Where should the pump on a closed loop system be ? I have a air cooled chiller sitting behind a 40 unit 4 story building. Should it be before or after the evap. Bundle?

If your working on that large of a system and qualified why ask?If it was me I would rather push than pull.

I ask this guestion because we had a new chiller installed and relocated by qualified people and the pump is pulling though the bundle and I don't get proper cooling up on the 4th floor on really hot days when the old chiller worked better. We went from an old b&g chiller to a newer package chiller and have flow problems and doesn't seem to have a load on the system like it should. All my other buildings hot water closed loops have the circulater pumps on the return side and the installers put this pump on the supply side pushing up though the building and my fan/coils when I think it would work better sucking down and though the coils and pushing though the chiller bundle.

It is the old push or pull pump question. I was always told to pump away from the boiler/chiller. Now if a company installed the new package chiller system the new pump supplied by the manufacturer may not be up to the job. If the old pump was reused it could be getting tired or not up the job as required by the new chiller. Chiller flow rates have changed from years gone by and it is possible you now have a slight mismatch performance wise.

Reality says that the old heat collectors be it cool beam or air are the same as before the new chiller was installed so the new chiller or the pump supplied with the new chiller is at fault. You really need to revisit the flow rate on the old system as it relates to the new system to see if a fault can be found. There should have been a engineer of record that sized the new chiller to the old system and performance sheets supplied by the engineer should tell all. There can always be a mistake in pump calculations and I know personally it happens quite often.

Since you paid to have the work done I would

First contact the installing company and tell them of the problem. Since money was paid for a specific performance standard they should carry the ball from there if not look at the plans and contact the engineer directly and have a chit-chat about the problem.

Before doing the above I would not try to modify or change anything in the system to compensate for poor performance on there part. Best to call them first and then if they do not respond properly you can take the necessary steps for repair and back charge the cost to the original provider of the new system components. Engineers all carry errors and omission insurance if the problem gets that far. Good luck.

Thanks hvac1000. We have been talking to the installers & their engineer. Never had any flow charts, my boss got a used chiller that was in good condition. By the time the demo guys cut out the old unit I didn't get to grab the old pump, new pump installed. Engineer said pump is fine 4 our building ? I have 26lbs supply 7lbs return on 4th floor unit. Their tech said we have a restriction in building so the chiller isn't under a good load, he took some presures test today. Talking about a storage tank and a secondary pump&loop 4 more gmp's through the chiller. Had a 50 ton now a 70 ton. The old unit ran unloaded and stayed at a constant temp, when new unit shuts down and my water temp rizes before coming back on.

I can see now why you have your hands full with that setup. Many of the older chillers allowed the water to flow easier with out as much restriction. The return is way to low on the 4th floor.


The old unit ran unloaded and stayed at a constant temp, when new unit shuts down and my water temp rizes before coming back on.

I believe they are on the correct trail to repair. Whatever happens you do not want to short cycle that new chiller. That is BAD on the unit and the demand electric meter. Instead of your bills going down they will go up with improper operation.

Getting that warmer water back to the chiller is imperative for proper operation so the new chiller will continue running and not drop out of circuit and then has to restart. I guess they are thinking the storage tank might take care of this situation but I hate to put a band-aid on a new unit. LOL

thanks hvac1000. We have been talking to the installers & their engineer. Never had any flow charts, my boss got a used chiller that was in good condition. By the time the demo guys cut out the old unit i didnt get to grab the old pump, new pump installed. Engineer said pump is fine 4 our building ? I have 26lbs supply 7lbs return on 4th floor unit. Their tech said we have a restriction in building so the chiller isnt under a good load, he took some presures test today. Talking about a storage tank and a secondary pump&loop 4 more gmp's through the chiller. Had a 50 ton now a 70 ton. The old unit ran unloaded and stayed at a constant temp, when new unit shuts down and my water temp rizes before coming back on.
They said a restriction; ask them what restriction, air lock somewhere or valves not open/close correctly. Before they install more equipment you should find out exactly why the chiller cycle off (trip out ?). What the min load ,or temp(high) it would run

By a restriction he said the bends and lengths of pipe through the building and they used old tower piping ( water tower replaced with air cool chiller) strainers on both ends. 4 story, 40 unit, fan/coil,in all apartments. So the whole a/c unit went from front of build.in garage to rear on 1st floor. Pump has 46lbs out 22lbs in located in front still. New pumps. Tech said never had enough water flow through evap bundle. On cool nights we trip freeze prot.on a set point of 44 deg. Problems adjusting flow switch. Lack of GPMs.

The chiller runs great, tech said needs more GPMs through evap. Can't adjust dead band anymore so unit won't short cycle.

the chiller runs great, tech said needs more GPMs through evap. can't adjust dead band anymore so unit wont short cycle.

Does the water loop have a by-pass,auto? You could have low temp and enough flow so it won't tripout
At low load, low out temp, do the upper floor have enough flow ?
It is not the pipings,pressure drop, fault