I have a hot tub that is currently heated by pumping hot water from the
house gas water heater through a copper pipe installed under the seats of
the tub. I have been told that this does not meet code, because of the risk
of a leak allowing "dirty" water to be sucked back into the city water
system if the city water is shut down for some reason.
If someone out there is familiar with the code requirements for such a
system, I would appreciate consideration of the following questions.
1. Is my current system in violation of generally used plumbing codes?
2. Would any of the following make it compliant?
a. Installing a check valve on the water heater input to prevent
backdrawing of water. (With associated expansion tank)
b. Installing a check valve on the house water input line.
c. Adding a simple counterflow heat exchanger. I see this as a 20'
section of 1" copper turing with 20' of 1/2 inch copper tubing inside it.
This would be coiled above the water heater, with 7-8' of it straight down
along the heater. The bottom end of the 1/2 in tibing would go into the
water heater drain hole, and the top end would connect to the hot water out
from the heater. I am hoping that convection would produce enough water
motion, so that an additional pump would not be needed. The current pump
would pump water from a closed system through the 1|" outer pipe and the
loop through the tub, going up through the added heat exchanger.
Any other ideas greatfully accepted.