ᐅ Trench Collector Ground Source Heat Pump or Air Source Heat Pump?

Hello everyone,

We had our first meeting with the builder yesterday. He quickly dismissed the heating topic since there is no gas connection but gave us some contact addresses.

The house has roughly 190 m² (2,045 sq ft) of living space and a heating demand of 6,600 kWh/year, or about 6 kW heating load.
So far, we have planned to install a ground-source heat pump with a horizontal collector, but the builder rightly pointed out that he would prefer some maneuvering space around the house. In the pink forum, there is a community advocating for DIY horizontal collectors, saying that the trenches including materials could be done for around €2,000. Including the heat pump gross price of €10,000, that would be €12,000 total. An air-source heat pump would cost at least that much for the unit alone.
Unfortunately, we are already a bit overwhelmed with the house planning and are not sure if we would trust ourselves to do the DIY installation. Does anyone have experience with the costs when contracting out the trenching and pipe laying?

As for consumption, we found a factor of about 1.5. So the air-source heat pump would be around 50% more expensive to operate than the ground-source heat pump, but we wouldn’t have to dig (in absolute terms, about €180 per year). We are also unsure whether having a photovoltaic system would be beneficial or not (we are skeptical).

Thanks for your experiences and advice.

You first need to determine whether a trench collector will work for your situation.

In our case, it didn’t work out (similar heating load and heated living area) – even though everyone recommended it beforehand. Now, we will have a 120–140 m (390–460 ft) deep borehole instead. In the end, I actually prefer this option, as it definitely works – the trench seemed too uncertain to me. Additionally, more effort is required in planning and coordinating with the shell builder, depending on the site layout.

The space would be available—if necessary, in the garden behind the house. I am also somewhat concerned about whether coordination and planning would work out smoothly. Drilling is too expensive for us, so we would prefer to install an air-to-water heat pump instead.

How much area of UNDEVELOPED land do you have? What type of soil?

Meltwater sand/fluvioglacial sand and glacial till clay. Approximately 650 m² (7,000 sq ft) undeveloped land – this also includes the driveway, where the construction access road is currently located (without that, about 580 m² (6,240 sq ft)).

Ok, that should really be enough for the basic data.