View Full Version : The Superheat pixie

monkey spanners
03-08-2007, 08:17 PM
The superheat pixie (possibly an elf) goes around adjusting expansion valves, sometimes open, sometimes shut, who knows?
I believe he has a little group of friends, The thermostat pixie, the pressure switch gnome, and the isolator elf (No, we havn't turned it off, you must have done it so i'd have to call you out!! What??)


US Iceman
03-08-2007, 08:23 PM
That is an astute observation. I'll make one of my own. His/her name is "Not Me". :D

chillin out
03-08-2007, 11:44 PM
No I think that when you ask a customer the answer would be "it was the last engineer that was here".


04-08-2007, 04:45 AM
Pixies, Gnomes, and Elves. This explains everything to me, except for the fact that "This has never worked from the day it was installed." You think Noah was involved? Naw, that would require a pair of errors.

monkey spanners
04-08-2007, 03:34 PM
And also, it hasn't worked since you where hear last (wants it fixed for free) You then ask how have you been running your business for 18 months with no cooling? Numpties. They must think we are stupid, lol

04-08-2007, 06:34 PM
What actually happened is that all these controls and equipment gets bored with their condition and start playing another game!

No, really, "somebody" (that is some body) bumps the expansion valve bulb in the coldroom in the wrong position and the valve acts accordingly.

"Somebody" left the pressure control cover off and left the door to the plantroom open, resulting in sand and dust buildup in the control that affects the setting.

"Somebody" sets the thermostat colder because the unit was in a defrost when "somebody" walk past and saw a high temperature.

"Somebody" had wet socks or jacket and the best place is to dry it over the compressor who in turn comes out on internal klixon or thermister.

"Somebody" saw this isolator, circuitbreaker or switch and thinks it is in the wrong position, so they reset it to where "Somebody" thinks it is in the right position.

"Somebody" wants to speak to his girlfriend, wife, mother in law in private over his cellphone and the best place is at the condensing unit of the island feezer which is very noisy according to "Somebody" and he/she switch the unit off to have a good conversation.

"Somebody" takes the meeting seriously about saving electricity and switches everything off, refrigeration, air conditioning and even the alarm system!

"Somebody" can be defined as an entity that can move forward, or backward, which is alive, have hands and something to walk on, and even can think for "Somebody" self.

How is that for elfs, gnomes, etc?

All of above have been recorded on security cameras!

04-08-2007, 07:54 PM
I,m an elf and I consider this harresment:mad:


The Viking
04-08-2007, 08:42 PM
But you all forgotten about the gas munching elf.
Horrible thing that is.

Some years ago now, I were called in to a commercial catering place, their walk in cooler had stopped working..

The installation was on the 3rd floor, 2m pipe run between the evaporator and the compressor unit (a small lunite' unit hanging on brackets outside the window).
On my arrival the system was completely empty of gas. No traces of refrigerant on any of the "normal" places so a full pressure test followed, still no leaks.
Now The Viking starts to be upset, such a small system I will find the leak.

Has anyone seen this machine working?
-Yes, up to last week it was keeping at 4 degrees, no problem.

Has anyone been touching it since then?
(Note; answered by owner)
-No mate, it just stopped working

Ok, not much to do. Can't find the leak so just to vacc out and recharge. Then I find that the HP switch won't reset so replace that as well (after cleaning the condenser).

Job done, started to chat up one of the ladies working there whilst monitoring the cold-room (that is one of our duties as good engineers but don't tell the missus).

Now, this lady told me that her boss had tried to "repair" the fridge himself!!

When I asked him what he done the answer was (you guessed it):

- I just let the air out of the system mate!
Yepp, he had opened the liquid service valve and seen that there were liquid coming out, then done the same on the suction side, he even tried it with the machine turned off until the air stopped coming out but there still weren't any liquid coming!!

Now, if he only admitted it at the beginning then he would have saved himself 2 days labour for me trying to find the non existing leak.

(Original problem? blocked condenser and a HP switch failure)

The Viking
04-08-2007, 08:44 PM
I,m an elf and I consider this harresment:mad:


Behave and you wouldn't be harassed!

US Iceman
04-08-2007, 10:02 PM
...started to chat up one of the ladies working there whilst monitoring the cold-room...

I always thought this was required to actually determine the nature of the problem. No one knows anything, but if you strike up a casual conversation with the ladies, you always find the true story.:cool:

04-08-2007, 10:57 PM
The Superheat Pixie works in my office.
When someone calls in for help he will often have the operator (Industrial Systems) tweak the TX valve up or down a bit.
Of course if this solves the problem once, it becomes the standard of care for all system ills, resulting in a plant full of mis-adjusted TX valves.

04-08-2007, 11:07 PM
In 99,9% of all cases the txv is not at fault, but something else.

Only after checking water/air flow over both evaporator and condensor, if watercooler/cooled water pressure, superheat, subcooling, compressor amp draw, filter/drier dT and such one can decide to look at the txv! Not at forhand!

Two weeks ago I was called out to a reciprocating unit we had maintained since it's install in 1979, but lost the contract a year ago when the building switched owners.

The tech from the new company thought the unit was running at a too low superheat, adjusted the txv and flooded the compressor!

The last time I was there, the unit was running at almost disign specs! And that after almost 30 years of operation!

US Iceman
04-08-2007, 11:38 PM
In 99,9% of all cases the txv is not at fault, but something else.

At last.... another true believer.:)

In most instances I wish the cap for the superheat adjustment was brazed onto the TXV to keep people from trying to adjust this at all.

Adjusting the TXV for the wrong reasons happens as often as putting in refrigerant when you see bubbles in the site glass.:o

04-08-2007, 11:38 PM
In 99,9% of all cases the txv is not at fault, but something else.

In most cases I agree with you.
However in the case of NH3 Tx Valves they have a habit of leaking through after a few years of service, particularly if the head pressure is low.
Another problem is that some Fan Evaps have trouble with setting the Superheat due to to faulty design or selection of components. I have seen many coils which worked well at high Superheats but would flood back when trying to adjust properly. (In the range of 10F (12C)

US Iceman
04-08-2007, 11:43 PM
However in the case of NH3 Tx Valves they have a habit of leaking through after a few years of service...

The valves need to be rebuilt every 2 years or so because of pin and seat wear due to flash gas erosion.

I have seen guys spend days trying to adjust these valves, when they should have been rebuilt. A lot less problems in my opinion.

monkey spanners
07-08-2007, 08:47 PM
Found a new one today. The Gearbox Gremlin. This causes the gearbox in the van to go pop 700 miles out of waranty:mad:

The Viking
07-08-2007, 09:53 PM
So did I.:mad:

This little ugly pixie was hidden inside a black Volvo V40.

As my speed got up to 95 her little lights started flashing.

09-08-2007, 05:32 PM
Found another one in my house!

The sock gobbler!

I have 23 pairs of socks, but only one sock per pair. Where is the other half?

19-02-2008, 11:33 PM
I had a call of "My walk in fridge is too warm", on a Sunday morning. Attended at double time, as one does, nothing wrong. Controlling at +2/+4. Found out operator had walked to work, ambient -6, took of jacket and went into fridge. Paniced and called. That cost him ! Pratt Gremlin ?