Some physics truths should be self-evident, but I am having problems with this GSHP shutting down, not making heat as it used to.
The original question was something about water flow...It is looking like there is not enough flow and the manuf was right that they need a lot more flow than usually is required on other manuf systems.

Today, by temping up some outflow piping, through the door and down the hill 6', I have verified there is at least 7 GPM, with more likely if I am using my discharge well piping which drops another 10' or so...(static head would/should then be zero.) Hey, maybe the frost broke my pipe and my static head is more like 16'???

First, my water flow measurements are not accurate as I am changing the configuration of the piping when I create a temp piping setup. It was suggested to use a paddle wheel gauge to measure flow.

Here is what is happening: The GSHP runs with the discharge water (outside open loop) is right at about 32f. Incoming water temp is 40f. Delta T on the house side is about 3f.



So, my flow must be too low, right?

The Welserver looks great, but I still do not know what the flow gauge looks like. This is open loop, did I say that already, so cutting some 2"pvc and T-in is do-able.

Attachment: GSHPOutflowTemp.jpg

joe.amiUser is Offline
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18 Mar 2014 07:34 AM
leaving water at 32F is going to shut any system down, so yes you need more flow.
Something like a Pentair flow meter would work for you, but I would Tee it off with isolation valves so you don't foul it with Iron when you arent using it.


Joe Hardin
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noobooUser is Offline
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19 Mar 2014 04:01 PM
I haven't bought the flow meter, but I have verified that I have flow at the top of the Geo loop of at least 7 gpm. There will be more flow due to the relatively low static head,



and my discharge pipe is intact, it will hold a vacuum, and it is not frozen. I remodeled my flow so that it properly came in from the bottom of the HX and exited the top. I also have removed the check valves at the top of the piping. The piping is fairly unrestricted with 2" pvc at the HX, reducing to 1.5" at the outflow.



My geo in temp and geo out temps read the same today, again, with water flowing...38f.



With the 'anti-freeze' function ON.



Is it time to put on the pressure gauges? I have the low side on already, it read 27psi.



Inside supply temp is 70f, return temp is 66f.



The last tilapia died from the cold...58 in the basement.




Brian



joe.amiUser is Offline
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25 Mar 2014 08:35 AM
"With the 'anti-freeze' function ON."

This means you told it you had antifreeze so it would run below freezing temperatures?


Joe Hardin
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noobooUser is Offline
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25 Mar 2014 01:17 PM
A review of the manual said the 'heat pump has anti-freeze function if the electricity is connected. So please keep the electricity always connected...'


The 'Anti-freeze running' icon does not seem to have a user adjustment but is an automatic function.


The manuf said the pressure was too low and has instructed me to empty the unit of water...



The low pressure is 125 with the unit off and will get down to 25 psi after 5+ minutes of operation and the high side is at about 58 psi.

The ground source side heat exchanger will start making popping sounds, like plastic air packing bubbles popping.

Water flow has been confirmed at an estimated 19 GPM by using a combo of direct flow measurement at the top of the loop and adding in the negative static head in the system, then checking the pump curve for the flow.


jonrUser is Offline
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25 Mar 2014 04:28 PM
If your EWT is 40F, you want to extract 36K btu/hr and you want a LWT of 35F, then you need 24 gpm of flow.


noobooUser is Offline
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25 Mar 2014 10:45 PM
Posted By jonr on 25 Mar 2014 04:28 PM
If your EWT is 40F, you want to extract 36K btu/hr and you want a LWT of 35F, then you need 24 gpm of flow.


Earlier, I was told: "4 GPM per ton on the source side seems excessive"...this figure now quoted is 8 GPM /ton. Please confirm.


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26 Mar 2014 07:52 AM
Good catch on the typo. 36000÷(5×8.3×60) = 14, not 24. So 4 GPM/ton (total tons, not extracted) is about right if 35F is the right minimum.


noobooUser is Offline
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26 Mar 2014 01:35 PM
Good to know...Then with my 18 GPM, I have some 'headroom' and water flow should not be my issue. I will investigate the low pressure cause as due to a leak in the refrigerant.


noobooUser is Offline
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26 Mar 2014 01:47 PM
Back to the flow monitor device and flow monitoring...

Is this a good choice for
a paddle wheel monitor :
http://www.seeedstudio.com/wiki/G1/2_Water_Flow_sensor ???

With the use of some math and calculate the area of the pipe, pressure and flow rate, should be able to obtain a quite accurate gpm?

If the paddlewheel got fouled with slime, that will indicate that it is time to clean the unit?


jonrUser is Offline
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26 Mar 2014 03:30 PM
Looking at the numbers differently, at 18 GPM, 40F in and 32F out, you would be extracting 72,000 btu/hr. Not going to happen on your 4 ton HP, so you need to check the numbers.


noobooUser is Offline
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26 Mar 2014 03:56 PM
What I don't grok with this flow stuff is what does it hurt to have more flow? I can see a downside with pumping energy over a total energy consumed equation and if I get the flow dialed in, I can be more efficient; but for now, if I have > flow, no big, rt?

As my system is now, I am not running it due to incomplete diagnostics, but it now looks like the issue is low R410.


joe.amiUser is Offline
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27 Mar 2014 12:33 PM
greater flow ultimately is greater wear on the coax


Joe Hardin
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noobooUser is Offline
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11 Nov 2014 10:19 PM
Continuing to document this open source system, we have ultrasonic flow mesurement now which shows 10gpm; the flow slowed from a previous 12.5 gpm to throw the error: "Outside Flow Low".

There were 2 months of adequate performance from the system after purging and re-charging with R410a. The issue was not low r410, but low flow.

The pump has been pulled and it is fouled with iron bacteria; more sauce that looks like Marinara.

It is a warm November here for us, so not a bad time to pull the pump and perform some maintenance.


joe.amiUser is Offline
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12 Nov 2014 08:42 AM
"There were 2 months of adequate performance from the system after purging and re-charging with R410a. The issue was not low r410, but low flow. "

That's why best practice is to establish good flow first.


Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
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noobooUser is Offline
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12 Nov 2014 10:26 PM
Posted By joe.ami on 12 Nov 2014 08:42 AM
That's why best practice is to establish good flow first.


Establishing good flow is Good Advice, Thank You!

Improper flow due to inadequate air bleeding has been an issue; this time a poor connection at the pump well head may have caused an outdoor water flow error (not low flow as I said a post ago... I applied anti-ox on the wires, cleaned the piping and it may be good.

Performance numbers on the system today are 9.5 delta-T on house side, 5.9 delta-t on outside wth 11.6gpm, 11,000 electricity BTU, maybe 3.9 COP?


jonrUser is Offline
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13 Nov 2014 08:25 AM
That's what the numbers indicate. But I wouldn't count on all the readings being perfectly accurate.


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