Testo 550 acting weird

[Txvman]

Used my 550 to recover 410a from several RTU's. After I unhooked them from the last unit I noticed that with zero pressure on the 550 that I was reading two different values in the temp section. Both psi sections were reading zero. I turned the 550 on and off several times and pressed the zero out button several times too. Anyone have this problem with their 550?

[coolwhip]

Uh oh....here we go again.:whistle:

[itsiceman]

Uh oh....here we go again.:whistle:

:rolleyes::grin2:

Most likely it is because of the manifold being cooled enough to affect the accuracy of the pressure sensor which BTW is mounted in the manifold.
There is a "dead zone" around 0 psig which explains the 0,0 reading.

Every thing should even out once the temp stabilizes.
This is something to be aware of though if you use them outside when its hot and would like to use them in a cooler or something. Let the unit temp stabilize then hit the P=0

[coolwhip]

Funny...some younger folks cant read an analog clock these days. They may have grown up with out one in their house or school and were just never taught how to.
I wonder if this is the reason why you guys like these digital manifolds.

[spark]

Funny...some younger folks cant read an analog clock these days. They may have grown up with out one in their house or school and were just never taught how to.
I wonder if this is the reason why you guys like these digital manifolds.

I surprised you older folk can still squint your eyes to look at the numbers that the needles are pointing to on your analogs. :grin2: Oh and the reason we have digitals are to make us look cool. :cool:

-Mark

[itsiceman]

Funny...some younger folks cant read an analog clock these days. They may have grown up with out one in their house or school and were just never taught how to.
I wonder if this is the reason why you guys like these digital manifolds.

:p http://www.youtube.com/watch?v=Z8VD4JXUozM

[itsiceman]

Used my 550 to recover 410a from several RTU's. After I unhooked them from the last unit I noticed that with zero pressure on the 550 that I was reading two different values in the temp section. Both psi sections were reading zero. I turned the 550 on and off several times and pressed the zero out button several times too. Anyone have this problem with their 550?

Sorry re read the post and saw you did hit the zero button
The other thing it could be is that R-410A is a blend and it does have a small glide and just one more thing you wouldn't have noticed with analog gauges ;)

[coolwhip]

:p http://www.youtube.com/watch?v=Z8VD4JXUozM

This is what it feels like when you purchase one of these and they no worky.

[EugeneTheJeep]

:rolleyes::grin2:

Most likely it is because of the manifold being cooled enough to affect the accuracy of the pressure sensor which BTW is mounted in the manifold.
There is a "dead zone" around 0 psig which explains the 0,0 reading.

Every thing should even out once the temp stabilizes.
This is something to be aware of though if you use them outside when its hot and would like to use them in a cooler or something. Let the unit temp stabilize then hit the P=0

That reminds me of my last set of high tech gauges 15 or 20 years ago, they were glycerin filled, and once you took them out of the hot truck, calibrated them in a cool basement, and went to work, they were just as inaccurate as the Testo's. Any ways, I am still keeping it simple with good old fashioned analog and my built in calculator in my head. :grin2:

[johnt2_2002]

Used my 550 to recover 410a from several RTU's. After I unhooked them from the last unit I noticed that with zero pressure on the 550 that I was reading two different values in the temp section. Both psi sections were reading zero. I turned the 550 on and off several times and pressed the zero out button several times too. Anyone have this problem with their 550?

mine does it too. with 0 psi, for example, T1 would read 65.2, and T2 would read 65.0. Its not off significantly though....

[itsiceman]

mine does it too. with 0 psi, for example, T1 would read 65.2, and T2 would read 65.0. Its not off significantly though....T1 and T2 are the actual temperature sensor readings. I though he might be talking about the saturation temps on the display that correspond to the pressure. This was from another thread.
http://hvac-talk.com/vbb/attachment.php?attachmentid=172832&d=1301362976

http://hvac-talk.com/vbb/showthread.php?t=789192&page=2

[itsiceman]

This is what it feels like when you purchase one of these and they no worky.

LOL I was thinking the other way around.

Maybe the 550 is just too good this time for some guys.
If you want to find something wrong with one I bet you could.
Some of it is not broken just not what guys are used to seeing.
Like ETJ pointed out analogs do similar things except you could never see it so obviously.

[johnt2_2002]

T1 and T2 are the actual temperature sensor readings. I though he might be talking about the saturation temps on the display that correspond to the pressure. This was from another thread.
http://hvac-talk.com/vbb/attachment.php?attachmentid=172832&d=1301362976

http://hvac-talk.com/vbb/showthread.php?t=789192&page=2

yes, that was what I referring too. It's still too early and didn't have my morning coffee yet--my bad!:oops:

[itsiceman]

Then its not off.
R-410A is a near azeotropic blend and still has a glide even though most pt charts don't show it.

[Txvman]

I did some cleaning and testing. Blew through with N2 and checked different refrierans. It shows off with all 400 series and 733. Its "right" with all others. Some are of a lot.

[Txvman]

Here are a few pictures of the screen.

[itsiceman]

http://www.rses.org/assets/rses_journal/0610_Superheat.pdf

TXVman read through this RSES article by Andy Schoen

There is some things in here I believe will help you with understanding what you are obviously seeing for the first time :putergreet:

[Txvman]

http://www.rses.org/assets/rses_journal/0610_Superheat.pdf

TXVman read through this RSES article by Andy Schoen

There is some things in here I believe will help you with understanding what you are obviously seeing for the first time :putergreet:
Soooooooooooo......What your saying is the low side is showing dew point temperature and the high side is showing the bubble point temperature. While I've used it on a PT chart and analog gauges, this is my first time using digital gauges. I never even thought of temperature glide (it didnt click) even thou it was mentioned earlier. Thanks a lot for your help and the article. Boy do I feel stupid for not picking that up. :couchhide: