Will a JLD612 let me build this temp control dream machine?

[brossa]

I was preparing to build my own PID-controlled setup for sous vide cooking at home, using a solid state relay to control a set of directly wired immersion heaters. Then I read about using the relay to switch an outlet instead, into which any kind of heater could be plugged - a crock pot, a heat lamp, whatever - so I was going to go that route instead. Then I realized that there are times when I might want to keep temps down rather than up, like running an exhaust fan or a window air conditioner or a chilled water pump.

So - looking at the JLD612 manual it seems as though I can switch modes from heating (SSR is on when temp is below target) to cooling (SSR is on when temp is above target). But is there a way to run two relays simultaneously to control two outlets - one for heating devices, one for cooling devices - without having to to switch modes? I don't anticipate pitting a heater and cooler against each other; only one device would be used at any given time. What I'm aiming for is a universal device that can be used by any yahoo without having to train them to change modes on the PID controller: plug hot things into the red side or cold things into the blue side, set the temp, and forget it.

[richiem]

You have to change the setting 612 from heat mode to cool mode, I think, and will likely have to change set values too, but other than that it should work OK -- just be careful about the loads on the SSRs.

[MikeFromHC]

If it's just one at a time you might try telling the machine a little lie.
Use a Normally open relay for heating and a normally closed one for cooling and a DPDT switch to decide which to use.
And a sing on the switch to tell which is which.

[brossa]

Thanks for the advice so far. On rereading the online manual for the JLD612, it looks like only one output from the device is a PID output, and it can be configured either as an internal relay or a control for an external SSR. Am I correct that the other outputs (the 'relay' or 'relay alarm' outputs mentioned in the manual) would not work to control a heating or cooling device, since they aren't controlled in the same way as the single PID output? Sorry if I'm not being very clear.

[richiem]

Yes -- the PID control is only either through the SSR output to an SSR, or through J1 relay but not both. The controller can be set up like a regular thermostat with just on-off control and no PID control, which will work OK for many things, but is no better and no worse than a regular electronic-type thermostat that has remote temperature sensing.

[tward]

@brossa - You wrote that "PID output... can be configured either as an internal relay or a control for an external SSR". I've read the manual and I can't figure out where this configuration is done. Can you describe this?

Also, you mentioned the "online manual". I'm trying to make sure I have the latest manual. Are you using the one at viewtopic.php?f=13&t=3 ?

Thanks for your good question that started in informative thread!

[tward]

Yes -- the PID control is only either through the SSR output to an SSR, or through J1 relay but not both. The controller can be set up like a regular thermostat with just on-off control and no PID control, which will work OK for many things, but is no better and no worse than a regular electronic-type thermostat that has remote temperature sensing.

I am trying to undertstand the latter method - controlling through the J1 relay. Per the manual it seems this would be done by setting outY = 0 (or = 1, I'm not sure). In any case it seems that regardless of outY setting J1 is always an alarm output. My question concerns electrical characteristics of the J1 output. In other words is it AC or DC and what the voltage and amps are. The first page of the manual indicates "Relay Contact: AC220V / 3A", but I'm not sure if that applies to J1 (and/or J2) and whether it changes based on the Operating supply voltage (I'm not using 220V, but am using 120V).

Really what I want to do is experiment with not using PID control for an application, but instead use the alarm.

I'm currently using outY = 2 and using the SSR output (#6 & #7) to control an external SSR (that accepts input from 3 - 32VDC)

Any and all help appreciated!

[richiem]

Reply has been/is broken -- made a reply that wouldn't post. Be patient, all will be explained.

[richiem]

OK, things seem to be working again.

The J1 and J2 relays do not output any signal by themselves -- they are just switch contacts. Thin of a light switch -- you can turn the switch on or off but if it's not connected to the AC line and a light bulb nothing happens. That's the case with these relays. The JLD turns them on and off -- latches and unlatches them. But you need to hook them up to a power source and to a load. The relay contacts are rated to handle 220VAC and 3A of current -- DO NOT USE THEM TO CONTROL MORE THAN 1 Amp.

The J1 relay has a common C contact at screw terminal 4, and normally closed contact NC at terminal 3, and a normally open NO at terminal 5. For your application, connect the 120VAC line to terminal 4 C and connect one end of a 120V rated coil on an external relay to terminal 5 NO. Hook the other end of the relay coil to AC neutral. Hook your heater to the external relay's contacts, supplying 120VAC to one of the external relay's NO contacts and the heater to the external relay's common C contact (or vice-versa).

As shown on page 3, figure 2 of the manual (see the link to the new manual on this forum by Tech_Marco) the J1 "alarm" relay can be used to control the external relay and through it, the heater. Set the AH1 setting to the *low* temp that you want the heater to come *on* at. Set the AL1 setting to the *high* temp where you want the heater to *stop* heating. This seems backward because normally you would want an alarm to come on when the temp is too high. Making the AH1 setting lower than the AL1 setting causes the J1 relay to latch when the temp is too low, which turns on the external relay and the heater. Make sure there is at least 1 degree of difference between the AH1 and AL1 settings. Set outY to either 0 or 1 -- either will work for this application.

All of this assumes you want to have heating -- it's all just the opposite for cooling.

[tward]

Thanks again very much richiem, I think I understand that clearly.

I figure I'd set AH1 0.5 degree below the desired temperature and AL1 0.5 degree above it. (I figure the 1 degree delta is fine whether I'm using Celsius or Fahrenheit.) (If I had a system that was subject to cooling momentum I'd bump the AH1-AL1 values up, while if I had a system with heating momentum - such as with a heating element with large thermal mass - I'd bump the AH1-AL1 values down.)

[tward]

... The J1 relay has a common C contact at screw terminal 4, and normally closed contact NC at terminal 3, and a normally open NO at terminal 5. For your application, connect the 120VAC line to terminal 4 C and connect one end of a 120V rated coil on an external relay to terminal 5 NO. Hook the other end of the relay coil to AC neutral. Hook your heater to the external relay's contacts, supplying 120VAC to one of the external relay's NO contacts and the heater to the external relay's common C contact (or vice-versa). ...

Lightobject only carries DC-AC relays. Any thoughts on where to get the kind of AC-AC relay you describe being used above?

[tward]

If it's just one at a time you might try telling the machine a little lie.
Use a Normally open relay for heating and a normally closed one for cooling and a DPDT switch to decide which to use.
And a sing on the switch to tell which is which.

I'm still coming up the learning curve on different types of relays, so I'm hoping you can describe this a bit more. I was thinking that the relay could go to a SPDT. One throw of the SPDT would feed a NO heating relay and the other throw would feed a NO cooling relay.