I just had a completely new ac and furnace installed with two zones, upstairs and downstairs, new duct work, etc., etc. and I wanted a way to monitor the temperature in our nursery for our new son, and adjust dampers and ducts accordingly to get a nice consistent temperature throughout the house. For this purpose this unit has worked great.

First off, if you are interested in the data logging don't even bother with the included software. Rather download the open source Weather Station Data Logger tool on sourceforge for free. You can do it now and play around with it, of course w/out data. Slight learning curve, but if you are interested in data logging to begin with you should be capable of learning the tool quickly. It graphs all the variables (namely temp and humidity) over time and allows you to customize the view if you so desire. You can label the series, like "Nursery", "Outside", etc. It also allows you to save the data off and load it back up, upload it places, etc. You of course need to have your pc connected via usb while collecting the data.

It was really interesting for me to see the various temperatures graphed overnight, including the base unit that I located in our bedroom where the upstairs zone thermostat is, one wireless sensor in the nursery and another outside. I could see as the outside temp goes down, the inside starts to follow it, and then I could see the blips where the heater started to cycle on. With some minor damper adjustments on the ducts I was able to get the other rooms to track very closely in temperature to the thermostat. It's comforting to know your baby is in a well conditioned room.

Outside of the data logging the unit is also quite nice. The red back lit lcd is a nice feature and easily accessible as a big button at the bottom of the unit. This allows you to easily check the readings at night without having to wake up too much.

The wireless sensor readings are displayed in a larger format towards the top of the display, while the local unit's temp is displayed smaller in the middle region, with the time/date slightly larger at the bottom (see pic).

The temperature readings seem reasonably accurate, within 1 degrees based on my observations and comparisons, which seems acceptable. They have a remote sensor with a digital display on it showing the temp and humidity, which is nice so you can read the temp directly from the sensor and from the weather station.

A couple of gripes, but not a big deal - to cycle through the wireless sensors you have to look on the back and find the button to cycle. Something on the front would have been nicer. You can't configure the names of the wireless sensors, they are just called "Outside 1", "Outside 2", etc. In my case it would have been nice to label the one in my nursery. I just have to remember that it is "Outside 2".

Overall a very nice unit. Although if you don't need data logging you might be able to find something a bit cheaper.

At one point I had three Oregon Scientific (OS) temperature/humidity instruments all at once - 2 of these and one more advanced weather station RMS600A that used the same sending unit. It was not my intention to collect these devices - it just sort of happened because the first two did not work properly and OS sent me the 3rd as compensation. It doesn't work either. But more of that later.

APPEARANCE: Eye of the beholder and all that aside, the reason I mention this is that there were two main reasons I bought this unit - OS reputation and the attractive appearance of this model. It was straightforward in presenting exactly what information I wanted - temperature in & out, humidity in & out, and time. It had no extraneous clouds, bars, graphs, or other filler to clutter up the display. It was of reasonable size, what I considered an attractive silver color that would not look out of place in my home, and looked like a well made product.

FUNCTIONS: The instrument displays outdoor temperature and humidity at the top of the display by default - it cannot be changed to display indoor readings there. The data is transmitted from the outdoor sensor THGN132N (included) which is powered by one AA battery. The main unit is powered by 2 AA batteries (all batteries are included alkaline Maxells which measured 1.52 - 1.54v when received) To the left of the temperature display is the indicator for which remote sensor is being read at the time, and a moving icon to display the signal strength. Up to 3 remotes can be used at any given time but only one displayed, which can be easily changed by pressing a button on the back of the unit. Next lower on the display, and slightly smaller but still quite easily readable is the indoor temperature and humidity, followed by the time and either day of week or seconds, your choice. Just above and to the left of the time indicator is the icon for the atomic clock receiver signal strength. The display can be lighted by pressing a bar at the bottom of the unit which triggers a light at the bottom of the display - the entire display is not backlit. This device can be connected to a computer but I did not test that function. Other reviewers have. None of the settings except time are adjustable.

ACCURACY AND RELIABILITY: CLOCK - Easy to set. Even in an area that gets no broadcast TV and few radio stations because of the terrain, the atomic clock receiver picked up a strong signal within 1 hour and maintained accurate time on all 3 units.

TEMPERATURE - Both indoor and outdoor temperature readings, compared to a calibrated laboratory grade digital thermometer, were within 3 degrees at temperatures varying from 2 degrees to 106 degrees F.

SENDING UNIT SIGNAL: All three units were adequately received from a distance of 130 ft obstructed only by a window. When a 2x6 outside wall with aluminum siding and fibreglass insulation and 4 - 2x4 interior walls were inserted into a 90 foot path the reception was intermittent. The current location is 60 feet with the same exterior and two 2x4 interior walls with excellent reception. The current unit is the RMS600A but prior was the RMS300 with the same reception quality.

HUMIDITY - Wildly inaccurate. The first week both of these units displayed inside readings of a constant 2% in a 45% environment, despite numerous resettings while the outside sensors failed to read at all. Eventually the inside readings displayed 10 - 18% below actual humidity, and outside readings suddenly showed up after the 9th or 10th reset. The outside readings settled into somewhere between 15 - 36% below the actual humidity as measured by a calibrated laboratory hygrometer. For a while I had contact with OS tech support every other day for 8 days but nothing they suggested improved the performance. New alkaline batteries were placed at least 4 times, each set checked to assure voltages > 1.52v. Switching sending units between main units did not make any difference, nor did the addition of the more advanced model RMS600A into the mix. In the end, none of the units ever displayed a humidity reading greater than 82% despite both the sending unit and the main unit being in dense fog and the laboratory hygrometer reading 100%. While the main units were not left outside in pouring down rain, the sending units were, although sheltered from the rain directly, and while the temperature was reported closely, the humidity was reported as between 64 and 79%, while actually 100%.

It was interesting to compare the readings between the receivers while all three sending units were clustered next to one another in a six inch space 6 feet from the receivers which were a foot apart. While temperatures were within 3 degrees, the humidity readings varied as much as 15%. The indoor readings varied between the main units too, by as much as 9%. Switching between sending units at each receiver produced irregular results as well in that sending unit 1 produced different results at receiver 1 than it did at receiver 2 and so on. The variation was as much as 11% between units. So it's not clear whether the defect lies in the sending units or the receivers by my small tests.

OREGON SCIENTIFIC SUPPORT: Prompt and polite, but redundant one-note support regardless of the message to them and ultimately unhelpful, although probably not because they didn't want to be, just because they couldn't be. Every response from them consisted of instructions to reset and resync the units, even if the message to them was that it had already been repeatedly done. That is apparently all they have to offer, but they offer it repeatedly with the admonition to contact them again if it doesn't help. You can guess the reply when you do contact them again. The point is that there's nothing adjustable on this device. So if repeatedly resetting it fails, they replace it. The one thing that was not tried was a different sending unit model, although the receivers were sufficiently unreliable as to have made that option unacceptable had it been made.

SUMMARY: Attractive standing unit, very accurate atomic clock, and fairly reliable temperature measuring instrument which is completely useless as a humidity indicator, inside or out. It is not even consistently inaccurate to be used as a guide for winter humidification. Sometimes it's off by 15%, sometimes by 36%. I returned both RMS300s to Amazon and only kept the RMS600 because OS sent it free. If I had paid for it I would have returned it too. For humidity readings I use the very accurate [...]

ADDENDUM: The reset/resync procedure as recommended by OS:
"Thank you for contacting Oregon Scientific Customer Support.

When you are replacing the batteries into the main display and the
sensor place the batteries into the sensor first and then the
main display.

One solution that I've had a lot of success with is a battery reset. A
battery reset consists of a few simple, but crucial steps.

*Please Note: Keep all components within the same 10 ft. radius to
re-sync.
1: Remove the battery/batteries from your malfunctioning sensor(s).
2: Remove the battery/batteries and AC power (if applicable) from your
indoor receiver.
3: Allow a minimum of 10 minutes for any/all capacitors to discharge.
4: Reinstall the batteries into your malfunctioning sensor(s). Press a
paper clip or pin into Reset hole into the battery compartment.
5: Reinstall the batteries in your indoor receiver. Press a paper clip
or pin into Reset hole into the battery compartment.
The units should re-sync immediately, however, we do recommend that you
allow 10-15 minutes for the units to sync before initiating any manual
channel scans (as outlined in your manual)."

I have had 3 self-setting-indoor-outdoor-thermometers so far. Actually I still do.

The cool part about this unit is the USB port. I have this unit attached to a laptop running downloaded "WX Data Logger" (open source) software. I read the reviews and based on that I never even got the disk out it came with. I bought an additional wireless sensor and now I can track in real-time the inside temperature, outside temperature and the temperature coming out of my furnace (which is a heat pump).

Since the efficiency of a heat pump varies radically based on outside temperature I use this thermometer to make sure I have the set-back thermostat configured to raise the house temperature at the peak outside temp in the winter; and to make sure I have it set to lower the temperature right after I leave in the morning when the outside is coldest in the summer.

I have returned a few of the indoor and outdoor wireless weather stations for one reason or another in the past few months.
This one is just right for me and gives me the three views that I wanted. Indoor temp and humidity, outdoor temp and humidity and the an atomic clock. Some of the weather stations have too much clutter for me to see without putting my glasses on. The overall size of this one is smaller than most but the numbers are of good size, one of the reasons that I bought it. It does not look out of place on my end table where I can view from my easy chair. I do not use the computer function at all.

I needed a simple temperature and humidity measuring weather station that would allow me to access the data on my computer in real time. This station does just that, using the USB cable that is included. I am able to do calculations and analysis of the data in real time for a low price.