Category: heat pump (Page 3 of 4)

We have made some good progress today.  The concrete floors in the extension have been laid.  The concrete was poured first thing this morning and by “going home” time it was possible to walk on it.

We have also finished excavating the land for the ground loops.  This is just as well since we seem to be running out of space to put all of the spoil.  Tomorrow we will put down sand on the base of the area and on Thursday, we will install a 1000m of pipework for the ground loops.  We aren’t entirely sure if we have the space, but we will only find out when we try.  Let’s see what happens later in the week.

We started pouring the concrete first thing this morning and by close of business we could walk on it.

Tomorrow we need to put around 60 tonnes of sand on the bottom of this patch of land before installing the ground loops for the ground source heat pump on Thursday.

We have installed 800m of ground loops for the ground source heat pump.  The hole has been back filled and we are now excavating the other half of the field.  This will hopefully enable us to install the remaining 1000m to pipework.  The pipes need to be spaced 750mm apart, there we need a minimum of 750 sqm of space.  We have EXACTLY 750 sqm, so this is going to be close, very close. We won’t know if we have enough space until we attempt to lay the pipework.  This is scheduled to happen on Thursday, so we don’t have to wait very long.

There is a 1000m of pipe to be laid in this hole once all of the ground has been cleared. We reckon it will be Thursday before we are ready to lay the pipes – once the hole is flattened, there is 60 tonnes of sand to lay on the base of the hole.

Once the large stones in the bottom of the hole haev been dealt with (crushed), we will add sand to the base of the hole to protect the pipework.

The ground loops are going to go right up to the new extension as we need to use all the land that we have available to us. With 1000m of pipe to install, we require around 750 sqm. We reckon we have exactly 750 sqm available.

We have the first 800m installed and have a further 1000m to go.  We have now back filled the area over the initial 800m and are now excavating the 2nd part of the field.  However, we had to move all of the top soil first that we had piled up on the other half of the field.

This is turning into a lot more work than we first imagined, however, there is no turning back now.

This is the second part of the field that we are going to have to dig up to install the final 1000m of pipework.

Here we have removed the top soil and a strip of subsoil. This takes the soil level down about a 1m – just enough for the ground loops.

More of the field exacavated.

This is the heap of sub soil that we have excavated as the second part of installing the ground loops. There is a lot more to come out before we are ready to install the last 1000m of pipework.

It is difficult to get a sense of the scale, but this heap of top soil is around 8-10m high.

It has been a busy couple of days and we have started to reinstate the field over the 800m of ground loops that we have installed. We have pressure tested these pipes and they still seem to be holding 1 bar of pressure.  The good news is that we will know straight away if any of the pipes get damaged.  I suspect that they are more sturdy than we give them credit for, but we don’t want to take any chances.  No one wants to have to dig them up later.

The drains are now all installed ready for us to pour the concrete slab in the new extension.  We have also connected up the drains to the septic tank.  We have put a rubber bung into the drain and then filled all of the drains with water.  If there are any leaks, they will show up straight away.  The building inspector turned up towards the end of the day and signed off the drains.  Tomorrow we will remove the rubber bung and let all of the water drain into the septic tank and then cover over the drains.  There are just too many holes now on this site and it will good to get some of them filled in.

This was taken by Ricky (one of the guys installing the ground loops) while stood on the spoil heap. The stones have been used to weigh the pipes down while it is being back filled. They are removed as soon as the sand is laid down.

Sand goes down first on top of the ground loops first, then the subsoil is carefully put on top the sand.

We have started to fill the area where the first 800m of ground loops have been installed. We have also finished sorting out all the drains in the new extension (see picture left). The hose is filling all the drains with water to test for leaks. There aren’t any!

This is a manhole full of water. We have filled the drains with water to test them.

We have installed the first 800m of ground loops and have decided to pressure test them.  This means filling the pipework with water and increasing the pressure.

We have put 1 bar of pressure into the installed loops and will see what happens overnight.

Of course, we had to repair the water supply to start with!

We have put 1 bar of pressure (water) into the first 800m of ground loops. If this goes down overnight, we know we have a problem.

We have laid the first 3 ground loops and are now in a position to cover them back over.  Each loop is 50m and there is a layer of sand below and above the pipework.  The subsoil is then carefully reinstated avoiding any very large stones.

There is a flow and return for each of the loops. Each loop has a tap that controls the flow to and from each ground loop. This allows the flow to be controlled to each loop compensating for the fact that some of the loops are further away from the pump.

Each pipe is 100m long, so each loop is 50m. Each of the manholes has a 6 port manifold so that is 600m of pipe connected to each manhole. There are 3 manholes making a total of 1800m of pipework.

The first 300m of ground loops are being covered using some of the subsoil that we removed earlier in the week.

There is around 100mm of sand on the bottom, then 100mm of sand on top of the ground loops. Then the subsoil is carefully reinstated.

The first 300m of ground loop disappearing under the subsoil.

Installing the loops for the ground source heat pump is turning out to be a lot more labour intensive that we were expecting.

Rather than digging trenches, we have decided to take up all of the top soil and sub soil to a depth of about 1m.  Digging 1 m deep trenches 1m wide and 1 meter apart is just to hard.  It is easier to remove all fo the soil in one go rather than digging trenches.  However, this approach has generated a lot of soil – and I mean a LOT!  We have mountains of the stuff.  We have even flattened the top of one of these mountains and are piling the soil on top.

The other problem that we have is that subsoil contains a lot of fractured stone.  It doesn’t contain any clay.  This means that we need to scrape the bottom and pack the subsoil down so that there is little chance of the pipework being damaged when they are laid.  The ground is then “tracked” in. This means going backwards and forwards and using the tracks on the excavator to flatten the bottom.  This also crushes a lot of the bigger stones.  Since we have upgraded to a 14 tonne excavator, it really does crush the stones in the bottom.

All of this means that it is taking longer (and costing more) to install the ground loops.  I am not sure that there is anything we could have done differently.  But we probably could have plan and estimated the ground work a little more accurately.  Clearly, the amount of effort involved in installing the ground loops will vary according to the quality of the ground.  It would be wise to check this out before starting on work like this.

The other issue to consider is access – can you get machinery of the right size onto the site.  Doing ground works on this scale requires big machines and getting them on site (or even to site) can be a challenge.  If your contractor is hiring machinery, make sure that the hire company has looked at the routes to the site and agreed that the machine can be delivered.  Then if there is an issue, this is down to the hire company and not you.

We have stripped the one half of the field and piled all the soil on the other half! We are now out of space!

We are starting to run out of space.

This is a 14 tonne excavator. We had to trade up from our 8 tonne excavator to try and speed things up. There is a lot of soil to move.

We are now starting to run out of space and are piling up the spoil.

We need to remove around 1100 sq m of soil to a depth of around 1m.  This is a lot of soil and we intend to install the ground loops in three sections.  We will dig each section, lay the pipes and then refill the hole.  We simply don’t have enough space to take all of the soil off in one go.

It took  the whole of the first day to remove the top soil (at a depth of around 100-200mm) on 1100 sq qm.  The top soil will not be put back until all three sections have been installed and the sub soil put back.  If we were to put the top soil back section by section, we would end up with a mess if it rains.

By the end of day 2, we have removed around 250 sq m of subsoil.  The mountains of soil are starting to build up and we are running out of space. 

We are using an 8 tonne excavator.  We tried to get a 30 tonne excavator on site, but it was too big to get up the road.  The 8 tonne excavator was the biggest we could fire at the time.  We have a 14 tonne excavator turning up in an attempt to speed up the ground work.

Start of day 2 of removing the soil for the ground loops. It took all of the first day to remove the top soil. Now we are starting on the sub soil.

We have started removing the soil for the ground loops. You can see the 150mm of topsoil and then the 700-800mm of subsoil. The piles of soil are starting to build up in the top field. We need to get the ground loops installed in this section so that we put the sub-soil back (making a bit more space!).

Each of the ground loops starts and finishes in a manpower. These are 750mm x 1200mm manholes that are going to be 1000mm deep. The bottom of the manholes are propped up on concrete block to allow for the pipework to be installed.

These are the manholes for the ground loops. You can see the drain pipes in the background. These are installed into the foundations of the extension before the concrete slab can be laid.

We have separated out the top soil and sub soil to make reinstating the field that bit easier.

All of this subsoil and topsoil has been removed to install the ground loops. The pole in the background is in the next field.

Not exactly treasure, but this is the only thing that we have found while digging up the field. It is an old electric bench saw.