HVAC controls and fire protection
Our state mechanical code calls for smoke detectors to shut down an air handling device if it supplies more than 2,000 cfm. Duct smoke detectors are required unless the entire area covered by the air handler is protected with smoke detectors.
My current project has a sprinkler system and a fire alarm system. The alarm contractor is only willing to supply a signal to my HVAC control panel to shut down the air handlers. I have told him that he must wire his system directly to the air handlers for purpose of shutting them down on an alarm condition. I tried to explain that my equipment is not rated as fire protection equipment but he doesn't seem to care.
I am expecting a showdown on Monday with the builder and the alarm guy. I am wondering if anyone can point me to any code info that will support my argument, if indeed I am correct. This is the first time that I have come across this problem and after searching the internet the code language seems to be kinda vague. There are statements such as 'the devices must designed for the intended purposes' etc.
Any help would be appreciated.
ps. I am in New York state if anyone has particular knowledge of the local code.
You don't mention VFD's or starters but I typically use a safety circuit that includes this as well as pressure safety, freeze protection safety, damper end switches etc all of which are wired in series normally closed to a VFD safety contact or a enable circuit to a starter. I prefer a safety relay that is powered through this series circuit so it is supervised.
Your system rating doesn't really come into play since it is all hardwired and the fire alarm system is controlling the fire alarm relay.
The fire alarm contractor usally places a shutdown relay next to the fan starter or VFD. I complete the wiring from the relay.
NFPA says this relay must be withen three feet of the starter or devuce to be shutdown.
These are 30 ton RTUs with VFDs. The units have all of the safeties that you mentioned. They do not have built in smoke detectors. Technically I am not hardwired to the controls but wired through a comm bus to the unit controller. These units are equipped with 'emergency shutdown' contacts that I contend he should be wiring directly to his control panel.
When I say 'equipment' not be rated for fire safety I am referring to the DDC control equipment.
Last edited by dapper; 05-03-2008 at 11:27 AM.
Reason: define equipment
Here it depends on the alarm contractor. Some will pull a wire over for us to connect, some will do the connection as long as we are all on the same page, some supply us a contact in the panel that we have to pull a wire to. The inspectors here don't really care as long as when we put smoke in the return the air handler shuts down immediately.
If NFPA says that it must be within 3 feet then use that reference, I have seen on many jobs the relay not within 3 feet. It really comes down to what the authority having jurisdiction will accept and coordination between trades.
Do the smoke detectors have AUX relays? If they do, then wire through them to your shutdown terminals. This won't affect the alarm guy's circuit, but will give you what you want.
Its really simple. He provides a set of contacts that (usually normally closed) open on a alarm. Then all you need to do is take control circuit thru this contact so unit shutdown happens immediately. I know this code exists in California as well. Also I have never seen a Fire Alarm installer wire an air handler . That is the Mechanical installers job. Typically the fire alarm installer provides and installs duct detector. We then provide the actual termination to shut down.
You would not want someone cuting wires in a piece of equipment that is brand new and you are providing a warranty for would you?
I guess it's a matter of simantics. I have never had a job where the alarm contractor didn't bring his shutdown control to my equipment. Whether I terminate or he terminates it or who supplies any necessary relay has never been a problem. This guy only wants to bring his wire to my control panel and have me do the programming with his input to shut down the fans.
My contention is that my system is not rated for fire safety. My system will be web accessible and it will be easy for many people to access the system and possibly over-ride any outputs. Besides, it seems to me that it is his responsiblity to shut down the equipment, not just provide a set of contacts if I wish to use them. He doesn't do that with the sprinkler guy with his flow alarm or tell the fire department where to hook up the phone line. If it was my responsibility to provide duct smoke detectors that would be a different story but his system negates the need for a duct detector.
Months ago I let them know that there was plenty of room in my conduit from the mechanical room to the units for his wiring. Honestly, I could do it in an hour with 150' of wire but thats not the point.
The next job I'll be wiring all the smoke heads too!!
No there's any idea to expand the product line......
I am still not clear,have you or the alarm contractor installed the smoke dectectors?
I would agree that in this situation it sounds like the fire alarm contractor should be 100% responsible for the alarm system and unit shutdown. However I don't believe you are talking about a system where the AHU's are used as part of a smoke control system/ purging system, if they are part of a smoke control system all components must be UL 864 (?) approved. I believe in your case you are just talking about meeting International Mechanical code or local code requirements to shut off the fans upon an alarm, in which case I think you putting the units into emergency mode will satisfy the inspectors.
I don't see anything in the International Fire Code about the fan shutdown requirements that is only referenced in the IMC
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He installed the smoke detectors.
kl, you are correct. This is not an engineered smoke control system. If it was 'engineered' then in my mind that would resolve me of the responsibilty to control the operation of the units if everything that I did was 'engineered, tested and approved'.
Yes, only the IMC mentions shutting down the fans but the IFC says that a duct smoke detector is not required if the entire area is served by fire system smoke detectors.
That's where I feel the responsibility is passed on to the alarm guy. If there was not a comprehensive smoke detection system and I had to provide a duct smoke detector then it would be solely my responsibilty.
The only other referrence is as phantomtech mentioned, the relay must be within 3 feet of the device to be shut down. Do you think they are referring to my control panel? My feeling is no.
I just have a serious disdain for contractors that try to weasel out of every minute portion of their job to try to save money. If the builder comes to me and says, 'The guy is an a**, just wire it and get it done.' I will do it. Like I said, it is not a big deal. His panel sits right alongside mine. I will pull the wires from the unit to his panel. I will not take ownership of the supervision of the shutdown.
I am still on the Standard Code Set down here, one of the forerunners of the ICC.
Typically air handlers 2000 CFM or more, or those serving an egress corridor require fan shut down so thay have duct mounted smoke detectors on them.
The duct mounted smoke detector can be supplied by the mechanical contractor, or supplied by the fire alarm guy, it depends on how the job was specified.
That duct mounted smoke detector is not there to detect a fire, it is there to stop the air handler from re-circulating smoke.
Typically what I see is the mechanical contractor would wire his control wiring through some contacts in the detector to provide the shut down.
A simple signal from the fire alarm to your main controller can be used to shut all air handlers down on a general alarm. Example a fire on the fifth floor results in the ground floor and all other floor systems shut off.
Better check the wording concerning duct detectors not being required if there are somke detectors, possibly it is 'complete' smoke detector covereage. Complete smoke detector coverage is rare unless the fire alarm is there to greatly exceed what code asks for. Usually the fire alarm will have smoke detectors along the exit corridors, storage rooms, elevator lobbies, elevator shaft/machine rooms but very rare to see them absolutely everywhere your AHU could be drawing return from.
Maybe there are big server rooms, and you do not want the AC shut off to them on a false alarm.
So if there are no duct dectors, there would have to be complete smoke detector coverage. Tell the fire alarm guy then to provide a control module (addressable relay) then for every air handler zone, if you have equipment you do not want shut off un-neccessarily. Duct mounted smoke detector on the units is the way to go.
Sounds like someone is going to eat the duct mounted detectors.