Styles and Types of TXV’s
DANFOSS TXV
SUPERHEAT ADJUSTMENT
To the LEFT of the TXV is what is known as a “BULLET STRAINER”. It is a type of filter for liquid. They can get plugged up and restrict liquid flow. If you take note of the tower loong item positioned at 12 0’clock that is how you adjust superheat on the particular type of TXV, simply remove the nut, and use a allen wrench to adjust in to drive superheat higher or open it to lower superheat.NOTE: If by chanch you ever have to install a Danfoss TXV such as this one pictured, they do not require large amounts of brazing rod, use approx 1″ otherwise you run the risk of the solder working it way back inside the TXV.
This is at the bottom of a SPORLAN TXV. This is how you adjust superheat. Turn it in, to RAISE or turn it out, to LOWER superheat. They are prone to leaks quite frequently as shown by the oil drip. NOTE: Notice how there is oil dripping from the bottom of the TXV, this bottom packing nut can be tightened up by using a sporlan tool or a special service wrench that has “TABS” on it,this should stop the leak.
NON-ADJUSTBALE TXV
REMOVABLE TXV SCREEN
These were popular to use on HUSSMANN “IMPACT” cases. They are factory set for approx 6-8 degrees of superheat.
This what the screen looks like inside a Q body TXV,more often than not this screen is a source of cases not making temperature due to being plugged with debris especially after a store refrigeration remodel.
BALANCE PORT TXV
HOW A TXV WORKS
Very popular to use in LOW/MED temp cases RIFF, RIIC, etc. Can be used in any application low or medium temp.
This is a pictorial of how a TXV functions.
DANFOSS TXV
To the LEFT of the TXV is what is known as a “BULLET STRAINER”. It is a type of filter for liquid. They can get plugged up and restrict liquid flow. If you take note of the tower loong item positioned at 12 0’clock that is how you adjust superheat on the particular type of TXV, simply remove the nut, and use a allen wrench to adjust in to drive superheat higher or open it to lower superheat.NOTE: If by chanch you ever have to install a Danfoss TXV such as this one pictured, they do not require large amounts of brazing rod, use approx 1″ otherwise you run the risk of the solder working it way back inside the TXV.
SUPERHEAT ADJUSTMENT
This is at the bottom of a SPORLAN TXV. This is how you adjust superheat. Turn it in, to RAISE or turn it out, to LOWER superheat. They are prone to leaks quite frequently as shown by the oil drip. NOTE: Notice how there is oil dripping from the bottom of the TXV, this bottom packing nut can be tightened up by using a sporlan tool or a special service wrench that has “TABS” on it,this should stop the leak.
NON-ADJUSTBALE TXV
These were popular to use on HUSSMANN “IMPACT” cases. They are factory set for approx 6-8 degrees of superheat.
REMOVABLE TXV SCREEN
This what the screen looks like inside a Q body TXV,more often than not this screen is a source of cases not making temperature due to being plugged with debris especially after a store refrigeration remodel.
BALANCE PORT TXV
Very popular to use in LOW/MED temp cases RIFF, RIIC, etc. Can be used in any application low or medium temp.
HOW A TXV WORKS
This is a pictorial of how a TXV functions.
More About TXV’s
In the above pictures there are numerous types of TXV’s, or the proper name “Thermostatic Expansion Valve”. They control or meter how much liquid goes into the evaporator coil.
There are three types of TXV’s popular to use in grocery store applications:
(A) Internally equalized
(B) Externally equalized
(C) Balance Port
An “INTERNALLY EQUALIZED” valve is a single pass only, meaning only one way the liquid goes in. These are commonly used on smaller self contained units.
“EXTERNALLY EQUALIZED” TXV’s are used on bigger coils, and have multiple pass liquid distributor lines.
“BALANCE PORT” TVX’s are the same as externally equalized, except they can and will still function even with low pressure liquid feeding them.
TROUBLESHOOTING TXV’s
Troubleshooting TXV’s can be a daunting task. Numerous issues can arise with a TXV not properly feeding liquid. If a TXV is found to NOT be feeding properly, ALWAYS check the SUPERHEAT. To check, put gauges on suction line schrader port and strap temperature probe to suction line, in close proximity to sensing bulb of TXV. If you have HIGH superheat and super low suction, plus TXV body is iced up, there are numerous things you can check. First start by turning liquid line hand valve off. It will either be “RED” or “BLUE”. Let system pump down.
Use a crescent wrench as a backup and with a 5/8″ wrench open the end on nut. NOTE: This only applies to “Q” body style TXV!
Barely crack nut open to see if liquid is gone. If not, tighten nut down and let system pump down some more. If there is a lot of back pressure you may have to shut off the suction line in motor room. If there is one at case then shut it off instead. (With all that said use caution. This is a judgement call based on experience). Then remove screen.
Clean with electrical contact cleaner on a rag. Hold up to light to ensure clarity.
Put screen back in.
At this point if power head shows any sign of rust, REPLACE IT!
When finished and the power head is TIGHT and the screen is cleaned, turn system back on, recheck superheat and proper TXV operation. If superheat is too high or low, there is a nut at the bottom of the valve, loosen it. To INCREASE superheat turn in with service wrench, if TOO low then OPEN with wrench, all the while checking superheat. Only turn adjustment 1/4 turn at a time and wait approx 10 minutes on each adjustment. LAST NOTE: NOT all TXV’s have an external nut to remove to clean the TXV screen. Some have a FLARE nut on the liquid inlet side and some TXV’s have a screen inside the liquid inlet that are inside of the Brazed type. SIDE NOTE: Sometimes even after cleaning the screen, the TXV will still show signs of being RESTRICTED,also the system being short on liquid refrigerant can give signs of a restricted txv as well check the rack to ensure you have a solid sight glass of liquid flowing through it. What happens is the PISTON inside the TXV gets stuck or gummed up with debris. At that point do the same thing. Pump system down to 0 PSI and take TXV apart. You will likely find the inside gummed up. At this point you can change the cartidge and clean/replace piston rod/rods Most of the time that will cure the problem. If not then you will have to replace it. Two major signs of a TXV not feeding liquid properly is the the WHOLE TXV BODY will be frosted over, up to and including the powerhead and high superheat.
TXV ICED UP
Notice how the TXV body is iced up, a few things to check is first check the TXV screen by pumping down the system/circuit then use a 5/8″ open end wrench to remove the screen and check for debris inside you can use electrical contact cleaner to clean the screen, now if the screen is clean check that the system has a proper refrigerant charge because this can also be a symptom of a low charge, now if both steps prove good then next take TXV apart clean out good use some oil to put internal parts back together and check superheat.
TXV Components
TXV INTERNAL SCREEN
SPORLAN TXV WRENCH
This is an internal screen for an EBS series valve. The screen can be removed with a curved pick. However if you have to go as far as pumping the system down, and removing this screen because your diagnosis shows screen is plugged, you will be better served to go ahead and change the valve out to an “S” body style, and not a bad idea to change the drier if one is present then replace it as well, this will benefit everyone in the long run (Including the customer).
This here is a sporlan wrench specifically used for removing the powerhead from a TXV. This wrench is good to have in your tool bag, but limited to KT43 series TXV power heads. NOTE:The 43 means milimeter size.
INTERNAL PARTS OF AN SBQE VALVE
SBQE CARTRIDGE
This is the inside of an “S” body TXV, the spring inside is what either helps open or close the steel rod (piston) inside the TXV to allow refrigerant flow.
This is what the cartidge looks like in an “SBQE” valve, notice the steel rod running through the middle of it, that is what moves up and down to either allow or stop refrigerant flow, also notice the color is BLUE,the color denotes tonnage or capacity of said valve based on the BTU requirements of the coil.
INTERNAL VIEW OF EBS SERIES TXV
What you see here is the internal screen inside the liquid inlet of the TXV, these have been known to get plugged with debris, like I have said previously if thats the case go ahead and change the TXV to an “S” body.
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