Trenching & Piping

The supply line is on the right, with the T connection to the East hole

Both returns run from the far hole to balance the flow.

(This posting was delayed; I'll explain in my next post).  The drilling contractor finished the outside work. This final step was referred to "trenching". An medium size excavator and dump truck visited. The trench they dug was impressive. Much bigger than I imagined.  They hit so many rocks that they have to come back to remove more boulders and dirt.


They used a hot-plate like device to heat the HDPE pipes to 500 degrees to join them together.

They used a torch to cut the pipe casings 4 feet below grade. But before they cut the casings, they inserted another metal pipe in to the casing to protect the HDPE tubes.


They ran both the returns from the farther hole to balance the flow between the holes. They also used different pipe diameters to balance the flow.

They put a rubber gasket around the top of the pipe casing to protect the HDPE pipes.

The picture on the right shows how they used a great big cork-screw drill to bore the 2 holes in the side of the foundation.

Once everything was connected, they flushed the tubes and performed a pressure test. Using water from my irrigation system, they filled the pipes, drained the air and pressurized the pipes to 90 PSI (lower right). It was a little unnerving to watch it steadily dropping  to 72 PSI. They said that was expected because of the expansion of the tubes.

Surprise discovery #1:  I have the rockiest lawn they've ever encountered. They dug up so many boulders they filled their dump truck and have to visit again to collect a few more.

Surprise discovery #2: a second unexpected pipe for the lawn irrigation system. This one with electricity attached. The irrigation company will visit on Monday to reconnect those wires. The trenching team reconnected the two pipes that they cut.

Totally Tubular

Quick update today. The drilling company installed the tubes and thermal grout in to the 290-foot-deep bore holes. The tubes will hold a water and propylene glycol solution that will be the heat transfer medium for the ground source heat pump. It only took a couple of hours.  You can see in the photo on the right a clever little jig they attached to the casing to help guide the tubes in to the hole.  

The tube is U-shaped and was pressure tested before they inserted it in to the well. On site, I believe they had to fill the tube with water before they could sink it in to the hole.

The big surprise to me was the thermal grout. The thermal grout is supposed to help the tubes make a good thermal connection with the ground. They used a substance called Therm-Ex. It is supposed to remain soft and flexible so that the tubes can expand and contract as they change temperature. Some how I imagined (incorrectly) that it would be more like a rigid cement.

When they pumped in the thermal grout, the water that had accumulated in the hole poured out. Now I realize why the last crew (the drilling crew),  just before they left,  dug a small pit and trenches to that pit. They were planning ahead for the pipe-and-grout crew.  It was impressive forethought based on their experience.  The pit kept the water spillage contained nicely.

Tomorrow the third and final outside crew comes to excavate a trench 4-feet down between the holes and then on to the foundation. They'll bore 2 holes in to the foundation. The two U-pipes will be connected in parallel and the connecting pipes will get inserted in to the basement. They run the pipes 4-feet down to use the ground as insulation for the water in the tubes.

We're in really in hot water now!

Well, not quite "in" hot water.  We just have hot water again.  Today was a great day for the project. Yesterday we ripped out the old oil furnaces and disabled the oil-fired hot water heater. We had 50 gallons of warm water in the tank which was enough to get us through to the morning.  Today the plumber and electrician visited.

Here's James from Kirkland and Shaw posing with his plumbing handiwork.  On the left is James.  In the middle is the GE Geospring air-source heat pump (ASHP) 50-gallon water heater. On the right is a 40-gallon electric water heater.  The 40-gallon water heater is not connected electrically. It is just a holding tank for hot water from the desuperheater  in the ground-source heat pump (not shown, not delivered yet).  Between the two tanks is a mixing valve to make sure we don't put water that is too hot into the Geospring.



Our electrician,  Gallant Electric, also was on-site today to install the subpanel that will provide power to the water heater, GSHP and auxiliary heat (and the condensation pump).  They pulled a big armored cable from the main service panel to the new subpanel.  They also installed the TED devices!   (I'll get a picture of Andy when he returns next week).

The TED devices measure the power used by the main electrical panel and the subpanel. The subpanel is dedicated to the water heater and the HVAC system.  The TEDs transmit their measurement data on the power lines. A device called a gateway plugs in to a normal electrical outlet and also gets connects to my Ethernet wires. The gateway is *really* cool. It basically has a little web browser inside. It can also transmit data to the google power meter so now I'm able to read my power measurements from my igoogle web page (see picture on the right).

The TED's have a really cool web interface as well (picture, right). It shows the power (kW) that my system is currently using, the cost of electricity or the pounds of carbon dioxide emitted to produce that electricity. It also has a cool graphing feature and can export the data.

The big dial in the center of the picture shows that at the moment we are using 2.7kW of electrical power. The bar in the middle of the left hand side shows that we've used 1.6kWh of electrical energy since we turned the TEDs on. That includes heating 50 gallons of water and cooking dinner this evening. If I click on the "$" it shows that we spent $0.28 on electricity today. The box in the upper right (if you could read it) says that the peak usage today was 5.7kW at 6:19PM (when corresponds to when we were cooking dinner).

The TEDs will allow me to measure the electricity use for the whole house and specifically for the GSHP and water heater. This will help us more deeply understand how much energy the new system is using. The graph at the right shows 3 bars per hour. The leftmost 2 bars (purple and green) in each group are the total power used by the house. The light blue bar (rightmost in each group) shows the power used by the Geospring. When we turned it on we were heating the 50 gallons up to 120 degrees for the first time using a combination of electrical resistance heat and the air-source heat pump. Once the water reached 120, I put the Geospring in "eheat" mode where it tries to avoid using the electrical resistance heat and relies more on the ASHP.  The GSHP will be included in the light blue bar when it is installed.



Tomorrow we get the glycol circulation tubes and thermal grout installed in the two 290-foot holes we bored last week.

Demolition!

On a day where the temperature peaked at 91 degrees, my GSHP installer ripped out the old heating and air conditioning system. They pumped down the refrigerant. They drained down and ripped out the oil lines. They cemented up the opening in my chimney flue.

They spent a fair bit of time fishing wires for one of the new thermostats. I'm thinking they should just sell wireless thermostats; They cost more than wired ones but it has got to be a net savings in installation labor.

After they left this evening, we painted the interior of foundation walls of the basement that had been blocked by the old system to match the rest of the basement. Most of it will be covered by  new duct work and new equipment but it looks a lot nicer this way and was much easier to paint.

I also patched up the holes where the refrigerant lines were running through the sill. To do that, I wanted to cut some circular pieces of wood to fit in to the holes. I have a hole-saw of the required diameter. A hole saw is basically a cylindrical drill bit that cuts out circles, in my case 1.5 inches in diameter.  Some hole saws have a center drill bit to stabilize the drill while you are cutting the hole. My hole saw does not and that makes starting the hole really tricky. The drill wants to dance around at first.  A few years ago for another project I managed to do it but it was really difficult to get the hole saw going.   Recently, while channel surfing one night,  I saw an episode of This Old House where they made a simple jig for the hole saw to keep it from dancing around. I used a couple of pieces of scrap wood as guides and made a V-shaped groove wide enough for the hole-saw! I was done in just a few minutes.

Next up are the plumber and electrician.  The final phase of out door work begins later this week when they install the tubes in the holes they drilled and thermal grout to keep it in place. After that they trench a path to the house and bore two holes in the foundation for those pipes. With any luck, the system will be up and running by the middle of next week.

Oh yeah, right, drilling uses energy too.

The drillers finished up on Saturday afternoon. They left the rig in place over the weekend with the 15 20-ft extension poles and the auger in the bore hole.  The front of the truck was jacked up because of the hill on my front lawn. It drew some really funny looks from people driving by. It sort of looked like the truck was flying through the air especially if you could not see the single support post in the front of the truck.

I was talking to the drillers. Nice guys. Their 73,000 pound drilling rig can use about 200 gallons of diesel fuel per day. My project probably used about 300 gallons of fuel. I'll have to factor that in to the carbon dioxide equation. 300 gallons of heating oil can get me through a big chunk of a New England winter.

Geology

The USGS has a really nice collection of geology maps for google earth.  According to the map, my house sits on a combination of two types of igneous rocks: Diorite and Gabbro.   Wikipedia states that "Diorite is an extremely hard rock, making it difficult to carve and work with. It is so hard that ancient civilizations (such as Ancient Egypt) used diorite balls to work granite."

Drill, baby, drill! (But in the good way!)

Day one of drilling for the ground source heat pump. The plans call for two 286-foot deep holes, 6-inches in diameter, 20-feet apart on the north side of my house.  Given all the boulders sticking up out of my lawn, the driller anticipated hitting bedrock at a relatively shallow depth.  Instead we were surprised that we didn't hit bedrock until 43-feet down! So it was slow going drilling through the clay and boulders that were encountered above the bedrock.  Turns out that they like drilling through solid rock as they don't have to worry about stabilizing the bore hole with casings.  Once they hit the bedrock, they say that they can often bore 100-feet per hour.  With the midday start and the unexpected clay, they were only able to drill 140-feet today.

We asked them to stop at 6PM  so my neighbors could enjoy their dinner in peace.  The drillers are actually coming back on the weekend to finish the remaining drilling work! Hard workers!

When drilling through the clay, they circulated water from a small pit they excavated next to the drilling rig. I assume that was both to remove the cuttings from the bore hole and to cool the drill bit.

As you can see from the photos on the right they had to raise the rig in the vicinity of a nice old silver maple. They had to prune a number of small branches.  They actually tilted the truck while raising the drilling platform to avoid having to cut some branches.

I have to admit I was pretty nervous about the whole process but I'm feeling much better now that they have gotten started and that they didn't find anything completely ridiculous (yet). I am optimistic that they'll be able to complete the two bore holes tomorrow. And we'll be able to keep our schedule for next week!

After drilling, what's next? 

1. Insert the water pipes in the bore holes
2. Pump in the thermal grout to stabilize the pipes in the bore holes and make a good thermal connection to the ground.
3. Remove the refrigerant in the A/C system and remove the compressor/condensers
4. Trench a path the foundation
5. Bore holes in the foundation for the pipes
6. Drain my oil lines
7. Demolish/remove the old HVAC system and water heater 
8. Install the new water heater, holding tank and lots of piping
9. Install the electrical circuits for the GSHP and the water heater. 
10. Finally install the flow center and GSHP! 

We expect to be without A/C from the 11th to around the 19th. Hope the heat wave is over for the moment!! Usually that is not a big deal, but this summer has been so ridiculously hot! Hopefully that is not the "new normal" on Eaarth.