Heater Craft 900H Series Hydronic Heaters - Manual (Page 4)

Page 3
Engine
Warning – Hot engine coolant can cause severe burns! Never open the cap on a hot radiator. Some
vehicles are equipped with electric fans that may start without warning even with he engine shut off. Wait
until the engine has cooled completely before installation.
Note – Due to the wide variety of engine applications, the following are general instructions for a gasoline-
powered engine hook-up. please call Technical Support (208) 687-4400 with your questions regarding your
specific engine application.
Always use silicone sealant or teflon tape on the threads of all fittings before installing to prevent
water/coolant leakage.
1. Refer to the engines manufacturers recomendations regarding the thermostat. The standard thermostat in
most factory applications is 142 degrees. The heater system will operate more effectively with a 160 degree
thermostat. If you are changing the thermostat, locate the thermostat housing on the engine. Remove the
existing thermostat and install a 160 degree thermostat. When installing a new thermostat, you may have to
replace the thermostat gasket or use RTV sealant.
2. Locate and remove the cooling system plug on the intake manifold. This would be located at the front of
the engine near the thermostat housing or on the thermostat housing itself. (On some applications it may be
necessary to rmove the temperature sending unit and install a brass tee.) Install the proper size hose barb.
Caution – The intake manifold also has vacuum ports. If you connect to a vacuum port, water/coolant will be
drawn into your engine and may cause internal damage.
Note – If you remove a sending unit, it is necessary to test the gauge operation after reinstalling to be sure it
is properly grounded.
The Hot water pressure will increase with engine RPM. This means on some applications the heater will cool
down during periods of extended idling. If your engine is normally operated at low engine RPM's it may be
necessary to install an in-line curculation pump. Please contact Technical Support (208) 687-4400 for
options.
3. Locate and remove the plug on the water pump hosuing and install the proper size hose barb.
Note – If your particular engine does not have a plug to remove, it is necessary to install a hose tee into the
large hose connecting the thermostat housing to the water pump. Please contact Technical Support (208)
687-4400 for options.
4. Cut the water/coolant hoses to length, attach with hose clamps, and secure in place.
Note – Fasten the hose clamps near the end of the hose to prevent the hose end from "mushrooming" and
to prevent coolant leakage.
Heater Craft
6672 Boekel Road
Rathdrum, ID 83858
Phone: (208) 687-4400
Fax: (208) 687-9700
www.heatercraft.com