CVHF- superheat/subcool

[ehsx]

See ashrae 15- 1994. Air shall not be used for pressure testing or run test.

Air run implies running a machine using air. Used to be a common test procedure on older equipment. Running a compressor temporarily / briefly with the suction off is not the same.

Wrong terminology and incomplete information can cause injury or worse.

Name plate charges on chillers nay be used as reference, but should be verified under job operational conditions.
Must have full log data for performance proving.

Just facts, no insults or name calling.

[Healey Nut]

Air running is a common practice . All Trane Centravac compressors are factory air run and balanced prior to being installed on the bundles . It’s also a common field practice such as after an overhaul .
It’s done with the compressor open (ie no compression is taking place), suction elbow off , vanes mechanically locked closed so the vibration equipment can look at the end of the shaft to get vibe readings .
What that code is referring to is using air as a pressure testing gas instead of an inert gas such as nitrogen or helium .

[ehsx]

York used to test run closed systems with “dry” air. Combination of pressure and temp caused combustion of oil and chiller exploded killing the testers. That was when ashrae changed the policy on using air for testing.

Difference being the air is recirculated.

[triggerhappy]

[QUOTE=ehsx;25980695]See ashrae 15- 1994. Air shall not be used for pressure testing or run test.

Air run implies running a machine using air. Used to be a common test procedure on older equipment. Running a compressor temporarily / briefly with the suction off is not the same.

Wrong terminology and incomplete information can cause injury or worse.

Name plate charges on chillers nay be used as reference, but should be verified under job operational conditions.



I guess what is confusing me is that a man that has been doing centrifugal work since before I was born ( which would make you at least 85 yrs old) is not familiar with the common nomenclature

Milkyway clearly asked the question pertaining to air run and balance along with dry run starter.

Air run is the term used by Trane as well as dry run starter. Im not even going to discuss med voltage equip with you.....that is 4160v if med voltage doesn't suit your fancy.

I asked what factory you worked for so maybe you would get a pass if your particular equipment is not balanced in the field.

What it appears is that you are a man with a google search engine with the ability's to copy and paste nothing more.


Just facts,
no insults or name calling

[ehsx]

Trane is the only company that I’m aware of that balances a wheel on the compressor. The term would indicate a different procedure in most cases. I had asked earlier that you clarify the procedure, which didn’t happen, just sarcasm.

Common nomenclature is not always common to all mfgs. I’ve worked for 5 chiller mfgs in different positions since ‘72, But not Trane, only rebuilt a few, split wheel, open rotors, pm’s, service.

The first post on air run did not reference impeller balance, but did say with suction off.

Safety was/is my main concern. I see way to many short cuts and rules of thumb that limit efficiency and reliability.

I’ve spent ~15 yrs in chiller/ac education and a big part of professionalism is in treating others, even if not in agreement with respect. Teaching can be a learning experience as can participating in forums. Personal attacks typically shut down communications and knowledge exchange/learning.

[milkyway]

Air running is a common practice . All Trane Centravac compressors are factory air run and balanced prior to being installed on the bundles . It’s also a common field practice such as after an overhaul .
It’s done with the compressor open (ie no compression is taking place), suction elbow off , vanes mechanically locked closed so the vibration equipment can look at the end of the shaft to get vibe readings .
What that code is referring to is using air as a pressure testing gas instead of an inert gas such as nitrogen or helium .

So when performing an air run , the tech should mechanically lock the vanes ? Disconnect from the actuator and use a pair of vise grips lol ? 🤐😬🤔. Actual Question .

[milkyway]

For the vibration test, the service bulletin shows how to make the chiller stay in the wye configuration and not transition. When I do balancing, I go ahead and let it transition as well since the balancing doesn’t take that long. I might do all of the work to prevent the transition if it was a 1280 CVHE since many those had issues.

I usually on did the dry run on a brand new chiller as part of the start up.

Jay, can I get that SB 😇🙏🏻

[Healey Nut]

You can mechanically lock them with wire or any other array of stuff techs have access to . You can also do it electronically in the controls if you know how but I’m not going into that on here in the DIY section .

[triggerhappy]

Trane is the only company that I’m aware of that balances a wheel on the compressor. The term would indicate a different procedure in most cases. I had asked earlier that you clarify the procedure, which didn’t happen, just sarcasm.

Common nomenclature is not always common to all mfgs. I’ve worked for 5 chiller mfgs in different positions since ‘72, But not Trane, only rebuilt a few, split wheel, open rotors, pm’s, service.

The first post on air run did not reference impeller balance, but did say with suction off.

Safety was/is my main concern. I see way to many short cuts and rules of thumb that limit efficiency and reliability.

I’ve spent ~15 yrs in chiller/ac education and a big part of professionalism is in treating others, even if not in agreement with respect. Teaching can be a learning experience as can participating in forums. Personal attacks typically shut down communications and knowledge exchange/learning.

Why else would you want to run a cvhe or cvhf with the suction ell off......we don't run and check oil flows anymore like we did with bench grinders.....Im sure that is a no no in your book as well.

Im not here to explain procedures to someone that portrays himself as knowing it already.

My mistake in this was mistakenly thinking that Mr. Milkyway actually wanted to put some ref in a chiller....it turns out he just wanted to discuss it....which is fine...my mistake.

May be shocking to you but that post convinced me of nothing.

When was the last time you trimmed a charge on a Trane Centravac…...Ill go ahead and answer your next question....last one I trimmed was last Wednesday just before I went on Christmas Vacation. and yes I used all information know to man to do it.

The reason I guessed McQuay previously ...is your post have the same tone of pretzel logic and nonsensical theory that you might expect to come out of McQuay Tech Assit.

[stanbyyourword]

haha bit harsh for xmas time! wait til new year

[triggerhappy]

haha bit harsh for xmas time! wait til new year

You are correct sir...….I'm done....

[R123]

Assuming full load design conditions, charge by subcooling. Verify ssh, dsh sh, evap approach, liquid line approach, & condenser approach.

Subcooling will drop as load decreases.
Ssh with txv will maintain sp, exv may drop based on processor control.
Discharge sh will rise as load drops, amount based on sh control.
Condenser approach changes with fan staging.
Evaporator approach will rise if multi circuits & circuits stage off.
Liquid line approach will cross reference subcooling.

Excess oil will affect evaporator approach, evaporator pressure, & discharge sh. Lp, high evap approach, normal ssh, low dsh sh, correct injection & ecomizer operation indicates excess oil.

Noncondensables will cause a false subcooling, higher discharge pressure, and higher dsch sh.

Liquid line approach is a good indicator of charge and condenser fouling since it is strictly temperatures.

Evap approach measures heat transfer efficiency, water side fouling, excess oil, lack of refrigerant will cause high approach.

Air cooled condenser approach will be affect by fan operation/performance, recirculation, fouled cools, noncondensables, over charge.

Water cooled condenser will be affected by recirculation in the water boxes, fouled tubes, noncondensables, overcharge.

May have missed a couple...
Use a full log sheet and cross reference readings.

Typically charge should be within 1-5%.

Don’t trust display, typically incomplete and ll readings not shown.

Did Trane start making CVHF’s with EXV’s and condenser fans? Cool!

[ehsx]

General info, listed water cooled & air cooled

[triggerhappy]

Did Trane start making CVHF’s with EXV’s and condenser fans? Cool!

Your wasting your time …..LOL

The whole thread is Ludacris.....including the title superheat/subcooling…...when did we start using that on a CVHF

You get any subcooling and you will have an inverted cond approach fault.

[stanbyyourword]

yes exactly flooded vessels SH SC negligible at best!

[milkyway]

Your wasting your time …..LOL

The whole thread is Ludacris.....including the title superheat/subcooling…...when did we start using that on a CVHF

You get any subcooling and you will have an inverted cond approach fault.

Well know I know not to ask a ludicrous question - thanks trigger, just cuz someone else pooped in ur Cheerios , don’t get all upset w the milk. I did learn a few things from this ridiculous stupid thread. 🤷🏻*♂️

But I did get a little insight on trimming a charge and now not to worry about superheat and sub cool.. yay

[R123]

Your wasting your time …..LOL

The whole thread is Ludacris.....including the title superheat/subcooling…...when did we start using that on a CVHF

You get any subcooling and you will have an inverted cond approach fault.

Agreed 100%! Saturated condensing temp is measured on the liquid line. No sub cooling. And I’m yet to see someone measure suction superheat on one of these machines…

[stanbyyourword]

we could all try and be a bit nicer and more supportive here , this should be something of a brotherhood. enough nastiness in the world

[stanbyyourword]

Im working on PH diagrams plotting kj/kg to calculate real time refrigeration output to be monitored at all times with changing conditions, now thats blowing my mind, not plotting the values on charts , but the equations required, alwys hated math still do

[triggerhappy]

Well know I know not to ask a ludicrous question - thanks trigger, just cuz someone else pooped in ur Cheerios , don’t get all upset w the milk. I did learn a few things from this ridiculous stupid thread. ����*♂️

But I did get a little insight on trimming a charge and now not to worry about superheat and sub cool.. yay

If you gleaned anything from this post it should be to pay no attention to the professor...lol