Control

[satnam123]

Hi
I am not sure if this is the right question for this forum
but you guys might have some experience.

The mechanical guys asked me for a solution, here is the situation.

There is a mining chute

http://texasgypsy.com/Scan/Mo/images/chute_for_mining.jpg

you can see how it looks at the link above. In our case, it is just a 10 ft long. It is inclined and we are putting a radiant gas fired tube heater. Now the manufacturer says that the temp may go up to 150 degree F and you need to shut the power off to heater and when the temp. outside goes -10 degrees we want this heater to restart. I am not an instrumentation guy, SO kindly advise where I need to look for it. We want to keep the burner temp. below 150 f and I am not sure what I need, may be a thermostat or honestly I dont know.Pleaase advise.

Thanks

 

[jraef]

First off you need to determine how for gas fired system is being controlled now, if at all. If there is a burner control system already, you will need to tap into it with some additional controls in all likelihood. If not, you will need to add one, contact Honeywell or FireEye for that. Then you will need a controller that has range settings, i.e. turn on at -10F, off at 150F. If you are completely unfamiliar, find a good control systems integrator with experience in gas fired burner controls. There are a lot of pitfalls to be careful of, too many to rely on a free advice forum for.

Eng-Tips: Help for your job, not for your homework Read faq731-376

 

[waross]

As jraef says, however;
The heater should have a control that will turn it on when the ambient drops below -10F. I imagine that the 150F will be the internal temperature of the shute, or the burner housing. This control is often called a Hi-Limit. It will be located in the area where the temperature shouild not exceed 150F.
In the simplest configuration these controls can be wired in series. Some heaters will have a wiring diagram attached which will show the terminals to connect the -10F thermostat and the 150F Hi-Limit.
yours

 

[itsmoked]

I concur with jraef. Lots of pit falls!
Also your set points are truly bizzar ON at -10F OFF at 150F. Is this correct and if so why?

Do you mean 140F to 150F is the control band?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[satnam123]

Thanks for u r feedback. The situation is
One detector will be inside and the other will be outside.
The insider temp when will go 150 F besides the burnes it
should go off and when outside becomes -10 then it should kick in. So that is what I want to figure out how an instrumentation guy will come up with some thing simple.
Manf. does not want to suggest any thing as he says that we will not advise putting a radiant heater in inclined position as this is not CSA approved and we will not suggest anything also as the burner is at bottom and vent is at top, which is not how manf. would advise to install but we still want to go for it. So that is why I was wondering if you could advise what kind of setup I should suggest as an electrical engineer interms of wiring and sensor. I would appreciate if you could suggest some thing here.
Thanks

 

[waross]

I think I mentioned that in my post of
19 May 06 17:55
SERIES.
yours

 

[satnam123]

Waross,

I agree with your answer. That measns for me to porceed I should ask the manf. about the wiring of the burner housing. The temp. here relates to burner housing. But there is no control from manf. as according to him the temp. never goes this much high if installed as per CSA configuration.
So here what I understood, I will take this a temp. detector and place is besides the burner housing and wire it in series with supply. It should be rated for the bruner ampacity and when the temp. will go up to that value this detector will break the connection to power. Please advise if it makes sense.
Next thing, there will be another detector will be outside the chute and when the temp. becomes less than -10, it should the heater should start. How can we make this work ?.
Thanks

 

[waross]

Wired in series with the supply. Some burner controls will have a specific connection or terminals for control. Check with the manufacturer if it is perrmissable to control the burner by interupting the supply.
Whatever the control method, connect both thermostats in series.
Then the heater will start whenever the ambient temperature is below -10F. If the interior temperature rises above 150F the second thermostat or detector will stop the burner. When the burner temperature drops below 150F, if the ambient is below -10F the first thermostat will still be closed and the burner will restart.
The 150F detector must have normally closed contacts opening at temperatures above 150F) and the -10F thermostat must have normally open contacts (closing at temperatures below -10F).
yours