BD35 compressor not making frost on plate .

[ColdEH]

Good day .

Just replaced my evaporator plate 32x16 aluminum rollbond, with a new one on my Novakool air cooled bd235 compressor .
The unit has the self sealing connections so just bolted the new one on . The plate was precharged .

The plate gets cold and developed plenty of moisture on it but does not get cold enough to make frost on the surface. I hear a clear gurgling from the plate so I know there is flow .
The compressor is drawing way to many amps , 3.4 on low speed, but does not seem like it is struggling.

Would this do this if the plate came over charged ?

Thanks for any help

[SV THIRD DAY]

Ah...but it's just a swap out. The plate comes vapor charged, which is not the same thing as being "charged", so when you removed the old plate you could have take out of the refrigeration loop more refrigerant than was in the replacement plate. Sounds to me like a classic symptom of an under charged unit.

If the system was overcharged, you would be seeing frost going back to the compressor, so the data point of not enough frost indicated a unit low on charge.

You have two ways to fix it.
1. The official way would be to vent off the refrigerant that is in there now and then charge with the exact amount the unit calls for.

2. or add refrigerant in 2-3 second spurts and then wait for 5 minutes and observe the frost line. You keep SLOWLY adding until you just start to see frost appearing on the copper return line exiting the evaporator and then let a spurt out. It can take a while to "blind balance" the charge like this, but it can be done. The KEY here is Patience and Going slow.

[ColdEH]

Hey Rich , thanks very much for the advice , I don't have my refill kit here with me at work , I have the unit sitting on my bench running off a battery.

I thought it seemed like a low charge but there was plenty of pressure behind the fill valve . The thing that was confusing me was the amps , 3.4 ?? seems like a lot .

I have it running now and watching it , tomorrow I will bring in my fill set and remove what is in the and add new stuff .

I will update with results .

Regards

[SV THIRD DAY]

3.4A doesn't sound too far off for the BD35....

So give us an update because we all learn from these types of things.

[ColdEH]

Ok will do . Should be fun since I'm not doing this hanging upside down with myself jammed in a cupboard . This is easy 🤒
Regards

Sent from my iPhone using Cruisers Sailing Forum

[leftbrainstuff]

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Originally Posted by typhoon

Good day .

Just replaced my evaporator plate 32x16 aluminum rollbond, with a new one on my Novakool air cooled bd235 compressor .
The unit has the self sealing connections so just bolted the new one on . The plate was precharged .

The plate gets cold and developed plenty of moisture on it but does not get cold enough to make frost on the surface. I hear a clear gurgling from the plate so I know there is flow .
The compressor is drawing way to many amps , 3.4 on low speed, but does not seem like it is struggling.

Would this do this if the plate came over charged ?

Thanks for any help

Several scenarios:[*] low on refrigerant[*] blocked capillary[*] compressor issue

Low charge is my first guess. What you're describing is not a symptom of overcharging.

Did you replace or add a filter dryer before installing the new evaporator? It's very easy to block the capillary when removing and replacing components.

You can fit a LED to check if compressor is fault free.

I'm in the process of switching out our evaporator which has a blocked capillary. Probably from a piece of thread locker from the self sealing fittings. Was fine for nearly 8 years.

I had to fit high and low pressure gauges to confirm a blockage. Gurgling was still evident. I could see the HP increase confirming a blockage.

Those self sealing fittings are a pain. Not having a filter dryer installed as standard before the capillary is stupid IMHO.

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[mayball]

The specs on the Danfoss BD35 for 2000 RPM and 0 degrees C is 4.0 amps.

[CSY Man]

I averaged 5.0 amp/hrs on my BD35...

[Cadence]

Originally Posted by SV THIRD DAY

Ah...but it's just a swap out. The plate comes vapor charged, which is not the same thing as being "charged", so when you removed the old plate you could have take out of the refrigeration loop more refrigerant than was in the replacement plate. Sounds to me like a classic symptom of an under charged unit.

If the system was overcharged, you would be seeing frost going back to the compressor, so the data point of not enough frost indicated a unit low on charge.

You have two ways to fix it.
1. The official way would be to vent off the refrigerant that is in there now and then charge with the exact amount the unit calls for.

2. or add refrigerant in 2-3 second spurts and then wait for 5 minutes and observe the frost line. You keep SLOWLY adding until you just start to see frost appearing on the copper return line exiting the evaporator and then let a spurt out. It can take a while to "blind balance" the charge like this, but it can be done. The KEY here is Patience and Going slow.

If he opted for 1, would he not have to pull a vacuum on it prior to charging?

[ColdEH]

Thanks for all the replies. I have removed most of the gas and am about to refill . Don't think I will have to vacuum I didn't open any thing . How many onces do these things take to get me close ? My evaporate plate is a good size 32x16

Rdgards

[a64pilot]

Originally Posted by Cadence

If he opted for 1, would he not have to pull a vacuum on it prior to charging?

No because pressure never gets to ambient so no way air could get in.
But since I over prepare everything, I'd want a drier in the system, and to do that you would have to open it up, sweat in the drier and pull a vacuum.
You can't pull too much vacuum nor can you leave the pump on too long either.

Oh and if you get a drier, be sure to get one with a sight glass

[ColdEH]

I have it up and running . I don't think I have the charge right . The evaporator is siting outside a box on a bench , would it still frost all up in the open air ? Right now it is running at 7psi for the last twenty minutes.
Compressor is just slightly warm and the condenser tubes and fins are cool.

Regards

[Cadence]

Originally Posted by a64pilot

No because pressure never gets to ambient so no way air could get in.
But since I over prepare everything, I'd want a drier in the system, and to do that you would have to open it up, sweat in the drier and pull a vacuum.
You can't pull too much vacuum nor can you leave the pump on too long either.

Oh and if you get a drier, be sure to get one with a sight glass

I think I would try opt. 2. It is probably the same a conventional. Charge until the line frosts and bleed off till the isn't?

[ColdEH]

Originally Posted by Cadence

I think I would try opt. 2. It is probably the same a conventional. Charge until the line frosts and bleed off till the isn't?

I have about 12 inches of frost running down the pipes from the evaporator , but the entire plate is not frosted , still running at 7.5 psi .

Regards

[a64pilot]

It will frost up in open air, unless of course open air is not a 100 deg day and a 20 MPH wind or something, but in a shop, yes.