Congratulations on having the most comfortable heating heating system, warm water !

Technically, water doesn't freeze until 32 degrees, but just because your thermostat is set at 32, that doesn't mean that pipes exposed to colder air won't freeze. Also, pipes that are in freezing areas don't just freeze and burst. It takes a bit longer of a period for that to happen unless the water has been sitting there forever.

You should determine where the coldest area of your house, containing water pipes is located and keep the temperature in the house at the lowest setting that will keep the coldest area above freezing. Of course, nobody wants to live like that, so I would think that 55 degrees is plenty warm to prevent pipes from freezing unless you find uninsulated pipes in a very cold area.

If most/all of your pipes are in the
basement and they go up interior walls.
You can probably set the temp to 44 if you are
going away.
If you have pipes in crawl spaces I would worry that
even 55 may not save them. if that zone remains off.
You can add antifreeze to the system to insure that
they will be ok. and the rest of th plumbing
will probably be ok at 44 degrees.