Aqua-Hot 375D, Installation Manual

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© 2008 Aqua-Hot ® 375-D Hydronic Heating System Installation Manual Rev. A
section 10: Purging the systems
Purging the Hydronic Heating System:
In order to provide the best freeze protection, boil-over
protection, and anti-corrosion and rust protection, a
50/50 mixture of “GRAS” approved propylene glycol
antifreeze and water is recommended.
Reference Appendices C through E for additional
information regarding the antifreeze and water heat-
ing solution. Be sure to use a “GRAS” boiler-type
propylene glycol based antifreeze rather than an RV and
Marine antifreeze or an automotive antifreeze/coolant.
If assistance is needed in selecting an appropriate an-
tifreeze, please contact the Aqua-Hot Heating Systems
Product Application Department at 1-800-685-4298.
1. Open the Aqua-Hot’s drain valve located at the front
of the heater. Reference Figure 45.
2. Connect a piece of 1/2 inch PEX-type tubing to the
drain valve. This piece should be long enough to trans-
port the antifreeze and water heating solution from its
source to the Aqua-Hot.
Only propylene glycol based “boiler” type antifreeze
deemed “GRAS” (Generally Recognized as Safe) by the
FDA shall be used in the Aqua-Hot’s hydronic heating
system. Failure to use the above specified antifreeze type
could result in serious injury or death.
Ensure that the overflow tube is connected from the Aqua-Hot’s
expansion tank connection to the expansion tank’s bottom con-
nection and from the expansion tank’s top connection through
the overflow tube hole in the motorhome’s bay floor prior to
beginning this antifreeze and water heating solution fill proce -
dure. Failure to do so could result in an antifreeze spill in the
motorhome’s bay. Reference Figure 11.
Figure 45
Figure 44
Drain Valve
Expansion tank
Connection
air-Release Valve