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Old 06-02-2015, 16:32   #16
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Re: Heat and Hot Water

Webasto st90 installed myself four years ago with radiators throughout the boat. Radiators in the hanging lockers to keep them dry and on demand hot water heat. Heat exchangers on the engines so they heat the system when running and the system can be used to pre heat the engines. Works flawlessly. Bought all the components from Sure Marine in Seattle. Great people to work with, provided good technical assistance through the installation process.

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Old 08-02-2015, 09:11   #17
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Re: Heat and Hot Water

Second the Hurricane was sceptical about the hot water heating but it works very well and I retired my demand hotwater heater, I have 4 zones and the water lines run under the decking (not behind the furniture) making a nice dry bilge and added in floor heating, I never insulated them on purpose.....

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Old 09-02-2015, 03:41   #18
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Re: Heat and Hot Water

Lou.... fabulous drawing!
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Old 15-02-2015, 17:23   #19
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Re: Heat and Hot Water

Sailorlou has a great diagram.

Don't mix the 2 hot waters. Use a heat exchanger. Most engines either have anti-freeze, or water pump lubricant in the water. Some diesels require an anti-cavitation mixture that probably isn't too tasty. Or engines have some other heavy metal residue.
I have a large hydronic system that uses a diesel fired boiler and baseboard type radiators. The boiler has a coil that hot water passes thru to heat the potable hot water in the water heater. With the tank above the boiler, no pump is required. I plumbed both main engines into the circulation system. Only one engine at a time is used for heat for safety reasons. Also, I have a pellet stove with a self built coil that also can heat the boiler.
The boiler system was installed when diesel was about 20¢/gallon. At $4/gallon I added the engine plumbing and pellet stove. None of the original piping was insulated so much of the heat went into the bilge and unused spaces. Also, I am changing the baseboard sections with a marine forced air heater in each cabin/compartment. I went from 2 zones to 5. The car type heaters heat a cold boat hours faster than the baseboards. It lets me direct air into cold spots, too.
The engine fresh water pump moves the water even when the system isn't calling for heat. The engines run at about 175º, so the boiler doesn't over heat. I have the oil blower/igniter disconnected and use the boiler's controls to turn on the circulation pump, thermostats and valves.
The way my system works now, the thermostat sends a signal to the boiler. That causes the circulation pump to come on and appropriate valve to open. The individual heating units have a 12V heat sensor on the supply line that triggers the fan on when it gets to 135º and off when the temp goes below 90º. That way no cold air on startup.
I've been changing over my electric system to run thru an inverter all the time so when off shore power I don't run a generator unless using something drawing high amps. So the 120V and 24V parts of the heating system run when only cruising on my mains. Main alternators keep the batteries up and when on shore power the inverter passes the 240V thru and also charges the batteries.
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Old 15-02-2015, 17:28   #20
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Re: Heat and Hot Water

Agree, find a good tech. We have an 8yr old Webasto 2010 and it's been almost flawless once properly installed.

We have a Racor 12 filter/water separator (2micron) that we change every year.

Tonight it's 5f, our big 18m/60' ketch is warm, about 8-11 L /24hr for 45,000btu

Can't imagine not having it

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Old 15-02-2015, 17:55   #21
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Re: Heat and Hot Water


Webasto is awesome for diesel heat. For your full time cruising, are you able to add a generator? The addition of a generator makes living on a boat much more enjoyable and solves most problems like water maker, heat a/c and battery charging.

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