MJM Yachts 40z Express - Manual (Page 36)

7.0
7.1
7.2
FRESHWATER SYSTEM
GENERAL
The 40z incorporates a pressurized freshwater system from either of two
sources (1) a single 100-gallon tank under the main saloon sole that
supplies a pump which maintains a constant pressure in the system, or (2) a
dock hose inlet located to port in the cockpit as shown at right. When
connected, dock water and pressure is used directly by all outlets in the
boat... by passing the freshwater pump and water tank. A check valve keeps
the dock water supply from backing up into the boat’s water tank and
overflowing it.
When using the dock water supply, be sure to turn OFF the “fresh water pump”
breaker on the 12V DC Panel, otherwise the ship’s water pump may win the battle of water
pressure and emptying your water tank into the city system.
When leaving the boat with the dock water supply hooked up, be sure to turn
OFF the dock water faucet. If there’s a failure of a fresh water fitting or the pressure regulator, the
boat could fill up with water and sink... as there is no limit to the amount of water from the city
source as there is with the boats own water tank.
FILLING WATER TANK
A deck fill is provided on the starboard side deck near the helm station and is labeled WATER. As
the tank is filled, air escapes thru the vent. This tank cannot be filled using the dock hose inlet.
FRESH WATER PUMP (at right)
The Jabsco Sensor Max VSD5.0 freshwater pump is turned on at the
DC breaker panel. It is combned with the Groco, 2 gallon PSC-1 which
accumulates pressure to 100 psi so the pump doesn’t have to scyle
repeatedly. If the pump s heard running continually, check that no
faucet has been left open. If this is not the case, turn off the pump and
check that the tank has not been emptied.
The pump is protected from sediment by an in-line strainer mounted
adjacent to the pump. The strainer should be checked periodically and
cleaned if necessary.
7. HOT WATER TANK
Water in the 13-gallon hot water tank is heated in one of 2 ways (1)
whenever the engine is operating or when the engine is not running,
by turning on the “Water Heater” breaker on the AC Shore 2 panel. It is
part of the freshwater system and does not need to be filled separately.
There is virtually no need for maintenance, but the connections at the
tank should be visually inspected occasionally.
The coolant lines from the engine to the tank have shut-off valves. These need to be OPEN in
order for the engine to heat the water in the tank. For service, or in case or a ruptured line, these
valves can be closed to stop this water loop.
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CHAPTER 7