Thanks again Kurt~

But as I said earlier…My Dometic distributor does not stock the small refer systems…So I could not make your deadline anyway…

I was only posting what I see as an advantage to the Adler/Barbour and hoping you could find a local source…

Steve~

Post edited 2:57 pm – October 22, 2010 by Steve Pooler

mixman said:

Hi Steve,

It's been almost long enough that I thought about starting another thread, but why clutter up your forum when this post is just a continuation?

I went with the Isotherm (Indel) 2501 system that has a BD50F compressor.  It's set up to pull "cooler" air from outside the boat (via the boat's factory installed forced air vent system through the anchor locker).  Just my luck that I get it installed and assembled and find that they forgot to charge it at the factory!  There was vacuum, but no coolant.  This was back in July.  I charged it myself and have been very pleased with the results. 

I wanted to check the following with you.  This week the ambient temp around the box has been in the low 60's.  Does it sound right for this unit to run for about 90 seconds, then shut off for around 10 minutes and then run again?…That depends on where the sensing bulb for the thermostat is mounted…If it attaches to the plate then the answer is Yes, I would think it fairly normal because it's sensing plate temp & not ambient air temp…It only knows what it senses, and that plate can get cold quickly (with a already cooled down box) when the compressor runs…If your box is maintaining the desired temp I would not be concerned… Also, I've gotten two different ansers from Indel about how to charge the system.  I was originally told that with the compressor running, I should be down to about 3psi and between 30-40 with the unit off for 10-15 minutes.  I was also told to be around 10 psi on the low side.  Which sounds correct to you for a BD50?….Both could be correct…But it depends on the heat load (temp of the box)…It could be full with 10 psi & a box temp of say 50 degrees, but with a box temp of say 30 degrees..3 psi may be the operating pressure with the system full of refrigerant…

The main thing is you want is a full evaporator (frosted bottom to top) with the box cold, and you never want the system to run into a vacuum before the thermostat cycles the compressor off. 

Thanks.

–Kurt

Hi Kurt~

As far as pressures…It's not the BD 50 that makes the difference… It's the refrigerant used which in this case is R-134a.

If you look at the below link to a pressure temp chart for differing refrigerants…R-134a is at about -8 degrees at 2.8 psi, and about 35 degrees at 30.4 psi….

http://seit.unsw.adfa.edu.au/c…..erants.pdf

When looking at low side pressure on a gauge….This will give you a pretty good idea of what the temp of the plate is at any given time….Compressor running or not running.

You can even tell box temp this way if the compressor is left off long enough to allow the plate to get to box temp.

When charging or running…You never want it to run into a vacuum, and you are looking for a plate that is frosted completely from bottom to top…

Look for the suction (larger low side line) line to frost just as it exits the plate or the box…Frosting on the suction line all the way back to the compressor indicates you have too much freon…So adjust your charge accordingly… 

Systems are charged by frost line and not by pressure…Pressure is more of a temp reading than indication of charge level…Pressures change with box & outside ambient air temp…

Hope all this helps  

Steve~

Kurt~

From your further description…I'm not so sure your new system was under a vacuum when it arrived…They always make that kind of sound when connecting the tubing to the unit…Yes they are pre-charged, but each component may be at a different temp, and what you are hearing is the refrigerant pressure "equalizing" from the unit to the evaporator when you connect the two.

Shipping that system under vacuum would not be good because of the chance of inducing moisture (vacuum sucking it in) while making the connections.

Again…Pressure & Temperature Correspond…The warmer component will have more pressure than the cooler one regardless of how much refrigerant each component is holding….

For instance…If the plate had only 4 oz of freon in it, but was warmer than the compressor unit that had say 10 oz of freon…The plate would have more pressure & when connected, it would flow to the compressor unit until all was equalized… 

If you don't see frost a few feet away from the plate then you probably didn't overcharge but I'm curious as to how much 134a you put in ???

Steve~

Steve,

I hardly put any 134a in.  I can't quite remember since it was a few months ago, but it wasn't like I had to open the valve and let it rip.  I would describe it as putting in a few "shots" until I got the low end to go no further down than about 3psi.  Indel now has me keep it at around 8psi on the low side right before it cycles off. 

The thermometer I keep in the evaporator/plate shows it staying around 20F in there.  Stuff stays frozen easily, and below in the box everything is nice a chilled.  The evaporator/plate is iced nicely.  Not enough I need to defrost yet, but it's covered with a thin layer of frost from top to bottom.

That being said, let me back up.  When I installed the system and connected the lines, I heard the change in pressure.  I applied power, and got no cooling at all.  I put a gauge on it and read zero on the low end.  I gave it a few shots of 134a and it started to chill.  I called Indel to report what I found and they came to the conclusion that the system wasn't charged at the factory.  They'd swap it out for a new one, but I wasn't in the mood to go through the uninstall/re-install process again.  I've reported back to them a few times and they think the system is running fine.  However, if you think it's time for me to call a pro to check it out, I can do that.  My semi-retired HVAC friend that repaired my last system could always use the money :-)

–Kurt

Also…Since you didn't add much…It probably had refrigerant in it but either some leaked out thru the quick connects during shipment, or maybe one of the guys at the factory bumped into the scale/jug while filling that unit…That would throw off the process & I have seen it happen…

Steve~