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FEISTY
18-04-2008, 04:11 AM
I am installing similiar equipment to replace outdated condensers. Need help designing simple yet HIGHLY reliable [ ?? ] switching control that will sense failure of temp. in walk-in cooler and start-up identical sister condenser to maintain temp. Using single evap coil and short distance rooftop located condensers. Failed unit to be cycle-off isolated so it wouldn't search and re-try start-up. Any help would be greatly appreciated. Thanks and have a great day !! jeffrey5151

daddyfixit
18-04-2008, 06:23 AM
Hello jeffrey5151..

I'm no expert in controls, but there are expensive digital/programmable controls that have an extra relay for an "alarm" ckt. This could be used to trigger a lock-out relay for the first and start-up relay for the second...
Just a thought..:)

I googled "refrigeration safety controls" and found an example....

eTRON M100
Compact Refrigeration Case & Coldroom Controller

I can't post the URL because of my new member status. I'm sure you can find other examples too..

Yes, what you want can be done. There are controls that will do it. But it may cost $$$. :( However, would it cost as much as product spoilage due to a failure? I like redundancy when needed. Enough $ on the line and you might want and need it.


Wish you the best...

nike123
18-04-2008, 10:06 AM
Any automation engineer cold do that with few relays and simple thermostats. Similar is described in this thread:
http://www.refrigeration-engineer.com/forums/showthread.php?t=11685&highlight=relays

750 Valve
18-04-2008, 11:16 AM
yep not very hard at all, you could even add in a change over relay that would switch between units weekly or monthly so as to ensure they are always operating rather than just sitting idle on stanby. It can be done with mechanical t'stats as far as the high temp cut in (alarm) and wiring if you want to steer clear of electronics

FEISTY
20-04-2008, 03:48 AM
Thanks to all who addressed my question on switching circuit. I am very interested in 750Valve response involving cycling units on time frame to keep both operational. I'm pretty good with mechanical and prob. solving but admit lack of electrical knowhow when it comes to design. Not to be a pain...if there is any additional help to be offered I am open to all of it. Funny note about cost of system vs. loss of product. This is for refer. system in medical morgue cooler. Thus the IMPORTANT need of success. Thanks so much for the help. Have a great day!!!! Feisty

daddyfixit
21-04-2008, 05:42 AM
Oh my:eek:! It is an IMPORTANT system. Don't want that product to spoil. Let us know what cool method you set up to keep your customers comfortable.:D


Wish you the best...

FEISTY
22-04-2008, 03:57 AM
COME ON....it's not as gross as many think it is. First you don't have to put up with customers questions. Next you don't get that " if I help can you lower the price ? " . Finally... just how long do they need the warranty?? [ sorry..it was too easy to pass up ]

FEISTY
22-04-2008, 04:18 AM
For future information...when would you want to install a suction accumulator and why?? What are the benefits ?