Hi all and Happy Easter!!
.... I thought I would do an update on the water coil project since I have about a month at most left this season. They performed better than expected! I was worried that my coils would either produce too much heat or not enough, but turns out it was just right. My preheat tank thermosiphon on the DHW did get kinda hot a few days during the winter when I was pushing the furnace hard. It got up to 160 a few times. To bring it down, we would fire up the clothes washer or something. The preheated tank feeds the electric tank. I left the primary electric tank powered up so I never had problem with not enough hot water. I'm sure the electric tank used a small amount of power but by sending water to it that was between 120 and 160 degrees (instead of 50) it didn't need to work very hard.
For the hot tub, I just recently replaced the tiny 12 volt circulator with a real one
..(pic below).. It works much better.. I thought I would end up needing a small temper tank for the hot tub because of heat loss back and forth to the tub, but the bare bones loop did just fine. I kept the hot tub in sleep mode so the internal heater wouldn't activate unless it got cold. The tub rarely got below 90
.. I would activate the internal heater when I wanted to get in it to get it up to 102, which turned out to be once or twice a month in the winter. Just yesterday I drained and refilled the hot tub (should be done every few months) and overnight it went from 60 to 69 degrees just from heat off the coal furnace water coil
The trip back and forth from the furnace to the hot tub is pretty lengthy. Its about 80 feet with 50 feet of it outside. I did a cheap insulating job just for experimental. I ran the 1/2 pex lines together thru a 1 1/2 inch electrical conduit. Then I wrapped it with the foam pipe insulators then wrapped it with duct taped then wrapped it again with a layer of fiberglass insulation then wrapped again with plastic sheeting so the whole mess couldn't get wet
... The pipes run under the 6x6's then up into the floor of the hot tub where I spliced into a jet line.. It looks bad but I plan to do something more permanent and maybe even bury it for next year.
I can only estimate my savings on electric since there is other variables using power during the winter months. I'm certain of a few givens to work out the estimate. I'm thinking I saved $90 to $100 per month with the coils..
Also below is a pic of what the hot tub looks like with 10 kids in it. That was last summer lol. I drained it and did a refill after that event too for obvious reasons hahahaha....