E stop

[readydave8]

"Design of air handling and ventilation systems must incorporate engineering controls to prevent intrusion of hazardous airborne contaminant (i.e. shut-off system, detection devices, and control air circulation and purging of contaminant from the building envelope)."

Dept of education note, it's not a public school but some kind of evening program

Customer wants me to install E-stops based on this

There is a building with conventional split system heat pump, a trailer with a minisplit, and a trailer with a Ptac.

I thought about running power to T/stats through stop switch but I think Blower would keep running for a minute or 2 until it cools off, how bout interrupting control voltage at unit?

And the minisplit has integral controls, so run line voltage through a contactor?

 

[hillbilly1]

Do they want a single e-stop to shut everything down at once? Or just individually? Low volt with relays to do as you mentioned to kill the control voltage would be the easiest and cheapest, and like you said, run the minisplit through a contactor controlled through the low volt e-stop.

 

[readydave8]

3 individual, 1 per building

 

[BillyMac59]

Be sure of what they want. As written, "hillbilly1" is describing a process stop. An emergency stop will require the ability to monitor that the actions needed have indeed taken place.

 

[BillyMac59]

The other side of the equation is the detection phase. How is the presence of the "hazardous airborne contaminant" detected? Will this detector automatically trigger the "e-stop" event?

 

[hillbilly1]

Be sure of what they want. As written, "hillbilly1" is describing a process stop. An emergency stop will require the ability to monitor that the actions needed have indeed taken place.

After re-reading it, it appears they want an automatic means, not a manual means of shutdown.

 

[readydave8]

Yes the quoted text does not match what customer is asking for

 

[BillyMac59]

Sounds like the customer might be looking for a $0.50 solution to a $100 problem. An automatic sensing and shutdown system won't be cheap.

 

[ptonsparky]

Sounds like the customer might be looking for a $0.50 solution to a $100 problem. An automatic sensing and shutdown system won't be cheap.

IDK if I would want the follow up work. Trip after trip...