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

[hollywood8118]

same goes for just a bowl of ice cubes, if you have a bowl of water or a solid bowl of ice you know the freezer thawed and refroze at some point.
Hollywood

 

[HeadedToTexas]

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.

Mine is a Mariner 37, hull #3, and it has both AC and DC breakers for the fridge.

I’m reading this today because when I arrived at the boat in this week’s heat wave, my beer and half & half was all warm and the ice was melting. I had always left the fridge on AC when on shore power, but when I discovered the warm beer and melting ice, there was no warm air coming out of the top front vent.

After maybe 10 minutes of thinking and sweating in the steamy 90+ salon, I switched over to DC and warm air at the top vent resumed shortly after the compressor started. I clearly have some more troubleshooting to do and will be doing a cleaning and perhaps a fan upgrade.

 

[HeadedToTexas]

In the event that I end up buying a new fridge, what brand and model is Helmsman using in the 38e today? And what is the best upgrade model that fits that space?

 

[rslifkin]

The AC side of the control modules gets flaky sometimes. Mine did earlier this year, so I just flipped the AC fridge breaker off and it's been running perfectly fine on DC all season.

 

[HeadedToTexas]

That may become my long term strategy as well.

 

[Helmsman]

In the event that I end up buying a new fridge, what brand and model is Helmsman using in the 38e today? And what is the best upgrade model that fits that space?

Helmsman supplies a NovaKool RFU 9000. One alternative would be to get the 9200 which has dual compressors, one for the fridge and one for the freezer.

 

[rslifkin]

Helmsman supplies a NovaKool RFU 9000. One alternative would be to get the 9200 which has dual compressors, one for the fridge and one for the freezer.

That would be my preferred upgrade. Anything else that fits in the same hole has a smaller internal volume. And the way the Novakools package their components it's fairly easy to add more insulation and make a few other tweaks for better performance.

 

[C lectric]

Another chime in here.
.
I have the Nova COol 4500. Now about 6-8 yrs.
Many fridges, not just Nova Cool have problems because the boat builders do a half baked job. Not all but too many builders.

Venting is critical. If there is inadequate ventilation of the recess/cavity into which the fridge is fitted it cannot cool properly, run and run as it will. It must be able to get rid of the hot air that accumulates in that recess as the compressor removes heat from the food as it tries to keep the food cool. Once that hot running is reached turning the temp controll will not change things as you saw. THe fridge compressor is doing all it can.

On the back of the compressor controller is an outlet that will provide up to 0.5A of 12VDC. or 500 milliamps to drive a fan that can be used to exhaust the recess. There are many 4" muffin type fans that can operate on much less than that current , approx 150 to 200 millamps. But that fan must be located at the top of the cavity and so it can blow out, not blow in.

Mine blows directly to the outside through a cover by a SS vent panel. That vent could be set to blow into the salon if there is no access to the outside. THat happens if the fridge is located in a galley down situation.

I too learned this the hard way. Years ago I had a Norcold that ran and ran and ran in really hot weather.. killing the batteries. I realized what was going on and rigged a fan like described above. That made a huge difference in the fridges performance. My old Norcold drew much more current though which is why I eventually gave it away even after some serious tuning improved things a lot.

If the cabin side the fridge is mounted to is beaten on by the sun that will raise the cavity temp. a lot meaning the fridge cannot do as effective a job as it is capable of doing. Protect that area with a canvas cover and the cavity temp. will drop and the fridge will perform better. Better cooling and less current draw from the batteries.

If the fridge runs then it is the boat that is the problem. Inadequate ventilation is a primary cause. Then look at the cavity protection and then maybe way down the list is the fridge itself.

Questions, then ask. And no I am not a refrigeration mechanic, just an owner who has been through this headache.

 

[C lectric]

I can't modify my above posting so this.

Do not use two smaller fans. I did that and it failed. Individually the two 3" fans were dead quiet, barely hear them. Together they made a lot of racket sounding like a small jet engine. I still have them at home but replaced them with one 4" unit of the same capacity and current draw. And a LOT quieter.
I have to listen for the 4" now.

Another missed item is air must also be able to enter the cavity at or near the bottom and rise up close behind the unit to draw heat from the cooler tubes.

I have not done it, no need as I've found, but some have reported the use of a second fan to simply force circulation inside the cavity seems to help also.

 

[HeadedToTexas]

Helmsman supplies a NovaKool RFU 9000. One alternative would be to get the 9200 which has dual compressors, one for the fridge and one for the freezer.

Is that second compressor worth the additional $1300? The power consumption listed is very similar for the two models.

And is it safe to assume it is a direct replacement for the old unit?

 

[HeadedToTexas]

Another chime in here...

Whew, that is good stuff. Thanks C letric!

 

[rslifkin]

Is that second compressor worth the additional $1300? The power consumption listed is very similar for the two models.

And is it safe to assume it is a direct replacement for the old unit?

In my mind, yes. It gives separate fridge and freezer temp control. So you can get the freezer colder without freezing stuff in the fridge. And it'll be a little easier to tweak to get maximum cooling power and minimum power draw out of the fridge portion.

Form factor wise, the 9000 and 9200 are the same. Just more stuff in the lower equipment section on the 9200.

 

[Helmsman]

Is that second compressor worth the additional $1300? The power consumption listed is very similar for the two models.

And is it safe to assume it is a direct replacement for the old unit?

I don’t know. Haven’t looked at the specs. I do believe it is the same size. The only other issue I can think of is the electricity usage and whether the wires, breakers and/or fuses are the right gauge for it. Probably are, but I would look at it. I would give NovaKool a call. They were tremendously helpful to me a couple of years ago when I had to replace the power unit.

I think the other “fixes” would remain important to do, if possible. The fan, the insulation, etc. the venting should be fine.

 

[HeadedToTexas]

I will definitely pursue the fixes I can do, but it's good to have that back up in my saved file. Thanks guys.

 

[Helmsman]

Here are the product specs.

https://static1.squarespace.com/sta...835/Spec+Sheet+ImperialMetricLT+2021+-+R3.pdf

 

[rslifkin]

Efficiency wise, with the 9200 you can add fans to move more air across the evaporator and then turn the thermostat up. That'll keep box temp and evap temp closer. Based on the compressor spec sheets that both improves cooling capacity and efficiency. Can't do that with the single compressor as the freezer will end up at fridge temp.

 

[HeadedToTexas]

Better intel on my situation after this week's trip to the boat. Our fridge is a Norcold DE0061. The manual troubleshooting guide says if the simple stuff checks out, which it does, either the controller board overheated at 212 F or the ambient temperature exceeds 110 F.

The support folks assure me that the controller is almost certainly way under 212 degrees, but the boat interior could easily be 110 degrees in the summer. The support folks explained that the manual should probably say "if it's that hot in your boat, don't expect your pop to stay cold."

That is the bottom line. Norcold's RV and marine refrigerators just aren't designed to cool in extreme conditions. Our fridge works just fine when the boat is in the 80s or lower. I found the freezer temperature at 13 F and the fridge at 30 F when the ambient temperature inside was 75. Can't ask for more than that. The moral of the story is do not leave perishable stuff aboard in the summer.

 

[rslifkin]

Better intel on my situation after this week's trip to the boat. Our fridge is a Norcold DE0061. The manual troubleshooting guide says if the simple stuff checks out, which it does, either the controller board overheated at 212 F or the ambient temperature exceeds 110 F.

The support folks assure me that the controller is almost certainly way under 212 degrees, but the boat interior could easily be 110 degrees in the summer. The support folks explained that the manual should probably say "if it's that hot in your boat, don't expect your pop to stay cold."

That is the bottom line. Norcold's RV and marine refrigerators just aren't designed to cool in extreme conditions. Our fridge works just fine when the boat is in the 80s or lower. I found the freezer temperature at 13 F and the fridge at 30 F when the ambient temperature inside was 75. Can't ask for more than that. The moral of the story is do not leave perishable stuff aboard in the summer.

That's part of why I typically leave the A/C running when we're not on the boat. I don't care if it's 80* inside, but I do care if it's 100+ and humid (both as far as the fridge staying cold and not damaging anything else aboard with heat and humidity).

 

[Comodave]

Get more ventilation around the back of the refer. Add a fan to circulate the hot air up and out a high vent. Have a low vent to allow cool air into the cabinet. We replaced ours with an Isotherm refer and the only problem so far is that it is almost too cold. It froze my wife’s yogurt in the fridge section. We have been turning it down so it isn’t as cold but we have been doing it gradually.

 

[Helmsman]

Better intel on my situation after this week's trip to the boat. Our fridge is a Norcold DE0061. The manual troubleshooting guide says if the simple stuff checks out, which it does, either the controller board overheated at 212 F or the ambient temperature exceeds 110 F.

The support folks assure me that the controller is almost certainly way under 212 degrees, but the boat interior could easily be 110 degrees in the summer. The support folks explained that the manual should probably say "if it's that hot in your boat, don't expect your pop to stay cold."

That is the bottom line. Norcold's RV and marine refrigerators just aren't designed to cool in extreme conditions. Our fridge works just fine when the boat is in the 80s or lower. I found the freezer temperature at 13 F and the fridge at 30 F when the ambient temperature inside was 75. Can't ask for more than that. The moral of the story is do not leave perishable stuff aboard in the summer.

Thanks for the report back. That will help others with the same issue. I guess the marine fridges have a trade off between energy used versus cooling capacity which makes sense to me.

 

[capran]

fridge update

Been out a month and this is the first internet and dock. Thanks to all who replied. Next year going to add the extra fan and also the idea of tupperware for keeping things organized and easier and quicker to retrieve. We did survive a week long 90+ week heat wave in northern BC waters. Fridge is behaving better with new fan and thermostat, as well as not opening it up as often. putting shades on the boat help so will do a permanent fix for next year. depending on heat outside, we've been able to maintain 15-18 freezer and 34-38 fridge with an occassional 40. when it's hot we have a quart frozen which we put in the fridge. on cool days seems like I'm going through about 80 amp hours in 24 hours, and on hot days closer to 100. Getting to know the boat better and taking care of issues as they come up. When we return to civilization, I'll have many more questions. thanks again.

 

[HeadedToTexas]

I guess the marine fridges have a trade off between energy used versus cooling capacity which makes sense to me.

I think so too. Optimizing heat exchange by keeping surfaces clean and fans moving air makes a difference. At the moment, I am weighing the benefits of cleaning and replacing the fan with what seems like a strong likelihood of breaking the 15 year old plastic trim when I remove it to gain access to the business end of the Norcold fridge.

 

[capran]

I think so too. Optimizing heat exchange by keeping surfaces clean and fans moving air makes a difference. At the moment, I am weighing the benefits of cleaning and replacing the fan with what seems like a strong likelihood of breaking the 15 year old plastic trim when I remove it to gain access to the business end of the Norcold fridge.

I wonder if you could install the extra fan at the top by pulling the whole fridge out rather than via those nice looking vents? In the past few weeks our fridge has been doing alot better, using @65 amps per 24 hours and keeping the freezer at 19 or 20 and the fridge at 34-35. it has been in the low to mid 70's outside. inside the cabin up to 79 or 82 max. first project will be flybridge side doors and front screens. that sun makes it super warm in the boat which can't be good for the fridge performance.

 

[Barrie]

"with what seems like a strong likelihood of breaking the 15 year old plastic trim when I remove it to gain access to the business end of the Norcold fridge."

Ours is also a Norcold DE0061. I had the fridge out last year. If you take it easy you should not break the plastic trim.
Barrie

 

[OldDan1943]

Down load from the library on the AT forum, "American Tug 34/41 Owner's experience".
NovaKool
There is a lot of good information in it for the AT. Turn to section Chapter 10. It talks about NovaKool, adding form insulation board and increase the air flow into and out of the fridge cave. Then add a 5 inch pancake fan inside the box to stir up the air. (cycle with the compressor on/off) I added 2 super quite pancake fans at the additional at the compressor air inlet, then finally I piped the hot air from the compressor cave, up and and out a dedicated air outlet.
I had a nice Stainless Lobster but, that died and taking the control module with it (approx. $500-$600 depending on DC only or AC/DC).

5 things to remember
1. increase air flow into and out of the fridge cave,
using a couple of fans forcing air in. (natural
convection is a myth when it comes to the NovaKool
in a cave)
2. add addition foam insulation board to 3 sides of the
boxes. (3/4-1 inch)
3. fan inside the box to stir up the air (cycle with the
compressor.
4. inside the boxes, humidity is the enemy.
5. restrict the opening closing of the doors of the main
box and freezer. Plan ahead.

Come to think of it, unless you have an AT, no need to down load it unless you have an A/T. I gave you the high points. LOL

 

[HeadedToTexas]

So after a significant amount of studying the manual and recruiting the wife to help me remove the trim strip, we got it removed without breaking what feels like fragile plastic. Minor miracle. Getting to the back of the fridge was easy from there. We found it clean with abundant space for air flow, but a fan that just would not start. It ran once I flicked it, but every time the compressor cycles it would fail to restart. A new 120 mm fan and it's ice cold inside again.

I can see how additional insulation would help, but the fridge cabinet is well inside the salon on the Mariner 37 and as good as I can imagine. When it comes to saving watts, I think there are bigger fish to fry on our boat. Additional insulation will have to wait. Thanks all for your help on this. And Barrie, patience is what it took. Thank you.

 

[motion30]

I am currently dealing with the same problem With the same refrigerator. My uneducated consensus is This unit is having difficulty dealing with 95ﾟ ambient temperatures I live aboard full time on the hook so AC is really not an option at this point. I also traded out the fan for a slightly larger one .August is the hottest month in the Florida keys so i am figuring by next month things should get better

 

[HeadedToTexas]

A Norcold customer service rep told me that their refrigerators "are not designed to keep things cool when it's 110º inside." Seems like 95º is in a gray area. Yeesh.

And the manual indicates that the freezer is for keeping things frozen, not freezing things. It's a limited application product.

 

[OldDan1943]

remember inside your fridge, humidity is the enemy unless you have an auto defrost fridge.

 

[Helmsman]

So after a significant amount of studying the manual and recruiting the wife to help me remove the trim strip, we got it removed without breaking what feels like fragile plastic. Minor miracle. Getting to the back of the fridge was easy from there. We found it clean with abundant space for air flow, but a fan that just would not start. It ran once I flicked it, but every time the compressor cycles it would fail to restart. A new 120 mm fan and it's ice cold inside again.

I can see how additional insulation would help, but the fridge cabinet is well inside the salon on the Mariner 37 and as good as I can imagine. When it comes to saving watts, I think there are bigger fish to fry on our boat. Additional insulation will have to wait. Thanks all for your help on this. And Barrie, patience is what it took. Thank you.

Seems like Occam’s razor worked for you. Glad to hear you got it fixed! We need details on successfully recruiting a wife to work on the boat!