fire alarm interlink query

[mrloy99]

Just a brief query,I have a job to do that has requested that the domestic type fire alarms with battery back up have to shut down the fans on a heat exchanger.(and also the co alarm has to shut down the gas solenoid valve)I have done this on comercial type of fire alarms but not with domestic.(presumably the interlink cable is used?)I'm not sure what the voltage output is on the interlink cable,I thought it was 230volts but then again if its battery back up maybe 9volts

 

[Edd]

I built an interface years ago that would set a system type fire alarm off when the domestic smoke alarms went off. this was 10 years ago now, if i remember right the interlink is sitting at 230v and drops when the alarm sounds.. sorry cant remember much else about it. but I bet they make a comercial interface now. i think ive heard x10 home automation type stuff had somthing that switched a relay.. sorry not more helpfull...

 

[RexT]

Hi mrloy99,

You could use a relay base for the smoke alarms. This relay base uses the interconnect as a trigger to set the relay of. The relays normally have common, normally closed and normally opern volt free contacts.

This should allow you to switch items subject to the relay current and voltage ratings.

Hope that helps.

Best wishes,

Rex

 

[NrVolts]

An interlink is used in the context i know as a cable to signal both ways between fire panels.what you want is one to act as a pickup signal from the common line (what ever the voltage maybe be i dont know and sometimes they are not linked together but should be) that links all these 240 detectors...im on the same page as Rext ...ide set the alarms off and find what that signal voltage was first.then get a relay rated at the right size to cope with whatever youre switching off.

 

[mrloy99]

ok thanks for your thoughts....but would that mean that if the circuit breaker was to operate(trip)on my smoke detector circuit,the circuit that I'm trying to control would also drop out?..probably not a major issue....at least they would know their smoke detector circuit has tripped when the gas boiler won't work:smile5:

 

[mrloy99]

Hi mrloy99,

You could use a relay base for the smoke alarms. This relay base uses the interconnect as a trigger to set the relay of. The relays normally have common, normally closed and normally opern volt free contacts.

This should allow you to switch items subject to the relay current and voltage ratings.

Hope that helps.

Best wishes,

Rex

cheers rex, found that relay base. brk doing one for 22.50.Just wondering would I need to install relay bases on all the detectors in the premesis or just 2. The appartments have smoke detector in each bedroom,one in hall and one in living room,also a co detector which shuts off the gas valve,but not the fan.There are 21 appartments so an additional 1500 quid odd if they all have to have relay bases.
Thanks for your help

 

[NrVolts]

not main fire system and 21 appartments? something not right here why isnt there a centralised fire system?

 

[mrloy99]

Sorry didn't explain properly.There is also a landlords fire alarm system with one device(combined smoke/sounder/strobe)located in the hallway of each flat.I've done a few jobs now for different contractors and this dual system seems to be the way they are doing it.

 

[kippaxkid]

The fire panel will have an output from it that will operate in the event of a fire activation.
This should be present in normal state and dropping off in alarm.
This should be used to hold open two relays. One for the power to the gas valve, and the second to the fans.
When the alarm is activated, the relay closes, the power to the two devices is removed and all is right in the world.........apart from the fire.
By wiring it this way, you know before a fire that all is going to work, rather than the alarm going off and the relay not firing.
You would of course require a seperate input from the Co alarm, or you could connect it directly into the fire panel.
As you have been told elsewhere in this thread, you need to match the relay to the neccessary input/output voltages.
I am sure that every combination of these is available.
PM me if you need further assistance
Chris