[sanchmanu]

Good morning tecs. I would like to get some opinions on this matter.
I´m having a discussion with the lead engineer of a local supermarket in regards to the correct piping arrangement of an upcoming installation.
It is a 30 HP medium temp condensing unit coupled to three walk-in cooler evaps. I´m proposing the piping as I always do: one single suction and one single liquid line, with tees and reductions as I go from one evap to the next. What they want is going all the way with the full sized piping from the condensing unit to a somewhat central location between the three evaps, and then install three equal size/ length branches for both suction and liquid, going from the main lines to the evaps (I guess it will look somewhat similar to a manifold at the end of the main lines). She says that this arrangement
is the best and more technically logic as it offers better balancing of the refrigerant flow! Has piping practices/guidelines changed recently?

 

[Snapperhead]

You know what I've learned over the years ..... you do what you are told to do , and put it in writing

If something doesn't work correctly , you are in the clear

 

[Snapperhead]

I just replaced a Evap fan motor on a Rigged up Walkin Keg cooler

Has 3 fans , one was locked up

This has been running 2 months , I have no idea who installed this.

Package Unit sits on top

I noticed Pan Heater , and a Coil heater , and Im like ... WTH ?

Ahh Ok , they took a Freezer , removed most of the controls , connected to a T-stat , Turned the temp up

Put my hand on top of the compressor and it was HOT AS HELL , So Im like , ok I will just adjust the SH to make it run colder , Nope , its a not adjustable TXV

I wrote on the invoice " This was a Freezer someone half assed converted to a Cooler which is never as good idea , I will not be responsible for any future problems "

 

[TechmanTerry]

"I WANT" is one thing ,for someone to say to me, I in-turn say to someone else,(Carrier,RSES,ACCA,Copeland). Does what "they" want screw up any of "You Guy's rules"?.. ASHRAE? ,DuPont? ,what say you? ,icemeister anyone? ?


So ,if no rules are bent/broken badly , so what KindaSorta. I will not admit to "new" rules until its proven to me. Physics is Physics, BTU is BTU, stuff like that.

 

[ehsx]

Couple of old school conflicts:
No double risers on scroll or low oil volume compressors. Rarely needed for comfort cooling.
Use ASHRAE riser tables for minimum velocities for oil return in all gas risers, not a fixed velocity for all sizes and locations. Different refrigerants, line temps and pipe diameters require different minimum velocities.
I and most mfgs slope vapor lines in direction of flow. Trane recommends counter flow for scroll units due to short cycling effects and low oil volume, I say eliminate short cycling.
Use of liquid line check/relief valves to prevent refrigerant drain back & migration.
Inverted traps. Avoid if horizontal slope is maintained.
Since inverter drive prices have become more practical and coil designs less practical for subcooler rerouting, flooded head pressure control has become far less common.
See conflicting info on multi evap coil tie ins on single circuit condensers.

Most new refrigerants/oils are more miscible and return better than hcfc/mineral.

In doing piping reviews for mfgs, most common mistakes:
Evaporator tie ins must be self draining, common trap & riser.
HGBP tie ins at evap must descend to feed connection to prevent oil scavenge, connect to top of discharge connection, solenoid at discharge line end to prevent liquid accumulation and slugging when energized, check valve required at evap connection if operation in ambient less than suction saturated.
Remote condenser units may not be able to use HGBP if discharge velocities low. Piping has to be sized before HGBP may be selected or considered.
Line insulation required based on high and low temperatures, condensation, safety, and energy loss.
Pumpdown capacity not evaluated based on required field charge and elevations, drainback, migration.
Liquid line solenoid location.
Expansion valve bulb mounting & location.
Check and relief valve requirements on remote condensers.
Vibration and sound isolation.

Most all piping literature I have found to be incomplete or have minor issues or directed at different applications. Refrigeration piping can be far more complex the comfort cooling with far more variables in designs.

 

[GoCougs]

I would be more inclined to agree with your idea for the piping.

Sounds like their main argument against it is the suction line pressure drop on the branch runs may vary, which would technically lower the capacity of the coils with the higher pressure drop. To me this is fundamentally different than what might be a necessary consideration for water piping and heat exchangers.

All in all though I think unless these coils are significantly far apart then there isn’t much cause for concern.

Either way it should be simple enough to calculate the required velocity for each branch suction line branch by using that coils capacity.

Another good practice would be to make sure the branch suction lines “drop down” into the main suction, and that the liquid branch circuits come off the bottom of the main liquid line.


Sent from my iPhone using Tapatalk

 

[GoCougs]

On another side note, just incase you havent seen these, I love using the insulated clamps instead of trying to insulate standard uni pipe clamps if the piping is mounted vertically, and using these saddles if the pipe is ran on a trapeze horizontally

Sent from my iPhone using Tapatalk

 

[icemeister]

Good morning tecs. I would like to get some opinions on this matter.
I´m having a discussion with the lead engineer of a local supermarket in regards to the correct piping arrangement of an upcoming installation.
It is a 30 HP medium temp condensing unit coupled to three walk-in cooler evaps. I´m proposing the piping as I always do: one single suction and one single liquid line, with tees and reductions as I go from one evap to the next. What they want is going all the way with the full sized piping from the condensing unit to a somewhat central location between the three evaps, and then install three equal size/ length branches for both suction and liquid, going from the main lines to the evaps (I guess it will look somewhat similar to a manifold at the end of the main lines). She says that this arrangement
is the best and more technically logic as it offers better balancing of the refrigerant flow! Has piping practices/guidelines changed recently?

To me, their approach is much ado about nothing. Your method is basic loop piping, which has proven to be both effective and economical.

Depending on how they intend to control temperatures in these coolers, this fancy piping to equalize pressure drops might well be a moot issue anyway.

 

[davejohnsonnola]

I just replaced a Evap fan motor on a Rigged up Walkin Keg cooler

Has 3 fans , one was locked up

This has been running 2 months , I have no idea who installed this.

Package Unit sits on top

I noticed Pan Heater , and a Coil heater , and Im like ... WTH ?

Ahh Ok , they took a Freezer , removed most of the controls , connected to a T-stat , Turned the temp up

Put my hand on top of the compressor and it was HOT AS HELL , So Im like , ok I will just adjust the SH to make it run colder , Nope , its a not adjustable TXV

I wrote on the invoice " This was a Freezer someone half assed converted to a Cooler which is never as good idea , I will not be responsible for any future problems "

Our facility has a combination walk in cooler with entrance to a smaller walk in freezer inside of it. Cooler compressor died a decade ago. No longer had need for freezer section due to other changes in building use. Propped open the freezer door, cranked up the Ranco mechanical stat to 38 and it ran like that for another 8 years of light duty seasonal banquet facility use; beer/water/wine. I didn't think it would last a season.

Finally going back in with correct sized new condenser and evaporator for the box next week.

 

[Poodle Head Mikey]

What do you do for a living Larry?

PHM
--------

I promote the new school. Because within industry, new piping is a system of pipes used to convey more performant fluids (liquids and gases) from one location to another.

 

[pecmsg]

I promote the new school. Because within industry, new piping is a system of pipes used to convey more performant fluids (liquids and gases) from one location to another.

What New School?

 

[BBeerme]

I think his brother, also named Larry, could better answer that question.

What do you do for a living Larry?

PHM
--------

 

[VTP99]

Poof 😃

 

[VTP99]

Mods are on top their game today 👍🏻

 

[pecmsg]

Mods are on top their game today ����

What did i miss?

 

[VTP99]

What did i miss?

Ohh the old 9 post then Link drop routine 🙄

 

[Careycarter]

I think you should go to a specialist because I already had such a practice and spent more money than I thought.

 

[Rosetolliver]

I think you should go to a specialist because I already had such a practice and spent more money than I thought.

Nice! usually people gather on forums to discuss the problem and find an answer, the 'ask a specialist' option doesn't work.

 

[Poodle Head Mikey]

If done properly both will work well - and both so closely as to present no discernible performance difference.

PHM
-------

Good morning tecs. I would like to get some opinions on this matter.
I´m having a discussion with the lead engineer of a local supermarket in regards to the correct piping arrangement of an upcoming installation.
It is a 30 HP medium temp condensing unit coupled to three walk-in cooler evaps. I´m proposing the piping as I always do: one single suction and one single liquid line, with tees and reductions as I go from one evap to the next. What they want is going all the way with the full sized piping from the condensing unit to a somewhat central location between the three evaps, and then install three equal size/ length branches for both suction and liquid, going from the main lines to the evaps (I guess it will look somewhat similar to a manifold at the end of the main lines). She says that this arrangement
is the best and more technically logic as it offers better balancing of the refrigerant flow! Has piping practices/guidelines changed recently?