In my opinion Well.
I just read where one foreign country scored a record high. I did the metric to USA translation and it was 125 Degrees.. Your water heater is 120 folks
When I was stuck in GA a few years ago every day for two weeks the news weatherman was announcing "New record of consecutive days over 90"
We now have 80+ in ankorage alaska (highest temp ever recorded)
And the evidence of Global warming (It's getting hotter out there folks) is like the brick wall that was behind me when the bullies lowered their heads and charged like enraged bulls.. Hard to ignore (me I got outta their way and let the wall take the hit) (hey their plan was to cause someone pain 300% successful they were as there were 3 of 'em.. Mine was to avoid pain and I was only 100% successful).
So I'd go with the 15Ks
IN fact... I did.