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May not get a answer in the open part of the hvac-tech.


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Can anyone tell me how to delete surge points or surge map in York Chiller having Model (YKDGDHQ75CNF)?

Got York to take a look at it. They reset the surge map and now it's running down in the low 50s Hz. Thank you all for your help, I really appreciate it!

Well, I get all the problems worked out with the buildings optimum start and go to clear the surge map and low and behold, it has it's own special password. I can't find manual 160.55 M1 which has it. ggggrrrrrrr!!!!

Run time is 15353 hours, starts are 16321.

I've been working on getting the starts down. When I inherited this machine last year, it had 15009 starts. I've been dealing and solving several problems with it over the course of the year that been causing it. I had a bad DP switch. Controls settings set wrong. Chiller/controls interface set wrong. Light loading because of lack of occupancy in my building & time of year. Optimum start/stop issues. These problems have been linked to the leaving chilled water shutdown and the excessive start/stops. All of these have been solved except the optimum start/stop. I have my controls guy working on reprogramming that because for some reason, it's starting the chiller way earlier than the AHUs to anticipate AHU start up. But it take only a few minutes for that chiller to take the CHW loop down to set point with no load on it. So it cruises past set point and trips on leaving chilled water temp.

Originally Posted by rjcuomo1

Total surge count is at 827 over the life of the machine which is 12 years old.

That doesn't sound too bad, but sometimes it doesn't take much to corrupt a map. The problem with the older machines is that there may only be a few points that are messing up the whole operation, but to get rid of them the entire map has to be cleared. The newer machines (last 5 years or so) allow for individual points to be cleared.

If I were able to stand in front of the machine and manually control the speed and have it remain in control without surging, yet when put back in auto it would ramp back up, I may be inclined to clear the surge map.

Another question or two...

How many hours and starts?

Are there excessive shutdowns on leaving chilled water temperature?

Total surge count is at 827 over the life of the machine which is 12 years old.

Originally Posted by rjcuomo1

Yeah, I'm simply not going to make tower water in the 60s anytime at this point in the year. It's too hot outside.

How many ACC surges are there on this machine?

Yeah, I'm simply not going to make tower water in the 60s anytime at this point in the year. It's too hot outside.

Originally Posted by DFWTECH

look at surge count if it is excessivly high i would try clearing the surge map also york yk's and yt's with vsd they recommend conndenser water in the 50's depending on time of year and location that may be hard to achieve but i would try to get water colder but never lower than mid 50's

I used to have the lower the better mantra, but it gets to a point where the law of diminishing returns causes more money to be spent that can be saved. Remember the savings provided by a VSD is geometric not linear. The bulk of the savings is achieved at about 40 Hz. Yes, there is savings below that point, but one has to determine if the extra HP being consumed to run all the tower fans at 60 Hz. can be "made up" by the chiller running a little slower.

With many years and all the different VSDs York used I came to realize that 60-65*F. water to the condenser was more than sufficient.

This man's problem is not tower water temperature. There's more going on here.

look at surge count if it is excessivly high i would try clearing the surge map also york yk's and yt's with vsd they recommend conndenser water in the 50's depending on time of year and location that may be hard to achieve but i would try to get water colder but never lower than mid 50's

Originally Posted by KnewYork

This chiller should be able to run at less than 60 Hz. with 76° ECW. I don't know where this chiller is located, but 65° condenser water cannot be achieved in many areas of the country in the summer even at night. The clue here is that when he manually slows the VSD an the PRV begin to open and it probably is running fine. As soon as he releases it it goes back to 60 Hz. Far more indicative of a corrupted surge map than condenser water that is too warm.

Originally Posted by tacxc

It make difference if there's no load. The gas cfm through the diffuser helps the gas from flowing backwards, so load is relevant to lift. Yorks don't operate well with light loads unless you lower the lift. Yorks have vaneless diffusers and a wider stall window than any other machine. I had same issue during winter time as was able lower condenser water, chiller purred like a kitten afterwards. In the case of your chiller has no load in summer time is another issue. Are they running 2 chillers together or is it that that machine is really that over sized? There definately alot of stuff you need to look at as others are mentioning here verifying flow and dumping surge map. In my case I dumped the map and after about a week I was back to square one. My chiller was running at 56 - 57 htz. Also vanes closed. After dumping map ran at 35htz with vanes closed. By setting my set point to 65 degrees I've been able to match the load to the right entering condenser water temp even though the tower is always able maintain that setpoint. The theory is, when osa conditions go up so does the building load. There is an article that explains these condition in more depth.

The pumps on both sides are constant volume. Single machine. The tower water is set at 71° so the tower just runs 60Hz all summer. I run the building from 7am - 6 pm M-F so the chiller doesn't run after hours save, optimum start.

Originally Posted by jayguy

please remember, when troubleshooting a problem, you need to verify and re-verify all measurements that the control panel is seeing. it doesn't know the inputs are wrong but it will make decisions with that faulty info.

I check the chiller readings against the control system's probes and the manual thermometers and gauges. everything is within 0.2° of each other.

Originally Posted by klove

You have nothing in your profile about you, or your experience level, and you're brand new to the forum. That needs to be corrected.

You did a pretty good job of posting your readings, although there's a lot more that could have been listed. If you have the experience and knowledge to get into the panel deep enough to adjust motor speed, then you should have the ability to check the settings and operating details to see what's out of line.

General info is given out in the public sections of the forum (much like my first response). When you get past the simple stuff, then it goes to the pro forum. Lots of reasons a York VSD might or might not slow down, and most folks are only willing to go just so deep in an open forum.

***You might want to check into that 5.5° delta T thing with 0% vane opening when you have time. You might also want to try and reconcile the fact that you're making setpoint at 0% vanes. Also, a VFD on a chiller is not designed to unload the machine, but for reasonable internal loads at a time when you can drive down the condenser water temps and allow the motor to slow down without getting into a stall or surge condition.

I fixed my profile. 2nd generation operating engineer, I've been doing this for 10 years now. I work for a property management company in Atlanta. I learned this field from father who is an union trained operating engineer with 35 years experience and a background in mechanical engineering. When I first got into the field, the first four years was at a central plant I where I worked with 4 R11 YTs in there at the building my dad worked at. Three of them were converted from SSS to VSD by York. I participated in converting the last one at a gopher capacity. I worked in that plant for 4 years and every time we had the units serviced, reactive or preventive maintenance, I work/learned along side with the mechanics so I can do most of the preventive maintenance and basic repairs on a YT. However, I do realize I am not an actual, trained chiller mechanic so I know when I need to back off and call in help before I go in and do any serious damage.

I did notice the 5.5° delta T. It did set something off in my head, but I wasn't sure if that was acceptable on a R123 chiller or not since this is the first R123 machine I've worked on. I know that's not overly acceptable with a R11 machine and we would be looking into the problem by now. It's not overly hard for this machine to make set point since my building is at around 70-75% occupancy (and on that day, it was raining/shady and not particularly hot out either) and it's just as not loaded it can be. The load just isn't there right now. On hot, sunny days, the FLA is in the high 50% range to low 60% range. This York was a replacement for a Dunham Bush R22 machine that was in the building originally. I suspect that it might be a little big for the building but without a full load and without the specs on the original chiller, there isn't really a way for me to confirm that. I'll look into the delta T.

It make difference if there's no load. The gas cfm through the diffuser helps the gas from flowing backwards, so load is relevant to lift. Yorks don't operate well with light loads unless you lower the lift. Yorks have vaneless diffusers and a wider stall window than any other machine. I had same issue during winter time as was able lower condenser water, chiller purred like a kitten afterwards. In the case of your chiller has no load in summer time is another issue. Are they running 2 chillers together or is it that that machine is really that over sized? There definately alot of stuff you need to look at as others are mentioning here verifying flow and dumping surge map. In my case I dumped the map and after about a week I was back to square one. My chiller was running at 56 - 57 htz. Also vanes closed. After dumping map ran at 35htz with vanes closed. By setting my set point to 65 degrees I've been able to match the load to the right entering condenser water temp even though the tower is always able maintain that setpoint. The theory is, when osa conditions go up so does the building load. There is an article that explains these condition in more depth.

Look at the history trends and then all the data readings that should give some indication.

Originally Posted by tacxc

Lower your condenser water set point to 65 degrees. At night it should be able to accomplish this. It sounds like you have may a light load/ high lift condition.

This chiller should be able to run at less than 60 Hz. with 76° ECW. I don't know where this chiller is located, but 65° condenser water cannot be achieved in many areas of the country in the summer even at night. The clue here is that when he manually slows the VSD an the PRV begin to open and it probably is running fine. As soon as he releases it it goes back to 60 Hz. Far more indicative of a corrupted surge map than condenser water that is too warm.

Lower your condenser water set point to 65 degrees. At night it should be able to accomplish this. It sounds like you have may a light load/ high lift condition.

Why is your cooler approach so high? Is it variable flow?

Originally Posted by rjcuomo1

I check and verified that both the prerotation vanes and VSD are indeed set in auto. I verified that the prerotation vanes will modulate by manually operating the drive down to 50 Hz and watching open to compensate to make setpoint. Once it made setpoint, I put the drive back into auto and it started to ramp up the motor and closed the vanes.

Sounds like a corrupted surge map to me.