Timer Thermostat

[Guest]

Hi

 

I have a garage unit heater and it is sized a little bit to big for the garage.

 

Currently the unit heater turns off and on frequently. I would like to make a simple program that when the heater turns on - it will run for a minimum of 10 min or until the temperature is 65 degrees. After the 10 minutes has expired set the set point to 65.

 

This program worked great last year, now this hear it seems that about every 5 min the program runs. I don't know why, unless the thermostat updates the ISY every 5 min giving it an "On" command. I didn't change anything unless a software update changed some settings.

 

Any help would be great.

[larryllix]

What are you trying to accomplish by changing the setting on your thermostat every time the heater runs?

 

What make and model thermostat are you using?

[Guest]

The heater is short cycling.

 

I just want it to run for a minimum of 10 min, so its constantly not turn on and off.

[paulbates]

Does the 2441TH offer a configurable deadband? Setting the deadband in the Thermostat for 2 or 3 degrees would be a more reliable way to do it

 

Paul

[larryllix]

There are a few ways to get around that problem but people need to know what they are dealing with to make suggestions.

 

What thermostat are you using and what is the heating source?

[Guest]

Insteon Thermostat 2441TH.

 

Heat source is a hot water unit heater.

[G W]

You could separate the thermostat from the heater and use an IOLinc for greater control.

 

I'm Gary Funk and I approved this message.

[larryllix]

Insteon Thermostat 2441TH.

 

Heat source is a hot water unit heater.

I guess the heater s wired directly to the stat so divorcing the control takes more hardware.

Since ISY can't turn on the heater by direct control the only way to manipulate the run time is the way you are doing it.

 

We just need to polish your program a bit.

My only concern would be that the Insteon signal fails somehow and the stat is stuck on 75 degrees. Not the end of the world though.

 

The other concern is heater / stat placement. causing short cycling.

[Guest]

The placement of the heater and stat is good. Its more of a problem when the wind blows in the direction of overhead door and i have air leakage. (has to be a strong wind - but that happens).

 

How would you suggest polishing the program?

[larryllix]

The placement of the heater and stat is good. Its more of a problem when the wind blows in the direction of overhead door and i have air leakage. (has to be a strong wind - but that happens).

 

How would you suggest polishing the program?

I am very sensitive to temperature fluctuations so...

Mine might be staged and a little more complex.

 

I tried to post one, but the idea is getting more complicated that I, or you might want at this point.

This will take more than one program and some deeper thinking for me.

 

In your program, everytime the temperature changes the first line will cause the whole If section to evaluate False and run the Else section, stopping your timer and the reset of the stat temperature will fail.

The heat_on trigger will never test True from another trigger (temp<65), but will test True only when it commands attention from its own test.

 

My first thought is to break your program up, into one that senses the heat_on trigger, calling a second disabled program. That way, once the timer starts, in the second program, it cannot be stopped by changing condition from the stat.

[stusviews]

What does the thermostat read when the program restarts?

[larryllix]

What does the thermostat read when the program restarts?

I meant to test that but IIRC the blank tests as 0 degrees and heaters run based on temp < x

[DennisC]

Hot water heating loops usually have a flow control valve. You should be able to lengthen the time it takes the heater to satisfy the thermostat by adjusting the water flow.

[larryllix]

Hot water heating loops usually have a flow control valve. You should be able to lengthen the time it takes the heater to satisfy the thermostat by adjusting the water flow.

You may not be able to adjust the flow, depending on the system. Hydronics systems usually adjust water temperature with a mixer and everybody gets the same, without creating another zone.

 

However the pump inside the heater may have a multi-speed pump in it.

[Guest]

The thermostat reads the current temperature. Looking at the event viewer my climate module updates every 5 min. I wonder if that has something to do with it.