Rule to reset smokes when not on SAUX

[RichardU]

I will power my 4-wire smokes via an ELK-P412. I have read a thread about how to do that, but can't find it after much looking.

Since the 4-wire smokes will not be connected to SAUX, I will need an alternate method to reset them. I have an M1RB. My plan is to run a positive from the P412 through one of the relays and trip it with a Rule triggered by a function key.

Is that the way to go? Anybody know what rule I need?

Thanks, Richard

 

[rfdesq]

Since you may only need to reset the smoke detectors once every couple of years, how about this. On an out of the way keypad, assuming you have more than one, set the F4 key to trigger for X seconds, the relay that cuts power to the smoke detectors.

 

[Sandpiper]

In the power circuit to the smoke detector, place a relay contact. The ELK-912 would be perfect for this. The relay coil should then be powered from the SAUX. This way it will work the same way as if you were powered from the SAUX. Then you can reset the smokes by using the "reset smokes" command, just as the system was designed.

The time to reset the smokes is after one has tripped. You don't want it to reset randomly or after a certain time interval.

 

[RichardU]

Great advice. That's exactly what I was looking for.

Thanks, Richard

 

[Sandpiper]

I forgot to mention........in case you don't already know........

To insure reliable operation of your smokes when powered from a separate power supply, make sure the power supply commons are tied together. That is, run a wire from any "NEG" on the M1 to the negative on the independant power supply. Do NOT tie the positives together.

 

[rfdesq]

The time to reset the smokes is after one has tripped. You don't want it to reset randomly or after a certain time interval.

I didn't mean to imply that four wire smoke detectors have to be reset at a certain time interval. I'm just used to women who think a smoke detector is a kitchen timer . If you use a relay, and power it all the time from SVAUX, the relays will draw anywhere from 30ma to 250ma for a fully loaded M1RB, all the time. Your original question referred to using the M1RB. Just figure that into your calculation when using an auxiliary power supply and figuring battery backup run time. I personally don't think that keeping a relay powered up day after day for a couple of years waiting for a one second reset is worth the power required or the chance for failure from a heated coil. Just my .02.

 

[Sandpiper]

The time to reset the smokes is after one has tripped. You don't want it to reset randomly or after a certain time interval.

I didn't mean to imply that four wire smoke detectors have to be reset at a certain time interval.

Now that I re-read your post, I understand what you meant. That will work. Sorry that I implied otherwise.

I personally don't think that keeping a relay powered up day after day for a couple of years waiting for a one second reset is worth the power required or the chance for failure from a heated coil. Just my .02.

With electrical power at a typical cost of 10 cents per KHW, the power to continuosly energize the relay for 1 year will cost $0.31, about the same as the cost for energizing a single smoke detector for the same time period.
It is very common to run relay coils continuously with any problems. They are designed for this. Relay coils burn out when they are cycled a lot, not when they stay on all the time.

 

[rfdesq]

With electrical power at a typical cost of 10 cents per KHW, the power to continuosly energize the relay for 1 year will cost $0.31, about the same as the cost for energizing a single smoke detector for the same time period. It is very common to run relay coils continuously with any problems. They are designed for this. Relay coils burn out when they are cycled a lot, not when they stay on all the time.

You are probably right about the coils, especially with ELK products. Spanky probably has one on his desk hooked up to a kite and a key . I don't care about the electrical costs. My big concern is battery backup run time. I always design my customer systems for maximum battery run time. Just shows you there's more than one way to ...

 

[RichardU]

Thanks for the additional insights. I had read about tying the negatives together, but it never hurts to be reminded.