tay, 1) Maybe, if you want the maximum pressure compared to taking water off your outside faucet which has its pressured reduced along with your house to about 45 psi. Usually the street pressure is somewhere between 55 to 70 psi. If the street pressure is too high then the pressure needs to lowered to about 60 psi with a pressure reducer. Lower pressure means more zones you will need to operate with your controller. 2) It is fine. It just means a higher velocity through the smaller pipe which causes more noise. If buried not a real problem. A larger pipe means less velocity and a larger maximum flow rate for a certain system pressure. 3) This question is confusing. Are you asking about installing a compression tee at your house mainline and then bring 1" pvc from there. Is that your mainline that feed your house at the bottom of the excavation. It looks small. Usually mainlines to houses are 5/8" up to 1". That line looks like a 1/2" main. My suggestion is test your system pressure then lets discuss you answers again. Aloha

I had to remove a Floodsafe supply line because it was falsely triggering in my house as well. The Floodsafe mechanism assumes that there's never going to be a really high flow rate unless there's a leak. Unfortunately, if you have fluctuating water pressure - even from flushing another toilet that's on the same line - it triggers on that. It also doesn't do anything about a slow leak, only a burst line. I'd rather use high-quality supply lines that just won't burst, and for anything where even a slow leak would be a disaster, a sensor-based system. They're a lot more expensive, but they actually work by having a valve that opens if the water sensors trigger - so in an actual overflow/leak event, the water shuts off.

I can't say about Miele fault codes .... but your problem apparently is that one of the water inlet valves (hot or cold, whichever supply faucet is turned off to stop the flow ... some Mieles may be only cold fill) is physically hung open and needs replacement.

How has the electrical been checked? Are you sure the correct voltage is present?