2005 Hunter 36 Fridge and Freezer Power Consumption

[drm1]

Hi, I have the original freezer and fridge provided by Hunter. My AGM house batteries are 4 x 6V AGM, with an isolated starting battery.

I think they are consuming a ton of my power budget.

I was wondering if anyone has replaced these and how it went? Looking for something that is a drop in replacement

dan

 

[Terry Cox]

Hi, I have the original freezer and fridge provided by Hunter. My AGM house batteries are 4 x 6V AGM, with an isolated starting battery.

I think they are consuming a ton of my power budget.

I was wondering if anyone has replaced these and how it went? Looking for something that is a drop in replacement

dan

Hi Dan. Different model boat, but if it were mine, first I would determine the draw from each unit, assuming these are completely separate with dedicated compressor, condenser and evaporator. Our separate units are made by Dometic Adler Barbour, each controlled by a thermostat. It would help to know the brand and whether yours are air cooled versus water. Do your units run all the time or do they cycle? If they are running all the time to maintain cold, perhaps time for a recharge. Lots of other questions before jumping to replacements.

 

[jssailem]

If they are running all the time to maintain cold, perhaps time for a recharge. Lots of other questions before jumping to replacements.

Terry is correct about recharge, and the unanswered questions.
There is no info provided on the age of your boat. Insulation was not always thought needed or was an after thought on older boats. Are there leaks of your chilled air? That will add to your power issues. Check out the info here on SBO by @Hayden Watson. He did a write up on his refrig modifications that helped him keep his food cold and reduce his energy needs.

Or you could just spend money with NovoKool on new gear. They are a Canadian company out of BC. Provide good hardware to chill your provisions.

 

[drm1]

Hi Dan. Different model boat, but if it were mine, first I would determine the draw from each unit, assuming these are completely separate with dedicated compressor, condenser and evaporator. Our separate units are made by Dometic Adler Barbour, each controlled by a thermostat. It would help to know the brand and whether yours are air cooled versus water. Do your units run all the time or do they cycle? If they are running all the time to maintain cold, perhaps time for a recharge. Lots of other questions before jumping to replacements.

Thanks Terry. Yes they are two separate units.

The refrigerator is made by Novakool model # R1600. Draws 2.4 amps @12VDC when it's running. On the hard now, so will need to wait for spring to guage how often the compressor is running. I think it is air cooled.

The freezer is also Novakool, model #F1900. Draws 4.4amps @ 12vdc when it's running. I think it's also air cooled. I do think the freezer compressor is almost always running.

Not sure how to recharge them. Have you done this before? I didn't know they were rechargable.

 

[drm1]

Terry is correct about recharge, and the unanswered questions.
There is no info provided on the age of your boat. Insulation was not always thought needed or was an after thought on older boats. Are there leaks of your chilled air? That will add to your power issues. Check out the info here on SBO by @Hayden Watson. He did a write up on his refrig modifications that helped him keep his food cold and reduce his energy needs.

Or you could just spend money with NovoKool on new gear. They are a Canadian company out of BC. Provide good hardware to chill your provisions.

Thanks John. I guess I didn't do a great job of including enough information in my original post. i added the age (2005 model year, original fridge and freezer).

The fridge and freezer are Novakool. The spec sheet says there is urethane foam in the cabinet and doors. IHunter did add insulation but i will need to do a visual check to confirm.

I don't think there are any chilled air leaks but I will check out the post.

thanks for the help!

 

[George Braun]

on our 2008 H36 we also have NovaKool units. Air-cooled, that's why the compartment behind the units is vented, and yes, they pull a large portion of your energy budget while cruising. Boat is still new-to-us, our first answer is going to be doing it the easy way, adding 100AH worth of additional battery capacity.

 

[Terry Cox]

Not sure how to recharge them. Have you done this before? I didn't know they were rechargable.

Good morning, Dan. Our Adler Barbour units are rechargeable. The top loader freezer unit is 1991 original and had to be recharged when we purchased our boat in 2002, but not since. The original top/front loader fridge unit compressor died in 2014 and I replaced the complete unit with same myself. I hire a marine refrigeration guy to recharge our unit as I do not have the necessary equipment.

While our system boxes are well insulated I did add door insulation strips to the tops in order to stop/reduce air bypass, which helped. Frosting up is one indication of air leaking in/out. Our units remain on all the time, but cycle depending on ambient temperature. Amp consumption for both remains about the same as you're 2.4 ah. Ours cycle about four minutes on and ten off depending upon how often we open. Our boat has two 8D AGMs that supply a total of 520 ah. Normally, I run the 8kw Genset for 1.5 hours every other day to keep the house bank up.

 

[Hayden Watson]

For recharging, most of these units only have the low-pressure port and it usually will have the old style Schrader valve. You can get a conversion fitting to screw onto the Schrader valve and convert it to the standard quick connect used on car systems. They are very difficult to use gages on because the volume is so small. The best way to check it is to run the system for about 10-minutes and the frost line on the evaporator should be 3/4 to full height but the return line should not have frost on it. Just add R134A a bit at a time until the frost level is correct.

 

[Peggie Hall HeadMistress]

Fwiw, turning off the fridge/freezer breaker every night last thing before you go to bed (neither will be opened again until you turn the breaker back on in the morning) really helps to reduce impact on your power consumption. Since neither will be opened when you're away from the boat, most contents will remain cold/frozen enough for several days.

That was my experience, anyway.

--Peggie

 

[drm1]

For recharging, most of these units only have the low-pressure port and it usually will have the old style Schrader valve. You can get a conversion fitting to screw onto the Schrader valve and convert it to the standard quick connect used on car systems. They are very difficult to use gages on because the volume is so small. The best way to check it is to run the system for about 10-minutes and the frost line on the evaporator should be 3/4 to full height but the return line should not have frost on it. Just add R134A a bit at a time until the frost level is correct.

Thanks Hayden!

 

[drm1]

Good morning, Dan. Our Adler Barbour units are rechargeable. The top loader freezer unit is 1991 original and had to be recharged when we purchased our boat in 2002, but not since. The original top/front loader fridge unit compressor died in 2014 and I replaced the complete unit with same myself. I hire a marine refrigeration guy to recharge our unit as I do not have the necessary equipment.

While our system boxes are well insulated I did add door insulation strips to the tops in order to stop/reduce air bypass, which helped. Frosting up is one indication of air leaking in/out. Our units remain on all the time, but cycle depending on ambient temperature. Amp consumption for both remains about the same as you're 2.4 ah. Ours cycle about four minutes on and ten off depending upon how often we open. Our boat has two 8D AGMs that supply a total of 520 ah. Normally, I run the 8kw Genset for 1.5 hours every other day to keep the house bank up.

Thanks Terry. I'll give the Nova Kool folks a call to see if our models are rechargeable.

I don't get any frosting up on the freezer, but I've tried turning off overnight to conserve battery and the food thaws a bit. So there may be an air leakage issue. I will check it out.

There is a small freezer section in the top right part of the fridge that gets frosted up almost immediately when we turn on the fridge. Not sure that's and air leakage problem though but it may be. I will check it out, along with the cycling.

I have 4x6V Deep Cycle 225Ah. Don't have a Genset, but when i replaced the batteries i upgraded the standard 60A alternator with 120A. Need to run the Yanmar every 2 days to recharge the batteries. Thinking of adding solar to top up so I can run the Yanmar less often

 

[drm1]

on our 2008 H36 we also have NovaKool units. Air-cooled, that's why the compartment behind the units is vented, and yes, they pull a large portion of your energy budget while cruising. Boat is still new-to-us, our first answer is going to be doing it the easy way, adding 100AH worth of additional battery capacity.

Thanks George. Just replaced the batteries, hopefully Li will be a little more cost effective in a couple of years when then need replacing again

 

[drm1]

Fwiw, turning off the fridge/freezer breaker every night last thing before you go to bed (neither will be opened again until you turn the breaker back on in the morning) really helps to reduce impact on your power consumption. Since neither will be opened when you're away from the boat, most contents will remain cold/frozen enough for several days.

That was my experience, anyway.

--Peggie

Thanks Peggie.

Yes a good suggestion. We do that sometimes but find that the food in the freezer thaws a bit overnight. I know that this isn't supposed to happen with a freezer since that indicates it's not sealed properly. May be an air leakage problem as Terry referenced. I will check it out.

 

[Hayden Watson]

...
There is a small freezer section in the top right part of the fridge that gets frosted up almost immediately when we turn on the fridge. Not sure that's and air leakage problem though but it may be. I will check it out, along with the cycling.
...

The condenser will frost up immediately if it is cooling correctly and that does not indicate air leakage. It is just the water vapor that it naturally in the air freezing to the condenser. The indication of air leakage is excessive buildup of ice on the condenser.

 

[Hello Below]

I think they are consuming a ton of my power budget.

Yes all marine fridges/freezers are power hogs regardless of manufacturer, some use a little less power, others use a little more. Power consumption will change depending on ambient temperature, unit door openings, ventilation amongst other variables. Also a full fridge/freezer is much more efficient than an empty one.

The refrigerator is made by Novakool model # R1600. Draws 2.4 amps @12VDC when it's running. On the hard now, so will need to wait for spring to guage how often the compressor is running. I think it is air cooled.

The freezer is also Novakool, model #F1900. Draws 4.4amps @ 12vdc when it's running. I think it's also air cooled. I do think the freezer compressor is almost always running.

Without knowing the duty cycle (ie how much the compressor runs on average/hour) I have to ask why do you feel the need to replace them? A check of the specifications for your Novakools show they are both on the money when running.

I have 4x6V Deep Cycle 225Ah. Don't have a Genset, but when i replaced the batteries i upgraded the standard 60A alternator with 120A. Need to run the Yanmar every 2 days to recharge the batteries.

Is 225Ah a total of your house bank capacity? If so, using a 33% duty cycle for both your fridge and freezer results in a usage of approximately 100 Ah over 2 days. This is not including any other additional load that you will obviously have during those 2 days. If you only have to recharge them every 2 days then you are doing well.

IMHO it is important to determine if the units are broke before you try to fix them or replace them.

NovaKool Specs

 

[ice breaker]

I have the same frig and freezer. The fridge has worked very well with no maintenance issues. The freezer is JUNK. And there are no slide in replacements. I had a small leak in the cooling plate that was repaired and then the system was evacuated and recharged with the appropriate amount of 134a. A couple of add on items can help reduce the running time. Get a digital thermostat; I keep it set to shut off at 16F and turn on at 21f. Also, there is a an OEM fan on the compressor trying to cool things down. I piggy backed a 12 volt large computer fan to the existing fan and drive the heat out of the freezer cavity to the under sink area. They both have helped to make it run less.
But as you say, they do use a lot of power.

 

[Terry Cox]

There is a small freezer section in the top right part of the fridge that gets frosted up almost immediately when we turn on the fridge. Not sure that's and air leakage problem though but it may be. I will check it out, along with the cycling.

You are most welcome, Dan. Hope this exchange helps. Our freezer runs for a couple of years before the evaporator plate needs defrosting. Ditto the freezer box in our fridge.

As others have said, our refrigeration system consumes the most ah during the course of a day. I keep our thermostats set at just below freezing so that I have ice and frozen food, but not super cold. Also, I try to minimize how often I need to open either one so as to minimize cold loss.

 

[Peggie Hall HeadMistress]

We do that sometimes but find that the food in the freezer thaws a bit overnight. I know that this isn't supposed to happen with a freezer since that indicates it's not sealed properly.

Or maybe insufficient insulation...?
--Peggie

 

[marcham]

1) do you have a power monitor ? ie: Victron SmartShunt?
2) How's the insulation around the fridge and freezer?
3) How's the condition of the door seal?
4) Is the seal where the cooling lines pass into the fridge/freezer in good condition?
5) What's your ambient temperature?
6) How's the ventilation in the compressor compartment?

For comparison, on my 380, the fridge/freezer combo burns through about 80 Ah per 24 hrs. Outside temps around 20 deg C, water around 10 deg C. Previous owner and installed extra insulation.

No such thing as a drop-in replacement refrigeration project. It's gonna cost many BOAT units and days of work, especially if cabinetry needs to be adjusted. Probably easiest to improve the insulation and replace with a new compressor and new evaporator.

Charging every 2 days doesn't tell us much .... for how long? At what RPM? Do you have an external regulator? It would probably take 5-8 hrs to fully charge from 50% using the alternator. If you're running the engine for 2-3 hrs every 2 days, you're probably just putting 100-150 Ah back into your 450Ah bank.
Like others have said, engine running every 2 days, assuming you don't discharge below 12.0V, you're doing really good.

 

[wpatch]

We had to get a new novacool fridge after a defrosting with a screwdriver went badly.
Frustrating, but the new model is awesome. I can make ice while underway in the ice cube tray!