Heat in Cabin from Forced Air - Turn it off?

[racurry@unb.ca]

The engine heat coming through Forced Air Cabin Heater needs to be off - its 30oC outside, so how do we do that without shutting off the 2 valves at engine? Is it ok to shut these off and not impact the engine cooling? Not sure I understand the design thinking on this one?

 

[watson1987]

Do you have the blower fan on for the cabin heater? There is a rotary dial with off/low/medium/high settings that control it at the helm, with it set to off, you shouldn't notice much heat transfer, although coolant is still pumping through the heater core

If you turn off the 2 valves at the engine your hot water tank will only be heated when connected to shore AC power, and not while underway with engine heat, as both the cabin heater and hot water tank are on the same additional loop.

 

[racurry@unb.ca]

Fan switch is off and still lots of heat venting. Engine shows normal temperature underway so nothing has changed other than outside warmer temperatures. Won’t I be able to heat water offshore via inverter if necessary?

 

[Full_O_Fish]

Unless you have re-wired the inverter/120v system the inverter only supplies the outlets and the microwave. Water heater element would pretty much max out the inverter output with nothing else running, so if you tried to use the microwave it would trip the inverter and would need to be reset. If you have a generator you can supply the 120v system with that, which is plenty for the water heater (2kW generator or larger).

 

[Full_O_Fish]

There are ways to re-plumb the lines so that no heat can escape, but you will need another fluid hear exchanger (cheap on Amazon) and a small electric circulation pump which gets wired into a dedicated switched power source.

Basically the new heat exchanger goes between the water heater and the fan heater, and the circulation pump goes between the new heat exchanger and the fan heater.

When the engine runs the coolant goes up to the water heater and then through the new exchanger, but since there isn't any flow in the new "loop" between the fan heater and the new exchanger not heat is transferred to the fan radiator. If the new circulation pump is turned on then fluid flows from the new exchanger to the radiator and the fan heater works as normal (with a minimal reduction in max heat transfer capability).

 

[racurry@unb.ca]

Great info and thanks - so it sounds like I can turn off those 2 valves for now without any impact on the engine cooling until I sort out what to do about heating water?

 

[watson1987]

Unless you have re-wired the inverter/120v system the inverter only supplies the outlets and the microwave. Water heater element would pretty much max out the inverter output with nothing else running, so if you tried to use the microwave it would trip the inverter and would need to be reset. If you have a generator you can supply the 120v system with that, which is plenty for the water heater (2kW generator or larger).

For what its worth, I did re-wire the hot water tank to run off the inverter or shore power and used an AC transfer switch

The last post of this thread outlines what I did and includes some photos. The hot water tank uses about 800W, well within the inverter's 1500W sustained output

 

[NorthernFocus]

The engine heat coming through Forced Air Cabin Heater needs to be off - its 30oC outside, so how do we do that without shutting off the 2 valves at engine? Is it ok to shut these off and not impact the engine cooling? Not sure I understand the design thinking on this one?

Duct tape...

 

[Headlee]

Great info and thanks - so it sounds like I can turn off those 2 valves for now without any impact on the engine cooling until I sort out what to do about heating water?

Yes, you can turn off those 2 valves without any impact. I just did that this season and no issues: no hot air or hot water underway, though.

 

[racurry@unb.ca]

The engine heat coming through Forced Air Cabin Heater needs to be off - its 30oC outside, so how do we do that without shutting off the 2 valves at engine? Is it ok to shut these off and not impact the engine cooling? Not sure I understand the design thinking on this one?

Duct tape...

Yes the Magic Tape has many uses (Red Green)

 

[racurry@unb.ca]

Great info and thanks - so it sounds like I can turn off those 2 valves for now without any impact on the engine cooling until I sort out what to do about heating water?

Yes, you can turn off those 2 valves without any impact. I just did that this season and no issues: no hot air or hot water underway, though.

Thank you very much!