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mth1993
02/11/2012, 08:00 PM
Please confirm my programming. I have been using a gas water heater closed loop to reduce my electric bill but have been getting worried about a temp prob failure. I have my 2*300 watt heaters still in the sump as backup.

Gas heater pump dc8 outlet 7

Fallback OFF
If Tmpx5 < 77.0 Then ON
If Tmpx5 > 79.0 Then OFF
If Tmpx5 < 75.0 Then OFF

Backup Electric heaters dc8 outlet 2
Fallback OFF
If Tmpx5 < 74.0 Then ON
If Tmpx5 > 75.0 Then OFF
If Tmpx5 < 40.0 Then OFF

I have a second temp probe in my display that I would like to use but I am not sure how.

I also have a a solenoid that I was going to hookup in case the the outlet for the pump gets stuck on. But I am leaning against it as it would just be things to go wrong.

Any feedback would be great.

Thank you.

Mike

ebacon
02/12/2012, 10:08 AM
Maybe I'm paranoid but this seems like a bad idea on several levels.

card_judge
02/12/2012, 06:19 PM
Gas heater pump dc8 outlet 7

Fallback OFF
If Tmpx5 < 77.0 Then ON
If Tmpx5 > 79.0 Then OFF
If Tmpx5 < 75.0 Then OFF

Backup Electric heaters dc8 outlet 2
Fallback OFF
If Tmpx5 < 74.0 Then ON
If Tmpx5 > 75.0 Then OFF
If Tmpx5 < 40.0 Then OFF


I do not know what advantage you get with the commands in red.

RussM
02/12/2012, 07:19 PM
I do not know what advantage you get with the commands in red.
When a temp probe fails, the reading usually is either 20F or 120F. Those statements are a safety measure to prevent the tank from getting cooked if the temp probe fails with an extremely low reading.

The <40 value is a bit unusual though.

card_judge
02/12/2012, 07:43 PM
Thanks Russ, good to learn something new.

mth1993
02/13/2012, 11:02 AM
The statements in red were to shut off if the temp probe went bad, just as Russ indicated.

I just picked 40 as a number as good as any other. If there is a better number to use please let me know.

Any thoughts on how to use my second temp probe as a fail safe?

aquamanic
02/13/2012, 12:47 PM
You can have your second temp probe activate the audible alarm and the email alert (you should do that with your primary temp probe if the temp falls below 75 also).

RussM
02/13/2012, 02:08 PM
I just picked 40 as a number as good as any other. If there is a better number to use please let me know. Most people, it seems to me, who use a fail-safe cutoff set it a few degrees below the normal range. 40 is fine though - just atypical IME.