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OK,

You will need four contactors to do what you are trying to do (for the heater part alone).

You will need two self latching contactors (one for each heater), use one of the unused pair of contacts off of each of your start/stop contactors, ie. ones not used in the latch circuit, to feed a switched supply in series with the thermostatic controlled contactor (ie. in series with each thermostat and coil).

This way you can independantly control each heater, and each thermostat can control the second contactor independent from the latch (stop/start) contactor.

It is difficult to put into words, I may see if I can draw it for you.

That would be fantastic.
 
OK,

You will need four contactors to do what you are trying to do (for the heater part alone).

You will need two self latching contactors (one for each heater), use one of the unused pair of contacts off of each of your start/stop contactors, ie. ones not used in the latch circuit, to feed a switched supply in series with the thermostatic controlled contactor (ie. in series with each thermostat and coil).

This way you can independantly control each heater, and each thermostat can control the second contactor independent from the latch (stop/start) contactor.

It is difficult to put into words, I may see if I can draw it for you.

Your explanation for the heating side alone only needs 3 contactors, you say 4 but only explain 3
The heating contactors should not be latching as the need to drop out when stat opens, its the closed stat switch which holds the coil in.

On a tangent a risk assessment would probably negate the need for a E-Stop but would require more info, but your wiring plan shows it as a latching stop button and wont comply the way you have connected it as this would usually incorporate a safety relay, although it not a problem helping you JP i feel you are jumping in the deep end here before you can swim. there are so many other factors to be considered excluding the control system that come with experience and as im not their to see the install its hard to pre-empt you
If your fitting all this in an enclosure like a push button panel then theirs things like indicator lamps, door interlocks etc etc... to be considered as their are guidelines to follow which is clear you are unaware off.
As you dont seem to be any further ill draft you a simple form schematic but this is only on the info you have supplied so bare with me ive a busy few days ahead.
 
Hi DW,

No he needs 4 in total for the heating alone, He needs two latches (start/stop) independent from each other, and two stat controlled contactors, again independent from one another.

Have a look at this drawing, and see if i have made a mistake, I have drawn the controls for one heater, he would need to duplicate this apart from the E-Stop, which is common to the whole panel.

I have added the drawing in PDF as the image is too small to see
 

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You have shown a diagram with 2 contactors on, K1 is you initial latching contactor (k1/1), k2 is your first heater control and using the common connection K1/2 to supply you 2nd heater would be fine, less expensive and leave more room as it removes the need for the extra contactor. (excluding E-stop and pump controls)
 
You have shown a diagram with 2 contactors on, K1 is you initial latching contactor (k1/1), k2 is your first heater control and using the common connection K1/2 to supply you 2nd heater would be fine, less expensive and leave more room as it removes the need for the extra contactor. (excluding E-stop and pump controls)

I think I understand the drawing, and I think my problem in my current design is the stop button is after the start button!... Spark68 / Darkwood thanks very much for all your help and time. Really do appreciate it very much. Here is a picture of what I have at the moment.

Just going to sit and work out how I can redesign my current box to work like above.
Control Panel for 3ph Heaters photo1qfz - EletriciansForums.net
Control Panel for 3ph Heaters photonfs - EletriciansForums.net
 
Finally think I have worked out my issue... I have now got four contactors, two for each heater.
One switches the main coil on and off, and the other switches the 3ph electric on and off to the heater.
I think my issue is that the contactor controlling the main contactor is not latched, and thus when power to A1 is lost the whole cirucit remains dead.
 
First of all the thermostat in the heater I take it is a control stat ? then there should be a high limit cut out safety stat Yes Ok if so these need to be left in the circuitry.

So Me think you need to fit a timeclock for occupancy times and a area or room stat but if the stat on the heater is on the return side then thats fine other than that have an override switch for not occupancy times.

If the stat on the heater is on the return side then you can control the area temp with this but if it is on the discharge side then you will need a area wall stat
 
The control relay will still drop out when the thermostat operates. The stop is in the wrong place and there's no need for the Aux on the contactor.
 
The control relay will still drop out when the thermostat operates. The stop is in the wrong place and there's no need for the Aux on the contactor.

Yeah sorry I just realised that I wont need that Auxillary anymore because their will be a constant supply to A1.
Why will the control relay still drop out when the thermostat operates? How can i change it?
 
I give up!

Follow the last drawing I've given you. It will work with no problems.

Tony I don't mean to offend you but your drawing makes no sense to me. I'm here because I need help. Again something that seems relatively straight forward to you is in actual fact very difficult to me.
 
I think you are struggling because you cant interpret tony's wiring diagram because you dont understand what the R1/1 etc means ....
R1 relates to relay 1
R1/1 relates to relay 1 and the first pole/way so looking at the diagram when you press the start button R1 will close.... this will close R1/1(pole no1) and because its in parallel with the start button it holds R1 closed.
R1/2 is the second pole of R1 so when R1 closes R1/2 becomes energised supplying the next part of the control circuit.

Try reading the wiring plans now with this info..... my worry is you will need to supply a wiring schematic with your control panel yet you can't initially read them yet alone draft one up.
 
I think you are struggling because you cant interpret tony's wiring diagram because you dont understand what the R1/1 etc means ....
R1 relates to relay 1
R1/1 relates to relay 1 and the first pole/way so looking at the diagram when you press the start button R1 will close.... this will close R1/1(pole no1) and because its in parallel with the start button it holds R1 closed.
R1/2 is the second pole of R1 so when R1 closes R1/2 becomes energised supplying the next part of the control circuit.

Try reading the wiring plans now with this info..... my worry is you will need to supply a wiring schematic with your control panel yet you can't initially read them yet alone draft one up.

Hi Darkwood, I am confused because Spark's drawing doesn't mention a relay. This one does? I have loads of contactors, but no relays in my stock and wanted to make it this week? So are we saying Sparks drawing will not work?
 
Tony has supplemented relays to do the control side as they are cheaper, less room etc, the contactors are just larger versions of relays for the heavier loads.... take the both as meaning the same if you have all contactors.
 
Tony has supplemented relays to do the control side as they are cheaper, less room etc, the contactors are just larger versions of relays for the heavier loads.... take the both as meaning the same if you have all contactors.

Thanks,I apprechiate that but just want to work it with contactors.
8 don't want to confuse myself any more lol.

What wwould I need to do to get my current drawing work? I thought I did it just like spark said?
 
You have shown a diagram with 2 contactors on, K1 is you initial latching contactor (k1/1), k2 is your first heater control and using the common connection K1/2 to supply you 2nd heater would be fine, less expensive and leave more room as it removes the need for the extra contactor. (excluding E-stop and pump controls)

Hi DW,
K1 could easily be a relay instead of a contactor (cheaper) as the control element in my drawing, K 1-1 and K1-2, are 2 pairs of contacts on the K1 relay, K2 is a 3 or 4 pole contactor which has the stat or cutout in series with the control coil.

I had cut this drawing down to it's most basic skeleton, the OP could have used extra contacts on the start/stop relay for status indicators and the like.

I had initialy assumed the OP was controlling both heaters from one stop/start circuit, but then he wanted to control both heaters seperately, hence the mention of three contactors initially, revised to four, to give independent control to each.

Half the trouble I had was the actual drawing with the software package (Tinycad), as Iam not used to drawing in software.

This was the circuit for one heater, as I said he would need to duplicate this circuit (apart from the E-stop) for additional heaters.
 
Hi DW,
K1 could easily be a relay instead of a contactor (cheaper) as the control element in my drawing, K 1-1 and K1-2, are 2 pairs of contacts on the K1 relay, K2 is a 3 or 4 pole contactor which has the stat or cutout in series with the control coil.

I had cut this drawing down to it's most basic skeleton, the OP could have used extra contacts on the start/stop relay for status indicators and the like.

I had initialy assumed the OP was controlling both heaters from one stop/start circuit, but then he wanted to control both heaters seperately, hence the mention of three contactors initially, revised to four, to give independent control to each.

Half the trouble I had was the actual drawing with the software package (Tinycad), as Iam not used to drawing in software.

This was the circuit for one heater, as I said he would need to duplicate this circuit (apart from the E-stop) for additional heaters.
Spark what you say is exactly what I want.
What I did on the paper above is what I think your drawing is telling me to do.
My drawing will be replicated for the 2nd heater as per your post, except for emergency stop which kills all three (2 pumps and heater)
What I'm asking is what's wrong with how I've drawn it out?
 

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