Where's the Blower?

[dacarter]

Richard,

Thanks, very interesting. You could be right that the lack of the pump is causing the heater not to work. I tend to think it will work when run harder, simply because I know the water in the water heater gets hot and it's on the same line, in series with the the heater. So that tells me hot water is circulating through the water heater, and must travel through the heater before returning to the engine.

I will probably put it in the Gulf on Friday and will be able to give it a good test. It will be in the 40's in the morning, so we'll need the heater.

[Richard_W]

That's interesting ... and the worst case from engineering point of view, to have both heaters on one water loop without a circulation pump.

If you connect both heaters in line (in series) that significantly reduces effective water flow due to the length of hoses plus dynamic resistance of both exchangers. Also, the first heater takes most of heat/energy from the water, the second heater in line cannot be very effective. My hot water heater is on a separate short water loop without a pump. The air heater is on a long water loop and is assisted by a water pump.

Try it and see how much time it takes to make the air warm, and how warm … I have hot air blowing right after the engine gets to operating temperature.

[GPSocal]

Let us know how your cruise went. I ran my engines for about 20 minutes this afternoon and I had good temperature from the heater in about 10 minutes. The hose run from engine to heater is about 5 feet. You also may be losing heat energy through the flexible duct hoses between the heater box and the outlets.

[DeepFrz]

You also may be losing heat energy through the flexible duct hoses between the heater box and the outlets.

Good point. I was thinking that it would be fairly easy to rig a solid or at least non-accordion type heat duct to the first bulkhead under the bunk. That would cut down some on the resistance to air flow.

Another thing might be to move the heater closer to the bulkhead, thereby shortening the length of coolant run by 6 to 10 feet or so. That might help the circulation some.

I guess the addition of the pump would be the one best improvement, but the other actions combined with the pump might be the ideal solution.

Easy for me to say...

[dacarter]

Took the boat out in the gulf of Mexico yesterday(no fish but beautiful day) and the heater did eventually blow warm air. Not quite as much as I would have hoped but it did work. Since I will probably never fully enclose the deck with the shrunken 10 year old plastics, I could easily change the deck vent to one that I can close. The dash vent is already closable, that would force all air to the cabin. Could even reroute one of the other ducts to the cabin. So success overall, but since I'm in Houston, I probably won't spend much more time or effort on improving the heater. Thanks for all the advice.