# wiring zones - residential system



## jim connolly

Hey guys, looking for a bit of advice here regarding 24v wiring...I'm a bit green when it comes to residential work. In my previous experience with commercial/industrial systems, the controls wiring was subbed out. Now that I'm newly self-employed, I'm attempting to learn it.
Start with a simple residential heating job. Two zones, using Honeywell 1000 series zone valve.

I'm a dummy when it comes to wiring diagrams. Its easier to me if it's spelled out. This is how I picture it being done:

- 18/2 thermostat wire comes from Thermostat 1, connected to yellow wires from Zone Valve 1.

- 18/2 wire from Thermostat 2, connected to yellow wires from Zone Valve 2

- Red wires (end switch wires) from BOTH zone valves are connected TOGETHER and to 18/2 wire from transformer.

- Line voltage from panel feeds boiler aquastat, then from aquastat to burner (oil) and circulator. Circulator is running constantly. (I know the line voltage is the electrician's side of the job, just trying to understand the bigger picture).

If I'm missing anything, or if I'm incorrect in any way please let me know.


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## Tankless

Well, you are actually missing a few things. An electrician is one of them.....


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## OldSchool

Hey guys, looking for a bit of advice here regarding 24v wiring...I'm a bit green when it comes to residential work. In my previous experience with commercial/industrial systems, the controls wiring was subbed out. Now that I'm newly self-employed, I'm attempting to learn it.
Start with a simple residential heating job. Two zones, using Honeywell 1000 series zone valve.

I'm a dummy when it comes to wiring diagrams. Its easier to me if it's spelled out. This is how I picture it being done:

- 18/2 thermostat wire comes from Thermostat 1, connected to yellow wires from Zone Valve 1.
*Should be Transformer in series with stat and motor of zone valve.... this way the stat operates the valve....once the zone valve motor has opened the valve then the end switch contacts should be closed and boiler will be activated through the TT connections on boiler *
- 18/2 wire from Thermostat 2, connected to yellow wires from Zone Valve 2
*one 40vac transformer can operate 4 zone valves*
- Red wires (end switch wires) from BOTH zone valves are connected TOGETHER and to 18/2 wire from transformer.
* end switches are wired to the TT of boiler*
- Line voltage from panel feeds boiler aquastat, then from aquastat to burner (oil) and circulator. Circulator is running constantly. (I know the line voltage is the electrician's side of the job, just trying to understand the bigger picture).
*Line voltage should go to low water cut off then to boiler control... boiler control should have aquastat and limit control and relay to start oil burner.*

If I'm missing anything, or if I'm incorrect in any way please let me know 

Let me know if this helps you


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## Scott K

Tankless said:


> Well, you are actually missing a few things. An electrician is one of them.....


I'm not sure where you come from, but in British Columbia Canada, and I'm sure this is probably the same or similar for the rest of Canada that utilizes the same gas code - CSA B149.1-05 or 10 (check your local regulations to confirm as well as your local provincial or municipal gas safety regulations/act before considering what I have said fact), my 'B' Gas Ticket and the BC Gas Safety Act Considers Control wiring an integral part of the Gas Appliance and subsequently only a licensed Gas Fitter can do control wiring. Basically anything that is neccessary to make the appliance function is considering gas fitting. This would include running line voltage wires from the pump control to the pumps for the boiler, and if I'm not mistaken, even line voltage wiring from the switch or junction box into the appliance as well. 

This is why I believe it is critical that people who install parts & components that connect to gas appliances, including hydronic piping, should have a gas fitting license. You can do A LOT of damage if you do not understand the relationship between your design, piping, and control practices, and how they affect the operation of the burner side of the appliance. You can cause short cycling, flue gas condensation on cast iron heat exchangers, premature component failure, and in serious cases heat exchanger failure with lack of knowledge or respect of gas fired equipment if you do not understand how these things function.


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## jim connolly

Scott K said:


> I'm not sure where you come from, but in British Columbia Canada, and I'm sure this is probably the same or similar for the rest of Canada that utilizes the same gas code - CSA B149.1-05 or 10 (check your local regulations to confirm as well as your local provincial or municipal gas safety regulations/act before considering what I have said fact), my 'B' Gas Ticket and the BC Gas Safety Act Considers Control wiring an integral part of the Gas Appliance and subsequently only a licensed Gas Fitter can do control wiring. Basically anything that is neccessary to make the appliance function is considering gas fitting. This would include running line voltage wires from the pump control to the pumps for the boiler, and if I'm not mistaken, even line voltage wiring from the switch or junction box into the appliance as well.
> 
> This is why I believe it is critical that people who install parts & components that connect to gas appliances, including hydronic piping, should have a gas fitting license. You can do A LOT of damage if you do not understand the relationship between your design, piping, and control practices, and how they affect the operation of the burner side of the appliance. You can cause short cycling, flue gas condensation on cast iron heat exchangers, premature component failure, and in serious cases heat exchanger failure with lack of knowledge or respect of gas fired equipment if you do not understand how these things function.


No natural gas out here....oil or electric only. Low voltage/controls wiring does not require a permit of any kind, and is usually carried out by the plumber or burner guy, whoever installs the system in question.


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## jim connolly

OldSchool said:


> Hey guys, looking for a bit of advice here regarding 24v wiring...I'm a bit green when it comes to residential work. In my previous experience with commercial/industrial systems, the controls wiring was subbed out. Now that I'm newly self-employed, I'm attempting to learn it.
> Start with a simple residential heating job. Two zones, using Honeywell 1000 series zone valve.
> 
> I'm a dummy when it comes to wiring diagrams. Its easier to me if it's spelled out. This is how I picture it being done:
> 
> - 18/2 thermostat wire comes from Thermostat 1, connected to yellow wires from Zone Valve 1.
> *Should be Transformer in series with stat and motor of zone valve.... this way the stat operates the valve....once the zone valve motor has opened the valve then the end switch contacts should be closed and boiler will be activated through the TT connections on boiler *
> - 18/2 wire from Thermostat 2, connected to yellow wires from Zone Valve 2
> *one 40vac transformer can operate 4 zone valves*
> - Red wires (end switch wires) from BOTH zone valves are connected TOGETHER and to 18/2 wire from transformer.
> *end switches are wired to the TT of boiler*
> - Line voltage from panel feeds boiler aquastat, then from aquastat to burner (oil) and circulator. Circulator is running constantly. (I know the line voltage is the electrician's side of the job, just trying to understand the bigger picture).
> *Line voltage should go to low water cut off then to boiler control... boiler control should have aquastat and limit control and relay to start oil burner.*
> 
> If I'm missing anything, or if I'm incorrect in any way please let me know
> 
> Let me know if this helps you


Thanks OldSchool, let me see if I follow
So...
-24v circuit is *transformer - thermostat - zone valve yellow wire. *This would be the circuit that opens the valve when the thermostat calls for heat.
In the case of two or more zones, how is each zone circuit separated when they rech the transformer? Or are they spliced/maretted together THEN attatched to the transformer?
-Line volt circuit is *circulator - zone valve red wire (end switch) - LWCO - boiler control. *This is the circuit that, when the end switch contacts close, starts the boiler itself, so it would obviously be line voltage. In the case of more than one zone, are the red leads from zone valve to 110v spliced together or kept separate before joining the circulator?

Thanks very much
Jimmy


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## Scott K

jim connolly said:


> Thanks OldSchool, let me see if I follow
> So...
> -24v circuit is *transformer - thermostat - zone valve yellow wire. *This would be the circuit that opens the valve when the thermostat calls for heat.
> In the case of two or more zones, how is each zone circuit separated when they rech the transformer? Or are they spliced/maretted together THEN attatched to the transformer?
> -Line volt circuit is *circulator - zone valve red wire (end switch) - LWCO - boiler control. *This is the circuit that, when the end switch contacts close, starts the boiler itself, so it would obviously be line voltage. In the case of more than one zone, are the red leads from zone valve to 110v spliced together or kept separate before joining the circulator?
> 
> Thanks very much
> Jimmy


Two systems

Zone valve motor system

Transformer (power source), T-stat (switch) and Zone Valve motor (load) with the wire from the neutral on the zone valve motor going back to the Transformer to complete the circuit. The T-stat closes and allows power to flow to the zone valves. Each T-stat/zone has to have their own individual wire coming off of the Transformer power circuit (hot wire). 

The other system would be the end switch system off of the zone valve. When the end switch closes, this obviously means the zone valve is open. When the zone valve is open it is safe for the pump to come on and start circulating water through the zone, and subsequently it's also safe for the boiler to come on. It's not a bad idea to have a flow switch downstream of the pump and this will confirm that the pump is flowing water, and then this will close another circuit allowing the boiler to come on. This would prove the circulator is working and add another element of safety. 

The end switch system can still be a 24 volt system as you can use a relay to turn on the circulator and a relay to allow power to flow to the boiler. But I think you know enough here to figure things out from here.


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## futz

jim connolly said:


> -Line volt circuit is *circulator - zone valve red wire (end switch) - LWCO - boiler control. *This is the circuit that, when the end switch contacts close, starts the boiler itself, so it would obviously be line voltage. In the case of more than one zone, are the red leads from zone valve to 110v spliced together or kept separate before joining the circulator?


*NO! NO! NO!*  *DO NOT* wire 110V through the end switches. You'll kill someone! Nobody expects that, and because they don't expect it they'll handle it live. You can't wire 110V with exposed wires and marrettes (wire nuts). Marrettes can fall off if not tightened properly or if abused over years - then that exposed 110V could touch anything - it could burn a hole in a pipe - it could start a fire - it could kill someone. Zone valve end switches are designed for 24V wiring. There's no way to use a proper BX connector on a zone valve, and there's no room inside the cover for connections anyway. If your zone valve has a knockout in it for a connector and an internal electrical box (not likely) then you can use 110V (I'm sure they exist, but I've never seen one).

The boiler typically has a fan center or something similar, with a relay that uses your 24V end switch signal to turn on the 110 to the pumps, and also switch on the boiler. All the 110V is connected inside a proper grounded metal box for safety, and all 110V to pumps and other stuff leaves the box through proper connectors and is wired in BX.

You really should have a handle on how to do this safely and correctly (to code) before you do it in customers' houses/buildings. If you don't know then hire someone who does - watch and learn. Or take a course. Or read a book - here in Canada we have the very good Electrical Code Simplified books. (... scrolls down) Ah, I see you have the same thing in the States.

Or just wing it and take the gamble. If you burn down a customer's house with bad wiring, they and their insurance company's lawyers will be coming for blood - this is not a joke. Do it badly and you could get yourself in a world of trouble.


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## OldSchool

Scott K said:


> I'm not sure where you come from, but in British Columbia Canada, and I'm sure this is probably the same or similar for the rest of Canada that utilizes the same gas code - CSA B149.1-05 or 10 (check your local regulations to confirm as well as your local provincial or municipal gas safety regulations/act before considering what I have said fact), my 'B' Gas Ticket and the BC Gas Safety Act Considers Control wiring an integral part of the Gas Appliance and subsequently *only a licensed Gas Fitter can do control wiring.* *Basically anything that is neccessary to make the appliance function is considering gas fitting*. *This would include running line voltage wires from the pump control to the pumps for the boiler, and if I'm not mistaken, even line voltage wiring from the switch or junction box into the appliance as well.*
> 
> This is why I believe it is critical that people who install parts & components that connect to gas appliances, *including hydronic piping, should have a gas fitting license.* *You can do A LOT of damage if you do not understand the relationship between your design, piping, and control practices, and how they affect the operation of the burner side of the appliance.* You can cause short cycling, flue gas condensation on cast iron heat exchangers, premature component failure, and in serious cases heat exchanger failure with lack of knowledge or respect of gas fired equipment if you do not understand how these things function.


I beg to differ..... A gas fitter is not in any sense licenced to design or alter control wiring.

Control wiring is a mechanical trade which is the scope of work for a mechanical contractor....

A gas fitter is not Allowed to run line voltage either. He is only allowed to make the connection at the equipment provided he gets a permit to do so.

I never seen a gas fitter ever have the knowledge to design hydronic system with just gas fitting experience..... he might have taken a coarse from some manufacture to him show how to do it... but that does not make him licenced to do it.

All that being said ..... the plumbing trade covers Mechanical Contractor, Control wiring and boilers ( hydronic or steam )...... at one time there was no gas fitters and gas piping was considered part of the plumbing trade.

So in reality a gas fitter is only allowed to run gas pipe, vent equipment, install gas appliances and repair said equipment or appliances.... By all rights they shouldn't even be doing any water lines on a HWT


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## Catlin987987

we were told in trade school, that gasfitters can do 24 Volt
in reality we do alot of 12/240, but just a few 460(pumps)


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## futz

OldSchool said:


> I beg to differ..... A gas fitter is not in any sense licenced to design or alter control wiring.
> 
> Control wiring is a mechanical trade which is the scope of work for a mechanical contractor....
> 
> A gas fitter is not Allowed to run line voltage either. He is only allowed to make the connection at the equipment provided he gets a permit to do so.


Actually, here in B.C. the gas safety branch forced all gasfitters to go back to school (about a week of nights of instruction and a test) and get an electrical endorsement. Had to buy an electrical codebook and learn a bunch of stuff (it was interesting, but most of it I don't use, so it was very quickly forgotten). It was really kind of a waste of time and money - I forgot most of what I learned, but they did it to cover their own asses I guess. The test was ultra simple - I was first out of there and a bit pissed off at how simple it was (after all that studying and worrying).

But now I am legal to connect any wiring to any heating equipment. Having to take the test was annoying to me because I understand wiring and was already doing it correctly.

An awful lot of fitters just *do not* understand wiring. During the above-mentioned course we spent a LOT of time spoonfeeding wiring dummies with the simplest concepts, and having most of it go right over their heads. Eventually rote memory did it's thing and I think most probably passed the test.



> So in reality a gas fitter is only allowed to run gas pipe, vent equipment, install gas appliances and repair said equipment or appliances.... By all rights they shouldn't even be doing any water lines on a HWT


Agreed. Unless they have tickets for both gas and plumbing.


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## jim connolly

Boys, thank you for everything.....been quite helpful. I think I have a grasp on it now...the relay was the missing piece of the puzzle. May I ask one more thing - where in the end-switch circuit is the relay located?

Please rest assured, I'm not going to attempt this without proper research and experience/guidance. The first few controls jobs will be subbed out, watched, and learned from.


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## OldSchool

jim connolly said:


> Boys, thank you for everything.....been quite helpful. I think I have a grasp on it now...the relay was the missing piece of the puzzle. May I ask one more thing - where in the end-switch circuit is the relay located?
> 
> Please rest assured, I'm not going to attempt this without proper research and experience/guidance. The first few controls jobs will be subbed out, watched, and learned from.


The end switch of the zone valve does not need a relay....the end switch wirer which are goes the the TT or stat connection on the boiler.... this of coarse is 24 volt. The 24 volt comes or is supplied by the TT 24 volt connection..

On this note: *all control wiring is 24 volt..*

Just to recap....

The zone valve motor is wired to the room thermostat and to your feild supplied 24 volt transformer....

Zone valve wiring for stat control ( 24 volts from transformer)

_____.transformer.___stat.______. zone valve.______back to transformer.

Zone valve end switch( 24 volt from TT on boiler 

_____. Boiler T contact 1.______. end switch wire one

_____. end switch wire two._______. Boiler T contact 2 

Note boiler has its own 24 volts coming from the TT contacts on boiler.

Hope this clearify things for you.


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## jim connolly

OldSchool, you are the MAN. This diagram is exactly what I was looking for the whole time. 
Two other (hopefully final) questions though:

There are 2 T T termianls coming off the boiler, w/ 24v leads. If the system has 3 or more zones (basically more zones than available T T leads), is the end switch wire from each zone valve maretted together to the T T wire ? As in one red wire from each zone valve, spliced together, then joined to a wire coming from the T terminal. I think this is what I've seen in the past, but its been a while and I want to make sure. 

And same question for the thermostat circuit, except substitute "yellow" for "red" and "transformer" for "TT terminals".


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## OldSchool

jim connolly said:


> OldSchool, you are the MAN. This diagram is exactly what I was looking for the whole time.
> Two other (hopefully final) questions though:
> 
> There are 2 T T termianls coming off the boiler, w/ 24v leads. If the system has 3 or more zones (basically more zones than available T T leads), is the end switch wire from each zone valve maretted together to the T T wire ? As in one red wire from each zone valve, spliced together, then joined to a wire coming from the T terminal. I think this is what I've seen in the past, but its been a while and I want to make sure.
> 
> And same question for the thermostat circuit, except substitute "yellow" for "red" and "transformer" for "TT terminals".


The end switches for all zones are maretted and share on the 24 volt TT contact at boiler... the end switches are no different than a light switch... all it does is open and close a circuit...no power is used up in them. You can have as many end switches your heart desirers...

However the zone valves need their own 24 volt power that is what the transformer is for.... one 40 VAC transformer can power 4 separate zone valves.


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## OldSchool

here is a pic I made for you


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## wundumguy

OldSchool said:


> .... at one time there was no gas fitters and gas piping was considered part of the plumbing trade.
> 
> So in reality a gas fitter is only allowed to run gas pipe, vent equipment, install gas appliances and repair said equipment or appliances.... By all rights they shouldn't even be doing any water lines on a HWT


Huh?

My mentor, soon to be retired, took the time and made the effort to become a bona fide Plumber, Steamfitter-Pipefitter, and Class A Gas Fitter. When a Plumber steps out of line and claims he can do pipefitting, my mentor simply asks the Plumber, when in his career he ever fit and welded stainless steel pipe at a nuclear facility, when he fit and welded glass pipe at a research centre, at what chemical factories he fit and wrapped fiberglass reinforced pipe, at what cogenerator shutdown he worked on a high pressure superheated steam system, and during which shutdown did he service the controllers and actuators at a manufacturing plant.

My mentor is an incrediblly fair and generous man with a bit of an edge if someone stepped out of line. He firmly believes in treating all persons fairly and equally and he would not hesistate to embarass a Plumber who claimed to be a Gas Fitter.

How about we send our Plumber to a gas fired system with atmospheric burners, 6 boiler banks each under 400MBH, multiple rooms too cold between between 6AM and 7AM, some of above rooms also too hot after 8AM and one boiler bank does not fire. Sounds like the perfect call for our Plumber with a G2 certification who's been doing gas fitting since before I was even born... until the 24V transformer, thermostats, zone valves, fan centres, outdoor transmitter and control modules turn into a... dual pressure pneumatic control system with freeze protection, staged fire, fast morning pickup, and ventilation controls with minimum fresh air volume and minimum supply air temperatures. Who you going to call?

So, if we send our Plumber to a gas fired system with atmospheric burners, 4 boiler banks each under 400 MBH, several rooms no heat, he will have absolutely no problem doing the job of a Gas Fitter. That means, when he arrives and the owner tells him that at least 1 DDC panel does not accept user command and/or has lost communication, our Plumber who has done gas fitting since before computers even existed will magically write a new heating program on a computer in a command language he's never seen or even heard of. Now What? Call a Computer Technician?

Why don't we send our Plumber to a gas fired system with power burners, 3 boilers each at 1,500MBH. several rooms with no heat, under heat, and correct heat. Ah, it's just another heating call for our Plumber with a G1 certification who's been doing gas fitting since before Gas Fitters even existed... until we get to the DDC system that includes a computer, 3 DDC panels, several sub panels, and more circuits than he's seen in his entire life. So, what's our Plumber going to do now? Call an Electrician?

God forbid we call give the job to a real Gas Fitter! Someone who can handle any gas fired system from start to finish, that is from the start of the gas supply to the end of the control system in any gas fired system, not just the pipes that any apprentice can join, or the 24V AC control system every high school graduate can follow -- someone who can:

Design, install and repair pneumatic control systems. Calibrate two-pressure stats, set up and repair actuators and controllers, for fresh, exhaust, return, mixed and tempered air volumes and temperatures. Select, install, repair and calibrate remote transmitters, high/low selectors, high/low limits, averaging relays, pressure-electric and electro-pneumatic switches, positive positioners, multi-input receiver-controllers, etc. Design, install and repair direct digital control systems. Write programs to stage and rotate a multi boiler system, implement freeze protection parameters, minimum fire time and post-fire pump time. Determine and select scale ranges, initiate DC input/output points, network computers with main and sub direct digital control panels, determine dead band and proportional bands settings, etc.

Ever pipe trades journeyperson possesses the skills and knowledge to perform the work of an APPRENTICE at some level in another pipe trade. When a journeyperson of one pipe trade holds himself out to be the equivalent of a journeyperson in another pipe trade, he can only embarass himself.


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## OldSchool

wundumguy said:


> Huh?
> 
> My mentor, soon to be retired, took the time and made the effort to become a bona fide Plumber, Steamfitter-Pipefitter, and Class A Gas Fitter. When a Plumber steps out of line and claims he can do pipefitting, my mentor simply asks the Plumber, when in his career he ever fit and welded stainless steel pipe at a nuclear facility, when he fit and welded glass pipe at a research centre, at what chemical factories he fit and wrapped fiberglass reinforced pipe, at what cogenerator shutdown he worked on a high pressure superheated steam system, and during which shutdown did he service the controllers and actuators at a manufacturing plant.
> 
> My mentor is an incrediblly fair and generous man with a bit of an edge if someone stepped out of line. He firmly believes in treating all persons fairly and equally and he would not hesistate to embarass a Plumber who claimed to be a Gas Fitter.
> 
> How about we send our Plumber to a gas fired system with atmospheric burners, 6 boiler banks each under 400MBH, multiple rooms too cold between between 6AM and 7AM, some of above rooms also too hot after 8AM and one boiler bank does not fire. Sounds like the perfect call for our Plumber with a G2 certification who's been doing gas fitting since before I was even born... until the 24V transformer, thermostats, zone valves, fan centres, outdoor transmitter and control modules turn into a... dual pressure pneumatic control system with freeze protection, staged fire, fast morning pickup, and ventilation controls with minimum fresh air volume and minimum supply air temperatures. Who you going to call?
> 
> So, if we send our Plumber to a gas fired system with atmospheric burners, 4 boiler banks each under 400 MBH, several rooms no heat, he will have absolutely no problem doing the job of a Gas Fitter. That means, when he arrives and the owner tells him that at least 1 DDC panel does not accept user command and/or has lost communication, our Plumber who has done gas fitting since before computers even existed will magically write a new heating program on a computer in a command language he's never seen or even heard of. Now What? Call a Computer Technician?
> 
> Why don't we send our Plumber to a gas fired system with power burners, 3 boilers each at 1,500MBH. several rooms with no heat, under heat, and correct heat. Ah, it's just another heating call for our Plumber with a G1 certification who's been doing gas fitting since before Gas Fitters even existed... until we get to the DDC system that includes a computer, 3 DDC panels, several sub panels, and more circuits than he's seen in his entire life. So, what's our Plumber going to do now? Call an Electrician?
> 
> God forbid we call give the job to a real Gas Fitter! Someone who can handle any gas fired system from start to finish, that is from the start of the gas supply to the end of the control system in any gas fired system, not just the pipes that any apprentice can join, or the 24V AC control system every high school graduate can follow -- someone who can:
> 
> Design, install and repair pneumatic control systems. Calibrate two-pressure stats, set up and repair actuators and controllers, for fresh, exhaust, return, mixed and tempered air volumes and temperatures. Select, install, repair and calibrate remote transmitters, high/low selectors, high/low limits, averaging relays, pressure-electric and electro-pneumatic switches, positive positioners, multi-input receiver-controllers, etc. Design, install and repair direct digital control systems. Write programs to stage and rotate a multi boiler system, implement freeze protection parameters, minimum fire time and post-fire pump time. Determine and select scale ranges, initiate DC input/output points, network computers with main and sub direct digital control panels, determine dead band and proportional bands settings, etc.
> 
> Ever pipe trades journeyperson possesses the skills and knowledge to perform the work of an APPRENTICE at some level in another pipe trade. When a journeyperson of one pipe trade holds himself out to be the equivalent of a journeyperson in another pipe trade, he can only embarass himself.


:laughing: and you think an adverage gas fitter can do any of that....

systems like that come from experience.... There is no way in hell any of that is bening taught in any gas course.....

Controls are instrumentation and electronics...... there is such a thing as a controls contractor....

I would like to see an adverage gas fitter go to a new big commercial job and think he is a control contractor.


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## wundumguy

I'm just yanking your chain... 
If you read closely, that's not gas... it's all HVAC stuff.

I moved into HVAC right after completing the Plumber apprenticeship.


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