cvhe economizer line cold and sweaty

[supertek65]

i just came across a cvhe, did not spend much time with it, just an inspection, no service call.

the economizer line between first and second stage is very cold and sweatttty!!!!!!!!!!!!!!!!!!!

machine seems to be okay

aproach is about 2 degrees amp draw did seem a little high

atleast compared to the one next to it!!!!!!!!!!!!!!

light load and hardly loading, but does load and unload properly


superheat is 2 degrees
discharge sh is 14 degrees

suction is 14-15"hg

42 degree leaving water

there is no 3 way valve chiller runs wild
so under this light load i only had a 6 degree delta t

i am sure i do not have much info here but i was really just wondering if you guys have seen this
the other line between 2 and three is not cold at all

thanx

st65


hi heavy

where u been?

i did not have the pump curve but pressure drop is 8 lbs or 18 feet

[klove]

By this time, you've already passed thru 2 orifices to flash off unwanted gas to the interstages. Saturated temp is low enough there that a cool, sweaty vent line doesn't surprise me, but that coupled with no more than 14* discharge superheat at a reasonably light load (6* ain't too awfully light) might indicate some issues. Oil in the refgt? Charge problems?

[supertek65]

i did not want to say it or put ideas in anybodys head

i was thinking it is over charged

thanks
klove

how is it goin
are you stayin busy???

we are slow

By this time, you've already passed thru 2 orifices to flash off unwanted gas to the interstages. Saturated temp is low enough there that a cool, sweaty vent line doesn't surprise me, but that coupled with no more than 14* discharge superheat at a reasonably light load (6* ain't too awfully light) might indicate some issues. Oil in the refgt? Charge problems?

[supertek65]

keep in mind i have 48 degree return water and 42 degree leaving
no 3 way valve and vfds are at 28 %
on the air handlers vavs mostly closed
chiller is completely unloaded just coasting along!!!!!!!!!

[supertek65]

i know what you are thinking!!!!!!!

I could close the leaving water butterfly valve down and increase the dt but then the water would be 38 degrees
i did not design it or there would be a 3 way valve

By this time, you've already passed thru 2 orifices to flash off unwanted gas to the interstages. Saturated temp is low enough there that a cool, sweaty vent line doesn't surprise me, but that coupled with no more than 14* discharge superheat at a reasonably light load (6* ain't too awfully light) might indicate some issues. Oil in the refgt? Charge problems?

[supertek65]

again i do not have the pump curve!!
or pump info

but i will get it!

[triggerhappy]

just came across a cvhe, did not spend much time with it, just an inspection, no service call.

the economizer line between first and second stage is very cold and sweatttty!!!!!!!!!!!!!!!!!!!

Isn't that line suppose to be insulated.

[supertek65]

smart arse!!!!!!!!!!!!!!1 lol

yes it is partially!!!!!!!!!!

the obvious thing is

the one between 2 and 3 is not cold at all!!

maybe there is no problem at all??????????????????????????????/

there is nothing wrong with the chiller...

maybe it is just real cold cus it is completely unloaded with very little load???


just curious..

just came across a cvhe, did not spend much time with it, just an inspection, no service call.

the economizer line between first and second stage is very cold and sweatttty!!!!!!!!!!!!!!!!!!!

Isn't that line suppose to be insulated.

[chiller rob]

65...

I would kinda expect the discharge sh to be up a little bit under that condition especially with an extended period of run time....

Your 3 stage vanes could be leading a little to much so it would rather pull thru the economizer than from the evap...

I would shoot the volutes and see if you see anything unusual especially on the lower half and verify that youre not carrying over...

I like wild coils...

Any water that is returned with a valve is waisted energy...

I have a number of systems like this (comfort cooling) and with the supply fan vfds and some chilled water reset logic you have yourself a nice little system...

28 hz I would expect that you would be near a stall on the fans... increase the water temperature a bit and that could help iron out a few things...

OR...

Put a drive on the chiller and a drive on the chilled water pump set up youre minimum flow for the barrol and ramp the pump speed off of a return water set point (nice and slow), use the chilled water reset to work in tandam with the pump control and you have one of my favorite systems...

As long as you can keep youre dehimidification requirements....

When starting the supply fans on call to cool keep the min speed for 20 min or so to let the chiller bring down the loop temp and stabilize before loading the fans...

Nice and simple and should show some good paybacks...

Chiller Rob

[supertek65]

hey rob!!!!!!!!

i agree with the wasted energy!!!!!!!!!!!!!!

wild coil wld be good if i could control the chw w a drive!!

or add some nice controls to the classic black panel


i was thinking that the 3rd stg vanes could be out of adjustment a little open or first stage a little closed???????????????

could be over charged, not sure no history, the old company calls it propriotery!!!!!!!!!!!!!!!!!!!!!

I will get a good look at it this week

thanks


frank

65...

I would kinda expect the discharge sh to be up a little bit under that condition especially with an extended period of run time....

Your 3 stage vanes could be leading a little to much so it would rather pull thru the economizer than from the evap...

I would shoot the volutes and see if you see anything unusual especially on the lower half and verify that youre not carrying over...

I like wild coils...

Any water that is returned with a valve is waisted energy...

I have a number of systems like this (comfort cooling) and with the supply fan vfds and some chilled water reset logic you have yourself a nice little system...

28 hz I would expect that you would be near a stall on the fans... increase the water temperature a bit and that could help iron out a few things...

OR...

Put a drive on the chiller and a drive on the chilled water pump set up youre minimum flow for the barrol and ramp the pump speed off of a return water set point (nice and slow), use the chilled water reset to work in tandam with the pump control and you have one of my favorite systems...

As long as you can keep youre dehimidification requirements....

When starting the supply fans on call to cool keep the min speed for 20 min or so to let the chiller bring down the loop temp and stabilize before loading the fans...

Nice and simple and should show some good paybacks...

Chiller Rob

[klove]

i did not want to say it or put ideas in anybodys head

i was thinking it is over charged

thanks
klove

how is it goin
are you stayin busy???

we are slow

Movin' along about like before with work. Hopin' it don't get too slow. Things get real slow, and I may take my wife to Manhattan to visit her relatives and come work with you for a while !!!

Assuming your design is 42* leaving and 10* split loaded (?), 6* isn't near fully unloaded. Turndown on that chiller will probably be in the 80% to 90% range fully unloaded - depends on the fit of the vanes. What Rob said is the same thing I was getting at on the discharge superheat. Generally running loaded you'll be around 11* to 13* on R123. Assuming (big word) the 10* split design and very close to design water flow, you're doing 60% of machine capacity. With any run-time at all under those conditions, discharge superheat will probably be somewhat higher than 14* with everything correct and clean. Carryover or short circuiting the evap thru the econo vent line will cause the DS to drop. It may help to take measures to load the chiller to 100% and see how it's operating there before nailing down a diagnosis. It seems like something may be out of kilter, but not drastically.

[supertek65]

hey klove
we'd love to have you here in kc!!!!!!!!!!!!!!!!!!!!!
providing you could live on 39.96 hr??????????

we are so slow it is making me worry, i have not missed any hours but it is coming!

I know exactly what you are saying.
I am not sure why the split is only 6?????????????????
i think i may slow the water down a bit get it to 10 and go from there

I honestly did not know exactly what my dsh was supposed to be, and got my answer from you guys.

it did seem okay.

I will load it up saturday and record everything possible and post it again


have fun in manhattan

you do mean manhattan kansas right!!!!!!!!!!!!!!!

Movin' along about like before with work. Hopin' it don't get too slow. Things get real slow, and I may take my wife to Manhattan to visit her relatives and come work with you for a while !!!

Assuming your design is 42* leaving and 10* split loaded (?), 6* isn't near fully unloaded. Turndown on that chiller will probably be in the 80% to 90% range fully unloaded - depends on the fit of the vanes. What Rob said is the same thing I was getting at on the discharge superheat. Generally running loaded you'll be around 11* to 13* on R123. Assuming (big word) the 10* split design and very close to design water flow, you're doing 60% of machine capacity. With any run-time at all under those conditions, discharge superheat will probably be somewhat higher than 14* with everything correct and clean. Carryover or short circuiting the evap thru the econo vent line will cause the DS to drop. It may help to take measures to load the chiller to 100% and see how it's operating there before nailing down a diagnosis. It seems like something may be out of kilter, but not drastically.

[supertek65]

the supply fans are 2 150 hp backward curved centrifugal fans

i know backward curved fans are non overloading
never even thought about them stalling!!!!!!!!!!!!!!!!!!!!
what a great centrifugal guy i am! lol

most vfds are set at 20%min which is 12 hz!!!!!!!!!!!!!!
i guess i should change that

i would need to see the fan curve to see the stall

how many hz would be good for min ??????????????????

thanks guys

frank

65...

I would kinda expect the discharge sh to be up a little bit under that condition especially with an extended period of run time....

Your 3 stage vanes could be leading a little to much so it would rather pull thru the economizer than from the evap...

I would shoot the volutes and see if you see anything unusual especially on the lower half and verify that youre not carrying over...

I like wild coils...

Any water that is returned with a valve is waisted energy...

I have a number of systems like this (comfort cooling) and with the supply fan vfds and some chilled water reset logic you have yourself a nice little system...

28 hz I would expect that you would be near a stall on the fans... increase the water temperature a bit and that could help iron out a few things...

OR...

Put a drive on the chiller and a drive on the chilled water pump set up youre minimum flow for the barrol and ramp the pump speed off of a return water set point (nice and slow), use the chilled water reset to work in tandam with the pump control and you have one of my favorite systems...

As long as you can keep youre dehimidification requirements....

When starting the supply fans on call to cool keep the min speed for 20 min or so to let the chiller bring down the loop temp and stabilize before loading the fans...

Nice and simple and should show some good paybacks...

Chiller Rob