Thanks for the great tips!

Here are some more facts about the setup:

- Hall size 5m wide, 8m long, 3.5m high
- concrete walls and ceiling, entrance via roller shutter
- Cable supply line is a 5x10 square, about 20m long, fused with 3x50 ampere
- the individual sockets in the container (stands in the hall) for the miners are connected with 3x 2.5 square and secured with 16 amps

This afternoon I was brave and have the Dayun Zig Z1 + as the 4th Miner connected. After a while, the temperature in the cold zone has risen by 1 degree to 22 degrees. The hashrate was normal (varies permanently with the miner, Monacoin in F2Pool)

Tomorrow I will look again at your many suggestions, and possibly start with the first adjustments. Of course there will be new photos, numbers and facts.

Nice evening everybody
Vinncent