And this afternoon, we went back to our Number 1 Energy Module to carry on
with the assembling of the underground hot water tank.

First of all, we drilled down a metre in the middle of the hole to allow for
a temperature sensor to be placed under the Energy Module. We inserted our
new 20mm plastic pipe to act as the conduit for the temperature probe, which
will be installed later.

After that, it was grabbing pieces of the PU foam to build up the required
200mm thick insulation barrier between the bottom of the module and the
ground.

We then carefully laid down the rubber membrane on top of the insulation
boards, ready to wrap around the plastic crates to hold in the water.

Then came the plastic Aquacell crates themselves, placing them in a grid of
5 by 2 to form the 1st layer of 2.5metres by 2metres block.

Then, we had to cut access holes to allow the insertion of the water pipe
and another temperature probe to go down inside the energy module, right to
the bottom, plus also a larger hole to allow for inspection of the water
level.

Then the second layer goes on, and more access holes are made, this time for
the 2nd water and temperature probe to be inserted.

Finally, we pulled up the rubber sheeting around all the edges and folded
the corners in, just like a parcel. We will put on a layer of DPM plastic to
seal off the top surface of the water tank to stop steam and moisture
escaping out of these Energy Modules.

Tomorrow, we will put down around the 4 sides more insulation panels and
then fill in the remaining gap with the sandy soil and compact it all down
nice and solidly.

It was our first hole to do (out of the total of 5!) and it is the 2nd
smallest one to dig out! It lives under bedroom 3, half in and half out of
its en-suite wet room.

We dug out 3metres by 2.5metres and 1.2metres down (10feet by 8feet by 4
feet down), to make room for the insulation (200mm thick under and around
the edges with 100mm on top), wrapping around the energy module, measuring
2.5metres by 2metres and almost 1metre tall, being made of 2 layers of 10
crates, to make a 20 Aquacell “hot water” tank.

We dug out most of the hole using the digger.

Then Shaun cleaned the bottom with a spade until it nearly level. We got the petrol powered plate vibrator (which is very heavy) into the hole using the mini-digger to lower it down (and back up again!) and ran it around make sure the bottom was compacted
nice and solid.

We needed to make sure the bottom is as level as we can make it so we put
down two edge strips and got them positioned using the site laser height
gadget and set the two edges exactly at 2.7 metres on the sighting pole. Just
to clarify, the level generator is sitting on a reference point 1 metre above
ground, and the foundations (and the whole house) is 500 mm down below ground
level, thus making the ground we are working on 1.5 metres below the
reference point so 2.7 metres minus 1.5 metres makes 1.2 metres which is the
depth of our hole!! Nothing to it!! Smile!

We scraped along the two edges with a flat straight CLS 89 mm timber and got
the bottom of the hole fairly flat and level so when the water tank (oops I
mean the Energy Module) is set down, the water will not spill out on one
edge or another as it rises and falls. We Hope!! Grin!

Tomorrow’s job is to cut and get ready the insulation boards and make up the
required thickness on the bottom and vertical edges, while we wait for the
delivery of the 20 mm plastic pipe that we are suing as a conduit for the temperature
sensors we want under the tank.