Foundation heat pump 110kg. Frost resistance

Hello everyone,

brief description: A heat pump is to be placed 30cm away from the house on a foundation. The house has a basement, so the heat pump would be located in the basement utility room. Weight of the heat pump is just under 110kg (1.3m long, 80cm high and 40cm deep). All lines from the heat pump to the house are flexible. What kind of frost heave can be expected if the foundation is not frost-protected? Or does the foundation for the heat pump even need to go down to the basement floor slab?

Thank you very much for your experiences

I want to push this topic again here!

It concerns me right now as well. The cellar is now buried, the recycling material was compacted in several layers. It was filled up to about 20cm below the finished top edge of the lawn/paving.

Now I want to prepare the ground for the outdoor unit. The outdoor unit is 90x40x120cm (WxDxH). The supply lines are in a 100mm KG pipe next to it.

The condensate should seep into a gravel layer. This means that I don’t want a concrete slab, but only two narrow strips where the feet of the outdoor unit are supposed to stand.

My question now: How deep do I have to pour the concrete there? According to the instructions of the outdoor unit, the strips are 10x55cm (WxD). The heating technician said that concrete slabs or something similar would also be sufficient, I wouldn’t need a concrete base, but I would feel safer with it.

I have never done anything like this myself, but I would now like to deal with it.

Can I simply take the 20cm plus ground clearance as height and pour the concrete onto the currently compacted ground? (Of course laid out in 10x55cm strips) That way I would have a height of about 30-35cm of concrete and later only 10-15cm would be visible.

Looking forward to your experiences.

We are doing that too, outdoor unit WP on a pedestal. I have been thinking back and forth about how to do it. In the end, I asked our shell builder. It now costs me 250 euros and I have peace of mind knowing it is done properly. Your planned 35 cm is not frost-free. For the columns, expect them to be at least 1 meter (the condensate that collects down there might possibly cause it to break).

2 separate bases made of 3, 4, or 5 stacked formwork blocks (each block 25cm high), then concrete them. Fill in between with frost-resistant material and done.

This concerns me as well right now. The basement is now buried, and the recycling material has been compacted in several layers. It was filled up to about 20cm below the finished top edge of the lawn/paving.

Now I want to prepare the base for the outdoor unit. The outdoor unit is 90x40x120cm (WxDxH). The supply lines run in a 100mm KG pipe next to it.

The condensate should seep away in a gravel layer. This means I don't want a foundation slab, but just two narrow strips where the feet of the outdoor unit should sit.

My question now:
How deep do I have to pour concrete there? According to the instructions for the outdoor unit, the strips are 10x55cm (WxD). The heating technician said that concrete paving slabs or something similar would also be sufficient, I wouldn't need a concrete base, but I would feel safer with it.

I have never done anything like this myself, but I would now like to get into it.

Can I simply take the 20cm plus ground clearance as the height and pour the concrete on the currently compacted ground? (Formwork, of course, for 10x55cm) This would give me a height of about 30-35cm of concrete and later only 10-15cm would stick out.

Looking forward to answers...

How did you ultimately make the foundation?