(Ground worker)


Initially a trench was dug, 1.4 meters deep and 0.6 meters wide, from the manifold pit to the position were the pipework would pass through the garage wall to the heat pump. The customer had a block paved driveway so to minimise damage it was not possible to take the direct route from the manifold pit to the garage, so we had to dig a trench around the edge of the drive.

The pipe work from the manifold to the heat pump was also not as easy as usual. Normally I would run two pipes at a depth of 1.2 metres with a distance between them of at least 0.7 metres. In this particular installation I was facing two major problems: the distance from the manifold to the house required a number of bends which meant it was difficult to maintain the required separation and we also had to worry about the other services in the ground next to the garage.

Because of the distance and number of bends, I had to use a larger diameter pipe to reduce the flow resistance in the system. And as we had to run the pipe in a shallower depth than preferred, 0.5 metres, due to the other services I decided to use a pre-insulated pipe to protect against energy loss. This is especially important in winter time when the ground is cold and the pipes would lose energy to the surrounding soil, reducing the efficiency of the heat pump.

Once the pipes were laid in the trench, we had to drill through the garage wall to get to the position that the heat pump was to be installed in. I used a core drill to drill the hole through the wall, installed the pipework through the wall, and then filled the hole and insulated the pipework to avoid any air leaks or condensation problems in the wall. Inside the garage we ran the two pipes to the filling station. The filling station is used to fill the ground loop collector and is the point at which the ground works end, and from which the plumber will start his work later.

Once all pipework was installed and tested, we covered the pipes with sand to protect them against sharp stones and also as a visual mark for future ground workers. I back- filled the trench and made good the block paving on the drive.


What we learnt: In existing houses the trenching and ground work can create a lot of problems. If brick work has to be replaced or gardens redesigned, there is potentially an extra cost, inconvenience and effort which the customer has to be made aware of during the site survey.