indeed, a dandy device. & just what every solar, geo, effeciency person like myself & others, would want. don't mind spending $ to save $. be nice if it were more like $200. after all, most DIY'S are frugal.

Interesting, but for that kind of $ I would look in to the Davis weather monitor, it can store and log temps over 6 months over years if you space out the sampling intervals. You can also get multiple sensors in wired or wireless, and you get a weather station to boot. I suppose if you add up enough weather station parts to match what they have it would be more, but you get more as well. Oh it can do web logging as well.

I hope I don't sound like a shill for the WEL, but it is much more capable than the Davis stations. Don't get me wrong, the Davis stations have a great reputation and I'm sure they are very good at what they do. But it's really comparing apples and oranges. At a glance the Davis seems to have capability for 8 extra temperature sensors. The WEL can handle up to 128 sensors (temperature, humidity, solar insolation, power, voltage, etc) and since the sensors are the Dallas 1-wire they are extremely cheap for the accuracy you get. I think I paid about $2.50 per sensor for 50. For geo systems the WEL can do real-time COP calculations, running averages, filtering, etc. There are also contact closure and pulse inputs. I have yet to find anything that comes close to having similar features at 10x the price. Actually, I take that back - a PC based system can be very cheap and flexible if you don't mind running it 24/7.

The WEL isn't perfect by any means. There are lots of features I'd like to see added or changed (local backup for data in the event of an internet outage is a biggie), but it is built by an enthusiast for other enthusiasts and as such is a great value for the money in my opinion. For what I use it for I would either need to run a PC with custom software and associated headaches, or spend several thousand dollars to get an equivilent "professional" datalogger.

It comes down to what you want to monitor. If you're just looking at a few temperatures, the Davis might indeed be a better option. If you're a nut like me and want a temperature sensor in each room, on each radiant loop, 3 spots in the buffer tank, ground loop, hydronic loop, compressor inlet and outlet, condensor, etc, as well as 2 flow meters, 2 power meters, several switches and probably others that I've forgotten, I'd recommend the WEL (or a therapist).

All very good points. I catch the voltage logging as well, very neat and it's true about he sensors for the Davis being pretty expensive for what they are. Now I ahve another thing to put on my "buy some day" list.

I have two WaterFurnace GSHP units, Envision models with 2-stage compressors and variable speed blowers, operating with a closed water-loop.  I put together a performance monitoring system, based on the WEL product.  Considerable power consumption and performance information is available, water temps and water/air deltaT data, and along with a good amount of weather and inside conditions data.  You can see details here: http://welserver.com/WEL0043/ .

I live in the Dallas area so it's hot right now - 100°F days at the moment.  My incoming water is about 78° and I'm consuming about 39 KWH per day to cool a 3400 single-story residence with a lot of windows, considerable air infiltration, a hot attic, and not so great insulation .

I'll be happy to answer any questions.  I'll put contact information in my profile.

Best regards,

Bill