Refrigeration system. Replace a DX ...? Need to decide...

[capaula]

I have lots of experience in HVAC, but this is my first refrigeration project.

I working on a refrigeration installation of 700 tons, direct expansion (R22). This installation is 20 years old, the compressors (Sabroe reciprocating) are making problems and there is a lot of refrigerant leaking (11,000 pounds of refrigerant leaked for the last 1 1/2 years). The compressors need to be replaced. I personally don't like refrigerant line running all over the site. Maintenance wise I don't think it is the best idea. I never run an installation like that myself, but I can feel the problem.

I wish I could use glycol. The temperatures needed are 0 degrees celsius & -8 degrees celsius .

How much would I loose in efficiency in a indirect expansion system compared to a DX system?

Of course the costs will be higher because the coils will have to be replaced. Is it really worth the burden? This project is supposed to pay back itself on energy savings.

- Expenses: New installation + an operation and maintenance contract for 10 year. O&M will be a fixed price per year.

A DX system will certainly increase the O&M expenses, but will be cheaper and more energy efficient. The glycol system will cost more, but will be cheaper to run.

I am in a cross road and would like to hear what other people think.

Thanks!

 

[CH5OH]

1.running costs/10 year DX:leaking refrigerant
2.glycolumping energy,heat leak (pipe radiation) costs/10 year +increased installation cost
cost 1 > cost 2?
it all comes down to the terms of contract and what you whish to spent time on (or not) for next 10 years

 

[RossABQ]

I don't feel so bad about my leaky R-12 car system after reading this. Is there a hole in the side of the compressor??

 

[MintJulep]

11,000 pounds of R22 leaking in a year and a half is criminal - literally.

Turn them in to the EPA, collect the reward, take a nice vacation.

Let someone else worry about the replacement system.

 

[Compositepro]

Back in the 80's I worked in a plant that had chillers that were several hundred tons capacity. When it was time for maintainance the Freon was vented and several one ton cylinders of R-12 were brought in to recharge the system. Freon was cheap. It was thought to be inert. These practices were so wasteful I always felt that banning Freon was an over-reaction. There were lots of ways to reduce Freon emissions. Oh well.