Condenser/evaporator/air handler compatibility


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Old 08-07-16, 07:59 PM
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Question Condenser/evaporator/air handler compatibility

I am checking for my grandmother, the AC in her house is not performing well and the installer isn't being very helpful.

After researching, I have found that she has a Mortex 96-8440-OP Coil Unit that is Rated for 4 ton Condenser. The outside Condenser is a Gibson JS4BD-060KA 5 Ton Condenser Unit. The furnace/fan is a Intertherm e3eb-020h furnace/blower rated for a 4 ton condenser. I have no idea if these systems are compatible, but after reading online I am skeptical about a 4-ton coil on a 5-ton condenser. The son of the installer came out and mentioned he was surprised to see a 4-ton valve on the unit. The house doesn't cool well during the day. Thoughts? Thanks!
 
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Old 08-07-16, 08:25 PM
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Welcome to the forums.

A location (state) would be helpful.
Is this equipment new and was just installed or was something recently replaced ?
If it's not new how old is it and was it installed together ?
Did it ever work correctly ?
How is the airflow from the registers ?
Has the filter been replaced recently ?

I am skeptical about a 4-ton coil on a 5-ton condenser.
I agree with your there but this is a little beyond my expertise. I'm not a design engineer.
I do know that a 4 ton coil can be run with a 5 ton condensor but it depends on the heat load of the house, the amount of air moving thru the coil and the device that controls refrigerant flow into the evaporator.

The tech should do a heat load calculation to better determine if this system is compatible. That combined with system operating pressures will tell the story.

I'd almost recommend calling a different company.
My forum partner, Houston, will probably add to this.
 
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Old 08-07-16, 09:58 PM
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Thank you! See below for answers:

The location is North-East Texas

Is this equipment new and was just installed or was something recently replaced ?
Installed about a year ago and a half ago. She was not in the house until about 6 months ago. Prior to moving in she left the house @ 78 so the unit wasn't very utilized. She did mention the previous unit that was replaced with the new units worked fine and cooled the house sufficiently. It was a 4-ton unit. The duct-work has been checked and has not been adjusted.

If it's not new how old is it and was it installed together ?
equipment is dated manufactured in 2014. and yes, all new components.

Did it ever work correctly?

No, when it was first installed the indoor coils froze over a few times.

How is the airflow from the registers ?

Airflow is strong near the unit, very weak away from the unit

Has the filter been replaced recently ?

yes
 
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Old 08-07-16, 10:12 PM
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Thanks for the replies.

One thing I wanted to mention in my first reply is this equipment is fairly large. A 4 ton unit can handle a fairly big house. Are we talking a large house here ?

You mentioned the son of the installer came out. Did he offer any other positive information other than a questionable expansion valve ? This equipment is basically new. They should be able to get it to work properly if they installed it.
 
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Old 08-07-16, 10:23 PM
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Thank you, 1,500 sq. feet at the most. It's a mobile home. The son had just finished his training for AC, so not sure he had much experience. Every time she calls the guy he blows her off and says "it's fine". I wasn't there so I'm not sure if he gave any more information. The visit was a few months ago. Cooling hasn't become an issue until the summer, it has been a rather mild winter and spring here in Texas. I haven't been involved much in the conversations, starting to get involved now because she is miserable during the day and night. It couldn't get below 80 degrees today, even at 9pm.
 
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Old 08-12-16, 07:43 PM
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Could use some help on this one.
 
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Old 08-12-16, 08:42 PM
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I don't know what to tell you. I was hoping my forum partner stopped by. To me it sounds like a problem with the metering device in the evap coil. The thing they called a valve.

It sounds like there is a mismatch problem that your installer won't remedy. I'd have to be there with gauges and a thermometer to diagnose the system.
 
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Old 08-13-16, 03:37 AM
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I am skeptical about a 4-ton coil on a 5-ton condenser.
You should be. I have never heard of a situation where the evaporator coil is rated LESS than the condensing unit. Going the other way, the evaporator slightly larger (one-half ton is not uncommon) than the condenser is often done to improve humidity control. Further, a four or five ton unit for a home of only 1,500 square feet, even a mobile home in Texas, sounds way oversized to me.

Short of doing a complete Manual J heat-gain calculation as well as Manual D duct sizing calculation I can't really advise anything. I will say that mismatched equipment is rarely a good thing but it can often be made to work IF the technician is willing to put in the time.
 
 

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