Flow Switch Timer

[eduncanjr]

 

Hi Forum,

I\'m still learning the Comfort programming language and I am having some trouble with timers....I hope someone can give me some advice on the program senerio below.

I have an inline flow switch which I want it to control a hot water recirculation pump. For this to work I need the following:

Step 1: Upon sensing flow the N/O contact on the flow sensor will close (this is wired to zone 44)...the coorsponding Zone Output from Comfort then be closed, energizing a relay (small ice cube style) that inturn turns on the pump..... 

Step 2. I want a timer to count down for 30 minutes then deenergize the relay. (this is the tricky part).....the flow sensor will still be sensing flow for a period of about 1 min after the pump shuts off..(causing a continious loop)....I need for Comfort to ignor this transition period while the flow in the pipe is coming to  a hault and thus resetting the system.

Looking forward to some assistance....

Kind regards

Edmon:?

[admin]

You can use a Timer for 30 minutes
eg
Do SwitchOffPump after 1800 seconds using Timer X

I supposed that this Response is triggered by the flow sensor not sensing water this causing the Zone 44 to detect an Open Input? If so you can use the Zone Off Response to call this Response

In the SwitchOffPump Response, you can start another Timer Y for 1 minute
Do Null Response after 60 seconds using Timer y

In the zone 44 On Response,
If Timer Y = 0
Then Output Z ON
Endif

This only turns on the pump output if the Timer Y is not running

Is this what you have in mind?

Other considerations;

What is the sensor detects flow again during the 30 minutes
delay?

[eduncanjr]

This flow sensor remains in the N/O position until it detects flow.....then it closes the N/O contact......this starts the pump....

If it continues to detect flow during the 30 min cycle it does nothing because the pump is on.....

In reaility what is happening, once the flow sensor detect flow for the first time it turns on as it should....the problem is that the movement of the water is continuing in the pipe for a period of about 30-45 seconds after the pumps shuts off....this gives the flow senor a false indication that a faucet is still turned on, when it in fact is not..

 

So should the on response and off responce you suggested still work with what I have outlined above?

 

Many thanks

Edmon

[slychiu]

The pump turns on for 30 minutes after the flow sensor detects water
What should happen when the sensor stops detecting water, should that turn off the pump?

[eduncanjr]

correct.....after the 30 minutes has elapsed it should shut the pump off....and then the next time a faucite is turned on the process starts all over again....

Our house is pretty big and what this allows us to do is not run the pump all the time....I have this expensive flow switch ( I bought on ebay) that can measure flow rate (so its really more than a switch).....I have it calibrated to turn on when (close a normally open, dry, contact) the flow exceeds 15fps.....so it would require several faucites to be on or a shower....by doing this we reduce energy cost and still have consistant hot water throughout the house.

I have the On Responce working now....I just can\'t seem to get the \"Off Response\" to work...

 

 

[slychiu]

You did not say what should happen when the water flow switch turns off, ie becomes open. The zone Off Response  will be triggered when the water switch turns off. Should it turn off the pump?

[eduncanjr]

This is where the more complex part comes in because I need to force the OFF responce once the timer has elasped....and this resets the system.

Once a faucet is truned on, the water starts to flow, closing the flow switch and starting the pump. Since the flow switch is in the stream, it will be flowing over the same switch that started the pump (will not reset based upon the the lack of flow, even when the faucet is turned off (the hot water system is piped in a loop through our house) so the pump would just continue to recirculate ....so how do I set this senerio up....

If a picture of the circuit would help  I\'ll be happy to provide it.

 

Many thanks

Kindest regards

Edmon

[slychiu]

I understand what you mean now

You should program the Zone ON Response as follows

If Timer Timer01 = 0 and Timer02=0 Then
    Do WaterPumpOn
    Do WaterPumpOff After 1800 Seconds Using Timer01
End If

The Zone Off Response should be
If Timer Timer01 = 0 Then
    Do NullResponse After 30 Seconds Using Timer02
End If

This zone ON Response switches on the water pump and starts a timer for 30 minutes to switch off the timer.  There is an IF Timer01=0 AND Timer02=0 condition so that if the 30 minutes timer is running, it will do nothing. Hence the water pump is switched on when water sensor first senses flow and it swicthes off after 30 minutes. During the 30 minutes, the pump timer will not be reactivated

The Zone OFF Response starts a timer Timer02 for 30 seconds IF Timer 01 is not running. This 30 seconds timer prevents the Pump from starting again if the flow sensor senses water for 30 seconds after the flow ha stopped just in case the flow is intermittent after the pump has turned off


The Zone ON and Off responses are only triggered when there is a CHANGE in state, from OFF to ON or ON to OFF respectively. That means that if the water is continuously flowing the zone ON response only activates ONCE and not repeatedly, until the zone goes OFF. Similarly thee zone OFF Response occurs when the zone first goes OFF and will not activate until the zone is back ON.

I have created the program and exported it as a Scenario attached
Import the scenario and see if that will work for you, see the tutorial on Scenarios at http://www.comfortforums.com/forum92/2185.html