Link: http://www.duanesworld.net/duanesworld.net.geothermal.WEL.live.htm

Well, since the replacement of the heat pump there have been a couple issues.

T6, the temperature sensor for the desuperheater hot water output was periodically not working. The T6 sensor has now been replaced.

The RunTime sensor for the Desuperheater has not been working. I checked the wiring today and the sensor is connected properly. The sensor is still not operating. Can’t tell if the Desuperheater pump is actually operating. Too much vibration from the compressor.

T2, the ground loop solution return is not still not operating. The wiring connections are proper. I will need to do some further troubleshooting and may need to replace this sensor.

I have added a new device for my Geothermal HVAC monitoring system. I had ordered an HVAC8S device from ourcoolhouse.com that will monitor the HVAC calls from the thermostat.

This addition was prompted by the thermostat not operating correctly. This past winter the Humidifier was not working, see previous posts in this blog. But what was also not working was the 2nd stage call from the thermostat. That meant that instead of a multi-stage heat pump / air handler system, this last winter my system was operating as a single stage installation. This undoubtedly has cost me more in electicity this last winter.

The HVAC8S is intalled and operating. I have not yet added this new data into my real-time monitoring page. I now have the ability to track the daily run time, monthly run time, and current status (on/off) of the Fan, Stage1, Stage2, and Auxiliary/Emergency Heat. I already have Auxiliary/Emergency Heat monitoring on my monitoring page but that is ok.

I will be updating the blog when this new data is being displayed on the real-time monitoring page.

Link: http://duanesworld.net/duanesworld.net.geothermal.htm

Great News ….. The ground temperature sensors are operating and looking good.

I am excited to see how they perform this winter and how consistent the ground temperatures are

As expected, I see the temperatures of the firs four feet fluxuating quite a bit. The sensors below four feet are fairly stable.

The only concern I have is that I may have made a mistake in construction and did not provide any earth or insulation inside the 1/2 inch CPVC piping down to the sensors. This will propbably be the next generation of sensors or a modification to be made in the spring of 2008. A little late in the season to change things now.

Stay tuned ……

I am happy to announce the ground temperature sensors are in place. There have been couple changes to the above plan.

First, there are now 11 sensors. The deepest one is at 11 feet. Each sensor is one foot lower than the previous sensor (1 foot to 11 feet in depth).

I placed 3/4 inch PVC in the ground for each sensor to the appropriate depth. This was to act as a sleeve to lower the sensor in the ground. I did this so that if a sensor needed to be replaced, I can replace an individual sensor without disrupting the others.

Each sensor was placed in a 3 inch piece of copper pipe with a cap at the end. Around each sensor, the tube was filled with fiberglass resin.

I used direct bury wire to each sensor individually. The wire was then sent through piece of 4:1 dual wall shrink tube and a 1/2 inch CPVC pipe. The CPVC pipe then connected to the junction box.

The junction box is a watertight fiberglass enclosure. The junction box is at a depth of about 12 inches below the surface. In the junction box, each ground sensor wire pair was soldered to a twisted pair which then goes back to the WEL unit. The solder connections were sealed with double wall shrink tube, liquid electrical tape or a combination.

For now, the ground temperature sensor readings can be viewed at the (real time data page)

Parts list for the final assembly of Ground Sensors:

• 11 – Length of 3/4 inch PVC pipe cut to 1 foot 6 inches short of desired depth.
• 11 – 3 inch pieces of 1/2 inch copper tubing.
• 11 – 1/2 copper pipe caps.
• Fiberglass Resin and Hardener.
• 1 – Watertight Fiberglass enclosure.
• 11 – 1 inch to 3/4 inch CPVC threaded reducers.
• 11 – 3/4 inch to 1/2 inch reducers.
• 11 – 1/2 inch CPVC pipe cut to 1 foot 3 inches short of respective lengths.
• 11 – 1/2 inch 90 degree elbows.
• 1 Roll of direct bury twisted pair cable (4 pair per wire).
• 4:1 Double Wall Shrink Tube (to secure 1/2 inch Copper pipe to 1/2 inch CPVC).
• 3:1 Double Wall Shrink Tube (for solder connections).
• 11 – DS18S20 Temperature Sensors (from (http://www.ourcoolhouse.com)

This was a fun project. And as usual, I found better ways of doing things after the fact, so I am thinking of a second generation ground sensor system.

Well, I am running into issues with deploying the ground sensors. Five of the 10 sensors which were originally assembled had to be replaced. Once replaced, these sensors seemed to operate well with all the existing sensors.

The next step was to place the sensors in a length of copper tube surrounded with bentonite (grout). This was not an easy task. Finding the right consistency of water and grout was a trick. Then during the drying process, the grout was compacted. I found that this is a difficult process to make sure that there are not air pockets left in the tubes.

Now the problem I am running into is the rest of the monitoring system. It seems that there is an issue which periodically causes the temperature sensors to register false readings, extremely high or no reading at all.

I checked the humidity in the crawl space which was very high. I started a dehumidifier to bring down the humidity level. The level is now about 50% and the occurrence of temperature spikes has been reduced. I have set the dehumidifier to 45% to see if this will eliminate the temperature spikes completely.

At first I thought it might have been caused by a bad temperature sensor again from the ground sensor group. All those sensors were already removed from the system.

I was hoping to get these sensors in before the start of winter (2006), but this may not happen this year.