Sight Glass Moisture Indicator

zootjeff said:

Hi,

I want to install a sight glass on my heat pump liquid line. Seems like Emerson makes them as well as several other manufactures.

Does anyone know much about these? Do they work very well? Should I spend 40 on one rather then 12? What is the take rate on these, do people use them on new installs?

-Jeff

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Of the dozen or so of contractors I interviewed, only one said that he installed a sight glass on every installation.

My guess is that he used it to quickly check the charge (bubbles) as he wasn't conversant with such things as static pressure, superheat, sub-cooling.

Needless to say, he didn't get the job.

V

only works if youre system is equiped with a txv

kennzz05 said:

only works if youre system is equiped with a txv

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Really? how is a TXV going to affect moisture content?
My system will have one, but that doesn't make sense to me.

Usually install them on new installs after drier before evap ,moisture indicators can be a helpful troubleshooting tool but not necessary.

If you have pulled a proper 500 micron vacuum etc you won't have a moisture problem and need the indicator. Sightglasses can eventually leak freon and I won't use them. On refrigeration systems, Yes. Using superheat/subcool/approach methods and or weighing in the charge is all I use.

Gotta dis agree with you to some degree Yuri.

I put one on a system to day cause i suspected I wasn't getting a full liquid head. I was right right. Needed 1 1/2 lbs of R22 to make it right.

My subcooling and superheat were within one and half degrees of spec and spec called for with +/- two degrees.

My line set was long and in this case the sight glass helped as the TXV could not be adjusted to compensate line set length.

I agree they can be useful but leave them there long enough and some can leak. I would not want someone not understanding superheat/subcooling etc and only using a sight glass. Good techs understand the fundamentals and not just using shortcuts. Here's one for you. Lots of furnaces nowadays have 3 ton capable blowers but a 1 1/2 ton unit is installed. Do the installers slow down the fan or just charge it on high speed and let it rip. Kind of blows away the logic of the charging tables? I find them left on high from the factory a lot.

yuri said:

I agree they can be useful but leave them there long enough and some can leak. I would not want someone not understanding superheat/subcooling etc and only using a sight glass. Good techs understand the fundamentals and not just using shortcuts. Here's one for you. Lots of furnaces nowadays have 3 ton capable blowers but a 1 1/2 ton unit is installed. Do the installers slow down the fan or just charge it on high speed and let it rip. Kind of blows away the logic of the charging tables? I find them left on high from the factory a lot.

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Yu're 'spossed to change motor speeds??


:laughing:

Some of these blowers have so much capacity it blows Granny's bedcovers off and freezes the old gal. Not to mention whistling etc. Put er down to red and it works fine.:thumbup:

Jeff............

zootjeff said:

Really? how is a TXV going to affect moisture content?
My system will have one, but that doesn't make sense to me.

Click to expand...

...he means the sight glass can only be used for charging a txv system only , you can't charge a piston or fixed orfice system with a s.g. are you only looking to see the moisture content with this glass??? What is your reason to have this item , as you'll need to perform all the work the other guys have mentioned . it hardly seems worthwhile to do all that is required if you're not coversant with sh , sc , db & wb to properly charge your unit . Please don't take offense at my comments as i don't know your experience level . The way you ask your question makes me wonder....Please be careful with liquid refrigerant

psilliman001 said:

...he means the sight glass can only be used for charging a txv system only , you can't charge a piston or fixed orfice system with a s.g. are you only looking to see the moisture content with this glass??? What is your reason to have this item , as you'll need to perform all the work the other guys have mentioned . it hardly seems worthwhile to do all that is required if you're not coversant with sh , sc , db & wb to properly charge your unit . Please don't take offense at my comments as i don't know your experience level . The way you ask your question makes me wonder....Please be careful with liquid refrigerant

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I don't plan to install it myself, but I do plan to buy it myself if I do buy it. I've found a guy to do the brazing charging and setup, I was just curious if I should get one of these and how people decide whether or not to get one or not on a brand new Install.

-Jeff

Ten bucks says he gets condensation inside the SG and wipes away the moisture indicator. :whistling2:


I know it did me Next one I'm gonna flare.:yes:

hvaclover said:

Ten bucks says he gets condensation inside the SG and wipes away the moisture indicator. :whistling2:


I know it did me Next one I'm gonna flare.:yes:

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Can you re-phrase that? I have know idea what you just said.

zootjeff said:

Can you re-phrase that? I have know idea what you just said.

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Sorry. It's the way you have to heat sink the SG or you get condensation on the inside glass.