REEME ( NEW ) 5TON AIR HANDLER RUNNING 25 DEGREE EVAP.

**coldboy** · 03-30-2005, 11:12 AM

I HAVE A PROBLUM WITH A NEW 5 TON SYSTEM GOING THROUGH COMPRESSORS DUE TO 29 DEGREE EVAPORATOR. I DID NOT INSTALL IT , JUST TRYING TO CURE PROBLUM. IT HAS A 20X40 RETURN AND PLEUM WITH EIGHT 8in. DROPS. STATIC PRESSURE AT RETURN IS .25, STASTIC AT SUPPLY IS .20. I CHECKED BLOWER SIZE, SPEED, AND ROTATION AND ALL CHECKS OKAY. IT USES A FLO-RATOR #82 AND AM RUNNING A 10 -12 SYSTEM SUPER HEAT. THE SUCTION LINE IS A LITTLE SMALL 3/4 INSTEAD OF 7/8 , BUT NOT ENOUGH TO CAUSE THIS. THE SUCTION LINE RUN IS ONLY 6FT. THE ONLY THING I DID NOT DO YET IS DISCONNECT THE BLOWER AND CHECK FOR FROST PATTERN ON EVAP. ANY IDEARS?

[Edited by coldboy on 03-30-2005 at 06:18 PM]

**BaldLoonie** · 03-30-2005, 12:07 PM

Wait a minute? External static of 4.5"? Static on an air handler should be .3" with coil in it.

8 8" drops seems light for a 5 ton. How is the supply?

**mark beiser** · 03-30-2005, 01:03 PM

Those static pressure readings can't be correct, at least not in inches of water. A standard blower in a residential unit could never generate those pressures under any conditions.

What are the return and supply air temperatures?

If your return air temperature is low, the 29 degree evaperator temperature could be normal.

What is your subcooling?

Make sure the orifice is the correct size listed for the outdoor unit. A #82 orifice seems small for a 5 ton system. That is a size I would expect to find in a 4 ton, or a high efficiency 3.5 ton system.

[Edited by mark beiser on 03-30-2005 at 01:08 PM]

**dash** · 03-30-2005, 01:53 PM

Furnace or air handler??

2.5 or .25 Static?

If 2.5 tell us more about the duct sizes!!

**docholiday** · 03-30-2005, 02:01 PM

Go back and get tha ACTUAL airflow. The obttom line is you lack airflow, could be that the coil is already frozen.

**coldboy** · 03-30-2005, 06:13 PM

THE STATIC IS .25 AND IT HAS EIGHT DROPS THAT ARE ALL EIGHT INCH DROPS. THE RETURN IS 20X40 INCHES. SUBCOOLING IS 1 DEGREE.

[Edited by coldboy on 03-30-2005 at 06:16 PM]

**conrad1** · 03-30-2005, 06:25 PM

1 sq. ft of return per ton. what is the size of your supply duct? 8 8" drops @ 200 cfm each is 1600 cfm which is a little low but not bad but we still need to know if you are actually getting that to those drops either way it is an airflow problem and it sounds like you need to look at the supply before you seperate the blower wheel

**coldboy** · 03-30-2005, 08:28 PM

YA, BUT THE STATIC IS GOOD .25

**acdude32** · 03-30-2005, 10:34 PM

HELLO ......... 1 deg of sub cooling ???? your low on gas period your coil is empty so either you have a discharge line restriction ( which i doubt) or your under charged but now lets be fair.... what is your superheat... if your at 25 or more add gas.

**Carnak** · 03-30-2005, 11:15 PM

The return sounds starved.

It also sounds like it is undercharged and under a low load.

Low load as in a combination low air flow, and the return air is not all that warm or humid yet.

[Edited by Carnak on 03-30-2005 at 11:18 PM]

**Shophound** · 03-30-2005, 11:34 PM

Originally posted by coldboy
I HAVE A PROBLUM WITH A NEW 5 TON SYSTEM GOING THROUGH COMPRESSORS DUE TO 29 DEGREE EVAPORATOR. I DID NOT INSTALL IT , JUST TRYING TO CURE PROBLUM. IT HAS A 20X40 RETURN AND PLEUM WITH EIGHT 8in. DROPS. STATIC PRESSURE AT RETURN IS .25, STASTIC AT SUPPLY IS .20. I CHECKED BLOWER SIZE, SPEED, AND ROTATION AND ALL CHECKS OKAY. IT USES A FLO-RATOR #82 AND AM RUNNING A 10 -12 SYSTEM SUPER HEAT. THE SUCTION LINE IS A LITTLE SMALL 3/4 INSTEAD OF 7/8 , BUT NOT ENOUGH TO CAUSE THIS. THE SUCTION LINE RUN IS ONLY 6FT. THE ONLY THING I DID NOT DO YET IS DISCONNECT THE BLOWER AND CHECK FOR FROST PATTERN ON EVAP. ANY IDEARS?

[Edited by coldboy on 03-30-2005 at 06:18 PM]

You're measuring one degree of subcooling and between 10-12 superheat? What were the indoor and outdoor conditions (temperatures) like when you took these readings?

How many compressors has this system eaten?

What is your temperature drop across the indoor coil?

Only thing I can figure at this late hour (and drooping eyes) is possible undercharge combined with poor airflow. Undercharge would explain low subcoooling and poor airflow would explain why superheat reads 10-12 vs. something a lot higher for an undercharge condition.

How are you sure the other compressor(s) were lost from the symptoms you're seeing now? Could've been for a different reason and the last person that worked on it created a new set of problems with his repair methods.

**docholiday** · 03-30-2005, 11:38 PM

Get the following information.

Outdoor Air Temperature
Indoor Air temperature
Return Air temperature
Supply Air Temperature
Actual Airflow (right now we have .45" total static)We want actual airflow.
Suction Pressure
Head Pressure
Suction line temperature at unit
Suction line temperature at indoor coil
Liquid Line temperature at unit
Liquid Line temperature at indoor coil.
Calculate Superheat at outdoor unit
Caluclate Subcooling at outdoor unit.
Measure liquid line leaving condenser.
Provide Line size for Liquid Line
Provide Line size for Suction line
Provide Line set total length
Provide the vertical seperation
Is the indoor unit above or below the unit.

Include Outdoor unit Model Number
Include Indoor Air Handler Model Number
Include Indoor Coil Model Number.

Provide accurate info and we can tell you what's wrong.
We'll figure out how to bill it later.

**Wild Leg** · 03-30-2005, 11:43 PM

Print this thread and go fill out Doc's questionaire.
That will give something to go on.

**ruud-man** · 03-31-2005, 11:06 AM

I don't see where you mentioned if the inoor unit is a furnace or an airhandler.

If it is an airhandler (RBHK, RBHC, etc.)did you follow the I&O manual and install a section of duct the same size as the discharge opening on the airhandler?

Good luck.

**dash** · 03-31-2005, 11:49 AM

Originally posted by ruud-man
I don't see where you mentioned if the inoor unit is a furnace or an airhandler.

If it is an airhandler (RBHK, RBHC, etc.)did you follow the I&O manual and install a section of duct the same size as the discharge opening on the airhandler?

Good luck.

That's what I was thinking also.

Now ,my question is ,without doing that or worse yet not folding the tabs up,can that account for a low static reading?
I think it can,as the blower isn't converting vaelocity pressure to Static Pressure.

**casturbo** · 03-31-2005, 12:24 PM

Originally posted by ruud-man

If it is an airhandler (RBHK, RBHC, etc.)did you follow the I&O manual and install a section of duct the same size as the discharge opening on the airhandler?

Never heard of this (I don't do alot of A/C). Could you elaborate or where can I find an I&O manual or reference?

**dash** · 03-31-2005, 12:27 PM

Only applies to their air handlers,bright red/orange tag on the blower outlet.Seems it's page 11 or 13 in the manual.

Check "docs" post "Static Regain",not too far down in residential.