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So no unloading ....at all...

You mean starting current etc?

Anyhow. It's just on/of by a contactor. No magnet valves etc... Circuit just straight basic with condenser, evaporator, txv and comp. Pressure controls... High Pressure and low pressure control.

No abnormal sounds when it's starting or stopping.

another thought ,,,I have a hard time wrapping my head around things in a text only setting with no live discussion or hands on ...

Is your compressor loading and unloading properly?

Good point ,I think he hit it right on the head ........ I would figure being a York chiller configurable for ewt control they would consider that in their control algorithm....

R123 has a valid explanation that's worth looking into ....

May be a configurable setting....

Being that it is controlled to entering temperature, the temperature controller should be a proportional controller (as opposed to a PI or PID controller). A proportional controller has a throttling range which means the setpoint will raise as the load increases. So if the setpoint is set at 46, then at no load or load load, the entering water temp will be close to setpoint. As the load increases, the entering water temp will drift upward. If the temp controller is set up properly for the flow rate you have, the leaving water temp should stay close to setpoint under all load conditions. Most older chillers controlled to entering water temp this way because we didn't have the advanced technology for leaving water temp control which uses PI or PID control. Proportional–Integral–Derivative (PID) control will keep the controlled water temp from drifting upward when the chiller loads so it is used for leaving water temp control.
If you are setting your entering water temp setpoint at 46 and the leaving water temp is reaching 37, than either you have extremely low water flow, or your temp controller isn't set up properly or isn't working properly.

Also ,I don't understand why your entering water setpoint has to be that low ....

What supply temp are you shooting for ?

Comfort cooling or process cooling ?

Many ewt controlled systems I see don't have 46 degree setpoints

Yours may require that but in my opinion that setpoint is begging for nuisance trips when running water and the safety trip setpoints are configured as such .

When we push that envelope we often run glycol so we can configure for lower temps ... And the fact many of our machines and or piping coils etc... Are outside

Hmmmmm.

looks like a flow issue but

Can measure a pressure diff and calculate gpm and compare both circuits ?

Is your flow fluctuating ? VFD ramping up and down the pump?

I guess for a temp measure you could raise the setpoint a few degrees until you figure it out.

Set point is 46f, starts at 53f. It's starting and stopping on inlet temp. Pure water, no antifreeze, no filters or anything like that

Anyhow, putted some loggers on both circuits. Correct circ having parallell curves, faulty circ having uneven curves, directly the machine starts the outlet is dropping to 37-38f and lays there until inlet temp is correct, or trips on freeze guard.

Mikeacman: Everything about the set temps etc... is written in previous posts.

The company that I'm doing the job for have several systems with this type of system and chillers. Just clean freshwater.

Also re-reading your posts I doubt you are fouled, but it is something to eliminate out of the equation.

You have a 9 degree td across the "good" circuit and 12.5 across the "fail" circuit

Read my above post and answer those questions if not only to yourself .

you may have flow issues, but I still wonder why you are running a chiller so close to the freeze trip point . In my opinion your asking for nuisance trips .

I would like to see your answer to my questions.

That approach doesn't sound out of line .

The normal approach is something you could find in the machines or heat exchangers design / build documents as it can vary.

I've seen approaches on fouled coolers upwards of 20 degrees !

I have another question (s)

Why is your water getting down to 37? is that setpoint ?

What is your water temp setpoint? if your running water and not antifreeze your asking for trips at 37, in my opinion.

Are you controlling temp by leaving water temp or entering water temp?

What is the freeze trip setpoint ? See next question

Are you running glycol/antifreeze or plain water?
If antifreeze can you configure the machine as so and lower the trip setpoint

I am used to seeing trip points in the area of 36 for water which you are very close to.

Faulty circuit
Evap +37f, leaving water +38,3f app=1,3f

Correct circuit
Evap +37f, leaving water +41f app=4f

what is a correct approach?

What's your evap approach?
assuming the charge is correct per manufactures guidelines.
Leaving water minus sat suction temperature. You said sat suction was +37 ,what's your leaving water ? 45????

Example
45
-37
= 8 approach

Compare both circuits .

If the approach is normal suspect low flow ,if the approach is high suspect fouling.

It sometimes trippin at set point, but often at freeze guard. The pressures is stable and vaporize is following the water temp as it should do. Nothing uncontrolled. My REFCO 4-way manifold has vapour and liquid scales. Checking the gauges several times per year against a digital reference gauge.

But yeah sure it's flow issues, a colleauge of mine is maybe going to clean the plate exchangers. All depends on the customer.

flow issues could be the problem. is the safety calibrated and tripping at the setpoint? how are the pressures as it is pulling the load down...stable and steady or losing control and 'wild'? keep in mind that R407c has a very high temperature glide and you must use the appropriate scale for liquid or vapor measurements. i wish we would all go metric...its a lot easier after you get used to it.

water/water, hermetic reciprociating comp, ycwm 150. there's 2 circuits in the chiller, both circs has own plate heat exc's for cold and warm side, the only thing that ties them together is incoming and outgoing water pipes.

the freeze guard is sensing the liquid (water) temp in the plate exch., tripping the circ that's have too cold liquid temp, if there's flow problem etc.

ah... the circs is independent of each other...

got me?

What kind of York chiller? Air cooled, water cooled, recip, screw, scroll? What's the model number? When you say "freeze guard at one circuit" what do you mean? I would think that would mean low water temp cutout, but that would shut down the whole chiller, not just a circuit. Do you mean "low evap refrigerant temp"?

Repost from original post now with farenheit scales

Well, i have fighted against a "yurk" chiller (loaded with R407C, yes i hate that refrigerant) that's trippin' on the freeze guard at one circuit, +37f (okay it'ts pure water on the cold side, a +53f/+46f system) Both circuits is a little underfilled, just about to flash in the sight glass.

However.... Suspicious about flow issues. Both circs is running with almost same values (+37f evap/+104f cond) but the circ thats trippin on freeze guard is running with deltaT 12,5f in/out on the water side, +5,5f subcool, +7f superheat, the other circ is +7,2f sub, +9 superheat and 5c deltaT in/out water side (yup it's plate heat exchangers), my service leader meaned that I would get a lower deltaT on the "problem circ" if I refilled it with refrigerant. But in my book... I would get a higher deltaT if its "Topped up" with missing ref., to get a lower dT, remove some ref. you get less effiency. I know that's its more factors that's making sense. But now. Just focusing on the ref. filling...


Oh... about my 407C issues... Ok, it might be a good ref. But not for me, i hate refs with big glide. I rather run 134a, 404A (or even better, 507) or 410A, ok 410 uses higer pressures, but that's no problem for me.

Originally Posted by R123

X2.....

You will get a lot more responses if you convert to deg F. And you can't convert the delta T, you have to convert the 2 temps to deg F then figure delta T.

For delta T C to delta T F you can multiply by 1.8 or divide by 1.8 to go from delta F to Delta C. Living in a metric system country and communicating with US factories you get nowhere quick if you cannot be fluent in both languages

Originally Posted by klove

Don't want to be the "ugly American", but since this is a U.S. based forum, you might want to convert your temps to °F before posting. I, for one, won't go to any great lengths to do that for you, and I know a lot of others that feel the same, so you limit your assistance by using the metric system around here.

X2.....

You will get a lot more responses if you convert to deg F. And you can't convert the delta T, you have to convert the 2 temps to deg F then figure delta T.

1) Why do you hate 407C? It's just a blended refrigerant - it hasn't done anything to you, has it?
2) Sounds like you may have heat transfer issues. Probably be a good idea to look at flow first, obstruction next, depending on how the waterside is piped.
3) Don't want to be the "ugly American", but since this is a U.S. based forum, you might want to convert your temps to °F before posting. I, for one, won't go to any great lengths to do that for you, and I know a lot of others that feel the same, so you limit your assistance by using the metric system around here.