Exhaust

The products of the combustion are forced from the heater to a hull fitting. This is a straight through skin fitting for a steel narrow boat, or an air cooled fitting if it is passing through a GRP or wooden hull.
The hull fitting is connected to the heater by a flexible twin wall stainless tubing, which is insulated for sound and heat and then over sleeved for safety.

Calorifier

This is the tank for domestic hot water and fed by the pressurised cold water circuit. Through the calorifier runs a coil that carries heated water from the Eberspächer. This transfers its heat to the domestic water, which feeds basins and showers.

Heater Location

The Hydronic is usually installed in the engine area or aft locker.

Fuel

The heater’s fuel metering pump draws the diesel that it needs directly from the boat’s tank, via an independent standpipe. It is not connected in any way to the engine system. The fuel is delivered to the burner at a pre set rate to be mixed with the combustion air. The fuel pump contains a filter in its intake side.

Space Heating

On narrow boats this is achieved by a traditional radiator system: usually running down one side of the boat. As an alternative, fan blowers can be used, located under berths or locker fascias.
Heated towel rails are a great way to extend the system into the bathrooms/heads.

How the Hydronic works

On starting the heater draws in combustion air (1) from the engine area or where the heater is located.

Fuel is drawn (2) from the boat’s tank and mixed with the combustion air.

A glow pin (3) ignites the mix and a controlled flame is established in the heat exchanger (4). The integrated water pump (5) now circulates the system’s water, passing it over the heat exchanger and onto the calorifier and radiator system (6).

Once the system is hot, the heater will regulate down to a lower heat level. This avoids unnecessary cycling and thus avoids wasteful repetition of the start cycle.

The heater in lower, or stepped output tops up the system to maintain optimum temperature.

When heavy demands are made on the system, such as showers or a fall in outside temperature, then the Eberspächer steps up again to regenerate the heat in the system.

All the components that go to make a full installation are purpose designed to work together reliably and withstand the tough marine environment.