Topic: PWS for HVAC monitoring?

[Old Tele man]

Anybody else here using their personal weather station (PWS) to perform HVAC monitoring and analyses?

1) Originally, I just used my Davis VP2 to monitor our evaporative cooler efficiency...that is...to 'alert' me when the aspen excelsior pads were "clogging-up" with salt encrustation and thus 'lowering' the coolers ability to "cool" the air; i.e., when the saturation efficiency number dropped below 0.80 I knew it was time to change the pads.

2) Now, however, I use an added Davis Envoy8X to monitor our HVAC operation and room-to-room balance, using five wireless Davis #6372 temp sensors (in family room, kitchen, and each bedroom). The VP2 gathers outdoor data while the Envoy8X gathers both outdoor and indoor data.

3) And, combining the daily "mean" temperature values with daily electrical power consumption numbers (kWhr), I was able to derive a mathematical approximation for the power consumption (kWhr) versus each daily "mean" temperature (T) for our house:

kWhr/day ≈ 0.0308*(T²) - 3.5112*(T) + 120.31; R² = 0.9277

Note that an R² value of 0.93 is pretty good, but not quite up to the "preferred" value of 0.95 or higher.

[C5250]

I have a 6372 in the attic and another in the crawlspace. Not really appropriate for living spaces though.

[Old Tele man]

I just plug each #6372 in (using both battery and #6625 AC power adapter) and route the sensor to 5-feet above floor in an unobtrusive spot in each room. That way, should the house power fail (we get summer monsoon thunderstorms) the unit continues to function; using both battery and VAC is my poor-man's backup system.

Sounds like you're located where winter cold can be a problem for under floor water pipes.

[C5250]

Sounds like you're located where winter cold can be a problem for under floor water pipes.

Exposed pipes are insulated, but there was one time when a pipe in the crawlspace burst. Which became: Where WTF is water running full blast??? Usually not a problem though. The 6372 did help prove my point of a piss poor dryer vent solution dumping way too much moisture into the crawlspace through, the dryer vent has since been rerouted to insure it is exhausted outside.

I also have both normally powered by an AC adapter, so the battery is only for backup.

I still wish a Davis console/envoy could "retransmit" it's inside data so I could use it as another station.

[Old Tele man]

Although I *started* with just a VP2, I added the Envoy8X to specifically allow me: (1) to use more than 1-2 extra #6372 temp units...and...(2) to get better 1-decimal place accuracy (XX.X vs. XX) which VP2 didn't provide.

Maybe I'm wrong, but it's my understanding the VP2 *can* retransmit the few station(s) that it does receive; but, I know the Envoy8X does NOT retransmit.

[C5250]

The standard Davis VP2 system allows for up to a total of 4 Temp or Temp/Hum stations, one ISS, one anemometer transmitter and 2 soil/leaf stations (with sensor limitations dependent on config, for instance a single soil/leaf station could provide 4 additional temp sensors with the proper config).

The retransmit is only of ISS data, and anemometer transmitter if so equipped and configured, not the indoor console data, nor any other stations.

[jeffland]

You might consider Wireless Tags from http://www.wirelesstag.net/index.html.  Don't let the fact that they're battery powered scare you off, because I've had mine connected to an HVAC vent for 11 months recording temps and humidity every 5 mins and the battery is still going strong.

[Bushman]

+1  Some of the wireless tags will last years on a battery.  Plus full web access.