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Section 7: Engine Preheat and Motoraide System
Engine Preheat and Motoraide System:
The Aqua-Hot 450-DE and 450-DM both include a
motoraide feature, which uses the circulation of the
motorhome's engine to transport the antifreeze and
water heating solution from the Aqua-Hot's boiler tank
to the motorhome's warm engine and back to the boiler
tank.
The Aqua-Hot 450-DE includes an engine preheat
feature. This preheat feature provides an easy engine
start-up whenever cool weather conditions are present.
Location:
The inlet and outlet ports on the vehicle's engine
should be kept as far apart as possible. This will ensure
that the entire engine is thoroughly preheated. Refer-
ence Figure 39.
NOTE: If assistance is needed in determining the best inlet and
outlet ports for a specific engine, please contact the
particular engine's manufacturer or chassis supplier.
The engine's coolant should be allowed to flow as freely
as possible to maximize the Aqua-Hot's engine preheat-
ing system.
The engine's inlet port is where the heated coolant is
transported to the engine block from the Aqua-Hot.
This port should be a high connection point on the
engine block. Reference Figure 39.
The engine's outlet port is where the engine's coolant
is transported to the Aqua-Hot. This port should be a
low connection point on the engine block or a pres-
sure outlet port on the engine's water pump. Reference
Figure 39.
Ensure that the engine preheat inlet and outlet hoses
are not placed too close to the engine's turbo charger.
Plumbing Requirements:
Use ¾ inch I.D. (Inside Diameter) plumbing lines/
automotive-type heater-hose for the engine preheating
system.
Lay both engine preheat lines as flat as possible and
avoid any extreme rises in height in order to eliminate
the potential for air traps.
Run both plumbing lines in areas where they cannot
be pinched off or damaged during normal operating
conditions.
Secure both plumbing lines where necessary and apply
protective shielding in areas where chafing may occur.
© 2008 Aqua-Hot
®
450-DE/DM Hydronic Heating System Installation Manual
NOTE: Rubber coated/closed-type clamps are recommended
when securing the plumbing lines.
Use one-piece engine plumbing fittings in order to re-
duce the potential for coolant leaks. It is recommended
that pipe thread sealant be used on all engine plumbing
fittings.
Installing the Plumbing:
1. Install both engine preheat plumbing lines and mark
with arrows and/or labels at both ends.
NOTE: The labels should indicate whether the plumbing line is
transporting coolant to the Aqua-Hot or whether it will
be transporting heated coolant to the vehicle's engine.
Reference Figure 39.
2. Drain the engine's coolant.
3. Remove the selected inlet and outlet port "plugs" from
the engine.
NOTE: Should one or both of the selected engine ports already
have plumbing fittings attached to them, it may be
necessary to "tee" into those existing plumbing fittings.
Please contact the Aqua-Hot Heating Systems product
application department at 1-800-685-4298 for addi-
tional assistance.
4. Install and tighten the plumbing fittings into the inlet
and outlet ports on the vehicle's engine.
5. Install and clamp both the inlet and outlet engine
plumbing lines/automotive-type heater hoses to the
engine's plumbing fittings. Reference Figure 40.
6. Install and tighten a plumbing fitting into the "Inlet"
port on the Aqua-Hot's engine preheating system.
Reference Figures 1 and 40.
NOTE: It is recommended that two wrenches be used when
tightening these plumbing fittings.
7. Attach and clamp the engine's incoming plumbing line
to the Aqua-Hot's outlet connection.
Reference Figure 40.
8. Attach and clamp the engine's outgoing plumbing line
to the Aqua-Hot's inlet connection.
Reference Figure 40.
9. Verify that all fittings and connections have been tight-
ened, then refill the engine's coolant system.
— Page 27 —
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