Welding Our HDPE for the Geothermal Ground Loop

We have a lot going on … connecting our geothermal ground loop, completing all of our underground drainage from the roof to our cistern and setting up the infrastructure for our photovoltaic solar panels.  The last thing we needed was someone to place a SAM storage unit by our property on Winchester Boulevard.

Importantly, the two-person team from 88HVAC, Justin and Mike, worked diligently to connect our ground loop between each of the 25 concrete piers.

Governor Schwartenegger Signed AB 1500 Yesterday!

New white carpool lane stickers for all-electric vehicles will expire on July 1, 2015. Our Nissan LEAF will have white stickers so we can drive in the carpool lanes.Yesterday, the Governor of the (Great) State of California, Arnold Schwarzenegger, signed Assembly Bill 1500, that extends the use of High Occupancy Vehicle in carpool lanes until January 2015.  The existing yellow stickers that were scheduled to expire on January 1, 2011 are extended and will now expire on July 1, 2011.  The new white stickers will expire on January 1, 2015.

On July 31, we put down a deposit on a Nissan LEAF so we’re looking forward to being able to drive in the carpool (diamond) lanes.

A Dangerous Situation

The SAM storage unit on Winchester creates a dangerous situation in two aspects.  First, the SAM storage unit blocks visibility for vehicles turning left or right from Via Sereno onto Winchester Boulevard.  Second, the SAM storage unit blocks the 25 mph sign on Winchester, exacerbating the problem.  Essentially, vehicles travelling Southbound on Winchester can’t see the 25 mph sign and vehicles leaving VIa Sereno can’t see them coming.  And, the vehicles are approaching faster.

There are 16 houses on Via Sereno, of which we are one, leaving 15 others.  A neighbor up the  street called us last night and mentioned that they thought our new SAM storage unit was blocking visibility on Via Sereno.  We corrected them promptly, explaining that the SAM storage unit was not ours.  Then, they asked if it belonged to one of the workers or sub-contractors that we were using.  No, it was not.

If one neighbor called to ask us about the SAM storage unit, we could only imagine that the other 14 neighbors were thinking the same thing but didn’t want to call us, yet.

Bryan took down the SAM storage unit number (420-200338) and called 1-800-GET-ASAM to advise the company that the person renting the SAM storage unit was violating an local ordinance.  They took the information and then called back within 10 minutes to say the person renting the SAM storage unit would move it by 12:00 noon tomorrow (09/02/10).

Let’s see what happens tomorrow …

Welding Our HDPE for the Geothermal Ground Loop

As part of our lower level (basement), we had to excavate 13 feet of dirt under our existing house.  Since we wanted to use geothermal heat exchange through a ground source heat pump, the shoring required for the excavation had tremendous synergies with the geothermal.

Since we needed a ‘ground loop’ for our ground source heat pump, we placed our HDPE (High Density Polyethelene tubing) inside the concrete shoring piers.  Each of these piers went 30 feet into the earth.

At this point, we needed to connect the HDPE in each of the 25 concrete piers so we could extract the energy from the ground (or put energy from the house into the ground).

First, the two-person team from 88HVAC connected the two U-tubes in each of the 25 concrete piers together.  Now, they had to connect each of the 25 piers together into four individual ground loops (two on the East side and two on the West side).

The process was very interesting to watch:

  1. Measure and cut the HPDE to the appropriate length.
  2. Chamfer and clean the end of the HDPE so the melting/welding would be consistent and uniform.
  3. Attach the cold pipe (special tool) to the HDPE with the chamfer tool in place.  The chamfer tool ensures the pipe length is measured accurately.
  4. Using the special heating tool, heat both the male and female ends of the HDPE tubing and slip fitting.
  5. Remove the heating tool, and connect and hold the two pieces of HDPE for at least 10 seconds.

Easy-peasy, right?

Sort of.

After making the connections, the system is tested to 100 pounds per square inch (PSI).  It must hold 100 PSI and not have any leaks.

Each of the steps in the procedure described above must be done perfectly, otherwise there will be leaks.

Leaks can occur wherever the welds (molten HDPE) are not complete.  If there are areas where the welds are weak then failures may occur in those places over time.  Again, each step in the procedure has to be done perfectly to minimize the probability of incomplete welds.  For example, the HDPE must be at the correct length otherwise it will be difficult to hold the heating tool for the correct amount of time.  If the heating tool does not melt the HDPE sufficiently then there will be a weak area or the weld will not be complete.

The team from 88HVAC took the time and paid attention to detail such that the welds were done correctly.

Measuring the HDPE to identify where to make the connection between the two concrete piers.

Measuring the HDPE to identify where to make the connection between the two concrete piers.

Cutting the HDPE to the correct length.

Cutting the HDPE to the correct length.

Chamfer tool, which removes the correct amount of HDPE from the corners of the pipe and allows the cold ring to be locked into the correct position that will provide sufficient surface area for the heating element (weld).

Chamfer tool, which removes the correct amount of HDPE from the corners of the pipe and allows the cold ring to be locked into the correct position that will provide sufficient surface area for the heating tool (weld).

Cleaning the HDPE where the weld will be made.

Cleaning the HDPE where the weld will be made.

Clamping the cold ring onto the HDPE in the correct location.

Clamping the cold ring onto the HDPE in the correct location.

Using the heating tool to melt both parts of the connection at the same time. Each step in the procedure must be done perfectly to weld each of the two pieces of HDPE together. This is a critical step.

Using the heating tool to melt both parts of the connection at the same time. Each step in the procedure must be done perfectly to weld each of the two pieces of HDPE together. This is a critical step.

After the heating tool creates molten HDPE, the heating tool is removed and the two pieces of HDPE are connected quickly.

After the heating tool creates molten HDPE, the heating tool is removed and the two pieces of HDPE are connected quickly.

The completed connection must be held in place for at least 10 seconds so the HDPE cools to create a complete weld.

The completed connection must be held in place for at least 10 seconds so the HDPE cools to create a complete weld.

Completed connection. This connection, done correctly, will last for the life of the HDPE, which is more than 100 years.

Completed connection. This connection, done correctly, will last for the life of the HDPE, which is more than 100 years.

Looking North on Winchester Boulevard, the view of oncoming (Southbound) traffic is impaired, which results in a dangerous situation.

Looking North on Winchester Boulevard, the view of oncoming (Southbound) traffic is impaired, which results in a dangerous situation.

The 25 mph sign is blocked by the SAM storage unit on Winchester Boulevard.

The 25 mph sign is blocked by the SAM storage unit on Winchester Boulevard.

Vehicles Southbound on Winchester Boulevard cannot see the 25 mph sign (behind the SAM storage unit).

Vehicles Southbound on Winchester Boulevard cannot see the 25 mph sign (behind the SAM storage unit).

Not seeing the speed limit, vehicles tend to speed up, exacerbating the situation for vehicles turing left (or right) from Via Sereno. This is dangerous.

Not seeing the speed limit, vehicles tend to speed up, exacerbating the situation for vehicles turing left (or right) from Via Sereno. This is dangerous.

The number of the SAM storage unit, which was placed in a dangerous location on Wichester Boulevard without a permit issued by the Town of Los Gatos.

The number of the SAM storage unit, which was placed in a dangerous location on Wichester Boulevard without a permit issued by the Town of Los Gatos.

To keep ahead of Izzy, who was trenching and putting our underground water drainage sytem in place, Bryan made three (3) trips to RV Cloud (which is only a couple miles North on Winchester Boulevard).

To keep ahead of Izzy, who was trenching and putting our underground water drainage sytem in place, Bryan made three (3) trips to RV Cloud (which is only a couple miles North on Winchester Boulevard).

Two sticks of 3 inch ABS pipe for Izzy (this will take water to our 3,677 gallon underground cistern).

Two ‘sticks’ of 20 ft long, 3 inch ABS pipe for Izzy (this will take water to our 3,677 gallon underground cistern).  Good thing we have a truck with an overhead rack!

The seven (7) electrical wires coming from the solar panels on the roof to the storage space under the pantry.

The seven (7) electrical wires coming from the solar panels on the roof to the storage space under the pantry.  These cables will be run to the solar inverter in the East Mechanical room.

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