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Old 25-01-2013, 09:09   #1
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Hot Water from Engine- How Long?

How long do you need to run your engine and at what revs to get hot water from the heat exchanger? mine takes forever to get warm, i am wondering ifi have a problem.
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Old 25-01-2013, 09:17   #2
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Re: Hot Water from Engine- How Long?

I could take a hot shower after 45 minutes of idling and battery charging with a 6 gal hot water tank.
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Old 25-01-2013, 09:19   #3
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pirate Re: Hot Water from Engine- How Long?

Flush and clean your heat exchanger...
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Old 25-01-2013, 09:36   #4
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Re: Hot Water from Engine- How Long?

Steven
i have 2 systems for heating water one through the normal dhw tank and i have also installed between engine and hot tank a domestic hot water plate exchanger with by pass valves fitted i get basically instant hot water once engine is up to temp these are the same type in combi gas boilers in uk
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Old 25-01-2013, 11:40   #5
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Re: Hot Water from Engine- How Long?

That will depend on your engine. Some take longer to get up to temperature than others and some never come up to temperature while just running at low RPMS with no load. Don't assume you have an engine problem. A clogged heat exchanger will give you the opposite problem, overheating. It is also possible that someone removed your thermostat and did not replace it. If your only running the engine to make hot water rather than also charging batteries, you might consider a propane hot water heater. Most boaters, including ourselves, pre generator, ran the engine at least an hour in the morning and an hour in the evening, depending on how much we needed to recharge the batteries and not to make hot water. It just worked out that it took that long to heat the water too. Chuck
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Old 25-01-2013, 22:10   #6
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Re: Hot Water from Engine- How Long?

Once your temp gauge shows near normal temp, feel the hose going into your heater to see if it feels as hot as the hoses on the engine. If not you probably have some restriction in the water circulation system. If at just above an idle, your temp gauge does not come up to somewhere near your normal running temp, then you probably have a stuck or removed thermostat. Ten minutes or so should bring your engine up to near normal temps, and as stated earlier, 45 minutes should give you plenty of hot water. Good Luck._____Grant.
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Old 30-01-2013, 09:31   #7
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Re: Hot Water from Engine- How Long?

Quote:
Originally Posted by stevensuf View Post
How long do you need to run your engine and at what revs to get hot water from the heat exchanger? mine takes forever to get warm, i am wondering ifi have a problem.
Precisely why I use my oil cooler to heat the coolant going to my hot water tank. I have a feeling i wouldn't have the need to do that in the tropics, but in New England, it helps to have scorching hot water when taking showers outside.
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Old 30-01-2013, 09:42   #8
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Re: Hot Water from Engine- How Long?

Your worried about hot water whilst living on a yacht in the Caribbean

Actually you might be better off running the Honda. Ours ran the water heater and the 40AH battery charger at the same time without even blinking.

However, the Volvo 2003 could run until hell freezes over at tickover and still not be hot, needed to be pushing the yacht a 5 knots and thereby burning diesel before generating heat. 3/4 revs in neutral didn't burn enough fuel either, engine needs to be working hard to generate heat.

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Old 30-01-2013, 10:29   #9
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Re: Hot Water from Engine- How Long?

My Yanmar 4JH3-TE won't heat water at idle. It doesn't get hot enough without a load, and that's a good thing.
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