Tuesday, July 17, 2007

Rite Temp GPMG8085C: Informal Review

Rite Temp GPMG8085C

Who would've thought that this blog would be one of the most often referred to sources of information about GPMG8085C... All right, if that's what y'all want...

Ever heard of "The Golden Triangle"? "Good, Cheap, Fast - Pick Two". So, this thermostat may just as well be the closest approximation. $20 cheaper than the next guy (Honeywell RTH7500, I'll come back to it another time), does the same job, if not better.

Comparable quality and length of DIY installation.

Installation complexity: no-brainer (YMMV). A few advices, though:

  • Make sure you RTFM;
  • Don't drop the wires into the wall;
  • Programming is best done when the thermostat is laying on the desk before you, not when you're standing next to the wall with the thermostat on it;
  • At least for me, the preinstalled battery still works after a few months of operation, may want to ignore that paranoid advice to remove it.
Significantly bigger and nicer backlit touchscreen than the competition has (to be completely fair, they do have a big touchscreen on VisionPro, but that one is almost twice as expensive, so no cigar), and it has a nice textured button that you can grope (English experts, give me a non-ambiguous word and have my thanks in return) in the dark without being afraid to push a wrong button and reset something.

You have to really hate your customers not to provide an option like that (example: RTH7500 needs you to press any button, and, invokes the action corresponding to that button, even in the dark. So you have to be really careful where you tread, and the fact that the screen is backlit is useless - you can't comfortably use it anyway).

There's a stylus and a holder, but feel free to ignore it - fingers and/or fingernails do the job just fine. No visible scratch marks after few months of use.

7-day programmability is certainly nice, but the schedule selection is really weird - you can't set the schedule boundaries at arbitrary time, but only at one of two settings (forgot what times exactly, will update later). Kind of inconvenient, and this is probably the most annoying feature, or, rather, lack thereof. Competing device shines here - you can have your heat and cold any time.

Side note: I'm wondering why nobody figured yet that anticipation is something you're quite willing to have for a period starting, say, at 6PM, when you return from work, but not really want for the period starting, say, at 9PM - when you are on a time of day electric plan, which makes energy after 9PM three times cheaper than before. Remember, you read it here first.

If you don't need 7-day programming, there are other, cheaper Rite Temp models that offer compatible feature set, but 5+1+1 or 5+2 day programming.

I'm quite willing to forgive lack of schedule configurability for including an extremely important feature - you can manually change the hysteresis. Setting it to the maximum value makes the temperature spread quite noticeable (up to 5°F), but makes the unit cycle about three times less often than it would otherwise do. Don't have equipment to measure the actual gain, but would certainly recommend this thermostat to people who are either energy conscious and don't mind little discomfort, and to people who have grossly oversized units - you guys may suffer from temperature swings even worse, but at least your electric bill will drop like a rock because the unit won't breathe like a dog outdoors in Arizona summer anymore.

Can't say anything about humidistat - not much use for it in the middle of Arizona summer.

Another useful feature - filter usage counter. Depending on the climate, your unit may cease operating for a couple of months in mid-season, so you can afford to buy a higher quality, more expensive filter without a fear that you're wasting money (just think of how much it'll cost you to clean the inner coil when the time comes, and reconsider buying that inexpensive $3 filter).

You definitely need to read the manual provided with it in order to learn to operate - but then again, this is true about any more or less complicated home appliance - it takes significantly higher IQ to figure out how to connect the 5.1 home theater and the rest of components together without electrocuting oneself, so no big deal here.

At least all the settings have icons assigned to them, and you can figure out what is what, unlike some other designs, where features are indicated with numbers (come on, it's not 1960 anymore...)


Well worth the money I paid for it.


God, what have we come to... Anyway - use your common sense, don't do stupid things, and read this first.


  1. Hey--I might be misunderstanding, but i think you can change the zone times in quarter hour increments--but you have to be in heat mode. i will verify later, but it seems that i remember reading (and changing) it...

  2. I owned this model for a couple of years, worked fine at first, but gradually performance degraded to the point that I replaced it with a Honeywell. Temperature reading became incorrect and the thermostat would cycle the furnace/air conditioner on/off for no apparent reason. Replaced batteries multiple times - didn't help at all. The new Honeywell works flawlessly. From reading about Rite Temp elsewhere I'd be wary before purchasing this particular brand.

  3. On the other hand, this thermostat (and two of the same brand at my friend's house) worked flawlessly since day one. You may have encountered a lemon.

    Reviews, as I was trying to point out, should be taken with a grain of salt - you never know how smart are the people that write them.

  4. I have had this same thermostat for over three years. I can not recommend this to anyone because it is not accurate. Currently about to buy another. Don't waste your money on this one!

  5. @Anonymous: don't know what you mean by "not accurate". Still works for me, verified by 1-Wire sensors, works just fine.

  6. I have had mine for 5 years. It has not had a problem at all and worth the money paid.

  7. Hi all - I have a problem with my Ritetemp 8085C: I have a dual-zone gas heat/electric AC system with a Honeywell TH811OU1003 thermostat controlling zone 2 that I loved but which died after about 6 years (which seems like a VERY short lifespan compared to my many other purely solid-state devices around the house, but that's another issue). Anyway, I replaced the Honeywell unit with the Ritetemp 8085C, and the wiring seemed to be quite simple and standard (4 wire: red, white, yellow, green) from both the thermostat end and the controller end down by the gas furnace. After installing the 8085C, which was easy and fast, it turns on the gas furnace but apparently does not flip the valve in the ducting to send the heat to zone 2; the furnace kicks on but blows the heat only through zone 1 vents. I've re-checked my wiring, but as I said, it seems pretty simple - maybe I'm missing something basic. The worst problem is that I've called Ritetemp (1-877‐505‐2353) 6 times over the past two days and am ALWAYS sent to voicemail, even though their pleasant-sounding voicemail person says "You will be connected to our next available agent" and "Your call will be answered in the order it was received". So, I'm giving up on them actually answering their phone and will apparently have to solve this problem myself (with YOUR help, of course!). Anyone have any ideas about why my Ritetemp 8085C will not control its own zone? THANKS for any help you can give! I've had this thermostat sitting on my workbench for a couple of years and would rather use it than go buy another expensive Honeywell unit. (Batteries are not an issue; I've replaced them. Besides, battery power output should have no impact on this type of problem.)