Heat sensors on 17A00 Expansion Enclosure

[neillt]

So I am really trying to run this to ground, as there is conflicting information out there.
 
I have an install with an existing OPII where the owner wants to put in an expansion enclosure for a new outbuilding.  As part of that, we want to put in 2 heat sensors to detect fire... one over a flammables locker and one over a welding workstation.  Smoke detectors are a no go as it's basically a metal shop outbuilding that will have grinding and what not going on, not really the best location for a smoke detector.  The install manual for the expansion enclosure is vague at best.  It talks about 4 wires, but nothing about a 2 wire zone.
 
The basic question is this:  Does the Expansion Enclosure support 2 wire heat sensors as a fire zone?
 
It's already too bad that HAI discontinued the standard temp sensor that worked on the expansion enclosure, now it looks like I hit another roadblock.  Pulling wire all the way back to the original OPII is not an option.  The data bus is coming off of another expansion enclosure that controls irrigation and an electric gate not too far away.
 
Has anyone seen first hand that a 2 wire heat zone will work?

 

[Desert_AIP]

You should be able to wire a NO heat sensor with parallel EOL to a zone.
It acts like a simple relay and doesn't require power.
I have them daisy chained in my attics and in my shop buildings, on different zones, using an expansion enclosure.

The 2 and 4 wire smoke detectors are powered units.

 

[neillt]

AIP, on the ball as usual.
 
My concern is the panel throwing troubles because it expects the fire zones to be supervised with an EOL relay, not just a resistor.  When it cycles switched power it should show dead open before the relay puts the EOL resistor back in to the path, correct?

 

[Desert_AIP]

There's no 12vdc hooked up to a heat sensor.
Power cycles have no effect.

I have all of my fire sensors (11 zones) wired this way (don't tell) and never have any trouble alerts from either the main panel or the expansion enclosure.

 

[neillt]

Did you set them as Fire zones?  
 
The lack of the 12 volts is exactly what I am talking about.  Normally when the panel removes the 12 volts to reset the smokes during a re-arm the EOL relay will open and remove the EOL resistor from the chain, so that the panel can confirm that the power is making it all the way to the end of the chain.  Here we have a 2 wire that will ALWAYS have the EOL resistor because there is no relay to disconnect it.  In theory that should produce a trouble since the circuit didn't show open as it should have.
 
I guess I should stop overthinking this, you say it works I am going to go with it!

 

[Desert_AIP]

The heat sensors are not powered.
They are relays.
When the rate of rise exceeds the specs, it closes the relay.
When the temperature goes above the specs, the epoxy melts and the spring fires and closes the relay.
They are not the same as a 2 wire powered smoke detector.
Yes they are set as fire zones.

The zone setting tells the panel what action to take or what report to make when it goes NOT READY.
The power cycling only operates on the switched 12VDC bus.
The two are related but not connected nor dependent.

 

[gatchel]

Heat sensors provide a N.O. dry contact that closes upon activation of a heat threshold being met.
Heat sensors don't require power to operate properly therefore a power supervision relay is not necessary.

 

[Desert_AIP]

This is the type of sensor I am talking about
 

 
They wire up like this
 

 

[gatchel]

It's all in the documentation available on System Sensors website.
 
http://www.systemsensor.com/en-us/Pages/Spot-Conventional-Heat-Detectors.aspx

 

[neillt]

We are going in circles here.  I totally understand that the heat sensors are not powered.  I get how they work.  Unfortunately the HAI manual states that *only 4 wire smokes work*.  The way 4 wire, powered, EOL relay zones work is to open the circuit when power is removed.
 
YES, I know that heat sensors are not powered.
 
But the panel expects the zone to go from ~150 with the EOL resistor to ~255 as an open circuit when the switched power that it thinks is running the 4 wire loop is turned off during a re-arm reset.... then come right back to ~150 when the power is reapplied.
 
The heat sensors have no EOL relay and no power, so the zone will stay at ~150 ALL THE TIME regardless of the "power" being sent because the EOL resistor is wired to the last sensor.  So when the panel cycles fire zone power the reading never changes like it should.  This should trigger a trouble alarm to indicate something is wrong with the wiring.
 
If it doesn't give a trouble then great no problem for this install, but it also means it's not supervising the wiring correctly.

 

[Desert_AIP]

If you are required to use the EOL relay for UL install (as stated in the docs), then power the relay from the 12VDC switched terminals as if the smoke detector itself was powered.
 
My guess, since the device is unpowered, it does not require a power supervision relay.
The docs are talking about powered smoke detectors specifically.
They do not address unpowered heat detectors.  Nor do the main docs.
 
The relay is not required for the panel. 
The zone operates as a fire zone with a standard dry contact NO and EOL in parallel.
It doesn't give a trouble signal.

 

[Del91574]

KISS. You'er overthinking the system and what it does and doesn't do and what it sees and doesn't see.
 
A supervision relay isn't required for UL and unpowered detectors (heats), nor would (or should) the panel care if the circuit opens or not and removes the EOLR from the equation....it's not a valid item for the panel to look at. It's not going to throw a trouble if the zone is within spec (remember, it's looking at voltage to give you the handy numbers). If it did, I'd question the panel and it's integrity.....we're talking a dumb alarm panel (with general logic abilities) not a full blown FACP that has software zones, boolean logic abilities and operands and a lot of data and other decisions being made.
 
In an alarm state, the EOLR is negated (short across zone) for either detector. In a powered device loop, the opening of the circuit removes the latch on the zone (short) caused by the smoke detector. In an unpowered zone, the system would no be able to reset because the detectors are generally self-sacrificing (barring ROR units). A 2 wire heat detector is electrically the same as a 4 wire detector.....except for latching.

 

[neillt]

Fair enough guys... I think we are all on the same page.  Like I said earlier my brain is just overthinking it... I am going to go with conventional wisdom and just put them in!

 

[jlehnert]

Late to the party, but I've had heat detectors wired to expansion enclosures in both the attic and the garage for many years without a problem.