Control Questions

[SteveJ]

I have been using an onboard zone/pump/boiler controller from a Saturn boiler - controls up to 4 zones.

I want move the controls outside of the boiler (possible replacement) and eventually move to a TS-7260 controller like nofossil.

Questions:
1. What exactly do I need to control a 24V zone valve?

2. What exactly do I need to control a 120V pump?

I know I need a 24V transformer, but do I need a 24V relay for each zone to be controlled by a thermostat or aquastat?

Can someone provide me a good reference?

I use nofossil's site as "the" reference, but I am missing the basics - how to switch a zone valve or circulator on based on thermostat or aquastat signal - eventually a 7260 signal.

Thanks,
Steve

 

[Nofossil]

I have been using an onboard zone/pump/boiler controller from a Saturn boiler - controls up to 4 zones.

I want move the controls outside of the boiler (possible replacement) and eventually move to a TS-7260 controller like nofossil.

Questions:
1. What exactly do I need to control a 24V zone valve?

2. What exactly do I need to control a 120V pump?

I know I need a 24V transformer, but do I need a 24V relay for each zone to be controlled by a thermostat or aquastat?

Can someone provide me a good reference?

I use nofossil's site as "the" reference, but I am missing the basics - how to switch a zone valve or circulator on based on thermostat or aquastat signal - eventually a 7260 signal.

Thanks,
Steve

I guess I ought to take this one ;-)

A 24v zone valve is actually two devices: a 24vac motor and a switch that's closed when the valve is open. Typically, you use a 24vac transformer to provide power. One side of the transformer is connected directly to the zone valve motor, and the other side goes to a thermostat, then to the other zone valve motor terminal. When the thermostat contacts close, the zone valve motor gets 24vac and the zone valve opens. When it opens, the contacts on the built in switch close and provide a demand signal to the boiler.

In the simplest case, you merely need to provide 24vac to the zone valve motor to open it. I often do that using relay contacts rather than a thermostat. If I want to control it with my TS7260, I use a small relay with a 12vdc coil that I can drive directly from the TS7260. The relay contacts switch the 24vac to the zone valve motor.

For circulators, I use exactly the same approach - a relay that's controlled by either the TS7260 or some other system signal, where the relay contacts switch the 120vac to the circulator.

My site has schematics that describe all of this, but it can be a bit daunting if you're not comfortable with relays and relay terminology. Wikipedia has a description that might help - see the section on poles and throw.

Basically, a zone valve motor or a circulator pump is like a light bulb or any other electrical load - you need to provide power to it to activate it. If you wire a switch or a relay to interrupt the power, then you can control it.

 

[SteveJ]

nofossil,

Thanks for the explanation - I think I got it.

Where do you mount all of your relays and connections?

Do you use a relay rack?

Where do you house all of the macro electronic components?

Nice to be able to see and replace but seems like a great deal of capacitors, resistors, and relays. Do you have pictures?

Do you have several breadboards for connections?

Which 12V relays do you use?

Why did you chose the individual relays (and mounting) over the TS-RELAY8 board (http://www.embeddedarm.com/products/board-detail.php?product=TS-RELAY8)? For ease of individual replacement?

For the 24V relays, you always go DPST so that the first pole is the control and the second pole sends a signal to the TS7260 - correct?

Can you post the missing "Connectors and 12V relay coils" schematic or pictures? (reference http://www.nofossil.org/schematic.html)


If I want to use the TS7260 to also be a solar differential controller, can I:

1) Calibrate 10K thermistors as on your page http://www.nofossil.org/thermistor/index.html and monitor the values from the thermistors using your flat file database approach described.

2) Use the values obtained from 1) above to trigger the TS7260 to drive a 12V relay that will open or close the circulator circuit.

Thanks again and I will continue to reread your site,
Steve

 

[Nofossil]

Wow - that may be a record for questions in a single post....

nofossil,

Thanks for the explanation - I think I got it.

Where do you mount all of your relays and connections?

Realys get mounted all over the place - inside the EKO hood, inside circulator electrical boxes, and so on. I do have a plywood panel with a bunh mounted with double-sided tape (my favorite - I'm too cheap to buy sockets). My connections are almost all crimped or push-in ethernet connectors.

Do you use a relay rack?

No. I should. I'm too cheap.

Where do you house all of the macro electronic components?

There really aren't many macro electronic components other than the computer itself. It's in a small wooden / aluminum box on the wall. See photo below - also shows ethernet connectors.

Nice to be able to see and replace but seems like a great deal of capacitors, resistors, and relays. Do you have pictures?

Do you have several breadboards for connections?

Very few extra components. You can see a breadboard that I used to provide a home for the resistors and 5vdc reference needed by the thermistors. It also contains high current relay drivers.

Which 12V relays do you use?

Whatever I can find cheap on eBay or Electronic Goldmine. Automotive relays are really cheap. Omron makes several models that switch a few amps - plenty for circulators.

Why did you chose the individual relays (and mounting) over the TS-RELAY8 board (http://www.embeddedarm.com/products/board-detail.php?product=TS-RELAY8)? For ease of individual replacement?

Neither. I do dicrete relays because they're cheaper, I can get the contact configurations that I need, and most importantly I can locate them next to the high voltage loads that they switch. I dont want 110vac inside my computer enclosure.

For the 24V relays, you always go DPST so that the first pole is the control and the second pole sends a signal to the TS7260 - correct?

Usually DPDT. There's usually no price premium, and it's amazing how often there's a use for the extra contacts.

Can you post the missing "Connectors and 12V relay coils" schematic or pictures? (reference http://www.nofossil.org/schematic.html)

Yet another documentation task :-(

For now, assume that they're driven directly by an output of the DIO64. One side of the coil is tied to +12v, and the other side to a DIO64 output.

If I want to use the TS7260 to also be a solar differential controller, can I:

1) Calibrate 10K thermistors as on your page http://www.nofossil.org/thermistor/index.html and monitor the values from the thermistors using your flat file database approach described.

2) Use the values obtained from 1) above to trigger the TS7260 to drive a 12V relay that will open or close the circulator circuit.

Yes. I do exactly that for my brother's system. I also play some more sophisticated control games with my 'poor mans variable speed pump'. If you're into C, all my source is available online.

Thanks again and I will continue to reread your site,
Steve

 

[kabbott]

Thats It, After reading this post and seeing that pic I have decided I want to be nofossil when I grow up!!LOL
Nofossil any pointers as to where one could learn there way around C ,just enough to keep the heat on so the wife won't kick me out.

 

[SteveJ]

nofossil,

Thanks for the detailed response and for your time. Do you take PayPal donations?

I like the use of the ethernet cable - I have several hundred feet laying around


Is the following parts list correct for the control system

1. TS7260 controller board (luckily I already have this )
2. TS-DIO64 digital IO board http://www.embeddedarm.com/products/board-detail.php?product=TS-DIO64
3. one or more TS9700 Data Acquisition boards http://www.embeddedarm.com/products/board-detail.php?product=TS-9700
4. 24V Transformer for 24V bus for zone valves
5. 12V Transformer for 12V bus for relay switching (probably can handle directly from the DIO64 without 12Vdc bus)
6. 12V Relays - like Digi-Key PB968-ND - one for each device (up to 8A@240V) I want the TS-DIO64 to switch http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=PB968-ND
7. 7805 voltage regulator for thermistors
8. 150K resistors for thermistors
9. Thermistors - DigiKey part 615-1019-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=615-1019-ND


Thermistors will be placed throughout system to provide control logic inputs for switching the various components.

More questions - (sorry):

What type of thermistor do you use for flue temperature?

Do you use the thermistors in capped copper dip tubes for measuring storage tank temps?

Can you show a large photo of your thermistor interface that is plugged into the breadboard?
Are the 0.33uf and 0.1uf capacitors (shown at http://www.nofossil.org/thermistor/index.html) internal to the 7805 or external on the thermistor interface board?

If I use the DIO64 and a 12V ref then will I need any 24V relays?
Do you connect 24V to pin 33 on the DIO64 as the clamp voltage?
Since the DIO64 with handle up to 40V output and sink 200mA or 400mA, can I do the system without the 12V transformer and swich the zone valves directly from the DIO64?

I guess then "failsafe" is gone :bug:

Thanks,
Steve

 

[Nofossil]

nofossil,

Thanks for the detailed response and for your time. Do you take PayPal donations?

I like the use of the ethernet cable - I have several hundred feet laying around

I'm not in it for the money at this point. Send me real data when you get it - have to feed my habit.

Is the following parts list correct for the control system

1. TS7260 controller board (luckily I already have this )
2. TS-DIO64 digital IO board http://www.embeddedarm.com/products/board-detail.php?product=TS-DIO64
3. one or more TS9700 Data Acquisition boards http://www.embeddedarm.com/products/board-detail.php?product=TS-9700
4. 24V Transformer for 24V bus for zone valves
5. 12V Transformer for 12V bus for relay switching (probably can handle directly from the DIO64 without 12Vdc bus)
6. 12V Relays - like Digi-Key PB968-ND - one for each device (up to 8A@240V) I want the TS-DIO64 to switch http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=PB968-ND
7. 7805 voltage regulator for thermistors
8. 150K resistors for thermistors
9. Thermistors - DigiKey part 615-1019-ND http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=615-1019-ND

On item 5 - you do in fact need a 12 volt supplt, but it has to be DC, The TS7260 can run happily off of a wide range of DC voltages, so I use a regulated DC supply that actually provides around 18v. Fortunately, automotive relays are happy over a wide range of voltages as well, so I use the same supply for both the TS7260 and the DC relays.

Thermistors will be placed throughout system to provide control logic inputs for switching the various components.

More questions - (sorry):

What type of thermistor do you use for flue temperature?

U use an stainless jacketed type K thermocouple. Digikey sells a very cool thermocouple signal conditioning chip that handles two thermocouples for about $12. Don't have the part number off the top of my head, and I don't have a schematic posted yet.

Do you use the thermistors in capped copper dip tubes for measuring storage tank temps?

Actually, all three of them are tied to a stiff wire that I run down a capped 3/8* soft copper pipe that goes through a fitting on the side of the tank.

Can you show a large photo of your thermistor interface that is plugged into the breadboard?

Are the 0.33uf and 0.1uf capacitors (shown at http://www.nofossil.org/thermistor/index.html) internal to the 7805 or external on the thermistor interface board?

External on the breadboard.

If I use the DIO64 and a 12V ref then will I need any 24V relays?

Yes, if you want to use relays that are controlled by the 24vac that's used by the thermostats and zone valves. I do quite a bit of that, so that my TS7260 can detect which thermostats are calling for heat, for instance.

Do you connect 24V to pin 33 on the DIO64 as the clamp voltage?

No, only 12vdc.

Since the DIO64 with handle up to 40V output and sink 200mA or 400mA, can I do the system without the 12V transformer and swich the zone valves directly from the DIO64?

You might be able to, but I decided to keep voltages and currents inside my computer enclosure as low as possible, and I've been careful to design for failsafe so that the system still works if I disconnect the computer.

I guess then "failsafe" is gone :bug:

Thanks,
Steve

 

[SteveJ]

nofossil,

Thanks again and data will be sent as soon as I am up and running.

Questions:

1. 12Vdc supply - will the http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=CDPM1001-ND 200ma supply work to switch 6 of the 12V relays (33.3mA coil current)? Which dc power supply do you use?

2. For software development - should I use a Linux box with Kubuntu http://www.kubuntu.org/? What do you use?

If okay with you, I am basically going to use your system - piping and controls and same monitoring devices.

Let me know when I become too much of a nuissance,
Steve