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Old 21-09-2013, 05:11   #1
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Generator -- Temperature Monitoring

When I installed a new N2K electronics system over the winter, I added temperature sensors on my generator (Kohler 6.5EFOZ, 1500 rpm) -- one on the top cooling system flange, and one on the water pump">raw water pump. This data is now on my network and can be displayed on my Maretron DSM250 at my nav table (probably some other instruments as well).

The idea of putting a temperature sensor on the raw water pump was to detect reduced raw water flow. When operating normally, the raw water pump is cooled by the raw water flow and will have temperature near the sea temperature. If the flow is restricted, the temperature will rapidly rise from friction of the impeller. I learned this when I was struggling with cooling problems a couple of years ago -- the raw water pump would get very hot if raw water was not flowing.

Well, in case anyone is thinking about doing something similar -- it is working extremely well. I have sea temperature on my plotter, and next to my plotter my DSM250 tells me the raw water pump temperature. When the raw water strainer starts to fill with seaweed (as it inevitably does), the raw water pump temperature will go up by a couple of degrees. So long before there are any actual problems, I know to clean it out.

The fresh water cooling temperature of this genset is very stable at 68 to 70 degrees C regardless of load. It will go up by one or two degrees if the raw water flow is just starting to be restricted by seaweed in the strainer.

It's really great having this data. My boat is on a mooring without shorepower, so I am highly dependent on my generator. It's great to be able to tell at a glance and without having to get into the engine space that everything is working properly.
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Old 24-09-2013, 20:33   #2
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Re: Generator -- Temperature Monitoring

Very good information. Rough cost of installing the sensors and monitors?????. ____Grant.
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Old 27-11-2013, 01:52   #3
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Re: Generator -- Temperature Monitoring

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Very good information. Rough cost of installing the sensors and monitors?????. ____Grant.
So, the sensors are cheap -- $20 each for the underbolt temperature sensors from Maretron.

Of course, you need the temperature monitoring module, which takes 4 low temperature sensors, and 2 high temperature ones (like EGT sensors). That costs $275, but I had that anyway.

For monitoring, various displays (or your laptop if connected to the N2K network) will show it. I use the DSM250 primarily for this. It's expense ($800 or so) but I had it anyway -- I use it for a multitude of functions, especially, displaying weather.
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Old 27-11-2013, 06:36   #4
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Re: Generator -- Temperature Monitoring

Fascinating so this system, I presume you can monitoring whatever they have transducers for, perhaps an economic alternative to tank & battery Monitor and add whatever you need like bilge etc. Can the system be configure to have both high and low level alarms analogue monitoring perhaps. Is this system meant for new builds and therefore compete with say RM or is it meant to compliment say RM, does it talk to say RM or any other. Does this NKview have software to create your own schematics and view data on your PC.

Or perhaps its meant for more commercial applications which takes it out of most cruisers budget.
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Old 27-11-2013, 12:58   #5
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Originally Posted by Oceanride007
Fascinating so this system, I presume you can monitoring whatever they have transducers for, perhaps an economic alternative to tank & battery Monitor and add whatever you need like bilge etc. Can the system be configure to have both high and low level alarms analogue monitoring perhaps. Is this system meant for new builds and therefore compete with say RM or is it meant to compliment say RM, does it talk to say RM or any other. Does this NKview have software to create your own schematics and view data on your PC.

Or perhaps its meant for more commercial applications which takes it out of most cruisers budget.
You should read up on NMEA2000 systems! They can do all that and much, much more. The Maretron site is a good place to start.
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Old 27-11-2013, 13:29   #6
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Re: Generator -- Temperature Monitoring

There are temp. probes for the exhaust system that mount through the exhaust hose just below the water injection elbow. This will alert you instantly if you have a water flow problem so you should be able to shut down before any damage is caused.
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Old 27-11-2013, 13:50   #7
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There are temp. probes for the exhaust system that mount through the exhaust hose just below the water injection elbow. This will alert you instantly if you have a water flow problem so you should be able to shut down before any damage is caused.
That woukd also work fine, but an underbolt sensor on the raw water pump is much simpler to install. Any flow problem immediately appears as increase in difference between sea water temp and pump housing temp.
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Old 27-11-2013, 15:45   #8
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Re: Generator -- Temperature Monitoring

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Originally Posted by DeepFrz View Post
There are temp. probes for the exhaust system that mount through the exhaust hose just below the water injection elbow. This will alert you instantly if you have a water flow problem so you should be able to shut down before any damage is caused.
This is a good suggestion because If the injector blocks or partly blocks and depending on the extent of the blockage you will melt through the dry hose in possibly a very short time. That will put the engine out of action or worse, but you will have no warning from the pump sensor as it will still be working. This is the biggest hazard of raw water flow failure.
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Old 01-12-2013, 16:29   #9
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Re: Generator -- Temperature Monitoring

I've been monitoring the exhaust elbow temperature for years. The slightest reduction in water flow will result in a very noticeable increase in the elbow temperature. It has saved me from damage on several occasions.
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Old 02-12-2013, 13:36   #10
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Re: Generator -- Temperature Monitoring

These folks have some interesting products. We are about to install the exhaust alarms on our engine and generator. Picks up problems WAY before you do:

https://www.aqualarm.net/comerus/sto...p?idProduct=64
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Old 02-12-2013, 23:49   #11
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Re: Generator -- Temperature Monitoring

I prefer this one as the probe is inserted into the exhaust hose.

http://www.google.ca/url?sa=t&rct=j&...57155469,d.aWM
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Old 03-12-2013, 00:24   #12
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Re: Generator -- Temperature Monitoring

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Originally Posted by bstreep View Post
These folks have some interesting products. We are about to install the exhaust alarms on our engine and generator. Picks up problems WAY before you do:

https://www.aqualarm.net/comerus/sto...p?idProduct=64
Belt and suspenders, for sure, but I also have these on both generator and main engine!

I like these because they are freestanding and simple and don't rely on the network.

So just in case I might happen to be running the generator, for example, with the network switched off, I still have warning.


Concerning probe inserted or not -- matter of preference, but I don't think you don't need a precise measurement of exhaust gas temperature. You just need to know if the system is heating up abnormally. For that, a simple surface mounted sensor is just fine, I think, and doesn't require another hole and another potential CO leak to fit.

The raw water pump temperature is an excellent proxy for water flow, and instantly shows even a slight blockage of flow (a few strands of seaweed in the strainer, for example) by showing a rise of pump body temperature of a couple of degrees. That's because there's a big difference between the sea water temperature (at least over here, where it's never more than 20 degrees C, and these days, more like 5) and engine room ambient temperature (usually 30 degrees or so on my boat). Besides that, the pump generates internal heat from the friction of the impeller blades, and heats up instantly if the flow of sea water is reduced. Heats up long before the flow is dangerously reduced.

It is much more sensitive than the simple on/off water flow alarm sensors, and is more useful than even a precise readout of flow rates would be -- because flow rate will vary with RPM, and needs to be interpreted, whereas pump temperature does not vary with RPM -- only if flow is not keeping up.

I have networked alarms set up to sound off in case this happens.
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Old 03-12-2013, 00:30   #13
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Re: Generator -- Temperature Monitoring

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Originally Posted by poiu View Post
This is a good suggestion because If the injector blocks or partly blocks and depending on the extent of the blockage you will melt through the dry hose in possibly a very short time. That will put the engine out of action or worse, but you will have no warning from the pump sensor as it will still be working. This is the biggest hazard of raw water flow failure.
You will indeed have warning from a pump sensor, because a blocked injector will block raw water flow altogether -- that's the only way the raw water has to get out. Even a slightly reduced flow of raw water from a slightly blocked injector will be instantly reflected in pump temperature.

But nothing says you can't monitor the exhaust elbow temperature, too -- I certainly do. It's really belt and suspenders, but the consequences of raw water flow failure are so dire, that I think it's really worth it.
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Old 03-12-2013, 14:07   #14
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Re: Generator -- Temperature Monitoring

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You will indeed have warning from a pump sensor, because a blocked injector will block raw water flow altogether -- that's the only way the raw water has to get out. Even a slightly reduced flow of raw water from a slightly blocked injector will be instantly reflected in pump temperature.

But nothing says you can't monitor the exhaust elbow temperature, too -- I certainly do. It's really belt and suspenders, but the consequences of raw water flow failure are so dire, that I think it's really worth it.
It is a partial restriction on the elbow that I was mainly thinking of such as where crumbling corrosion blocks a section of the nozzle. Partial blockages are know to cause a burn through of exhaust hose. I am not sure the restriction would be enough to raise the impeller temperature and trigger your alarm as flow in the good part of the nozzle will increase somewhat to compensate for the blockage. If you have a rubber feed hose to the nozzle the system could be tested by squeezing it a bit. If you are monitoring this area anyway then it doesn't matter to fine tune it unless you want to use your sensor inputs for other things.

Another scenario to protect from might be where you are in a grubby harbour full of junk. You start the engine and let it warm up. Just at that instant a bag blocks your intake. The engine and impeller pump is cold, but the exhaust is very hot. Without an exhaust monitor it may blow through very quickly and before other temperature alarms can be activated.

I also don't like the idea of puncturing the exhaust hose, though that type of sensor will give the quickest possible response.

My boat has an arcnet coaxial network installed by the first owner with sensors measuring absolutely everything measurable, even if hatches are open or closed. There are so many false alarms the system in unusable, but I do have a plan of getting much of the important stuff going again. The network you have sounds great.
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Old 03-12-2013, 21:46   #15
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Re: Generator -- Temperature Monitoring

I never did buy into the TV/VCR or TV/DVD combo. I want simple systems that I don't have to worry about whether or not the network/integration is up or not. That's why a simple exhaust monitor works for me. Is it hot? Sound the alarm.
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