Monday, August 26, 2019

Monitoring the House

We don't have a smart house in the sense that term is used these days.  No self-bugging features like Alexa or the Nest thermostat.  We do, monitor though.  We have some simple wireless thermometers that we use to keep track of the spare refrigerator (which is old and barely still cooling), and the big freezer.  We can read those temperatures from the kitchen.  We have several of the so-called Atomic Clocks which include a temperature sensor in them, so we can look at the temperature in every room if we walk into the room.  We have a digital thermometer that can monitor the temperature where it's positioned.  Plus we have some of the ubiquitous cameras, a smart doorbell and so on.

When we had our lightning strike back on August 1st, among the very first things we found was blown was our central air conditioning thermostat, and it was the first thing we called in to get fixed.  It was repaired within a few hours on the 1st.  It wasn't long after getting that repaired that I started to notice I wasn't as comfortable as I had been in the house.  I felt like it was damper and that I was sweating more than I had been.

The new thermostat is different from our old one in some ways I don't like.  The first thing is that my old thermostat had a setpoint that behaved in a way that I'd gotten used to: the cooling would come on when the temperature reached two degrees higher than its setpoint, the air would cool until it returned to the setpoint and then would turn off.  By contrast the new thermostat triggers as soon as it senses the temperature has gone up one degree - the controls theory term for that is less hysteresis.  The other thing is an annoyance: I could tell by looking at the old thermostat from a few rooms a way that the unit was on by a green LED, and the temperature display had a low level illumination so I could read it at night without turning on a light.  The new one has no indicator light and the panel won't even light to read the temperature without pushing a button.

I spent several hours over the last couple of weeks reading the manual and searching online to see if the central air having a different On/Off hysteresis could make it feel more humid, or if I could change the hysteresis at the thermostat.  No results.  In addition to that we've been setting a temperature and checking it primarily on the clock in our bedroom.  With the old thermostat, we'd find that the temperature in our room was usually two degrees warmer than the thermostat setting.  Lately, the temperature was four degrees higher and some results said it didn't matter what we set the thermostat to achieve, it was always four or five degrees higher.

Around noon, Mrs. Graybeard concocted a brilliant impromptu experiment.  She took the digital thermometer and put it on top of the thermostat.  The thermostat was set to 76.  After a little while to acclimate, the second thermometer read 80.  We experimented with that by changing the thermostat several times.  The comparison thermometer always reads four degrees higher once the cooler turns off and the system fully shuts down.

We did this all day.  The main complication I can think of is embedded in the old proverb: a man with two watches never knows what time it is.  Which one is right?  Time for a double check with a completely independent sensor: an old model FLIR One infrared camera for my not-quite-as-old iPhone.  This evening with the thermostat set to 74 the FLIR read the temperature at that location at 78.3.  Case closed. 

The thermostat is not really controlling to the set temperature.  Is this another one of those EPA rules like water temperature in the washing machine or dishwasher? 

This would explain the difference in my comfort level.  I spent another half hour or hour today looking for settings to fix the thermostat with no success.  For now, I'll simply set the thermostat four degrees cooler than I otherwise would.  There's a possibility it's simply bad, so we'll contact the folks who put it in. 


  1. How about - the new thermostat manufacturer wants you to think that you're set for 74 but is actually intentionally 4 degrees high to save you money, or to be "green". Like low-water toilets, low-water showers, low-phosphorus dish detergents, etc.
    Wandering Neurons

  2. Hey man, this is "stealth" justice. We gonna save the planet whether you like it or not.

    Power surges fried my honeywell aquastat a few times- till I discovered the problem- there were wire legs of a resistor soldered into a printed circuit- in large scale, it would have looked like a 1" diameter solid copper slug soldered on end to a sheet of aluminum foil. Of course it vaporized the foil around the resistor leg. Took five minutes and 5 cents worth of solder to fix a $100 unit.

  3. It's a sad state when we can't even trust the integrity of thermostats.

  4. Raven and Anon 9:58 PM,

    This is exactly what I was talking about in that second to last paragraph about EPA rules like water temperature. Our washing machine isn't allowed to use the Warm Water setting, because the EPA rules say our water is already warm. We only get to use Warm on a handful of the coldest days every winter. The rest of the time it takes twice as long to fill because only one tap is on.

    The EPA doesn't care about my time or how long it takes to get the clothes clean, they just want to make sure I don't use energy warming water that they think is already warm.

    1. Many years ago, I did a partial fix for this sort of stupidity, by installing a bypass switch that connects the hot and cold solenoids so I would get warm water for rinsing. The machine only had cold setting for rinse.
      Easy to switch back to the original cold rinse if needed. Drawback is that if it is engaged, the wash cycle only has warm. The trick was to leave the lid up during wash cycle, so the lid switch would stop the machine until you hit the switch for warm, and closed the lid. Mildly awkward, but I've never bothered to do it better. Never expected that washer to last this long. 30 years old! Bad thing is that agitator beats up my heavy clothes, so my pants don't last as long as they should.

    2. BTW, someone finally figured out the reason for the worldwide increase of bedbugs that travelers have encountered. The EPA and associated Greenies suggested/mandated hot water heaters everywhere be set at 120F, when they used to be set at 140F.
      Want to guess what temp it takes to kill the little buggers?
      Yep, 140F.

    3. Will, I can't tell you how many times I've said I'm going to hack the washing machine, but that thought usually evaporates when I'm not looking at it. I wouldn't have a problem with hard-wiring them together except it would probably blow out the driver that turns them on.

    4. A few years ago I had to replace malfunctioning fancy digital washer (it came with the house) so I went to the local used appliance place and bought an old Whirlpool. It does what I want manually with no trouble!

  5. This sounds like a fairly simple project with a small microcontroller. Once it's digital, you could always add features.

  6. BTDT and also used a third instrument to find the culprit.

    I I guess having such a narrow dead-band would make the system appear to be more responsive, but that comes at the cost of cycling the system more often.

    Not good for a system that wasn't designed and built for the increased cycling.

  7. My NEST 'smart' thermostat has to be TOLD what the REAL temperature is vs what it's internal thermometer reads. Once that is programmed in it follows the actual temperature rather than what the built in thermometer reads.

  8. I have one of the cheapest and simplest t-stats I could buy. It won't even switch from heat to cool by itself. I leave it set to the same temp year round (with the only exception being when we need to chill the house because it can't keep up with the late afternoon heat load)and leave the fan on "run". It circulates the air, runs it through the filters, and helps balance out hot and cold spots.

    We went to expensive but simple washer and dryer (speed queen) after messing around with the high efficiency front loader nonsense for years. The controls are manual. There is an "eco" setting, but the manual explains that it's only there because the EPA requires it, and suggests avoiding it as it doesn't do a good job of cleaning. My understanding is that they finally bowed to the EPA and got rid of their last fully manual model (no computer board) a year ago. The funny thing is, all the affluent moms in the area have done this too. Basic machines, but FAST and effective. So now, getting whites washed takes only 15-20 minutes instead of the 3 hour "sanitary" cycle on the front loader, and the dryer gets clothes dry in one cycle. I don't care how much water it uses. The water is cleaned and returned to the environment, and I live in a swamp anyway. I can do 3 loads of laundry in the time it used to take to do one, and they're cleaner.

    I'm tired of other people thinking they know better how to spend my limited time on this earth (MS updating my pc no matter what I've got to do, washers that take hours because of political ideology) and I'm tired of pinch-mouthed scolds haranguing me wherever I turn.

    Don't even get me started on refrigerators that are so "energy efficient" that they can't keep food cold if the door is opened too many times in one day. (and again, having money to spend gets you past that- high end "commercial" style fridges and actual commercial rated fridges will still get cold quickly and are sized to deal with frequent door opening, but cost more to buy and to operate.

    A pox on all their houses.


  9. I just moved into a place which has a Nest thermostat and the darn thing is already driving me crazy with its "learning". I don't want it to "learn", I want the temperature set where I choose. But it thinks if last Thursday the A/C was set to 73 degrees for 4 hours it should be that way every Thursday. It's driving me nuts, I want to shotgun the damn thing.

  10. Have you done a search for the model thermostat that you liked???? Chances are you can find one. Heck, find two. I believe that if you find something you like, keep it. I also refer to myself as being an 'Analog' person in a 'Digital' world.

    1. Yeah, I understand. I designed analog control loops for 30 years.

      To be honest, I don't know if you directed that at me or Will in Il. For me, I don't have a thermostat picked out. I wouldn't mind an old fashioned bimetallic strip with a mercury filled switch. I don't even know if they're still out there...

    2. All the thermostats in out house are 1970's vintage bimetal strips that close a set of contacts connecting the 240VAC to the heaters in each room.

      Kind of a "Zone Control" in a way, but they work, they're repeatable, and once you figure out that the scale markings do NOT directly correspond to the actual room temp, you're golden.

      Simple, cheap, reliable, just not real "High Tech"!

  11. Do you know if your thermostat has a thermocouple, or an RTD sensor? Either way, the signal conditioning is what makes the difference and I've seen units before that were off, though usually only by 1 degree, not 4.
    I have a very simple non-programmable unit that maintains a temperature pretty close - it hold within 1 degree.

  12. I have a Hunter Set n Save II that I bought at Home Despot back in '74. When I moved out of the house that it was originally installed in I took it with me and re-installed the original bi-metallic Honeywell model that the house originally had. The Hunter is still working fine after all these years. The slide switch that controls whether you're heating or cooling sometimes needs a little firmer push towards the cooling side to get it to work. Other than that, works the same as it did when first installed. It has a +/-2 degree over/undershoot depending on which mode, heat/cool, is in use use.

    I also have one of those indoor/outdoor temp./atomic clock/weather stations that reads, consistently 3 degrees low on both indoor and out door temp. It's like it's a conspiracy or something ;^)).


  13. Hey, remember when the EPA classified milk as petroleum? Same cleanup procedures for spilled mike as for spilled oil. Good times, good times.