Heat Exchanger Hose Connections and water circulation

May, 2012

After taking the Seakamp heat exchanger off the Universal M25 diesel (again) and getting it repaired, it was about a month before getting it back on the boat. Sometimes a picture is worth a thousand words when you're putting something back together.

Heat Exchanger salt and fresh water circulation system, hose connections

Universal M-25 Diesel heat exchanger water circulation system
Heat Exchanger water circulation system - click to enlarge

The heat exchanger set up on Reality Check has the Antifreeze/Fresh water plumbed with a bypass valve (behind the bulkhead) to the hot water heater.

Photo diagram descriptions (left side, top to bottom):
  • Salt water exits the heat exchanger and goes to a vented loop. (exhaust system connections not shown) Another hose from the vented loop goes to the exhaust mixing elbow to cool the exhaust. The salt water is ejected from the boat with the exhaust.
  • Salt water from the sea water strainer goes to the salt water pump.
  • Antifreeze/Fresh water entrance to the heat exchanger. This hose is the return from the plumbing behind the bulkhead that also goes to the water heater. The connections are hidden behind the bulkhead.
  • Salt water from the salt water pump enters the heat exchanger through this hose.
Photo diagram descriptions (right side, top to bottom):
  • Heat exchanger zinc is on the bottom of the HX (can't see in this pic)
  • Antifreeze/Fresh water exits the heat exchanger and goes up through the fresh water pump, engine block and  thermostat back into the manifold. The hose where it comes out of the heat exchanger is hidden under the exhaust flange (in the pic).
  • Antifreeze/Fresh water hose from the manifold to the plumbing behind the bulkhead, which also goes to the hot water heater. The return from the plumbing and the hot water heater goes into the heat exchanger to be cooled. The connections to and from the hot water heater are hidden behind the bulkhead.

Seakamp 3" Heat Exchanger hose connection diagram

Seakamp 299835 CN / 302631 heat exchanger hose connections on the Universal M-25 Diesel
Seakamp 3 Inch Heat Exchanger hose connections on the Universal M25 Diesel. This part is #302631, not the #299835 CN. The difference in the parts is the angle of the tubes.

Hot water heater bypass valve

Hot water heater, heat exchanger bypass valve
Heat Exchanger hot water heater bypass valve (behind the bulkhead).
This valve is OPEN on Reality Check.

Related topics:
Heat exchanger and overheating - upgrade to the 3 inch and you will not be sorry
Removing and reinstalling the heat exchanger


Universal M25 Diesel

Heat Exchanger

Engine Compartment Insulation / Soundproofing

Anchor Locker





Bimini for the Boat



Edson Pedestal Controls