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Discussion Starter · #1 ·
New member here. Got a 55kw diesel, towable Kohler genset. It is set up as a Standby generator. When set to Auto, it alarms for coolant temp any time the temps drop below 60 degs F.
Per the Decision Maker 555 manual, this 60 degs setpoint is not user programmable. Genset has a coolant heater but I don't want it running all the time during the fall/winter months (in central Texas).

From what I have gathered so far, the coolant heater is not needed unless the temp is below freezing.
If I connect the coolant heater, it heats the eng to ~ 100 degs or so and keeps it there.

Is there a way to over ride the low coolant temp setpoint? I.E. some way to enter/modify the factory settings??
Does this genset need the coolant heater when temps are between freezing and 60 deg F?

Thx!
 

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yup
use a thermo block.
let me know if you need links for those.
i run heaters on the diesel units at 45-55 deg f or below.

here is the rub.
this helps keep the oil warm as well as the head temps for a better start and run.
and helps with startup wear.

i also like a battery charger with desulfate and a battery blanket heater to keep the battery warm and up to full charge.
 

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yup
use a thermo block.
let me know if you need links for those.
i run heaters on the diesel units at 45-55 deg f or below.

here is the rub.
this helps keep the oil warm as well as the head temps for a better start and run.
and helps with startup wear.

i also like a battery charger with desulfate and a battery blanket heater to keep the battery warm and up to full charge.
I’m curious, what do you mean by thermo block?

New member here. Got a 55kw diesel, towable Kohler genset. It is set up as a Standby generator. When set to Auto, it alarms for coolant temp any time the temps drop below 60 degs F.
Per the Decision Maker 555 manual, this 60 degs setpoint is not user programmable. Genset has a coolant heater but I don't want it running all the time during the fall/winter months (in central Texas).

From what I have gathered so far, the coolant heater is not needed unless the temp is below freezing.
If I connect the coolant heater, it heats the eng to ~ 100 degs or so and keeps it there.

Is there a way to over ride the low coolant temp setpoint? I.E. some way to enter/modify the factory settings??
Does this genset need the coolant heater when temps are between freezing and 60 deg F?

Thx!
Is the generator connected to your home via an automatic transfer switch?

Block heaters can really effect your energy bill. Diesel block heaters at least on trucks draw about 10amps. If the block heater was active 24/7 for a month... That’s over a hundred bucks a month. If the heater is thermostatically controlled then it won’t need to run constantly, that might validate just keeping it connected and keeping generator ready to go.
 

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Discussion Starter · #4 ·
Yes, the genset is connected thru an ATS. My current block heater has a thermostat so once the coolant reaches ~110 degs F it will cycle on and off so it wouldn't run 24/7. However I'd like to save energy and wear & tear on the heater when it's not really needed.

I could add a thermostatic switch inline with the power cord for the heater and have it come on when it gets close to freezing, however the low coolant temp alarm will still be going off once coolant temp drops below 60 degs F.

One idea I had was to add a custom selected resistor across the coolant temp sensor to offset the indicated coolant temp. For example when coolant drops to 40 degs F, the controller would see that as 70 degs F. Taking this idea one step further, the resistor could be connected across the temp sensor thru a normally closed relay. When eng starts, the relay would energize, opening the circuit (taking the resistor out of the circuit) and coolant temp would read correctly again.

Being able to adjust the factory setting for the "coolant temp low" set-point would be the ideal method but no clue if that can easily be done or not.
 

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The manual says it's a fixed value.


You can use an external programmable thermostat to control the coolant heater, assuming it runs off 120V directly. Some wiring modifications are necessary.

With this, you can set the high and low temperature window at which the heater should operate.

Something like this:

If you just need dry contacts to interrupt the heater circuit while retaining most of the factory wiring, use something like this:

Both have external temperature sensors that you can mount near the factory coolant temp sensor. You may need to experiment a bit in sensor placement and calibration. There will be at least a few degrees difference between what the factory sensor is seeing vs the external sensor.
 

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Yes, the genset is connected thru an ATS. My current block heater has a thermostat so once the coolant reaches ~110 degs F it will cycle on and off so it wouldn't run 24/7. However I'd like to save energy and wear & tear on the heater when it's not really needed.

I could add a thermostatic switch inline with the power cord for the heater and have it come on when it gets close to freezing, however the low coolant temp alarm will still be going off once coolant temp drops below 60 degs F.

One idea I had was to add a custom selected resistor across the coolant temp sensor to offset the indicated coolant temp. For example when coolant drops to 40 degs F, the controller would see that as 70 degs F. Taking this idea one step further, the resistor could be connected across the temp sensor thru a normally closed relay. When eng starts, the relay would energize, opening the circuit (taking the resistor out of the circuit) and coolant temp would read correctly again.

Being able to adjust the factory setting for the "coolant temp low" set-point would be the ideal method but no clue if that can easily be done or not.
How well does the generator start in cold temps? The whole point of the block heater is to have a reliable start. If the unit fires up in cold temps without throwing a failure to start code in automatic mode then faking the temp signal through a relay and resistor is a feasible idea.

Seams like the better plan would be separate controller for the block heater with a lower set point. The factory 110degree setpoint is probably Ideal for starting but definitely a drain on the wallet in electricity.
 

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Discussion Starter · #8 ·
OrlyP>> I saw the same thing in the manual. I've worked with various controllers for many years. Many have a "secret" factory service mode that allows for some additional tweaking. Others have the s/w parameters (limits) burned into an EPROM and they are much more difficult to change. I suspect the latter, but it would be nice if there was a easy way to access it.

I found a basic analog style "heat only" thermostat rated at 22 amps. Requires hard-wiring but I think I would be able to easily connect it so it controls the existing 120V outlet the block heater plugs into. This would provide a cleaner/more OEM appearance IMHO.
TPI KT110 Industrial Series Thermostat, SPST Heat Only, Wire Leads: Amazon.com: Tools & Home Improvement

The "block heater" is technically a "coolant pre-heater". It's supposed to regulate coolant temp in the block to 100-120 degs F. all by itself but not sure exactly how it does that. Suspect the "brains" are within the sealed heater unit.. Probably wouldn't be able to change the 100-120 deg range it regulates itself to.

Weird thing about the Kohler site is they recommend a block heater if temps approach 0 degs at one place, then say 50 degs F at another place.

Not sure if I really need a remote temp sensor on the proposed new temp controller. I was envisioning just using the ambient temp within the enclosure to trigger the block heater.

drmerdp>> So far, the coldest temp I've started it at was 57 degs F. Fired right up at that temp. I have some experimentation ahead of me.
At the moment, I don't hear the alarm unless I open the enclosure, but I have a remote annunciator panel (yet to be installed) that will alarm inside the house and needlessly irritate the family.


Iowagold>> Gotta love the EPA!!

Another concern is that I have no idea how reliable these coolant per-heaters are. They don't appear to have any moving parts but if the heater element fails, I'm SOL. Was thinking abt picking up a spare. Any thoughts/experiences on reliability??
 

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Unless you can find a detailed datasheet of the heater core, we can't for certain determine how it self-regulates the temp. Very likely just a mechanical thermostat but I can't be certain.

You'd want the external temperature probe for the controller to get its reading from the block itself so it knows when to power down the heater once the upper limit is reached.

If you just leave it to measure ambient, you can have a situation in which the ambient is 60 or lower but the block is still being maintained at a balmy 100-120 (factory preset), which I believe was the original problem. With a proper feedback, you can set the heater to run only if the block goes down to 60 and shuts off the heater when it reaches 85, for example, well ahead of the OEM 100-120 preset.
 

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My question to all involved… Is there any concern about internal condensation with a block heater running as much as this one is? That was always a concern with small aircraft, thus only turned on several hours prior to use…
 

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Discussion Starter · #11 ·
My question to all involved… Is there any concern about internal condensation with a block heater running as much as this one is? That was always a concern with small aircraft, thus only turned on several hours prior to use…
This is a concern for me also. Sorta like have a car that only gets driven a couple of blocks each day. The condensation builds up from the thermal cycling but never gets hot enough to evaporate out the moisture.



Unless you can find a detailed datasheet of the heater core, we can't for certain determine how it self-regulates the temp. Very likely just a mechanical thermostat but I can't be certain.

You'd want the external temperature probe for the controller to get its reading from the block itself so it knows when to power down the heater once the upper limit is reached.

If you just leave it to measure ambient, you can have a situation in which the ambient is 60 or lower but the block is still being maintained at a balmy 100-120 (factory preset), which I believe was the original problem. With a proper feedback, you can set the heater to run only if the block goes down to 60 and shuts off the heater when it reaches 85, for example, well ahead of the OEM 100-120 preset.

The heater uses "thermosiphoning" to move the coolant (no actual pump) so I envisioned just a thermal switch inside the heater to maintain the coolant temp. Once the heater element shuts-off, the flow stops.

Sounds like this method of remote temp sensing would necessitate some type of sensor that screws into the block somewhere and had the same temp/resistance curve as the sensor that comes with the temp controller. That might be a challenge, not sure. One thing for sure is that I'll need to experiment with starting the gen at gradually decreasing temps to find where it's no longer happy starting up. In most situations I'd be concerned abt starting and applying a heavy load immediately to a cold eng, however since we use propane for heat, there wouldn't be much of an electrical load, in the winter anyway.
 

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i bet the 0 deg f is for the gasoline version.
as this is a back up power diesel gen set so they like to keep it warm and ready to run all of the time...

this also brings up the question of fuel heater on the fuel filter.
as long as you drain the water out of the fuel filter you should be ok.

we had this last week when the temps dropped to 15 deg f a water separator burst on a new clients unit.
we have it marked in the check list for daily drain....
the operator did not even check the oil or the coolant as instructed... but just signed off the check sheet.
yup does not work for them any more....
i did add a fuel and oil filter blanket heater they work well for the super cold days.
and tank heaters for the metal hyd and fuel tanks.
I have a feeling it will be a coollllddd jan and feb in Iowa.
 

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If you run a good synthetic small engine oil that will be a great help in cold weather starts. The Amsoil Synthetic Small Engine Oil 10w30 has a pour point close to -50c I believe. It’s diesel rated too. That means in any temperature warmer than that the oil will flow throughout the engine instantly at startup. Very important for sure… There’s currently a promo for free shipping. Pm for a link.
 

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it is all about the warm temps for the clean start up burn and parts fit as well.

just like in F1 cars the tight fitting parts you need the engine warm before you fire it up on these units.
 

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Sounds like this method of remote temp sensing would necessitate some type of sensor that screws into the block somewhere and had the same temp/resistance curve as the sensor that comes with the temp controller. That might be a challenge, not sure. One thing for sure is that I'll need to experiment with starting the gen at gradually decreasing temps to find where it's no longer happy starting up. In most situations I'd be concerned abt starting and applying a heavy load immediately to a cold eng, however since we use propane for heat, there wouldn't be much of an electrical load, in the winter anyway.
That's true. I mentioned before that some experimentation is necessary. Getting unstuck between a rock and a hard place is never easy. ;)

Now, you have to decide:
1. Best for the engine.... keep the heater running, leaving it to its own devices and let it use up as much energy it needs to get the job done.
2. A little compromise... find a sweet spot where the heater operates within a smaller temperature window relative to the OEM, just enough to not trigger the low coolant temp alarm. It shouldn't draw as much power over a 24h period.
3. Sever all diplomacy.... leave the heater unplugged from power and put a switch on the alarm to mute it.

Personally, I'd choose #2 every time.
 

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Discussion Starter · #18 ·
While I was working on something else today, I plugged in the heater just to see how hot it would get before shutting off. Started at 60 degs and it had already shut off when I came back to check after abt 90 mins. Rough estimate would be ~0.5 degs/min for the eng heating rate . Thermal camera showed hottest part of block at 106 degs.. Hose leaving heater was at 119 degs so I don't think it had been shut off for very long. Will need to repeat test when I have more time to devote to it. Did notice the cyl wall of the eng was the warmest part. Bottom end of eng didn't appear to warm up much at all.

Also measured current at 12.5 amps (@120V) which matches wattage on data sticker of 1500W.
Referenced manual for part# on heater (326228) shows it to be ON at 120 degs, and OFF at 140 degs!! Also noticed there is a sensor for the heater that screws into block. Followed the wire from sensor and it goes into a small box that the 120V wiring for the heater passes thru. May be able to get a different sensor for it or maybe just connect a resistor across it??

Finding real data on eng wear vs eng temp at start-up would probably be very difficult to find and would be subject to various unknown variables. Finding the temp where eng has difficulty starting would be much more straight forward and will most likely be what I will use to judge the best compromise.

Font Electric blue Technology Gas Rectangle
 

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we do a head heater as well as an oil pan heater...
then use the thermal cut out.
and if the heaters are large enough 15 min before you start will help...

we use 200 on the head and 600 watt on the oil pan and 600 watt on the coolant.
and then a 100 watt on the fuel filter water separator.

if you are super cold like below -1 deg f use a 600 watt on the metal fuel tank.
and any hyd tanks as well. if it is like a skid loader etc.

for a gen set if you do a gen shack you can use a room heater or pex in floor radiant heat with oil as the solution for no freeze.
if you can keep the gen shack temp at 80deg f on a cold day that is all you need for a proper diesel start.
and you must use an heat ex-changer preheat for the air intake.
 
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