Temperature readings

[Andy]

I have a four year old Fine Offset WH1081 on which I recently replaced the anemometer. I don’t know whether it is a coincidence but more recently I am now getting unusual high/low ‘blips’ in the outside temperature recordings as per http://www.claxton.me/weather/trends.htm. These recordings seem to coincide with an unusual wind direction which may be carrying exhaust fumes from two domestic boilers some sited some 15 and 25 feet distant, or are the temperature ‘blips’ an indication that the whole unit needs replacing.
Grateful for any opinions.

[steve]

I believe it has been demonstrated that one cause of temperature spikes can be some kind of interference from the anemometer and/or anemometer cable. Alan (AllyCat) will probably to able to confirm or refute this.

[AllyCat]

Hi,

Yes, WH-1081s manufactured more than a few years ago employ a "shared" Analaogue-Digital conveter, to report both the external temperature from a thermistor (variable resistance) and the wind direction (one of 16 switched resistance values). The A-D input is "permanently" connected to the wind cable (if plugged in) so any "crosstalk" can create spikes in the external temperature measurement. This can be a particular problem if the wind cable has been extended, or if any moisture finds its way into the cable/connectors.

My guess is that some moisture (rain) has got into the wind connector or sensor, to create crosstalk from the vane in some particular direction(s). Or just possibly, water could be condensing out of the boiler fumes into the wind sensor/connector, with a particular wind direction. I do note that your sig. file is reporting a high humidity at present.

Unplugging the wind cable (and ensuring that the transmitter is dry) should confirm if it's a crosstalk issue. Possible solutions are to use "Battery grease" or similar in the connectors, or perhaps a spray of WD40.

Cheers, Alan.

[Andy]

Alan (and Steve)
Thanks for your highly detailed explanation.
It could well be moisture causing the issue - the anemometer was replaced on a rather wet day so despite trying to keep the connections dry there could well have been ingress setting in train the current issue.
I will tackle this at the weekend - when hopefully it will be dry(er) - and try a squirt of WD40.
Your advice is appreciated.
Thanks