Need help Bidding on Hood

[frank_n]

I'm trying to bid on a installing a hood in deli. The hood will have two motors, one for the intake and one for the exhaust. There is a sensor in the hood that recognizes a fire. The sensor can be wired either N/O or N/C. When the sensor recognizes a fire, it should shut down the intake motor and activate the alarm. The building does not have a central alarm system, so a horn/strobe needs to be installed in the kitchen area.

It has been more than 10 years since I did any work on motors, but I did figure out the breakers, fuses starters, etc. If it wasn't for the alarm, I'd be alright, but I don't know how to do the alarm part. What materials do I need and how do I wire it? Anyone have a wiring diagram?

Frank

 

[mengelman]

Find out who is doing the fire suppression system and contact them. We do one of these every once in a while and we allways get with the fire guys to make sure.

 

[480sparky]

I've never seen a seperate sensor to detect a fire. I've always used the contacts in the fire-suppression system (Ansul).

 

[Mike Lang]

I 've done a bunch of these recently. Is the exhaust and make up air (intake) the same voltage ? 110V - 220V or 3 phase? The switch supplied from the fire supression company is usually 110V. If the voltages are different I've used def. purpose contactors with a 110V switch to make them work together. Sometimes the fire suppression company supplies a really nice control box that will have the contactors inside and most of the work is done for you. The switch inside will accept 110V normally closed and you then connect your horn and strobe to the NO side. When the sensor and ansul system trips it will reverse the switch and send 110V to your horn and strobe.

Remember if any applicances under the hood are electric you'll have to put them on a shunt trip breaker to shut down when the horn and strobe go off.

 

[LarryFine]

If it wasn't for the alarm, I'd be alright, but I don't know how to do the alarm part. What materials do I need and how do I wire it? Anyone have a wiring diagram?

Frank, if you can answer a few questions, yes. I've done many of these, both new and re-fits (which are more challenging), and love figuring them out.

1. Each fan's voltage, phase, and current.
2. One or separate manual-operation switches?
3. Any hood lights? Switches grouped?
4. Any receptacles/electrical appliances?
5. Electrical gas valve and reset box?
6. Any shunt/trip breakers already installed?
7. Any specs state one or several circuits?

As Mike asked, will there be a control box supplied? Will the hood contain its own switches? In other words, besides the sensor, what else will be supplied and/or installed? Who chooses the basic layout and locations ove everything?


The basic rules are, if the system trips:

1. Exhaust fan turns/stays on
2. Intake shuts/stays off.
3. Any electrical under hood off.
4. Under-hood lights shut off *
5. Gas off with manual ex. fan off *
6. Horn/strobe activation.

* 4 and 5 are not always required. Restaurant owners hate #5.


Frank, feel free to PM me if you want my phone number. It can save a lot of typing to talk.

 

[LarryFine]

I 've done a bunch of these recently.

As have I. They're a lot of fun. Half of the work on re-fits can be just figuring out how the present system is wired. Sometimes, the switches are nowhere near each other.

Most of the ones I do come with tank-mounted control boxes containing a pair of micro-switches. I like to see how much I can do with only one micro and no extra relays.

I usually use contactors instead of shunt-trips unless the latter are already installed. They just cost too much, and it can be a pain to route a new dable back to the panel.

 

[gadfly56]

I usually use contactors instead of shunt-trips unless the latter are already installed. They just cost too much, and it can be a pain to route a new dable back to the panel.

Second the motion. Not only that, but unless the shunt coil is powered by the same circuit it shunts, you could have a dead shunt and never know it. Until it's too late. Lose voltage on the contactor and the equipment doesn't even operate. On the other hand, I have a tech who loves shunt trips and hates contactors. Next time, I'll ask him to make up the difference in material costs!

 

[hardworkingstiff]

Second the motion. Not only that, but unless the shunt coil is powered by the same circuit it shunts, you could have a dead shunt and never know it. Until it's too late. Lose voltage on the contactor and the equipment doesn't even operate. On the other hand, I have a tech who loves shunt trips and hates contactors. Next time, I'll ask him to make up the difference in material costs!

I think shunt trip breakers should be outlawed, for the problems stated above.

 

[Mike Lang]

As have I. They're a lot of fun. Half of the work on re-fits can be just figuring out how the present system is wired. Sometimes, the switches are nowhere near each other.

Most of the ones I do come with tank-mounted control boxes containing a pair of micro-switches. I like to see how much I can do with only one micro and no extra relays.

I usually use contactors instead of shunt-trips unless the latter are already installed. They just cost too much, and it can be a pain to route a new dable back to the panel.

Yea I agree I found these kind of fun also. The first one I did had a sweet micro switch box with everything included. It came with no directions just a schematic that was hard to read so I spent some time playing around and figured it out. It's days like those where I have fun and realize that we have one of the best jobs around.

I didn't figure out how to use the contactors instead of the shut trip on that one but I'll be thinking about it until I get it now.

 

[quogueelectric]

Second the motion. Not only that, but unless the shunt coil is powered by the same circuit it shunts, you could have a dead shunt and never know it. Until it's too late. Lose voltage on the contactor and the equipment doesn't even operate. On the other hand, I have a tech who loves shunt trips and hates contactors. Next time, I'll ask him to make up the difference in material costs!

That is why you need to have faith in your work. Just stop it now you are killing me.

 

[LarryFine]

I didn't figure out how to use the contactors instead of the shut trip on that one but I'll be thinking about it until I get it now.

Let me know if you want some ideas. PM if you want my phone number.