How to add high temp shut off

[Bricklayer]

What is used to add a high temp shutdown to an RO? I've been looking at using a PID connected to a relay. But thought that there must be something out there that has the relay built in. I've looked through all the big names in HVAC controls for what I'm looking for but can't seem to find anything.
I do like the PID because it will display the temp in real time. But I figured there was something less bulky and smaller that would work. If I use a PID I would need to mount if in its own box separate from my control enclosure for my RO. Since there is no more room.

[wiam]

I know your ro is home built but I went the pid/relay route on my older seprotech. It did not have high temp shut down. Works well. I added a T after feed pump and used a compression fitting to install the temp probe. If I had it to do over I would consider this control http://m.ebay.com/itm/10A-110V-Digital-Temperature-Controller-Temp-Sensor-Thermostat-Control-Relay-US-/121314210967?nav=WATCHING_ACTIVE I have used them for other applications and they have worked well. You would still need a relay. Only reason I used the pid is I did not have a spare temp control at the time and had an extra pid.

[wiam]

I also added a timer to the control circuit on mine so if I want to do a 10 minute rinse I can walk away. I also use it when flushing sugar out.

[Clinkis]

Should be able to tie it into your shut off line for your main contractor. This is what I did for my high/low pressure switches.

[Bricklayer]

That was one of my questions
Where to put the temp probe. on the feed pump inlet

Next question is if instead of a regular relay, would a solid state on delay timer work? Once it gets power so say when it hits the set temp it runs for 10 minutes then activates the relay and shuts system off? Would temp not rise in those ten minutes though?

[mellondome]

With a multistage pump the temp will still rise as long as the pump is running. With a displacement pump (procomm) it will not rise any noticeable amount.

[Bricklayer]

Since the high temp shut down is used mostly for washing cycles. My plan is to make it interrupt the main power to the RO with a relay. I'm going to wire the main power for the controls through the common and normally closed contact. This means power will flow through when the relay is idle. When high temp activates it will operate the coil on the relay moving the relay to normally open. Resetting the RO controls and shutting down system.

[Urban Sugarmaker]

My PID temp probe is in the low pressure feed to the high pressure pump. In my case the signal goes to the computer and the logic says to cut the power when it receives a signal from the PID controller. But, you can probably just find a relay that can accept more than one input. I would check out Automation Direct online. They have free tech support and an expert can help you pick one out. Just tell them what you want to do. Regular relays are cheap.

[Bricklayer]

I know your ro is home built but I went the pid/relay route on my older seprotech. It did not have high temp shut down. Works well. I added a T after feed pump and used a compression fitting to install the temp probe. If I had it to do over I would consider this control http://m.ebay.com/itm/10A-110V-Digital-Temperature-Controller-Temp-Sensor-Thermostat-Control-Relay-US-/121314210967?nav=WATCHING_ACTIVE I have used them for other applications and they have worked well. You would still need a relay. Only reason I used the pid is I did not have a spare temp control at the time and had an extra pid.

Is this temp control unit not the same as a PID controller? And it dosnt say what type of sensor it uses. Can I buy replacements if needed?
Since it's for heating and cooling what setting would it be on for the RO?
Just trying to wrap my head around how it's going to work
I've been playing around with the PID that came with my autodraw and it's pretty simple. Set temp the PID gives power. Goes below it power goes off.
I've heard nightmares about the Chinese instructions that come with these units.
Is there a benefit other then price on going with this unit instead of say an Auber PID ?

[wiam]

Simpler control. I'm guessing you would have hard time finding the correct replacement probe. You would want to set it for heating as you want it to turn off when it gets to temp. I have had good luck with Chinese pid's from eBay. This is the one I have for high temp shut down. Comes with pt 100 probe. I also have 3 of these in a box for evap temps. 2 for pan temps one for stack. I like the pt 100 probes because they read out in tenth a of a degree so you can see trends better.

[Bricklayer]

Right on. I will give it a try. For $10 can't go wrong.
Does it send a 120v current when it hits the set temp or a 12v? Just wondering because I will need to get a relay for the high temp shut down also

[wiam]

There are 2 terminals for the switched part. Paperwork says 10 amps/110 volts. I think the switched terminals are independent of the 110 volt powdering the unit. So could use different voltage. Depending on how your ro is switched you will want to set it up so it does not start back up when the temp drops back below set point.

[Bricklayer]

My RO is controlled by 3 relays that are in series. 1 for startup ( low pressure pump) 1 for high pressure pump and once pressure is reached the 2 fall out and power is run through 1 main relay. If that falls out due to high pressure or low pressure the system shuts down. Whole control system only draws about 2 amps. So with this temperature control unit I can run the main power right through it? I would need it to let power pass through untill temp reached then when high temp reached it switches off. Even for a split second the system will shut down.

[Bricklayer]

Simpler control. I'm guessing you would have hard time finding the correct replacement probe. You would want to set it for heating as you want it to turn off when it gets to temp. I have had good luck with Chinese pid's from eBay. This is the one I have for high temp shut down. Comes with pt 100 probe. I also have 3 of these in a box for evap temps. 2 for pan temps one for stack. I like the pt 100 probes because they read out in tenth a of a degree so you can see trends better.

Did I read this right? You use a pt100 probe for your stack temp? I was always under the understanding that a k type was needed for anything over 700-800 degrees.

[wiam]

Did I read this right? You use a pt100 probe for your stack temp? I was always under the understanding that a k type was needed for anything over 700-800 degrees.

NO! Sorry. I used a high temp probe for that.

[Bricklayer]

NO! Sorry. I used a high temp probe for that.

With the cheap Chinese temp controller?

[wiam]

With the cheap Chinese temp controller?

Yes. I bought a K type probe on eBay. You have to change the pid to K type but instructions are pretty well written.

[wiam]

Here is my temp box. If I remember correctly the pid will only go to about 1230. If switched over to Celsius it will go to a higher temp. I have one probe by draw off and one where it comes in from back pan.

[Bricklayer]

Nice. What PID did you use? Thee are a ton of them on eBay
I'd like to do something similar with my stack temp. But have it turn off the blower at high temp.

[wiam]

Nice. What PID did you use? Thee are a ton of them on eBay
I'd like to do something similar with my stack temp. But have it turn off the blower at high temp.

Sorry. Thought I had put a link in an earlier post. http://m.ebay.com/itm/Digital-PID-F-C-SSR-Thermostat-Temperature-Controller-PT100-Thermocouple-Sensor-/280879156946?hash=item4165b3ced2%3Ag%3AD7UAAOxyVaB S1QvY&_trkparms=pageci%253A5d15b80b-c70f-11e6-a50d-74dbd1800a47%257Cparentrq%253A1ea68ae41590a605a4cb 59c6ffd4c8ec%257Ciid%253A1
That is the same as in the box. Also same one as high temp shut down in ro.

[Bricklayer]

Got the temp controller in the mail today. Installed it tonight and works like a dream. Only problem is the probe cord is not long enough to place the probe on the intake of the feed pump. I do have enough room to put it about 6" from the intake of the high pressure pump. Will that be ok? I'm sure if I added to the cord length it would screw up the thermistor probe readings.

[wiam]

What your protecting from over temp is the membranes. So before high pump should be ok. My probe is between pumps. Adding wire to probe should be ok as long as you have good tight, clean connections.

[Bricklayer]

I would assume I would have to use same gauge wire? It's super fine wire. Probley smaller then 24 gauge. I contacted seller to see if there are sensors with longer cords available. Try that route first before I try to rig something up.

[wiam]

As long as the connections are clean the resistance should not change especially in a few feet.

[Bricklayer]

I'll try soldering and heat shrinking the connection.