ReplyPressure differential on the chiller barrel or the pumps would work fine.
Professional Member
I am working a system with a 3o ton trane chiller with 2 chilled water pumps in parrallel. It has a standard m&m paddle type flow switch on chilled water loop. The bas monitors pumps with current sensors and shuts off chiller call if no chw or cond pumps. The flow switch is part of the actual chiller control. We just replaced it several months ago. the switch failed today not so much a paddle issue. This chiller is very critical for a rare books area(humidty/temp control). My question what other options do I have that may be a little better more reliable. I understand I have seen this style flow switches 20 years old?? The customer is always trying to improve things. I was thinking diff pressure. also the pumps are on hand off auto switches.the way we are runnig them now is pump is on hand valve open while the backup pump is off with valve closed. we rotate bimonthly. I have suggested switching them automatically. thanks for your input.
Professional Member
Pressure differential on the chiller barrel or the pumps would work fine.
Professional Member
Are you having nuisance trips on flow? Do you have low flow through the chiller? I had a chiller that the flow was at the low range of the chiller and sometimes was not enough to operate the flow switch. We also had a 3 way valve in the picture too, though. I think a DP is more accurate than a paddle.
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What about efector flow switches? They are really reliable and easily calibrated.
Professional Member
my recommendation too. oh...never use a dp switch across a pump to prove flow...look at a pump curve chart...at 0 gpm you have maximum pressure differential.Originally Posted by joey94
"Right" is not the same as "Wise".
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Just because you can measure it, doesn't mean it is important. Just because you can't measure it, doesn't mean it isn't important.
Professional Member
The flow is within trane specs. Not really nuisance trip total switch failure. The switch was sweating that probably doesn't help. I looked at those flow sensors. I didn't see any on off control. I am surethey have them. Looks like high quality controls though
Professional Member
Your post is making me wonder why I see them ALL the time on the pump.
Professional Member
For my money, IFM Efector is the way to go! I have lots of them installed and no failures yet! No moving parts, easy set up.
Don't pick the fly crap out of the pepper.
Professional Member*
Here's another vote for IFM Efector. Also, beware of putting DP switch outdoors (air-cooled chiller?). Small lines with no flow + low ambient temp = freeze damage on small line and loss of water. Also, Turbo, maybe they were put there by building controls guy for feedback on pump status? If so, hope they are not also using them for flow status. A running pump does not neccessarily mean flowing water.
Professional Member
bergermech do you know what model you use. All I need is to send signal back to chiller to sense flow. look like high quality controls
Professional Member*
if you go differential mount the switch on the wall and pipe over to the taps the pump and water in the pipes willl make even more problems...if not on the walll...saw those resistance flow switches were they sense water flow and you set the sensitivity with the pumps on and then cycle for brake...saw them on a hostital York chiller MER job never again...swetting flow switch is always fun on the chiller side
"when in doubt...jump it out" http://www.youtube.com/watch?v=U1qEZHhJubY
Professional Member
This is the stuff I use. These part numbers are from their website...
SN0150 VS3000 controller
EVC074 M12 angled connector
E40174 clamp adapter
SF6200 SFG flow sensor
Don't pick the fly crap out of the pepper.
Professional Member
I HATE THOSE DP THEHY ALLWAYS PLUG EVEN CHILLED WATTER OR COOLING TOWER CONDENSING WATER ,EVEN ON FLUID COOLERS THEY ARE A PAIN LIKE THE PADDELS MYSELF.
Professional Member
The Yorkies definitely know more about this than me, but I think they have been using the electronic flow sensors for a little while. We also have a hospital we take care of with a bunch of big YK's and they all have it. I have also seen some air handlers that measure return and outside airflow using these sensors.if you go differential mount the switch on the wall and pipe over to the taps the pump and water in the pipes willl make even more problems...if not on the walll...saw those resistance flow switches were they sense water flow and you set the sensitivity with the pumps on and then cycle for brake...saw them on a hostital York chiller MER job never again...swetting flow switch is always fun on the chiller side
I think the term they are using for them is "thermal dispersion sensor". I could be wrong, but as I understand it, there's a heater in the probe, and the controller keeps track of the heater temperature and the heat loss from the probe. It compares the two and determines whether flow is present.
Don't pick the fly crap out of the pepper.
Professional Member
Quote:
Originally Posted by jayguy
my recommendation too. oh...never use a dp switch across a pump to prove flow...look at a pump curve chart...at 0 gpm you have maximum pressure differential.
Because JAYGUY scenario only happens if somebody CLOSED the shutoff discharge valve.
If we evolve from the monkey then why are there still monkeys.
GOD Bless America.
Professional Member
There are lots of different scenarios where a pump could be dead-heading without someone physically closing the discharge valve. If you're trying to prove flow through a heat exchanger, the only way to do it with a DP is with the differential across the heat exchanger.
Don't pick the fly crap out of the pepper.
Professional Member
guess what...you have just pointed out a scenario where the dp switch on a pump is a poor choice...also...
the 2 way valves are not opening (or at the very least: not enough 2 way valves are opening), chiller isolation valves not opened far enough, strainers get plugged up or partially plugged, etc.
there are lots of things that can cause LOW FLOW...it does not have to be NO FLOW to cause a problem.
"Right" is not the same as "Wise".
Don't step on my favorite part of the Constitution just to point out your favorite part.
Just because you can measure it, doesn't mean it is important. Just because you can't measure it, doesn't mean it isn't important.
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Last edited by jpsmith1cm; 06-27-2013 at 09:55 PM.
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NukeTech
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