Coldplate Reefer Questions for the Pro's!

[HappyMdRSailor]

OK Gurus!

Oh... and for us hacks too... You know us... the one's that use a ratchet for a ball peen, and a screwdriver for a scraper...

I need help with an AC coldplate refrig system that has been down really ever since I had it… A long time ago (years) when I tried to bring it up to snuff, the best I could get was cold sweating on the plate… Fast forward to a couple months ago, breaker would trip on startup, investigation lead to a locked up compressor…

Well… we all know how quickly you can throw money down the black hole of reefer resurrection with an old system, so I procured a compressor from an old domestic fridge to start some diagnosis. This “test” compressor is about a smidge less than 50% percent capacity of what came out 205W/8cc displacement vs 550w/21cc displacement. I figured I would get an idea of “push forward and fix the pig” or “ditch the pig and get a new system”

Cobbling together went well… evac for 2 hrs in 85f ambient. Crack the 134 a few times and start her up… ran well, no compressor complaints, audible gas/liquid gurgling, good temp differential at the water exchanger condenser, nice system pressures… 100 high/0 low, wait 30 min…

NO COOLING… well… I could tell the low side was maybe 10f lower than ambient at the compressor suction. No change observed side to side at the expansion valve. Three more cracks of the gas with 30 minute observations in between led to no change except 3 nice steps in pressures to 150 high/2 low… Still no frosting of the lines after the TXV to the cold plate evap… Thinking I have a bad expansion valve… Or crap in the system…

BTW, this is all hard wired test mode, comp and exchanger pump. No control problems for cooling test… Pics and more info to come…

[HappyMdRSailor]

Soooo… I took out the cold plate, dissembled the TXV and had a few thoughts/questions!

1. The TXV says R12, I assume this is normal and it has a 134 orifice???
2. Things looked as clean as they get inside the TXV, is there a way to test the valve/bulb operation? Does the line to the bulb ever get clogged?
3. Do I just get another dang TXV to slap on???
4. The cold plate is about ¾ full… I’d like to top this off, but not sure of the brine concentration??? Read somewhere Kollman recommends around 25f freezing point for a reefer plate

Going to fill the plate, slap it back together, draw it down, and crack some more gas into it… Pics of the plate, TXV, etc. attached… Big fridge, 11 cu ft, cold plate is 3x12x20, all components Frigoboat/Danfoss…

[SV THIRD DAY]

Originally Posted by HappyMdRSailor

Soooo… I took out the cold plate, dissembled the TXV and had a few thoughts/questions!

1. The TXV says R12, I assume this is normal and it has a 134 orifice???
2. Things looked as clean as they get inside the TXV, is there a way to test the valve/bulb operation? Does the line to the bulb ever get clogged?
3. Do I just get another dang TXV to slap on???
4. The cold plate is about ¾ full… I’d like to top this off, but not sure of the brine concentration??? Read somewhere Kollman recommends around 25f freezing point for a reefer plate

Going to fill the plate, slap it back together, draw it down, and crack some more gas into it… Pics of the plate, TXV, etc. attached… Big fridge, 11 cu ft, cold plate is 3x12x20, all components Frigoboat/Danfoss…

Lets take these in order:
1. That TXV is designed to function with R12, so you will need to replace it with one that is designed to work with R134a. The sensing bulb and capillary line is filled with R12 in a R12 TXV and R134a in a R134a TXV, so you need to use the correct TXV designed for your specific refrigerant gas or you will throw the TXV out of whack. The TXV tries to maintain a 10-deg temperature difference between the TXV inlet and holding plate outlet, and uses the capillary tube and sensing bulb to do that filled with the correct refrigerant gas. So use the wrong TXV and you will not properly/efficiently control the temp.

2. The line on the Bulb is gas and should never really get clogged but can be damaged if kinked. The only way to know if a TXV is working is to run it on a test bench and see if it is performing correctly and adjusting the refrigerant flow. But you need to replace this one any way since it is R12 and you need a R134a TXV.

3. Yes...easy pleasey. You will get a new TXV and make sure to replace the orifice at the same time with the same size that is in there now. The TXVs can handle a BTU range much greater than can your compressor, so you MUST have the right size orifice inside there to set the TXV range. They are Bolt On/Bold Off.

4. Since you don't know what is in there now, the best thing to do is not Mix eutectic solutions but just dump out what you have in there now and refill it. We use a 10% mixture of AntiFreeze and 90% water for a refrigerator plate. That will give you a 25-degs freezing point and is pretty typical in the industry and the "go to number". You can go fancy with food grade antifreeze or go to the auto supply store and boom....done. The TRICK is to MAKE SURE you depress in on the center of the plate and ozze out some of the solution while at the same time screwing in the cap on the plate. That will preflex the holding plate so that when it freezes you don't expand and rupture the holding plate.

11CF...well that is big for sure for a BD50 compressor and if you were trying to do a Freezer/Refrigerator spill over box I would be screaming "Danger Will Robinson...Danger" but a refrigerator box takes a lot less BTU's to pull off, so if you insulation is good, you should be ok. You might need a fan to help distribute the air to avoid uneven temps in a box that big. All you need is a 10CFM fan...to pull that off.

Good luck and ping me if you need any help.

[HappyMdRSailor]

Originally Posted by SV THIRD DAY

Lets take these in order:
1. That TXV is designed to function with R12, so you will need to replace it with one that is designed to work with R134a. The sensing bulb and capillary line is filled with R12 in a R12 TXV and R134a in a R134a TXV, so you need to use the correct TXV designed for your specific refrigerant gas or you will throw the TXV out of whack. The TXV tries to maintain a 10-deg temperature difference between the TXV inlet and holding plate outlet, and uses the capillary tube and sensing bulb to do that filled with the correct refrigerant gas. So use the wrong TXV and you will not properly/efficiently control the temp.

Just another funny French Joke in a long list of French jokes that I simply do not get... Or think is REMOTELY FUNNY! The thing I don't get, is that everything ELSE is labeled 134, the comp, cold plate inlet, connectors on all the lines... And somebody did not cobble this TXV on later... The bulb was under the low side insulation going from the plate, clearly wrapped in 134 marking tape

2. The line on the Bulb is gas and should never really get clogged but can be damaged if kinked. The only way to know if a TXV is working is to run it on a test bench and see if it is performing correctly and adjusting the refrigerant flow. But you need to replace this one any way since it is R12 and you need a R134a TXV.

Adjust the flow according to bulb temp, inlet and reference (bulb helper) pressures? I gots an adjustment screw!!! Prolly best left for a professional screwdriver... and I don't mean the tool nor the cocktail...

3. Yes...easy pleasey. You will get a new TXV and make sure to replace the orifice at the same time with the same size that is in there now. The TXVs can handle a BTU range much greater than can your compressor, so you MUST have the right size orifice inside there to set the TXV range. They are Bolt On/Bold Off.

So match the orifice to the compressor BTU??? Obviously my "test" compressor is far less than what was in there, <1/2 capacity in watt/displ... I am not finding a BTU capacity for either compressor in the data sheets. Old=Danfoss 8140 (attached) Test Embraco FGS 90 HA (attached)

4. Since you don't know what is in there now, the best thing to do is not Mix eutectic solutions but just dump out what you have in there now and refill it. We use a 10% mixture of AntiFreeze and 90% water for a refrigerator plate. That will give you a 25-degs freezing point and is pretty typical in the industry and the "go to number". You can go fancy with food grade antifreeze or go to the auto supply store and boom....done. The TRICK is to MAKE SURE you depress in on the center of the plate and ozze out some of the solution while at the same time screwing in the cap on the plate. That will preflex the holding plate so that when it freezes you don't expand and rupture the holding plate.

So I can return my $0.54 Great Value Walmart salt? I bought non Iodized... I didn't think my plate needed any added nutrients... Auto-no-freeze for me please... And boy did the previous air inside play havoc... When I began the latest foray into the reefer, I was a tad shocked how much the plate tank had kinda exploded... Sometimes it does get to 10-12 million degrees inside the boat, and higher in the locked fridge...

11CF...well that is big for sure for a BD50 compressor and if you were trying to do a Freezer/Refrigerator spill over box I would be screaming "Danger Will Robinson...Danger" but a refrigerator box takes a lot less BTU's to pull off, so if you insulation is good, you should be ok. You might need a fan to help distribute the air to avoid uneven temps in a box that big. All you need is a 10CFM fan...to pull that off.

Indeed big... It's a dual AC fridge that you know about, DC freezer for the small 0.75ft freezer that is a spillover with a removable door... this system is ALSO DOA compressor, but I know what killed it... My house simply died a quick death after I installed a 100A charger... The batts were simply at the end of their life and couldn't make the transition from solar maintained to shock therapy... Without the battery ballast, I killed my BD35 for the freezer... I'm going to partition the space and make it something like 4ft freezer and 7ft fridge... a new 50 and evap plate for the freezer section. Putting this off until the new house bank is squared away... (another question and priority here) Imma poke MaineMan for that!


Pics of:
R12 TXV bulb under 134 marked insulation
Fridge - Daytime lower port, 1700 upper port...
and current orifice stamped 02 454


Good luck and ping me if you need any help.

Thanks a million for the help Rich!

[HappyMdRSailor]

So now time for a funny...

I have a good friend from here on CF.... He is BEYOND HELPFUL in so many ways... Mostly to bounce stuff off of... But also he's reducing his carbon footprint in the “good way”… By that I mean pennies on the dollar for surplus items that I have a need for, and he needs the space for… Or finding insane deals that help me out immensely... But more than anything, a very good friend...

Anyway… his helpfulness borders on funny nearly all the time, but he got me yesterday… I sent him a picture of what I found behind the holding plate… Yet another French joke…



His reply???

(deadpan)
“Well…. Did you check for holes behind the plastic?”

[captmikem]

Just a note for you... my reefer was working fine, but my freezer plate would not do anything but get cool. I pulled the TXV out to replace it and found a little cone filter in the line filled with black stuff. I cleaned that, put it back together and it has ran fine ever since.

MM

[SV THIRD DAY]

Originally Posted by captmikem

Just a note for you... my reefer was working fine, but my freezer plate would not do anything but get cool. I pulled the TXV out to replace it and found a little cone filter in the line filled with black stuff. I cleaned that, put it back together and it has ran fine ever since.

MM

Image of TXV Orifice:


Since the TXVs are good for a wider range of refrigerant flows, an Orifice is used to set them into the range of the 12v DC compressor. That orifice has a screen in it that can, as Capt Mike points out, get clogged with crap that was either not properly flushed out of the system after soldering it together OR the most common thing I see is a it getting clogged after someone gets the bright idea of putting leak stopper or dye in their system.

[[Just a note: You should never use leak stopper or Dyes in any of these systems]]

Regarding the correct size of orifice for HappyMDRSailor, if you are using a 12v Danfoss or Cubigel compressor you will want to use a #00 Orifice or Danfoss Part No 0682003. We sell them, but you can also buy them easily anywhere online. Here is a link: https://www.amazon.com/Danfoss-06820.../dp/B00QW2QB1M

Another Techy note:
It worries me that you have a R12 TXV but the systems was R134a...why. Because if you have the R12 compressor oil still in your system it will be snotty and can clog up the TXV and orifice. So you should blow out the holding plate and all lines with Acetone to remove any of the old R12 oil. This little issue can screw you big time and of course it will strike out in the middle of no where or on a big ocean crossing and adios freezer/refrigerator and food.

[Rorzech]

I have a 24 cu ft Side by side frigidare fridge/freezer and it only draws 130 watts of power and the other day I tested a 15 cu ft fridge/freezer and it was drawing 0.85 amps at 120 V, you can do the math. Sounds like your old equipment is a typical power sucker. Pre 1994 fridges drew from 2.5 amps to 4.5 amps. Since then compressors started using run capacitors along with other enhancements and they became very efficient. Now a typical fridge draws about 1.2 amps.Having a TXV you may be stuck with a Cap start Compressor. I'm pretty sure you could be cooling 10 cu ft with a 100 watts domestically. We may be talking apples and oranges but sounds like your fridge has some commercial use like for a fishing boat.

[HappyMdRSailor]

Originally Posted by captmikem

Just a note for you... my reefer was working fine, but my freezer plate would not do anything but get cool. I pulled the TXV out to replace it and found a little cone filter in the line filled with black stuff. I cleaned that, put it back together and it has ran fine ever since.

MM

Thanks for your help Mike !
This was my first suspicion, as I should be getting the giant temperature differential on either side of the TXV... Alas, she was clean, and it seemed as though the orifice insert was doing what it was supposed to... check valving...

Glad yours was a simple fix...

Originally Posted by SV THIRD DAY

Image of TXV Orifice:


Since the TXVs are good for a wider range of refrigerant flows, an Orifice is used to set them into the range of the 12v DC compressor. That orifice has a screen in it that can, as Capt Mike points out, get clogged with crap that was either not properly flushed out of the system after soldering it together OR the most common thing I see is a it getting clogged after someone gets the bright idea of putting leak stopper or dye in their system.

[[Just a note: You should never use leak stopper or Dyes in any of these systems]]

Regarding the correct size of orifice for HappyMDRSailor, if you are using a 12v Danfoss or Cubigel compressor you will want to use a #00 Orifice or Danfoss Part No 0682003. We sell them, but you can also buy them easily anywhere online. Here is a link: https://www.amazon.com/Danfoss-06820.../dp/B00QW2QB1M

$9??? I'll take ten!!!

This is on the high voltage AC system... Compressor was a 220v Danfoss 8140, 550W/0.73HP.New test compressor is a 110 Embraco 205W/.028HP

Another Techy note:
It worries me that you have a R12 TXV but the systems was R134a...why. Because if you have the R12 compressor oil still in your system it will be snotty and can clog up the TXV and orifice. So you should blow out the holding plate and all lines with Acetone to remove any of the old R12 oil. This little issue can screw you big time and of course it will strike out in the middle of no where or on a big ocean crossing and adios freezer/refrigerator and food.

I'm tellin' ya Rich... This has got to be a:
"Pierre, hand me that 134 TXV... "
"But Mr. Jean Frog... we only have R12"
" That's OK we feex eet so she make cold enough"

Every single part has a Figoboat or Danfoss part number sticker clearly marked with 134. Compressor, cold plate, each line connection...

It's a jungle behind the panel... 2 compressors, driers, heat exchangers and plumbing, water pumps, control boxes, pressure switches and what must be 12 miles of lines in about 7 different zip tied coils... I had a friend who runs a very successful marine repair biz on the boat, and his quote was: "HOLY CRAP... I wouldn't even know where to start" I'mma cut zip ties, and make a diagram of what the hell I got, and maybe something else will be obvious...

Originally Posted by Rorzech

I have a 24 cu ft Side by side frigidare fridge/freezer and it only draws 130 watts of power and the other day I tested a 15 cu ft fridge/freezer and it was drawing 0.85 amps at 120 V, you can do the math. Sounds like your old equipment is a typical power sucker. Pre 1994 fridges drew from 2.5 amps to 4.5 amps. Since then compressors started using run capacitors along with other enhancements and they became very efficient. Now a typical fridge draws about 1.2 amps.Having a TXV you may be stuck with a Cap start Compressor. I'm pretty sure you could be cooling 10 cu ft with a 100 watts domestically. We may be talking apples and oranges but sounds like your fridge has some commercial use like for a fishing boat.

I know it's insane right??? Night and day on efficiency... Don't think I'm not tempted!!! Something like ripping the guts outta a small apartment fridge/freezer has been discussed! I mean when you can buy a brand new 5 cubic ft fridge/freezer for $150, it almost makes sense to consider fridge guts like a consumable part

[HappyMdRSailor]

Ok Mr. Rich!

Update... was having an easier time of finding a cheap R12 TXV than I was 134, and I am 100% sure the R12 one was stock install... EVEN IF IT'S COMPLETELY WRONG do do so.... At one point this baby ran cold with what was there... I can do it again...

$20 later and a can of 134 juice and I have... Viola... cooling for the first time ever (old orifice was utilized)

Now comes the refinement... I got about 60% of the plate frozen after about 4 hrs... only 48 in the box cause it's huge... I might still be going down, but I'm hard wiring the compressor for a 75% duty cycle... 45on/15off so I duzn't kill the tiny compressor...

Remember this was a "test compressor"

This “test” compressor is about a smidge less than 50% percent capacity of what came out 205W/8cc displacement vs 550w/21cc displacement

Pressures 8-10 low, 125 high... Think it ran higher, as the waterpump (heat exch) in the orig system didn't kick on until 140 high (temp waterpump connected)

Sooo... Do you think I have:
1- Too much juice?
2- Too little juice?
3- Too little compressor capacity to adequately test?
4- Can I mess with the superheat screw??? Can I?!?! Can I?!?!
(I already did, in one from stock to see a change... waiting... )

Btw, a buddy asked about the lines... no frosting after the TXV to the plate, and no frosting after the plate to the comp... Only frost/ice on the system is on the plate as pictured...

Thankya!!!

[SV THIRD DAY]

4hrs....heck let it run overnight and lets check in the morning because that just isn't enough time for the holding plate to freeze down and the system reach equilibrium. So lets check the temps and pressure again in the morning and then we can start the tweaking. A huge mistake people make (me included) is to not have some patience and let the box reach equilibrium before tweaking...then the tweaks send us off in the wrong direction because more than one variable is changing.

The low pressure reading will not stabilize until the plate is frozen but will keep coming down towards the ideal of 0-5 but perfect being 2-3psi. So if we tweak the TXV before the unit is stable we fool ourselves with the reading.

I'll be here all day tomorrow...ping me with some data Amigo and we will dial things in.

[HappyMdRSailor]

Originally Posted by SV THIRD DAY

4hrs....heck let it run overnight and lets check in the morning because that just isn't enough time for the holding plate to freeze down and the system reach equilibrium. So lets check the temps and pressure again in the morning and then we can start the tweaking. A huge mistake people make (me included) is to not have some patience and let the box reach equilibrium before tweaking...then the tweaks send us off in the wrong direction because more than one variable is changing.

The low pressure reading will not stabilize until the plate is frozen but will keep coming down towards the ideal of 0-5 but perfect being 2-3psi. So if we tweak the TXV before the unit is stable we fool ourselves with the reading.

I'll be here all day tomorrow...ping me with some data Amigo and we will dial things in.

Aww heck... Really??? I'm naturally a pretty patient guy, but I calculated that by not looking for the good ice chest and using the crappy one... I was spending $103.41/mo on ice...

So I think you can see my motivation here hmmm???

I could ping you with hourly updates until the morning??? We'd be really good friends know each other quite well by then... really

Excellent info on my low side, TY... I've put a decent fan on the poor little undersized compressor... He's unhappily warm... (read 1 mississippi hot). But that was without... I think he'll be ok running all night...

Now that I know this system isn't quite ready for float testing, I'll start looking for an appropriate sized compressor... Or heck... I'l probably get away with an undersized with such a large holding plate if I can tolerate the cool down duration???

We're ALMOST... Out of the "Danger Zone"!!!

[a64pilot]

Run the little bugger continuously, I think they can tolerate it, I'd bet that in 45 min of running its at it hottest temp it will reach anyway.


Sent from my iPad Pro using Cruisers Sailing Forum

[Rorzech]

If you can hold your hand on the top of the compress for the count of 3 then your compressor can run 100% duty without hurting it. But if you can only keep your hand on the compressor for the count of two then you've got problems coming your way. Your cold plate should be completely flooded (frosted) with refrigerant right up to the TX valve. if it ends up only being able to make that plate sweat then your compressor is way to small and you may have to reduce your refrigerant to lower your suction pressure and your TX valve will just stay wide open and just act like an orafice. But you won't cook your little compressor, and it might give you enough cooling if you have enough insulation around your ice box.The more insulation you have ,the less HP you need.I is good to have a little sight glass in your liquid line for the wet/dry yellow/green indicator. If it shows yellow you will create sludge that will plug stuff up over some time.You want to see nice bright green to indicate a dry system that will ensure a long running system free of sludge. Sludge looks like a light coloured clay build up that scrapes up into a powder. I've been using leak stoppers for a couple of years now without any failures so far , so until I have a problem with them , i'll continue using them. I've seen some miracles with that stuff that was hard to believe. I've never seen it ever plug anything up. Oxygen and water combined with refrigerant causes the stuff that blocks things up.The proof is in the pudding.

[HappyMdRSailor]

Originally Posted by a64pilot

Run the little bugger continuously, I think they can tolerate it, I'd bet that in 45 min of running its at it hottest temp it will reach anyway.
Sent from my iPad Pro using Cruisers Sailing Forum

I think you nailed it Mr. Pilot... Didn't seem any hotter at 45 min, as it did 10 min into a new cycle... With the fan on it overnight, it was an easy 10 mississippi... way cooler... Course I gotta non contact thermo... trying to figure out why I'm going old school guesstimating...

Originally Posted by Rorzech

If you can hold your hand on the top of the compress for the count of 3 then your compressor can run 100% duty without hurting it. But if you can only keep your hand on the compressor for the count of two then you've got problems coming your way. Your cold plate should be completely flooded (frosted) with refrigerant right up to the TX valve. if it ends up only being able to make that plate sweat then your compressor is way to small and you may have to reduce your refrigerant to lower your suction pressure and your TX valve will just stay wide open and just act like an orafice. But you won't cook your little compressor, and it might give you enough cooling if you have enough insulation around your ice box.The more insulation you have ,the less HP you need.I is good to have a little sight glass in your liquid line for the wet/dry yellow/green indicator. If it shows yellow you will create sludge that will plug stuff up over some time.You want to see nice bright green to indicate a dry system that will ensure a long running system free of sludge. Sludge looks like a light coloured clay build up that scrapes up into a powder. I've been using leak stoppers for a couple of years now without any failures so far , so until I have a problem with them , i'll continue using them. I've seen some miracles with that stuff that was hard to believe. I've never seen it ever plug anything up. Oxygen and water combined with refrigerant causes the stuff that blocks things up.The proof is in the pudding.

Spectacular info Rorzech... Thanks a ton for posting... Turns out the little compressor is probably adequate for now... Entire plate frozen... A sight glass would be an easy install...