Happy New Year Douglas
Your talking to a California Boy here Douglas, whose spent more time on a skateboard than a snowboard and thats the Gods honset truth.But I'll give it a try
You should consider insulating both your hot and cold copper lines with the heaviest poly foam insulation you can buy,,,i'm talking 3/4 to 1" thick and I mean every linear foot of pipe,,,,
Now having said that,its my understanding that in colder climates there are systems where you actually wrap your water supply piping with heating wire to prevent freezing,Of course the key here is you must have 24/7 electrical power to the wiring.
Now to my new friend Alex M,,,
In a word Alex ,youre off to a good start,,,,,
For my money ,your cant beat the Noritz tankless water heater products,,,,in the first place,,,if you have a troubleshooting issue ,they send their tech guy out to your house to check out your problem with your unit,,,you heard me right,,,
Secondly ,they are a class act,,,,I'll say it like this ,,,contractors like myself LOVE THEM ,,,because we get no call backs from Noritz products,,,,
Bare in mind ,,,the secret to tankless is;
You want to install them on an outside wall ,,,why? No venting thru the roof ! just keep the unit code distance away from any window,,,
A tankless install is considered a "home improvement " gang,,,OK? You must be ready to increase you gas pipe by one size,,,if your running 3/4" black pipe get ready to increase to 1".You must run a dedicated 120 volt circuit to the unit.
You must ready ready for maintenance ie flushing out the unit with a mild acid solution every 4 to 6 months,,,,
If you can handle that,,,,,,the good news is ,,you now have a water heater that will last and last a long time without replacement ,,,,,if youll do the maintenance,,,,no more leaky tanks,,,,,,if your unit fails its usaully an inexpensive electronic component problem ,,easy to change out ,,,,
OK gang ,,Im off my soapbox,,,,Best of luck in 2014
Dave Doyle
Los Angeles