I'm working an application where a fire alarm system needs to be connected to a WaterFurnace unit such that if there's a fire alarm then the unit shuts down.

Typically with many manufacturers this simply requires opening an otherwise shorted connection within the HVAC unit, or, closing an otherwise open connection.

The WF unit is an Envision.

The Envision indeed has a 'Shutdown' input on the control board.  Documentation about this says: "A 24VAC common signal to the "shutdown" input on the control board puts the unit into shutdown mode.  Compressor, hot water and fan operation are suspended."

I'm a little uncertain exactly what this says.  Is it saying that simply making a connection from the Shutdown screw terminal to the adjacent C terminal (which connects internally to the common side of the 24VAC transformer) is all that's required?

And if so, does the Envision's shutdown function do anything if only the blower fan is running (i.e. tstat is in Fan On mode, not Fan Auto, with no call for heating or cooling)?

I'm hoping there are some Envision experts here who might be able to help.  Many thanks!

Best regards,

Bill

Just guessing here, but I would think that you need a relay contact from your fire alarm system that closes when the system is in alarm and connects that 24VAC common signal to the "shutdown" input on the control board.

Posted By arkie6 on 11 Nov 2010 05:26 PM
Just guessing here, but I would think that you need a relay contact from your fire alarm system that closes when the system is in alarm and connects that 24VAC common signal to the "shutdown" input on the control board.

Yes, fire alarm systems typically include relay control, to turn things off when a fire alarm event occurs, like HVAC equipment.  The relays come both NO and NC to accommodate the particular HVAC equipment.

In the case of the Envision, I've figured out that what's needed is NO connected to the Envision's Shutdown and Common terminals.

An interesting learning is how use of an IntelliZone panel causes the Envision's Shutdown mode to not work completely.  If there's an IntelliZone connected to the Envision, Shutdown mode is not capable of turning off the blower fan.  This is because the blower fan's low voltage (PWM) control is direct connected to the IntelliZone panel, bypassing the blower fan control within the Envision unit.

So the learning here is that if a fire alarm panel is to function properly with an Envision, where an IntelliZone panel is present, now the fire alarm relay needs to be NC, and connected in series to the 24 VAC supply (red wire) voltage from the Envision to the IntelliZone. 

Best regards,

Bill

My Intellizone pdf shows a "LO" connection, which I take to mean Lockout, between Intellizone and thermostats. I'm not sure how that relates to this issue.

Per our manual, the "LO" or lockout terminal on the board of our Envision unit sends either a 5VAC lockout signal or a pulsed signal depending on dip switch setting (SW2-8). We have the "LO" terminal connected to an ARB board to (isolate the LO signal from) our thermostat (which causes a lockout alert to appear on our thermostat in the event of an Envision lockout). I don't know if the "LO" on the Intellizone serves the same purpose. I don't know if this is helpful with Bill's situation either...

Posted By a0128958 on 11 Nov 2010 10:36 PM

Posted By arkie6 on 11 Nov 2010 05:26 PM
Just guessing here, but I would think that you need a relay contact from your fire alarm system that closes when the system is in alarm and connects that 24VAC common signal to the "shutdown" input on the control board.

Yes, fire alarm systems typically include relay control, to turn things off when a fire alarm event occurs, like HVAC equipment.  The relays come both NO and NC to accommodate the particular HVAC equipment.

In the case of the Envision, I've figured out that what's needed is NO connected to the Envision's Shutdown and Common terminals.

An interesting learning is how use of an IntelliZone panel causes the Envision's Shutdown mode to not work completely.  If there's an IntelliZone connected to the Envision, Shutdown mode is not capable of turning off the blower fan.  This is because the blower fan's low voltage (PWM) control is direct connected to the IntelliZone panel, bypassing the blower fan control within the Envision unit.

So the learning here is that if a fire alarm panel is to function properly with an Envision, where an IntelliZone panel is present, now the fire alarm relay needs to be NC, and connected in series to the 24 VAC supply (red wire) voltage from the Envision to the IntelliZone. 

Best regards,

Bill

Your understanding is correct the intellizone has no shut down terminal.

Posted By engineer on 12 Nov 2010 08:59 AM
My Intellizone pdf shows a "LO" connection, which I take to mean Lockout, between Intellizone and thermostats. I'm not sure how that relates to this issue.

I don't think it does.  Instead I believe it relates to the communication method to 'indicate' lock out on the thermostat display, depending on what type of thermostat is being used and whether or not there's an IntelliZone panel between the thermostat and the Envision unit.

Best regards,

Bill

Posted By geotek on 12 Nov 2010 10:22 AM
Your understanding is correct the intellizone has no shut down terminal.

Thank you. 

Indeed I had to wire in the fire alarm to open the 24VAC supply wire (Red) from the Envision to the IntelliZone panel.  Not ideal, but, a fire alarm relay opening of this connection does shut down all Envision functions - water pumps, compressor and blower fan.

The 2 minor drawbacks are that power is removed to the tstats and thus they run on battery, and, dampers don't return to their closed position.  But, considering that a fire alarm is hopefully a rare if not never event, these two drawbacks are pretty inconsequential.

Best regards,

Bill

Be certain there is no code requirement to shut dampers.

Posted By engineer on 13 Nov 2010 07:51 AM
Be certain there is no code requirement to shut dampers.

Good point.

I'll have to think for a while on how to do this when an IntelliZone is in place and the more expensive 3-wire (Belimo) dampers are being used.  At the moment, nothing comes to mind.

Looks like the combination of WaterFurnace's IntelliZone panel and and Envision weren't designed to be interfaced to fire alarm systems (no shutdown terminal on the panel, or a communication method from the Envision's shutdown terminal to the IntelliZone, or a means for the Envision to shut down the blower fan when an IntelliZone is present).

It's possible use of WF's 2-wire, spring-loaded dampers may be the only path to being code compliant when connecting a fire alarm system to an Envision where an IntelliZone panel is present.

Best regards,

Bill