novacool fridge

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duetto
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novacool fridge

Post by duetto » Sun Mar 03, 2019 7:09 pm

hi all,

this winter we had our challenges with our fridge. the current one is a direct replacement in 2016. right from installation it frosted up much more than the original, but what did we know. this winter we had a series of complete defrosts. in the end we had 2 problems: 1) the primary one was a corroded spade connector under the fridge. this is a dry place. so you may want to inspect/clean/lubricate this connection. 2) we actually discovered this first. EVERYONE swore our problem was loss of freon. when we actually tested the freon level, it was twice as high as novacool's specification. so, it wasn't leaking and was overcharged from the factory.

on another note, based on the length of the wire from breaker to compressor, novacool specifies #8 or #10 wire. pdq installed #14. we will upgrade this next fall. also we will install an exhaust fan in the back of the fridge compartment. i recommend reading https://esc-pod.com/pdq-34-upgrades-mod ... -upgrades/ for ideas on improving your fridge's efficiency.
john & diane cummings
duetto mv34 #23

deising
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Re: novacool fridge

Post by deising » Sun Mar 03, 2019 7:24 pm

Thanks, Duetto.

On our previous boat, the fridge worked poorly when the battery voltage was less than 12.5 because of undersize wiring and the subsequent voltage drop. I have not checked the voltage at the compressor when running on this one yet, but really should.
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Re: novacool fridge

Post by Expatriate » Mon Mar 04, 2019 2:59 pm

As far as I know, we have the original refrigerator on our boat. Last year it frosted up all the time. We had to defrost once a month, sometimes more often. Then we replaced the batteries and added two more solar panels. In the morning at sunup the voltage is 12.4 and rises to 13 in a few hours. Now we defrost about every three months, maybe longer, we don't record it. That is all we have done, no mods to the fridge itself.

I am surprised by the recommended wire size. Size 8 AWG is huge. Any electrical book, like the one by Nigel Caulder, will have tables of voltage drop over distance for various wire sizes and currents. Our fridge draws about six amps and I think 14 gage is what we have. Twelve gage would be better, but any larger seems like a waste. However, it won't hurt anything.

I have used my infrared thermometer to look for cold spots on the outside that would indicate insulation failure and have found none. He fridge runs almost all he time, but I found that, if I remove the little tray between the evaporator and he thermostat, it does not run as often. There a lot of games to play in the refrigeration arena.

Tim
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Re: novacool fridge

Post by Ortolan » Wed Mar 06, 2019 10:33 am

Don’t underestimate the voltage loss. Figuring 6 amps & 25’ (which it is - I replaced my wiring):

Factory 14 AWG: 6.5% loss = 11.2 volts
Replacement 10 AWG: 3.1% loss = 11.7 volts

Granted, your battery will normally be well over 12 volts, but on the other hand, anchored out, our battery is usually only 12.3 by dawn, before solar. While the Danfoss controller theoretically will allow the compressor to run down to 10.8 volts, it does run slower. In our case, that caused the front portion of the fridge cold plate to defrost, while the compressor would run continuously, unable to cool sufficiently.
Russ
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Re: novacool fridge

Post by Expatriate » Thu Mar 07, 2019 8:39 am

Russ,

Point taken. Before the new batteries, our fridge dripped some from the front edge of the evaporator. The new batteries and more solar made a big difference, but wiring size is important. I do believe it is 25 feet, twice as far as my old sailboat. I might rewire. Did you have to slide the fridge out to get to it. I see no other way.

Tim

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Re: novacool fridge

Post by deising » Thu Mar 07, 2019 9:13 am

FYI - Some of the numerous wire sizing charts available are adjusted to use a ONE-WAY distance from the source to the device. Some do not make it clear that the wiring run length is TWO-WAY (from the source TO the device, and BACK to the source).

It is important to know which run length to use for your sizing chart.
Duane Ising
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Punta Gorda, FL
2006 PDQ MV 34 - hull 91, 75HP, 3-blade

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Re: novacool fridge

Post by AMCarter3 » Thu Apr 18, 2019 4:40 pm

This has been a useful dialogue. I’m going to upgrade the fridge wiring from 14 or 10 AWG (tinned). Question... should this be done on both the + and - wires? And, for those that have already done this, is the run for one wire about 35’?

I’m also going install a exhaust fan.. both the fridge and for venting humid air and food cooking smell from the galley.I’m purchased a single 12v DC temperature controlled super quiet fan. I’m curious about where to mount it...
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
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Re: novacool fridge

Post by deising » Thu Apr 18, 2019 4:53 pm

Yes, you would always need to upgrade both the pos and neg wires.
Duane Ising
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Re: novacool fridge

Post by Expatriate » Thu Apr 18, 2019 5:40 pm

After three months in the Bahamas, our defrost frequency appears to be just short of two months, at least six weeks. Anyway, one thought that I have is the placement of the thermostat. Ours is three inches below the evaporator. It seems like a more central location would be more accurate overall, maybe lower down. Also, some installations (not Novacool) have a spillover from the freezer to the refrigerator section. I have been a little puzzled by the two evaporator design. Any ideas?

Tim
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Re: novacool fridge

Post by Ortolan » Thu Apr 18, 2019 5:45 pm

Mac,

I’ve done this upgrade. It’s a 25’ run from the breaker to below the fridge (it’s not practical to terminate 10 gauge wire at the fridge controller - terminate the 10 gauge wire at a new terminal strip below the fridge, then re-use the 14 gauge for the last few feet - leave extra so you can pull the fridge out without disconnecting). To be “official” (using the proper wire colors - orange/yellow) & economical, order the wire from bestboatwire.com

A very good idea to install an exhaust fan. The fridge was designed to be installed in a “sleeve” to exhaust the hot air past the compressor & out. As it is, the built-in fan can’t exhaust - it just blows the hot air around & hot it is. You have the heat from the fridge, the sun hitting the deck above, the oven/microwave adjacent & the generator behind! I installed a small pancake fan between the back of the fridge compartment to the compartment above the genset diesel tank - I can try to get a photo/measurements if you’d like.
Russ
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Re: novacool fridge

Post by AMCarter3 » Fri Apr 19, 2019 12:41 am

Russ,

Yes... please send a pic of the fan location if you can. I'm pretty sure I know where it is mounted, but a pic would help. I'm assuming it it mounted high on the PORT side wall between the fridge and the aux. diesel fuel tank locker on the forward deck. (we do not have a genset). That location is next to the hole in the wall separating the Fridge from the galley microwave. My intention is to have the fan serve two functions: a) provide air circulation for the fridge; and 2) be an exhaust fan for the galley.

NOTE: We recently decided to downsize our microwave to a 700 watt model (from a 1250 watt model) to reduce the huge "hit" on the battery when it is used while off shore power. That's why it looks tiny. We're having a custom shelf built by a craftsman friend of ours that fit over the top of the microwave and make the space fully useable.
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Wall next to Microwave.jpg
Microwave.jpg
Mac Carter
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Home Port: Bellingham WA 98229
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Re: novacool fridge

Post by AMCarter3 » Fri Apr 19, 2019 1:27 am

Russ,

Amazing prices at bestboatwire.com... even with shipping, better than I can get around my area.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

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Re: novacool fridge

Post by duetto » Fri Apr 19, 2019 9:03 am

hi mac,

we have an early boat and our setup is slightly different but where does that "hole" go that is to the left of the microwave in the lower picture?
john & diane cummings
duetto mv34 #23

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Re: novacool fridge

Post by Ortolan » Fri Apr 19, 2019 11:20 am

My fan is mounted 12” back. Of course, look carefully from behind & drill a tiny hole first to check for anything in the way.

Mine is powered 24/7 as the power usage is tiny. I left off the inspection port cover between the port locker & the anchor chain locker. The hot, dry air travels thru the port locker, the anchor locker, then out the windlass chain hole - you can actually feel it.
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Russ
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Re: novacool fridge

Post by AMCarter3 » Fri Apr 19, 2019 11:31 am

That hole in the wall of the microwave cabinet is a direct access to the fridge space. You can touch the starboard sidewall of the fridge just inside the hole. Opposite the fridge's sidewall is the port sidewall of the Auxiliary diesel fuel tank locker. That's the wall where Russ installed his fan and where I will do the same.
Mac Carter
2006 34' PDQ PowerCat "All Heart"; MV 98; twin 100 HP Yanmars
Home Port: Bellingham WA 98229
Member of San Juan Sailing & Yachting Charter Fleet: http://sanjuansailing.com/charter-detai ... .php?id=35

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