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ga1279
12-19-2009, 02:35 PM
I have 2 York YK's with York's analog flow switches in the chilled and condenser water lines. These are identical to the switches used by Carrier in the 30GX screw chillers with the red, yellow and green LED's to show flow or loss of. My question is are the York versions adjustable ? Carriers had a covering over an adjustment screw that you could used to calibrate flow switch sensitivity. The York is hard plastic and doesn't appear to be adjustable only replaceable.-GEO

klove
12-19-2009, 04:01 PM
They're not supposed to be adjustable, but if you can get the cover off and adjust it without rendering the thing useless, we won't tell anybody.

deux
12-19-2009, 04:30 PM
They are sealed so you cannot tweek them for less flow. They come set to the min flow rate at the factory. Are you having flow issues? They are tricky in the cold weather, they seem to read an empty pipe on a long shut down in the cold, even with glycol. I am not sure why. I shut my systems down for the winter anyway, but I leave the chiller in standby incase we get a warm snap , in the fall ,they alarm. I am not sure I like them as much as the old mechanical ones.

henrichrl
12-19-2009, 04:41 PM
why do you want to adjust the switch? if your having flow problem, did you install the right one?

york56
12-19-2009, 07:14 PM
They're not supposed to be adjustable, but if you can get the cover off and adjust it without rendering the thing useless, we won't tell anybody.

I can fix broke but I can't fix stupid !

yorktek37
12-19-2009, 10:54 PM
They are a thermal type flow sensor. I have found that if any crud builds up around the stem it will cause problems. I always remove them and run a brush into the holes during annuals. I have never cracked one open but why would you want to take the chance. Once you do that and the barrel freezes uo for lack of flow then who is to blame. If you don't like them or have problems with them then install a paddle type switch. The board will work with either type. Just a change in the jumpers and in the software setup.
Personally I like to sell the thermal type as an upgrade from the paddel type switches. They can be ordered as a add on.

klove
12-19-2009, 11:36 PM
One of the problems with the thermal switches is the grade of stainless they use in the stem. Once it starts corroding, it insulates itself, and that 24 volt signal builds a lot of heat. Quality of water effects the corrosion issue, also. Bad grade of steel and bad water can kill one in a hurry.

All kidding aside, adjusting it probably won't do any good if the installation overall is correct. Popular opinion is that they're set for minimum flow for a chiller, but the reality is that they're set for a certain feet per minute of flow rate, and that flow rate changes for any given gpm being shoved thru a given size nozzle. Min/max flows change with the tube bundle and tube type, but ft/min remains constant for a given flow thru an orifice. If the field connected piping is too small in and/or out, it will affect the operation of the sensor. I'd recommend a d/p switch calibrated in feet of H20 if that's the case. Get one with gold or platinum contacts and you can use it on the 5 volts going to the switch contacts and won't have to change anything except to kill the 24 volts to the device. Or you can run 120 volts to it and as yorktek said, change the program to accept a digital input to the I/O board.

ga1279
12-20-2009, 12:19 AM
York 56 I sure your comment was not meant for me. I have pulled and cleaned the sensor body and the problem is still there. The chilled water loop is not the cleanest, but the chiller next to this one does not have the problem. Same York YK same analog switch, same dirty chilled water. No,I did not install them, they were installed at the factory. I also did not install the M/M paddle flow switches in the chilled and condenser water lines. However I am smart enough to know that I can scroll through various parts of the program and switch to a digital flow input. My customer wants to use the analog switch working or not. As it shows flow when all pumps are off I would like to try and adjust it, if not I would just as soon replace it once and for all. The customer has already signed a form releasing me from any responsibility in the event of a freeze-up-GEO

yorktek37
12-20-2009, 02:12 AM
York 56 I sure your comment was not meant for me. I have pulled and cleaned the sensor body and the problem is still there. The chilled water loop is not the cleanest, but the chiller next to this one does not have the problem. Same York YK same analog switch, same dirty chilled water. No,I did not install them, they were installed at the factory. I also did not install the M/M paddle flow switches in the chilled and condenser water lines. However I am smart enough to know that I can scroll through various parts of the program and switch to a digital flow input. My customer wants to use the analog switch working or not. As it shows flow when all pumps are off I would like to try and adjust it, if not I would just as soon replace it once and for all. The customer has already signed a form releasing me from any responsibility in the event of a freeze-up-GEO

as klove even said there are jumpers to be set also. If they gave you a form that releases you I would get 3rd party witnesses to sign because if you look a $50k+ barrel it can get nasty. As far as cleaning its like they welded in a coupling into the nozzle and it only lets just the tip be exposed. Thats why I'll run a brass brush into the hole. However there are many instances that Paddles work sooo much better. the MM Paddles are the best I have used. Much better than the JCI ones. Klove is right though. I would use a DP Switch. I just hate having to deal with the tubes getting clogged up causing the DP to not sense correctly.

york56
12-20-2009, 08:37 AM
First my comment was not directed at you , all opinions by yorktek37 & klove are right on , digital efector switches are ajustable but the anolog are not it amazes me to this day how many people still don't understand the critical nature of that saftey switch. I have seen installations incorrect and even service to maintain the integrity on paddle style , differential pressure , or even efector , just some examples paddle style mounted vertical , differential pressure for water outdoor temp below 32 deg. no heat trace guess what happens next etc....!

ga1279
12-20-2009, 02:32 PM
Gotcha ! But seriously both these chillers have VFD's on the chilled water pumps with lower speed limited to 40htz. At this speed the chiller receives 60% of design flow. They were originally set to 20htz and all that caused was low temp. shut-downs. My customer will want to have the existing control replaced with same. If the switch is calibrated to the machine design flow that could make things difficult, even if it is based on flow velocity. I have adjusted many of the Carrier style switches using a DP gauge and have had no problems with them afterwords. I do respect all of your opinions.-GEO

klove
12-20-2009, 03:01 PM
York 56 I sure your comment was not meant for me. I have pulled and cleaned the sensor body and the problem is still there. The chilled water loop is not the cleanest, but the chiller next to this one does not have the problem. Same York YK same analog switch, same dirty chilled water. No,I did not install them, they were installed at the factory. I also did not install the M/M paddle flow switches in the chilled and condenser water lines. However I am smart enough to know that I can scroll through various parts of the program and switch to a digital flow input. My customer wants to use the analog switch working or not. As it shows flow when all pumps are off I would like to try and adjust it, if not I would just as soon replace it once and for all. The customer has already signed a form releasing me from any responsibility in the event of a freeze-up-GEO

If it shows flow with all pumps off, I wouldn't think that it would be a candidate for adjustment. If it ever worked correctly, sounds like replacement is more in it's future. Only thing that might override that is if you have some sort of convective flow set up in the chwtr loop, but that can be determined by shutting off the iso valves and see if the switch remains closed.

On a second note, I'd like to comment on the "I've got it in writing from the customer" thing about the freeze-up protection. I know that sounds good, and lots of folks do it at different times, and everyone says it works - but who do you know that's actually had to test it in court? York had a situation several years ago where they had just that take place, and for all the signed documentation, the customer still wound up with a new chiller on York's nickel. Judge said that the customer was not a subject matter expert on chillers, and thus didn't fully understand the ramifications of signing that document. BE CAREFUL!!!

ga1279
12-21-2009, 02:05 PM
K-Love I never really thought about it that much except for the customer accepting responsibility for their own decisions, I do agree with you to a point. The same could hold true with a gas furnace or boiler that is in an unsafe condition, the customer isn't a expert, that why they called us in the first place. I can't believe that with all of York's legal talent that one got by them. I was involved with a case at the U of Houston were a chiller froze up the tubes. The machine was only 2 years past start-up and it was proven by a group of professional licensed engineers that it was a defective machine practice in the manufacture and maintenance of the machine. This chiller was still under York's care mind you as it wasn't turned over to the power plant yet. It ended up costing the state of Texas $215,000 for repairs, manhours, dehydration and re-charge. It went to court and York won the case.-GEO

milkyway
12-24-2009, 09:07 PM
...I would think for safety reasons that there would be a DP and a paddle flow switch in line in series. Am I right


First my comment was not directed at you , all opinions by yorktek37 & klove are right on , digital efector switches are ajustable but the anolog are not it amazes me to this day how many people still don't understand the critical nature of that saftey switch. I have seen installations incorrect and even service to maintain the integrity on paddle style , differential pressure , or even efector , just some examples paddle style mounted vertical , differential pressure for water outdoor temp below 32 deg. no heat trace guess what happens next etc....!

klove
12-25-2009, 12:21 PM
...I would think for safety reasons that there would be a DP and a paddle flow switch in line in series. Am I right

Not a bad concept, but then where do you draw the line on exactly how many redundant direct flow related safeties to install? Normally the factory will tell you to have 'A' flow safety in the chilled water. Most veteran mechanics like to see condenser and chilled water direct flow safeties, with the pump auxiliaries in the flow safety circuits, also. Depending on circumstances, sometimes you get more than that, sometimes less.