Adjusting Sporlan TXV for SH

[Ryan@PMS]

Hi all,

First post here, I've done quite a bit of research but I wanted to get some more opinions. I'm new and I don't know everything, but I've been fighting a Lennox unit that goes off on low pressure safety frequently.

I did all of the basics, the blower is running well, filters have been replaced, however the superheat is running about 23 degrees.

Since this is a package unit, I'd like to adjust the TXV to bring that down and help with the low pressure. Am I correct in understanding that the Sporlans are clockwise to raise and counter to lower. Any suggestions and advice is appreciated.

[Brian_UK]

What makes you think that the TXV needs adjusting?

Are the airflows correct, has there been a gas leak, what are the operating temperatures ?

[Ryan@PMS]

I'm not sure that it does. I'm hearing a lot about not adjusting the TXV however I'm hearing a couple of guys that I trust say that if the SH is too high and suction is too low to go ahead and adjust it.

Are the airflows correct, probably not, this unit is probably oversized for the duct. Has there been a gas leak, I can't confirm or deny that, I've only been working on this unit for about two weeks out of it's three year service. The set point is 72 degrees farenheit, ambient ranges anywhere from 50 to 100 degrees farenheit.

I don't normally adjust TXV's but I'm hearing thats a way to go if the SH is high and the suction is low.

Thanks Brian

[TRASH101]

Adjusting the superheat setting may only serve to mask your problem and should not be undertaken lightly.

You should really be sure of your the air volume across the evap and the load its generating.

Does the unit have a sight glass, whats the liquid temp, is the TXV bulb secure and placed properly. Are you sure there is no blockages or non condensibles present the list goes on and on.

The bottom line is that nobody in their right mind will advise you to adjust the superheat setting without knowing the system data.

[Gary]

TXV's rarely need adjustment. Everything else should be ruled out first.

We need to know the air in/air out temps for both coils, the liquid line and suction line temps, and the pressures.

[Ryan@PMS]

There's only two things that I can see at this point that could be wrong. The evaporator coil may possibly be dirty. It is a fast food chain, although visually, the coil looks clean. The other is that the bulbs are mounted at 12 o'clock position. That's gonna be fixed, but aside from the unit being oversized there's nothing else wrong.

The unit runs about 55#'s of suction and about 220 head at 65 ambient.

[Gary]

The other is that the bulbs are mounted at 12 o'clock position. That's gonna be fixed...

While you have the bulb off, hold it in your hand and check the superheat. If warming the bulb doesn't lower the superheat, then turning the adjustment stem won't lower it either.


... but aside from the unit being oversized there's nothing else wrong.

We don't know that because you haven't provided enough information for us to tell what's wrong... and we can't see it from here.


The unit runs about 55#'s of suction and about 220 head at 65 ambient.

Knowing the pressures doesn't do any good if we don't know what refrigerant is in the system.

[Ryan@PMS]

Sorry Gary, thought I posted. It's R-22.

I'll get all of that other info tomorrow. Thanks.

[littleyapper]

this is from sporlan"all sporlan txv are preset at the factory to give the best performance on an average syst. a valve should not be adjusted unnecessarily"....but if you really have to clockwise to increase anti to de crease... what i have found is that the belows can sometimes leak ... open the head being careful not to loose the pins .. if there is oil there then it's possible that the belows is faulty.... also in my limited view the txv is the last thing to be touched :)

[bwd111]

When I hear air in/out what cfm?? or temps ??