Two questions re: refrigeration use when cruising & Novakool specific ?

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capran

Senior Member
Joined
Apr 11, 2022
Messages
192
Vessel Name
Honu
Vessel Make
Helmsman 38/Mariner Saville 37
One general and one NovaKool Referigrator specific. 1) when you are out cruising and the motor is running, do you turn your refrigerator temperature setting to coldest (7) to lower the temp while motoring and then, after anchoring, turn it back to your regular setting of 4 to help conserve battery drawdown? And question 2- NOVAKOOL refrigerator on Helmsman 38: Yesterday was very warm day for PNW at 87 degrees. After adding shopping things to refrigerator and freezer, which had been set at 4 which keeps freezer at 23 and refer. at 37, during cocktail hour 4 hours later temperature started going up and fridge was cycling on and off every few minutes. When temp had gone up to 40 in the freezer and 50ish in the fridge wife turned the temp setting at 7 (coldest) which seemed to have no effect on lowering the temps. we monitored every hour. 8pm: 20/45. 9pm 25/48. 1030pm 22/44. (temp readings refer to freezer/refrigerator). This morning, after being on setting of 7 (coldest) at 430am freezer at 10/refer at 37. Have now moved temp setting to a 5. This is a new to us boat, and we are currently at a dock until noon on the 30th. trying to get someone out to check and service but very worried about heading out and draining the battery with a fridge that isn't working right. Hot days like this are unusual but do happen occassionally.
 
1.) I leave thermostat settings same, under way or on shore power. Otherwise eggs and salad freeze.

2.) Assuming you are on shore power at the dock. Sounds like the "nevercool" is dying. Any idea how old it is?
Things to check: defrost the freezer. Voltage at the fridge, is it at 120VAC on the dock, and is it 12 VDC on the house bank. Clean dust off the condenser. Look for corrosion, signs of leakage on coolant piping.

I had similar experiences when I acquired my boat. Tried recharging the system, no go. In dialog with marine refrigeration guru in Anacortes, he convinced me to just go get a new one, as his fees to come down and tell me that would just add to the cost of replacement. It's a boat-buck project.

Old fridge is now my dock box, works great for that!
 
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The Novakool fridges (and many others) cycle based on evaporator plate temperature. And many off the shelf marine fridges will struggle in hot weather without added insulation.

To help performance, consider adding a small fan inside the fridge to keep a little bit of air circulation in there. That'll keep the temperatures more even inside the fridge and will often improve cooling power a bit. Don't get too much airflow across the evaporator plate though, as if you get fridge temp and evap temp too close you won't be able to keep the freezer cold enough with freezing everything in the fridge.

More airflow across the condenser will help as well. My Novakool RFU9000 performs a bit better since I swapped the original condenser fan for a slightly higher airflow (and quieter) one and also turned it around to pull air in and blow it onto the condenser vs just pulling air out from the condenser area.

I don't mess with the thermostat on mine normally. It stays set to around 4.5 and that keeps the fridge around 35* or so (freezer is usually in the mid teens on average).

The Novakool fridges tend to have borderline undersized compressors, so in very hot weather they'll often run non-stop, but the power draw isn't super high with the small compressor. A bigger compressor would cycle more, but also draw more power while running. Adding more insulation around the outside of the fridge (if you have space) will improve performance and reduce power consumption as well.
 
If everything has worked correctly in the past, it sounds like a refrigerator problem, maybe the thermostat or possibly it needs to be defrosted. From my limited experience, if it can reach desired temperature, it's unlikely to be the compressor. I'm not familiar with NovaKool. Are the evaporator coils (what make the cold inside) exposed? It's worth checking to make sure they and the air passageways are free of ice.

Ted
 
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1. Humidity in the boxes the enemy. Based upon my experience.
2. There are many entries addressing the NovaKool forum. I have a 9000 12vt. I have done many modification to improve the operation and efficiency. maybe it work a little bit but I feel it was worth it.
3. see #1. Don't open the door too many times during the day. The NovaKool is not a household fridge. It is not an auto defrost as I am sure you have discovered. Word has it, no more than 1/4 of frost before defrosting.
4. Chill or freeze everything at home before putting it in the boxes on the boat.
5. Replace the door gaskets.
6. Put a grill low and a couple fans to force air in the compressor area and to force air across the condenser.
7. Put vent up high to get the hot air out from behind the boxes.
8. Put and tape insulating board on the top and 2 sides.
9. Investigate the Stainless Lobster. I have one installed. One benefit is, it shuts the system every 12 hour for a user defined time. I set it for 20 minutes every 12 hours.

To recap, the NovaKool is not a home type fridge, keep the door closed, humidity is your enemy.
I hope the above helps.
Ah one more caution, 40F in the main box, is a safe temp. The freezer, gotta keep the ice cream from melting. That means the ice cream has to share the ice cube area.
 
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"This is a new to us boat, and we are currently at a dock until noon on the 30th. trying to get someone out to check and service but very worried about heading out and draining the battery with a fridge that isn't working right. Hot days like this are unusual but do happen occassionally."

Are you identifying a fridge operational problem, a battery and power system problem or a fridge/power consumption problem?
You haven't given enough clues to know which, as you don't tell us whether your Novacool is DC, AC or AC/DC. Nor di you tell how old it is, how old your battery bank is or its capacity. All of that information would help identify the problems.

When our boat was new to us, the fridge was a Norcold AC/DC that performed much the same way as you have described. A local "Freddy Freezer" correctly diagnosed and fixed the problem. Out came the internal inverters , internal to the fridge, and the rest of the AC/DC fridge systems went into his garbage, as they consumed an excessive amount of power, that our house batteries failed to properly support. In went a DC only Danfoss unit, reducing daily power need to so far below our capacity that on the next battery replacement the house bank was reduced to 1/2 of its former total amp capacity. Since then, even after adding a DC freezer, our house bank has an new average of over 10 years between replacements, 4x6v Golf Cart FLA batteries. The fridge is performing flawlessly, as is the freezer. Those changes were done roughly 24 years ago. ymmv.
 
This is the best part of Trawler Forum. Grilled veterans offering experience-based advice. A lot of us have Novacool fridges and have had what I can only describe as “bad days/weeks” with them, then they settle down and go back to normal. I think it is all about overloading them with too much warm stuff, then turning them up to compensate and all the lettuce freezes. Then back to equilibrium if you let things settle. As one said, it is not a household fridge, that is for sure.

But there was a thread here in the advice I would like to know more about since we are adopting a Helmsman 38. There are repeated suggestions—or variations on that theme— to add fans to get air into the compressor area and across the condenser. I get the rationale for this, but wonder how to pull this off since most of us have Novacool (enjoyed the “Not-so-cool snark) fridges that are built in with little room to mess around. Am I missing something?

thanks.
 
I meant “grisled” veterans. Darned autocorrect.
 
Our last boat had a Vitrifugo in it. It didn’t cool well or freeze well. I added a small 50 mAmp fan that was powered off the circuit board to run when the compressor ran. Also added a vent both high and low in the refer cabinet. The fan drew cool air into the cabinet and blew over the compressor. It blew cool air into the cabinet and hot air up and out the high vent. The performance of the refer increased dramatically. Most boat manufacturers don’t provide adequate venting for the refer cabinet.
 
Thanks. What you are describing, I think, is something close to those very quiet computer cooling fans that draw very little amps. I have studied the Helmsman 38 and there is a vent above the fridge, which is good. So perhaps a fan that can force air out of that is sufficient, providing there is enough flow into the cabinet behind the fridge. To be determined once I have hands on the boat.

I have struggled with this problem on our Ranger Tug, so am happy for advice.
 
This is the fan I used. Got it on Amazon. Very quiet and extremely low current draw. The only problem is the wires for it are very small and a bit of a pain to splice.

Noctua NF-F12 PWM, Premium Quiet Fan, 4-Pin (120mm, Brown)
 
Respected boat expert and author Nigel Calder published a book on refrigeration, from design, build, to maintenance. Useful book. Even if I struggle with how heat produces cold.
 
There is no cold, that is just us humans reference scale.
Everything has heat, has a temperature. Refrigeration just moves heat from one place to another.
 
koliver said:
"This is a new to us boat, and we are currently at a dock until noon on the 30th. trying to get someone out to check and service but very worried about heading out and draining the battery with a fridge that isn't working right. Hot days like this are unusual but do happen occassionally."

Are you identifying a fridge operational problem, a battery and power system problem or a fridge/power consumption problem?
You haven't given enough clues to know which, as you don't tell us whether your Novacool is DC, AC or AC/DC. Nor di you tell how old it is, how old your battery bank is or its capacity. All of that information would help identify the problems.

When our boat was new to us, the fridge was a Norcold AC/DC that performed much the same way as you have described. A local "Freddy Freezer" correctly diagnosed and fixed the problem. Out came the internal inverters , internal to the fridge, and the rest of the AC/DC fridge systems went into his garbage, as they consumed an excessive amount of power, that our house batteries failed to properly support. In went a DC only Danfoss unit, reducing daily power need to so far below our capacity that on the next battery replacement the house bank was reduced to 1/2 of its former total amp capacity. Since then, even after adding a DC freezer, our house bank has an new average of over 10 years between replacements, 4x6v Golf Cart FLA batteries. The fridge is performing flawlessly, as is the freezer. Those changes were done roughly 24 years ago. ymmv.
Click to expand...

I'm on a pretty steep learning curve after 21 years with my Cataline 34 (with a Sea Freeze of America low draw ice box and4 T105's in two house banks ) But today I finally nailed down a few things. I am pretty certain the boat is a DC only fridge. The fridge only has an off/off breaker/switch on the DC panel. No fridge on the AC side. Talked to the PO today at length, and that's what he thinks. We have been at the dock only so far, and there is AC poweron the boat and a Vitron inverter/charger. But at the dock it is switched to charger only. And if you turn off the power on the DC side that says "refrigerator" the fridge goes off. So at the dock, the charger should be taking care of the battery charging needs. Have two Rolls 6 volt batteries. They both say 820 amps, and as per prior post, learned that when putting 6 volt batteries in series, it double the volts to 12 but does not double the amp hours. (when I first saw the 820 AH on each battery, I thought "wow, that's 1640 AH, but alas, I learned it is 820 total AH. The boat is an 08 and probably original batteries and getting close to their advertized life of 15 years as per the manufacturer. I posted a pic of them in a recent thread here. All battery cells are measuring 13 with a hydrometer. so I hope it is something as simple as needing a freon recharge, and a miracle occured as I got a refer. company from a nearby town to commit to coming out Thursday afternoon. Hope it's not bad news. but going to look up the info on Dan Foss.
 
Capran
If it were me, I would pull the fridge out of its enclosure and get eyes on it. That way you no longer need to guess what your hardware is made of.
Google Danfoss compressors. If yours look like it, great, if not, you might find some identifiers.
 
I don't know the setup of Novacool fridges, but we do a couple of things that would be universal for lowering electrical use. I bought "fridge organizer" bins like these.
They come in many shapes and sizes, so it takes some time to get the right size for a particular fridge. They serve several purposes. First, when the door is opened, the bins limit the amount of air exchange (cold in, warm out). Second, if they are really used to organize, they can save door openings and time searching by having all "sandwich condiments," for instance, in one bin. Mustard, ketchup, mayo, dill pickles, etc. all out on the counter in a single bin with one door opening.

We have a circulation fan installed on the back of our fridge. I also put in a new vent so that the area behind the fridge has good circulation. I set it up so that the fan exhausts warm air into the cabin and draws in cold air from outside. Obviously, that works in the PNW. In hot climes that could be reversed.

We keep our freezer section completely full of blue ice blocks. That allows us to turn off the fridge for 24 hours after a long day's cruise. We also turn it off at night. I've never been comfortable using my freezer section for meat, etc. Too much chance of undetected partial/total thaw and refreeze. We've figured out simple work-arounds to avoid using the freezer qua freezer and instead use it to reduce the electrical draw of the fridge.
 
Most of the Nova Kool 9000 fridges I have seen are AC/DC. Capran, yours might be, too. The outlet for the fridge may be on the galley or salon circuit. The new 38E’s come with a separate AC breaker for the fridge.

I had to work on a NovaKool 9000 before. My issue turned out to be the AC DC converter. Look at the wiring inputs, generally on the left side. The AC DC module is 101N0510. The compressor runs off 12 volt power, so the AC is converted to DC with this module, along with running the compressor, the fan, the lights, etc. you can change from DC only to AC and DC by switching out the module. Not necessary, but can if you want to.

If I were you, I would pull the fridge, and clean it well. That may go a long way towards fixing the issue. I would check the wire connections for corrosion, clean if necessary, and then I would take the advice about opening it too often. Adding a fan that is a little more powerful also will help, though make sure you look at the manual, and don’t put one in that exceeds the amperage draw for that circuit.

The last step would be calling a technician.
 
I would start by pulling the refer out of the cabinet and running it. See if it works well. If it does then it is most likely a ventilation problem. I am going to do this to the refer in our current boat because it runs but doesn’t cool well. If it doesn’t cool well outside the cabinet then you can start searching for some other problem.
 
Helmsman said:
Most of the Nova Kool 9000 fridges I have seen are AC/DC. Capran, yours might be, too. The outlet for the fridge may be on the galley or salon circuit. The new 38E’s come with a separate AC breaker for the fridge.

I had to work on a NovaKool 9000 before. My issue turned out to be the AC DC converter. Look at the wiring inputs, generally on the left side. The AC DC module is 101N0510. The compressor runs off 12 volt power, so the AC is converted to DC with this module, along with running the compressor, the fan, the lights, etc. you can change from DC only to AC and DC by switching out the module. Not necessary, but can if you want to.

If I were you, I would pull the fridge, and clean it well. That may go a long way towards fixing the issue. I would check the wire connections for corrosion, clean if necessary, and then I would take the advice about opening it too often. Adding a fan that is a little more powerful also will help, though make sure you look at the manual, and don’t put one in that exceeds the amperage draw for that circuit.

The last step would be calling a technician.
Click to expand...

That will be a top question. In my newbie attempt to understand the power involved, about all I could do was make sure the AC power was on, and the fridge was running and light comes on inside, and when we turned off the only breaker that is labeled refrigerator (which is on the DC side of the panel) the fridge stopped working and the light did not come on, which makes me think there's no AC power involved. I cleaned it as best I could without removing anything. It was 89 degrees in the boat both days it failed to keep things cold. Today it is rainy and 70 and the fridge seems to be working fine, and at night after the hot days it seemed like it was back into the 10 degree range on the freezer and 37 in the fridge. I do feel lucky I was able to get a tech to schedule for the afternoon of the 30th. Won't be cheap, as it's 120 service fee plus 1 hr minimum, and we'll have to pay the daily rate at the marina since our monthly rate expires, but hopefully they will give me answers to your great suggestions- things like insulation, circulating fans both inside and outside, etc Fingers are crossed. An American tug just pulled in and he said on hot days he has had the same thing happen, so maybe that's reassuring. And maybe the tech can tell me which one I have, as I have no manual aboard, which is disgraceful! I had a manual for everything installed on my Catalina 34 as well as an actual boat manual with diagrams of all original systems (wiring, plumbing, etc) Can't believe Helmsman sells such as expensive boat and can't be bothered to produce a manual. LOL
 
capran said:
Can't believe Helmsman sells such as expensive boat and can't be bothered to produce a manual. LOL
Click to expand...

Have you called and asked them for the manuals ??

I will be following your experience with great anticipation
 
capran said:
That will be a top question. In my newbie attempt to understand the power involved, about all I could do was make sure the AC power was on, and the fridge was running and light comes on inside, and when we turned off the only breaker that is labeled refrigerator (which is on the DC side of the panel) the fridge stopped working and the light did not come on, which makes me think there's no AC power involved. I cleaned it as best I could without removing anything. It was 89 degrees in the boat both days it failed to keep things cold. Today it is rainy and 70 and the fridge seems to be working fine, and at night after the hot days it seemed like it was back into the 10 degree range on the freezer and 37 in the fridge. I do feel lucky I was able to get a tech to schedule for the afternoon of the 30th. Won't be cheap, as it's 120 service fee plus 1 hr minimum, and we'll have to pay the daily rate at the marina since our monthly rate expires, but hopefully they will give me answers to your great suggestions- things like insulation, circulating fans both inside and outside, etc Fingers are crossed. An American tug just pulled in and he said on hot days he has had the same thing happen, so maybe that's reassuring. And maybe the tech can tell me which one I have, as I have no manual aboard, which is disgraceful! I had a manual for everything installed on my Catalina 34 as well as an actual boat manual with diagrams of all original systems (wiring, plumbing, etc) Can't believe Helmsman sells such as expensive boat and can't be bothered to produce a manual. LOL
Click to expand...

There is a manual available for the fridge. As to the electrical inputs to the fridge, check the model number on the power module behind the lower vent. NovaKool sells both a DC and an AC/DC model.

Look at the owner’s notes on San Juan Sailing. Those notes may help for your boat.
https://sanjuansailing.com/charter-detail/power/amyann/content/amyann_owners_notes.pdf
 
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Here is the manuals for NovaKool.

https://www.novakool.com/guides-and-manuals

Here are some videos from NovaKool that should prove useful.

https://www.novakool.com/support-videos

Here is the two modules.

AC DC

https://www.suremarineservice.com/Galley/Nova-Kool-Parts/ELECTRONIC-ACDC.html

DC

https://www.suremarineservice.com/Galley/Nova-Kool-Parts/ELECTRONIC2000.html

Older models had a silver box beside the DC module to convert the AC to DC. They were problematic and were replaced by the combined module above. An easy change out for me.
 
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I am not a big fan of NovaKools. Our Fridge was icing up a lot during the summer and I had to remove the ice from the evaporator tubes every few days during peak humidity months. I put an Isotherm in there a couple years ago and no more ice problems with the fridge, and only minimal in the freezer. The Isotherm still struggles a bit during the warm humid months and I have to keep the dial setting fairly high. It has low and high venting, but the comments about an air circ fan across the condenser in the enclosed cavity space are good. I will probably do that at some point.
 
I've been happy with my Novakool, but I really, really wish they'd started offering the dual compressor RFU9200 before I bought mine (it came out about a year after). The extra cooling power and separate freezer temp control would be very nice. Mine definitely builds ice, but nothing I'd consider excessive. And interestingly, ice buildup (within any reasonable amount) doesn't seem to have much effect on performance. So I just defrost a couple of times during the summer (every 4 - 8 weeks) and call it good.

Isotherm makes good units too. The guts are basically the same, just different packaging. In my case, the Novakool was easy to add insulation to and a slightly better fit in the hole I have, on top of a slightly larger internal volume.
 
Helmsman said:
Here is the manuals for NovaKool.

https://www.novakool.com/guides-and-manuals

Here are some videos from NovaKool that should prove useful.

https://www.novakool.com/support-videos

Here is the two modules.

AC DC

https://www.suremarineservice.com/Galley/Nova-Kool-Parts/ELECTRONIC-ACDC.html

DC

https://www.suremarineservice.com/Galley/Nova-Kool-Parts/ELECTRONIC2000.html

Older models had a silver box beside the DC module to convert the AC to DC. They were problematic and were replaced by the combined module above. An easy change out for me.
Click to expand...

Thank you all for the info. Now to sort it out. I did open it up today to see if there is a model number. but nothing that says "model number". do you know what these numbers mean? BD35F DanFoss 101Z R134a 6757FTEA 0204 made in germany serial number 247418. those are all on the round tank like thing which I assume to be the compressor. It feels warm to the touch. also, noticed a drop of water coming from the copper line with a bit of coiled copper on it just before where the insulation is just above the compressor. tried to submit a pic but not really computer literate. not sure if that is a leak or condensation
 

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That is the compressor. Look to the left of it at the power module and the number will tell you whether you have a AC/DC or just DC. The fan is to the right of the compressor I think, and the cooling fins are to the back. Clean those off. This is from memory, but I think I am right. Make sure your fan is running when the compressor is running. Cleaning the cooling “fins” May correct the issue for you, but you will probably need to pull the fridge out to do that. Eight or ten screws along the sides of the fridge, put a piece of cardboard down and slide it out on to the cardboard. A good time to clean everything off, open the fridge and let it heat up a little, then place a house fan along the back and how it cools down. If it cools fairly quickly, then you need more cooling in the back. A good time to also defrost it.
 
When anchoring we often shut our inverter off at night. With a 12/110 volt fridge this is a huge at anchor power savings with the fridge slipping into the 12v mode. There is a separate breaker for both voltages. Our Nova K is into its 14th year and performing well. Boating in the PNW is pretty easy on a fridge though. Fish freezers, now that is the challenge for many.
 
Helmsman said:
Here is the manuals for NovaKool.

https://www.novakool.com/guides-and-manuals

Here are some videos from NovaKool that should prove useful.

https://www.novakool.com/support-videos

Here is the two modules.

AC DC

https://www.suremarineservice.com/Galley/Nova-Kool-Parts/ELECTRONIC-ACDC.html

DC

https://www.suremarineservice.com/Galley/Nova-Kool-Parts/ELECTRONIC2000.html

Older models had a silver box beside the DC module to convert the AC to DC. They were problematic and were replaced by the combined module above. An easy change out for me.
Click to expand...

Wow. very interesting. from my pic I can see that I have the 101N0500. and yet "refrigerator" is only on a breaker on the DC side, and when I turn off the DC side "refrigerator" toggle, it shuts off. I will post what the tech guy says tomorrow before cocktail hour. Very curious!
 
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