Carrier RTU

[HVACTECHND]

Found belt broken causing y2 to call and bring on mechanical. Thinking about adding an outdoor lockout to stop mechanical cooling from coming on as the compressor were a huge block if ice

[timebuilder]

Found belt broken causing y2 to call and bring on mechanical. Thinking about adding an outdoor lockout to stop mechanical cooling from coming on as the compressor were a huge block if ice

Many units use a low pressure safety, too.

[Dchappa21]

Or a freeze stat.

[hvac wiz 79]

That is possible. A lot of guys have no interest in learning how an economizer works, or how to troubleshoot it.

So true. Economizers have kept me very busy during the winter over the years. On many new accounts I often find enthalpy sensors disconnected with nothing else wrong. I tell young guys to learn about them because they generate work for the cold months when some get slow. I urge guys to not look at the controller and get overwhelmed. I tell them to break each circuit down and things get much less complicated. That is of course once they get an understanding of them

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[hvac wiz 79]

Or a freeze stat.

That was my initial thought . .

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[timebuilder]

Or a freeze stat.

Also a good idea to have that in the chain. We also install a low ambient control for those Y2 calls on cooler days.

[Cold shot]

Economizer would disable 1st stage mechanical cooling if outdoor conditions were suitable (sounds like they are) for free cooling. Suction line freeze stat on 2nd stage compressor or Low ambient thermostat for 2nd stage lockout. These units are not designed to protect the compressors from ANY unit malfunction.

[timebuilder]

I can't say that I know of any design that "protects the compressors from any unit malfunction....."

[Cold shot]

True, but there are several things that can be added. Air proving switch, freeze stat, low & high pressure switches, discharge line thermostats, phase monitors. All to protect the compressor.

[timebuilder]

True, but there are several things that can be added. Air proving switch, freeze stat, low & high pressure switches, discharge line thermostats, phase monitors. All to protect the compressor.

I'll go with that. You can protect the compressors from SOME malfunctions.

[git-r-dun]

Economizer would disable 1st stage mechanical cooling if outdoor conditions were suitable (sounds like they are) for free cooling. Suction line freeze stat on 2nd stage compressor or Low ambient thermostat for 2nd stage lockout. These units are not designed to protect the compressors from ANY unit malfunction.

Just to prevent any confusion, when second stage cooling is energized while a system is economizing, first stage compressor energizes and comes on (compressor 1 and not compressor 2)

[VTP99]

I always shake my head when I see a economizer installed but never hooked up.