Green, efficient and comfortable

[paulbates]

This is a testimonial about the ISY and energy management. My energy company provides analytic reports that compare my home's use of energy vs other homes in the immediate area. Not a perfect measuring stick, but it does eliminate factors like heating degree days... everybody's bill in the same area should be affected by a warmer spring for example.

 

I replaced furnaces in 2014 and insulated in 2015 and that brought the score down.  Last years work on fan cycle and humidity have helped it even more. Last year at this time I was close to a third of the way between "Efficient Homes" and "Similar Homes". This year I nudged up on the top 20 efficient homes.

 

This change is related to ISY program tweaking for:

• HVAC fan calls - running the fans for both units 24x7 proved to be unnecessary and used too much electricity. But periodically cycling the fans keeps humidity and temps even through out the living spaces. It can push off a heat cycle or two per day depending on conditions.
   
• Humidity set point adjustments - Keeping the humidity set point higher makes us more comfortable and holds more heat in the air. However, when the temps drop, higher humidity sweats and frosts the windows. Tweaking the set point to drop with colder outside temps to just where sweating started allowed it to stay as high as possible.  I use the climate module for the outside temp.
  
  A related factor is that heat and humidity fluctuate differently and at different times. Calling the humidifier and fan separately from heat makes a difference in the humidity being just high enough at all times without sweating the windows.

Paul

[Michel Kohanim]

Hi Paul,

 

Thanks so very much for sharing!

 

With kind regards,

Michel

[MWareman]

Paul,

 

I'm interested in finding out more about your humidity control algorithm, and how you've implemented it on ISY. Looking to do the same myself! (Currently, I manually adjust down the humidistat as the outside temp drips... Not good!)

 

I have most of the hardware interfaces done (ISY can turn on/off the humidifier, one-wire temp sensors in the air return, air send and outside). Just need a humidity sensor that can feed data to ISY...

 

Michael.

[paulbates]

Hi Michael

 

There's 2 ways I have to do this:

 

The first is part of venlink and Venstar under Nodelink. io_guy added functionality to his software for venstar that manages humidity between a set range based on a number of inputs. It provides a number of settings for humidity range, window type and fine grained adjustment plus or minus. It really sophisticated but specific to the Venstar colortouch thermostats with humidity control.

 

The second is a set of simple ISY programs that look at the outside temp. Each program owns a range of outside temps and adjusts the humidity setpoint down/up. I have a 1 degree "deadband" between each program so that its not constantly calling when the temp is switching between the boundary temps. I had pushover notifications when initially tweaking the programs, and the constant back and forth at certain temperatures generated an annoying number of notifications.

 

The "Thens" for these programs simply sets a new humidity level in the venstar colortouch thermostat. I think I have 9 programs. I'm not home this week and forgot my surface, can't get in right now, but its very simple and straight forward. Something like this, times 9 to cover the highest humidity to the lowest

 

if outsidetemp => xx and outsidetemp <yy

   set humidification zz%

 

This gently steps it down and up. I have a couple of windows in a windward corner of the house that were hard to get right and the programs let me tweak humidity inside of temperature ranges until they are dry all of the time. The pushover notifications used variables to help with the tweaking. 

 

For stats that don't support humidity but have ISY fan calls, it could be accomplished with the climate module,a relative humidity sensor and contact closure controlling a 24vac relay for the humidifier.  I would have the "then" in the 9 programs set a variable to the desired humidity.

 

Add one stand alone program to control humidification: 

 

If indoor humidity < desired humidity

    Set fan on

    Set humidifier on

else

    set humidifier off

    wait 2 minutes     //blow through the last of the water 

    Set fan off

 

Not terribly sophisticated, but very effective. Keeping the humidity as high as possible is good for the bills and also family/pet health

 

Paul