Originally Posted by Hamlet53
Thanks to you both. Last night I went crawling in my crawl space
with a flash light and a borrowed electric hand hair dryer and solved the problem. This is the first time in all the years that I have had the problem. I think it was a combination of the days of very cold temperatures combined with almost no snow on the ground. Snow around the foundation seems to act as a decent layer of insulation.
I'm glad you got your hot water back. I forgot to mention the foam insulation. They are sold in hardware/home improvement stores here and are not very expensive.
Snow is a natural insulator.