Heater Craft 900H Series Hydronic Heaters - Manual (Page 3)

Page 2
Heater System
1. Layout the heater system in the boat before installation and make sure the mounting location of the
heater unit and routing of all the hoses will work.
Warning – Do not mount the heater unit into the bilge area or any compartment that may draw air form
the bilge.
Types of Heater Installation:
Ducted units typically mount under the helm or in a storage area that will allow routing of the vent
hoses to desired vent locations.
Grill Mounted units typically mount into a stairwell of into a storage area.
Note – Our heater units are equipped with with 5/8" or 3/4" heater core outlets. Please make sure that you
have the proper size of heater hose and fittings for your installation. if the hoses and heater core outlets are
not the same size, it is necessary to install a hose coupling with the proper hose sizes to prevent coolant
leakage.
2. Determine your source for the hot water supply.
Main engine – This installation is like your automobile, engine coolant will circulate from the engine
to the heater unit and return to the engine.
Caution – If your engine application has a freshwater closed cooling system the heater unit should be
mounted below the level of the radiator cap. If heater is mounted above this level is is possible for air to be
come trapped in-line. IF there is air trapped in-line it will not allow the water to circulate efficiently and may
cause the engine to overheat. If the heater unit is mounted above the radiator cap it may be necessary to
install an in-line air bleed valve at the highest point or an in-line circulation pump.
Main engine with separate coolant loop for the heater – This installation will require additional
components. You will utilize a water exchanger to transfer heat from the engines' cooling system to
the heater loop. A pump is needed to circulate the water in the heater loop. Basic instructions are
outlined on page 8.
Boiler-type system – Refer to the manufacture's instructions for hook-up information.
Note – Be sure the hoses are not kinked or pinched an any way, and do not contact any moving parts, sharp
objects or edges. They can be secured with a plastic tie.
3. Route and secure the heater water/coolant hoses between the heater unit location and the hot water
source.
Heater Craft
6672 Boekel Road
Rathdrum, ID 83858
Phone: (208) 687-4400
Fax: (208) 687-9700
www.heatercraft.com