Air-conditioning fixes

Recently we've had some problems with the KAIRA RF-container air-conditioning again. The problem this time has been that the refrigerant has been too cold and has lost pressure. This has taken a little while to resolve, but we now have fixed the problem. This has been done by heating the airconditioner!

Yes, that's right, we have put in a heating coil which is variably heated according to temperature. Thus, in the bitterly cold winter nights, this coil warms up sufficiently to keep the partial pressure of the refrigerant at sufficiently high pressure to allow the compressor to continue working. It is a tough fix to make, but we hope to have improved reliability again.

Servicing the air-con unit at KAIRA. (Photo: D. McKay-Bukowski)

Toivo explains the changes and the new heating system. (Photo: D. McKay-Bukowski)

KAIRA frozen

Yes, it is the Arctic, but for the most part, KAIRA copes with the cold. Having a lot of warm signal processing electronics and computers keeps the inside of the RF container pretty toasty. However, in the early hours of this morning, we came unstuck.

Due to a computer failure, we scheduled a 5 minute UPS power cycle to reset the station. In the end the outage lasted a total of 7 minutes. Following the re-establishment of power, we did not recover the cooling system. Our suspicion (although we are still working on testing and checking this is that during the outage, the load on the air-conditioning dropped, thus allowing the low outside temperatures (approx. -35 deg C) to adversely drop the pressure of the refrigerant. This caused an air-conditioning failure.

Outside temperatures. The UPS was shutdown at approx. 0400 on 20-Jan-2014.

The irony is that, when the power was re-established, the internal computing and electronics overheated. Made even worse by the near-zero humidity, giving little heat transfer capacity to cycling air. The final error message before the system self-shutdown to protect itself indicated an internal temperature of 35 deg C... some 70 deg C greater than the outside ambient!

Within an hour of this shutdown, the temperature will have plummeted again.

We have checked the site today, but there is not a lot we can do without major work. Our best chance is actually to wait for some forecast warm weather ("warm" means > -25 deg C), which is expected later this week.

In the meantime we are off air awaiting the better conditions.

Such are the hazards of Arctic operation.

Warming up the electronics

Another part of the post-winter checks was making sure all the electronics were okay and that the systems were operational. Because winter can get extremely cold (–40 degrees) it is actually necessary to provide heating to ensure that the systems do not ice over!

The RF-electronics in the container at KAIRA.

Seriously! Where else would you find radiators in an electronics cabinet!

Everything was in good condition and the container was at a good temperature. Excellent news and we proceeded to continue configuration and testing work.

Air conditioning

Another winter-sensitive part is the heat exchanger of air conditioning unit on the end of the RF container. This is completely exposed to the elements and there was a large potential of ice and snow building up and causing problems.

The the heat exchanger of the air conditioning unit is located at the end of the RF-container. 

We asked around a bit, and heard of this type of a snow shield specifically designed to keep snow and ice out of air conditioners, without interfering too much with the primary function of dissipating heat.

Snow shield

Here is a picture of the snow shield installed on the RF container:

The snow shield, GPS antenna, and the already slightly weathered hawk owl's nest box.