Monthly Archives: June 2019

Chilled Water System Service near Saint Basil's Cathedral

Global Chilled Water System Service

Moscow Visit

Always good to get out of the country to carry out chilled water system service around the globe. Just had a little free time this visit to see Red Square and Saint Basil's Cathedral. Most of the visit was bogged down resolving issues

Electrical Problems

One of the water cooled chillers was pumping down due to electrical problems. One of the solenoids for the evaporator was not opening. All checked out okay with the solenoid coil and valve. Following the wiring diagram lead to the relay board. The relay board is responsible to run various components around the compressor. It was not obviously blown and there were no dry soldered joints on the back. I decided to tighten up the wiring and unplug, then plug all the connectors back in. When I ran the chiller again the problem went away

Chilled Water System Global Service

As we provide a global service for chilled water systems: we cannot get back the day after leaving site. Therefore, after resolving the above issue, I ran the system in local with some of the other systems off to prove it. All was okay. After completing the rest of the service on the chillers I put the whole of the plant back in Auto to prove it all together

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Flow Switch Failure During Global Chilled Water System Service

The flow switch failed in one of the most remote plant rooms in the globe for chilled water system service. This is due to security issues. As one of the service checks- I tried to trip the chiller on flow fail. The chiller did not stop. I didn't want to valve off the water system repeatedly as the air handlers are old and 'dead heading' could cause failure. Instead I decided to use the Hand/ Off/ Auto switch for the pump. There are two adjusting screws on the flow switch. After several attempts I got it to settle down, then carried out tests to make sure it would not happen again

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Chilled Water System Flow Switch Maintenance

Chilled Water System Maintenance

Maintenance of the Chilled Water System Flow Switch

The chilled water system flow switch requires regular maintenance due to a to build up of contaminants on the sensor. Over time, slime accumulates giving false readings. The problem is relatively easy to sort out: a wipe with a cloth

Retrieving the sensor

The more difficult part is deciding how the retrieve the sensor. It is fixed with a bolt into the chilled water system being maintained. Therefore there is pressure inside. The textbook way to do the job is to valve off the section of pipework, then drain the glycol into a vessel. There are other ways known to an engineer

Snatching the Flow Switch!

Although not text book: snatching the flow switch is a considerably easier way of maintaining the chilled water system! One of our seasoned engineers unscrewed the bolt whilst holding the flow switch in. He whipped it out- gave it a quick wipe and stuck it back in! Only a small amount of the secondary coolant was lost (which shot out- loosing no height) He re-tightened the bolt and the job was done

0161 370 7193

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Checking the Fault Out Level

As you can see from the picture: there is a green light on 0. This indicates that the pump is off. Not to be confused with pressure, as there will be a couple of bar on a roof an 6 bar or so in a basement. The higher pressure in a basement is due to the head of water pushing down. With the pump on: the green lights go all the way up to 9 with the fault out level showing red on 7

Maintaining the Chilled Water System Fault Out Level

Maintaining the chilled water system flow switch can be achieved with a terminal driver. Using the manual that comes with the flow switch: the buttons can pressed a number of times to 'self test' Also, the fault out level can be set

Testing the Flow Switch

As part of the maintenance, the flow switch is manually tested using one of two methods. This ensures that the switch will function correctly when it needs to

Read more about flow measurement on Wikipedia


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