Thinking of creating a DIY WiFi enabled PID controlled hot tub control system - Anybody wanna help?

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
The 25 year old control system on my '95 Hot Spring Grandee has finally failed. The PWA Interlock timer board appears to have died. Being so old it's NLA (of course) and 100% pure fresh-squeezed unobtainium. :(

I had a used late 1990s IQ2000 control system as a backup for that eventuality. I got it in a package deal where I bought all the guts from a different dual jet pump Watkins (Tiger River) tub that a guy scrapped because it got frozen. I swapped that system in only to find out that there is an issue with the control panel circuit board. It doesn't communicate with or read the signal it's getting from the temp control thermostat and as a result the green Ready light starts flashing about 5 seconds after the tub is powered up and the system is shut out for calling for heat. I've checked and double checked the heat sensor and it's good so the problem has to be in the control head/panel (this is according to Watkins' tech support). :cry:

So that control system is pooched as well. For the time being, I've hot wired the heater and am manually keeping the water warm by turning the 30A GFCI in the hot tub's GFCI panel on and off. I can limp along that way for quite awhile while I figure out what my next move is going to be. I can't find another used IQ2000 or IQ2020 system that I can buy right now and I absolutely cannot afford to buy a new IQ2020 system from Watkins or anyone else. Besides that, I'm hesitant to buy a new control system that I know Watkins is going to make obsolete and discontinue supplying parts for in a few years like they've done with every one of their previous control systems. :mad:

I've done some research and I think I'm going to try and build a new control system using off-shelf-stuff but try to do it in a way that still has the same safety systems that my original control system had. Below is the architecture for my original system. I plan to base my new system design on that system but replace the Heater Control and High/low temp limit functions with the SmartPID M5 Pro which you can see on this page (scroll down a little ways) and this page. You can also check out this video on it. It's quite the little gadget!


The nice thing about this system (if I can build it), is that I'll be able to control my hot tub temperature and check the status of its temperature control system on my phone and the system will send me alerts through the cloud if an alarm condition occurs. If I replace the mechanical on/off relays in the heater circuit with SSRs I'll also be able to run the heater in PID mode which may save some energy and keep the water temperature more stable.

To protect the heater from no flow condition, I plan to run the ground wire for the heater relay control signal circuit through the flow switch (like it was before) so the heater can't be turned on if the flow switch isn't detecting any flow in the circ pump/heater line.

The SmartPID M5 Pro model is dual channel and can read off dual sensors so I plan to use Channel 2 to also monitor water temperature with a second sensor but this time be in On/Off mode if the water exceeds 115 F or drops below say, 45F or whatever. I was thinking Channel 2 will deliver the control signal for the circ pump, jet pumps and ozonator relays when the H2O temperature is between the two limits so those components will be able to get power under that condition but they won't be able to get power when either temp limit is reached. When the circ pump is shut off, the flow switch opens up and that will shut down the heater and/or prevent it from being turned on. That kind of duplicates most of the original safety systems I think.

If anybody is interested and can lend a hand with ideas and suggestions for how to design this DIY control system around this SmartPID and make it safe as possible, please feel free to come forward and make suggestions in this thread. I only have a rough idea as to how I'll design the system and given that I'm not an electrical engineer or technician, I'm sure my ideas can be improved upon greatly by people with more expertise and knowledge in this area and I know there a number of those types on this forum! ;)



1995 Grandee electric.jpg
 
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DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
Okay, nothing but crickets. I guess no one is interested in trying to do something like this or at least wants to lend their expertise to the project.

Well, maybe if I ask specific questions someone will be nice enough to help out on things I'm not sure about.

Since between the two non-working control systems that I've got, I have quite a number of Potter & Brumfeld panel mount general purpose DPST NO relays with a 12 VDC switching voltage, I'm planning on using 12 VDC as the switching voltage. For that, I'll need to incorporate a AC/DC converter/power supply into the system.

In the design I'm contemplating, I'm thinking of using four (4) 100A SPST solid state relays (SSRs) for the heater interlock and heater relays but all the other relays will be the P&B 30A gen purp relays I already have. I'll need 2 for the jet pumps, 1 for the circ pump, and 1 for the light. The original system also had a relay for the Ozonator but I'm not using it for that. I'm using that to power for my WiFi controlled chlorine injection system. That system stays powered permanently so I don't need a switch for it. Based on that, I don't see a need for controlling it through a relay. Is there one? Could I not just wire that circuit direct to 115VAC power and skip the relay?

The P&B gen purp relays have a coil current of 35 - 140 mA so I'll count on their maximum draw as being 4 relays x 140 mA = 560 mA. Just in case I do decide to run the ozonator (now chlorine injector) power off a relay as well I'll add that in so now we're at 700 mA if all relays are being triggered at the same time and they're all drawing maximum current which seems pretty unlikely to happen.

The SSRs draw 35 mA so times 4 that's 150 mA. Total it all up and we're at 0.85A.

For a power converter/supply I thought I'd go for one of these:

AC 110V-220V TO DC 5V 12V 24V Switch Power Supply Driver Adapter LED Strip Light | eBay

and was thinking of going for the 12V - 2A (24 Watt) version. That would be plenty large enough wouldn't it? I don't want to go too large because I'm planning on putting this system in my IQ2000 controller box and it's not that deep.
 

jseyfert3

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Hmm. The tricky thing here is doing this properly. I'm decently familiar with codes for general house wiring, but I I do know that "I don't know what I don't know" when it comes to designing spa wiring/controls. This is after all, not only where electricity and water mix, but where you step into that water on purpose! Doing stuff like a 1-to-1 replacement of a control panel or motor is one thing, but designing it, and throwing in random electronics, is entirely different. Please please please proceed with loads of caution!

For example, do you really want to throw in a bottom-of-the-barrel chinese electronic converter? That seems bad on so many levels. No ratings, it's not sealed but you're going to put it into a wet environment, etc. For example, mounting aside, here's the 12 volt supply for my hot tub LED lights:


Immediately several things should become obvious (I hope). First is that this is a sealed unit. Unlike your eBay special, this case is not covered in holes. If you were to look in the wire connectors you'll see it's fully potted, so water cannot enter. Note that the label says "Class 2 OUtput/SEV V-equivilent. Wet or Damp or Dry location" (emphasis mine). A quick google search shows that a Class 2 device:
https://www.ecmweb.com/national-electrical-code/code-basics/article/20888526/classifying-and-using-class-1-2-and-3-circuits said:
The NEC defines a Class 2 circuit as that portion of the wiring system between the load side of a Class 2 power source and the connected equipment. Due to its power limitations, a Class 2 circuit is considered safe from a fire initiation standpoint and provides acceptable protection from electrical shock.
So it has fire and shock protection built into the design. Does the ebay special?

Maybe it would be better to just buy a new off-the-shelf control system? You're said you can't afford what, a $400-$600 for a complete retrofit control system. Keep in mind though that this is a luxury item that's also 25 years old. Things break, and need replacing. New covers, new pumps, new heaters, new control systems, fixing leaks. All things that hot tubs will eventually need. Not to mention the what, $50 a month or so in electricity this thing eats every month? There's a saying that goes something like "If you have to ask how much the maintenance costs, you can't afford it." I know this sounds harsh, but this is a big safety issue too.

I get the DIY standpoint, truely I do. I used to DIY everything. But I'm learning, slowly, that there are some things I should not DIY, or that are not worth my time to DIY. DIY swap a control board/motor or even a complete heater/control system? Sure, if you understand what you're doing and follow instructions. DIY design a spa control system? That crosses a line, for me at least, because I do not understand how to design it in a manner that is safe.

If I replace the mechanical on/off relays in the heater circuit with SSRs I'll also be able to run the heater in PID mode which may save some energy and keep the water temperature more stable
On the latter part yes. On the former part no. You will not save more energy. In fact you'll use ever so slightly more, as switching SSRs in PID is not as efficient as relays, so you'll have some energy loss in them. The advantage to PIDs for resistive heating is only more stable temp control, not efficiency.

I'm assuming since you have a low power circulation pump it's 24/7 operation? If not, and it switches on when the heat is called for and shuts off when the heat is not called for, you'd use even more power using SSRs to run the heater in PID mode, cause the heat output would be lower so the pump would run more than it would if the heater was on at 100% power.
 

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
@jseyfert3 I understand your concerns about the power supply I'm thinking of using. I'm planning to put this system inside the Watkins IQ2000 control box which keeps all of the components inside it dry. The Watkins system has transformers, a junction block and a motherboard covered with various components and relays etc. in that box and they'd all get wet and wreak all kinds of havoc if water was to get inside this box but it never seems to. As such, I don't see how it's terribly unsafe to keep put a small, low output power converter inside that control box but I do get that there's maybe some more risk involved because it's unrated.

I wanted to use that converter because it's the only one I could find that small in size and and low in output. There's not a lot of room on the height dimension inside that Watkins control box so I need to use a power converter that's just powerful enough to power everything it has to and have a reasonable amount of capacity left over so that the component will never be pushed near its capacity limits.

I'm still trying to find out how many amps the SmartPID will draw just to operate but I'm guessing my total maximum power requirements on the 12V rail will be around 1A or maybe just a hair more. And that is when ALL of the relays are receiving 12V trigger signals at the same time which won't happen very often, if ever. So that's why I'm thinking the 2A/24 Watt power converter is all I'd need.

Edit: I wasn't aware of those waterproof LED power converters. I'll go with one of those. I'll get the 30W version of this one. It's IP67 rated which is much better than your IP64 unit. Does that make you happier? ;-)

Another issue I have is that the SmartPID is not waterproof and not IPxx rated. I'm currently trying to find an IP65 or higher rated control box to house it in. I'd like to have the controller display on the outside of the tub so I'm specifically focusing on boxes with clear hinged, firm latching covers. I won't ever have to open up the cover in adverse weather conditions because after it's set up I can control and monitor pretty much everything on the SmartPID with my phone. But if I can't find suitable waterproof/resistant containment for it of that type then I can look at keeping it inside the engine compartment in a suitable IP65 or better rated control box to keep it safe and dry. I don't have to have the SmartPID display on the outside of the tub because I can see everything I need to see on my phone but being able to see the display on the outside of the tub would be nice if I could make it work and make it safe.

If anyone can recommend a suitable watertight control box for housing that unit in, please do so. I'm still on the hunt for the perfect thing.

As far as the idea of purchasing a new off-the-shelf control system, my only choice would be to buy the Watkins IQ2020 system which will require me to buy the IQ2020 control box, the control panel and the control head that attaches to the control panel. That will set me back well over $1000 CAD which I can't afford. I'm projecting the DIY system to come in between $350 - $400 CAD including back-up components (eg an extra SSR) bought to have on hand for spare parts in case of any failures. Most of that cost is the SmartPID M5 Pro which costs 166€ (~$260 CAD)

I've spent quite a bit of time learning what the SmartPID M5 Pro can do and also studying the architecture of the original control system and I'm pretty confident I can duplicate the safety systems the original control system had including a high temp limit shutoff of entire system requiring manual reset and no heat if water not moving through the circulation system.

On my system, and I think just about any Watkins system (except maybe in their lower lines), the low flow circ pump runs 24/7. I have the latest version of their circ pump installed and that one only draws a maximum of 0.35A at 120V (42 Watts). The previous versions drew .55A (66 Watts).

And if it turns out the tub uses more energy running temperature control in PID mode, I'll have the option of running in traditional On/off mode. I'm hoping by eliminating a lot of the overshoot the current system no doubt has, running in PID mode will, in the long run, save a little bit of energy. We'll see if that turns out to be the case or not if I actually go through with this plan. I'm still trying to suss a few things out before I decide whether I'm going to go for it and start ordering parts.
 
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jseyfert3

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As far as the idea of purchasing a new off-the-shelf control system, my only choice would be to buy the Watkins IQ2020 system which will require me to buy the IQ2020 control box, the control panel and the control head that attaches to the control panel. That will set me back well over $1000 CAD which I can't afford. I'm projecting the DIY system to come in between $350 - $400 CAD including back-up components (eg an extra SSR) bought to have on hand for spare parts in case of any failures. Most of that cost is the SmartPID M5 Pro which costs 166€ (~$260 CAD)
Why is the Watkins IQ2020 system your only choice? Am I missing something? Doing some searching, it seems there are lots of options out there, pre-built with a heater/control box/control units that could be retrofitted. I know nothing about these, but talking about something like this Gecko unit (though it's only 4 kW and specs minimum of 18 GPM which I doubt your circ pump does), or even cheaper here's this Apollo 11 system (not sure why they named that), $350 usd for heater/control/pad, 5.5 kW heater. Doesn't spec a minimum flow rate, you may have to contact them. Again I know nothing about these, but they are both complete units with heaters, control boards, and topside control pads. Everything but the pumps, power cords, and perhaps some minor re-plumbing.

Perhaps @RDspaguy has input on pre-made control systems that could be easily retrofitted and would be cheaper than the Watkins system?
 

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
On of the issues with trying to adapt other control systems to a Watkins tub like mine that I see is that the line going to the heater on Balboa and other similar systems is large like 1.5" or 2" or whatever it is. The line going to the circulation pump and heater on Watkins tubs like mine is 3/4" hose. I don't think their (Watkins') heater supply line would have near enough flow capacity to properly supply the heaters on those Balboa type packs.

I don't know a lot about how other systems work but it seems to me that Watkins' way of doing things is quite different than most other companies. They use a very small, low-flow circ pump that pumps water 24/7 through a 3/4" line to this low flow hydroquip (Watkins re-badges it as a Watkins No-Fault) heater. Some of their smaller tubs use a 4KW version of that same heater. The Ozonator, if installed, is also on that 3/4" circulation/heater line. The heater is completely separate and away from the control box and is on a completely different line than the jet pumps are. My tub has 5 filters. Each jet pump gets 2 and the circ pump gets 1 but the circ pump/heating line is low-flow and low capacity.
 

jseyfert3

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Ah, that makes a little more sense.

What our tub (Cal Spa) does is it has two pumps. The heater (2") is on one of the pumps, which is dual speed. When heat is needed, this pump automatically turns on at low speed to pull water through the heater, and shuts off when the heat is off. It also turns on at low if the tub wants to run the ozone, or once every 15-20 minutes or so for a minute or two to circulate water and check the temp, at which point it will turn on the heater if needed or shut back off for another 15-20 minutes.
 

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
Watkins' philosophy is that running large pumps at very low speed is inefficient energy-wise and that it's better to run a very small little energy efficient circulation pump constantly. The circ pump they have now is only 0.35A so draws very little power. The earlier version circ pumps were actually 0.65A and not 0.55A like I said before. The new ones are much quieter (practically silent) and much more energy efficient than they were before.
 

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
At any rate, I don't see what all the apprehension is about me not using an off-the-shelf control system and instead building this DIY control system is. The Control System that tub came with and lasted 25 years comprised nothing more than a couple of small IC boards and a larger Interlock Timer board that also had a transformer/power supply on it to create a 5 VDC and 12 VDC rail. Beyond that, the only other things that were located in the box were 6 of these Potter & Brumfield 30A DPST relays bolted to the floor of the control box and a whole bunch of wires connecting to them. The control head was completely mechanical and had no circuitry in it at all. It was actually physically connected to the control box through the side of the wooden tub surround.

With the exception of the two relays in the heater circuit that will be replaced by two larger capacity SSRs, my new system will again be a bunch of these same P&B relays in the same box being run the same way but now the functions of those three circuit boards will be transferred to the SmartPID M5 Pro which can likely do a way better job of managing the heat and a new IP67 rated DC power supply which will be much safer than the original power conversion system. I will wire the circuits pretty much the same as they were wired in the original system so all the original safety features will still be there and functional. All of this stuff will be housed the same way it was before in one of the Watkins control box housings so nothing much will be changing there and everything will be just as safe as they were originally and some things will actually be safer.

The only area of added risk that I can see is that the brains of the system (the SmartPID) is not waterproof or IPxx rated. To mitigate that risk, I plan to house it in a suitable IP65 or better rated control box as I explained in a previous post. I'll never need to access the control panel of the SmartPID in inclement/wet weather because I can do anything I need to with the SmartPID remotely from my phone, tablet or PC. As such, I'll never have to risk getting the SmartPID wet so I should be okay there so long as I'm careful.

The only other things left are the light and the jet pumps and I plan to get waterproof switches for controlling those and make a new panel to cover up the opening where the old control panel came out of. That shouldn't be that difficult.

What I'll get in return for 1/3 or less of the price of a new Watkins control system and for taking on the small but present additional risk posed by the SmartPID not being waterproof or IPxx rated, is a WiFi enabled smart control system that should do a better job of controlling the heating system and can be monitored and controlled remotely from a mobile device. I'll also get the pride of having created the system myself and satisfaction in knowing that I can troubleshoot, maintain and repair the system far more inexpensively than I could a new Watkins system and that I'm protected from Watkins making my system obsolete and eventually no longer making parts for it like they've done on every one of their previous control systems.

What's not to like here? ;)
 

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
Oh and I forgot to mention another good piece of news I figured out today. The SmartPID is compatible with a number of different temperature sensors. One of them is the NTC 10K thermistor type. Today I managed to figure out that Watkins uses that exact type of thermistor in their proprietary temperature sensor and hi-limit sensor thermistors that screw into the head of their No-Fault (actually made by HydroQuip) heaters. This means I can keep on using the temp sensors that are already in my system and just wire them into the SmartPID. Easy-Peezee! :giggle:(y)
 

RDspaguy

In The Industry
Mar 21, 2020
1,098
Cabool, Mo
The heaters used by balboa, gecko, trinity (apollo11), and many others require a minimum flow rate around 23 gpm if wired for 240v on the heater, which the small watkins circulation pump will not provide. It will keep up if the heater is wired 120v.
I have no clue what a SmartPID is, so couldn't say if it will work. But everyone wants you to buy a system because we lack confidence in your ability to duplicate the safety features and functions of a spa controller, and fear you will end up regretting your decision, dangerboy. As long as YOU are the ONLY person endangered by your experiment, then do what you want. But all of your theories and assertions regarding your and a SmartPIDs capabilities mean nothing at the hospital or in court. Which is exactly where you are likely to end up, in my opinion.
Best of luck.
 

bwilford

Member
May 23, 2016
10
Los Altos, CA
I added automation to my hot tub about 3 years ago. I have a Jacuzzi J-375. I added a raspberry-pi between the buttons and the main controller. This allows me to control when the heater operates. It's on wi-fi so I can adjust things from my phone, but it's runs just fine without any intervention, so while I did intend to build a phone app., in the end I never bothered. I get low cast electricity at night, so I heat the hot tub to 106 at about 6am, which leaves it at 103 when I want to get into it in the evening. I can change the temperature or switch pumps on and off from the phone, but never need to.

After that I added a peristaltic pump to add a little chlorine every day. So I only add dichlor to adjust the cyanuric acid (CYA) levels as needed about monthly. I find that the Spa burns off the CYA. I only inject chlorine when the circulation pump is running. I have just added a pH sensor to allow me to read the pH without getting off the sofa. Atlas scientific were going to build a chlorine probe, but it's not done, if they do I may use this to measure the chlorine levels.

I thought about re-working all the electical parts of the hot tub as you seem to be doing, but I was not having issues with the Sundance controller, and I decided to keep the original as it has a bunch of safely interlocks.

Bruce
 

DangerBoy

Well-known member
Oct 4, 2018
152
Calgary/Alberta
@RDspaguy It seems to me there are a few types of people in this world. There are those who are dreamers and creators, who see possibilities for doing things in new and different ways and voice those ideas; there are those who can appreciate that and can offer support and advice and contribute ideas and thoughts; and then there are those who seem to be only wanting to criticize and Crud on the ideas and dreams of the first type I mentioned. I don't know what you're really like so I make no judgments about you but your negative and judgmental sounding response on this thread does kind of make it seem like you might be the third type mentioned above. If that's the case and if that's the only sort of response you can offer then please stay off my thread as that sort of negativity is not welcome or needed in this thread.

If, on the other hand, you're willing to contribute ideas and technical advice/constructive criticism in order to help me and whomever wants to contribute ideas towards creating something cool and useful, then you're most welcome to continue posting on this thread and I would very much appreciate your input and expertise.

As it turns out, I likely will not be going ahead with this plan right now but I probably will at sometime in the future. I was actually just about to pull the trigger and start ordering all of the things I needed to make the system I had dreamed up when I came across someone in my city selling a similar but slightly newer Grandee for cheap because the circ pump/heater circuit had frozen and cracked in one location. I was able to negotiate a good deal to strip out all of the parts from the tub including the heater, circ pump, jet pumps, ceramic filters, etc. and a complete working IQ2000 control system for just a little more money than what it would've cost me to build the DIY system I was planning to build. So for the time being, I will be using this new (to me) IQ2000 control system to run the tub but I may still try to make some small modifications to it at some point.

Notwithstanding that, I had everything worked out as to what I needed and how I would build a system that would've had a dual channel "smart" PID temperature controller that has:
  • the ability to learn how to optimize when and how much current to send to the heater in order to minimize temperature overshoot and power consumption while accurately maintaining water temperature; and
  • Wifi internet connectivity so that I could monitor and control the water temperature from anywhere I can get a data connection on my cell phone and get alerts sent to me if, say, something like an overheat condition occurs.
The system would've also incorporated:
  • a high temperature cut-off safety system that would automatically cut off load power to the heater relay through a heater interlock relay if a high temp cutoff set-point is reached. At that point, no load power can get to the heater relay without a manual restart. This system would prevent any load power from reaching the heater relay (and thus power going to the heater) in the event anything happens (e.g. a temp sensor failure or heater relay failing shorted) to cause the tub water to reach the overheat set-point (which I can set); and
  • a safety system that would prevent any control signal power reaching the heater relay in the event no flow is detected at the flow sensor/switch which is located in the circulation pump/heater flow circuit. This would prevent the heater from being turned on when there's no water in the tub or the circ pump has stopped running.
The above two safety systems were the two main safety systems my tub's original control system came with.

The SmartPID temperature controller would use the original Watkins temperature and high limit sensors as these are actually standard NTC-10K thermistors which the SmartPID temperature controllers are pre-programmed to use. (They can use about 3 or 4 other standard types of temperature sensors as well.) The system would use almost the entire original control system from my tub in the original control box and would be wired and configured pretty much the same way so most or all of the original safety systems would be maintained or duplicated.

I think it would've cost me about $400 - $500 USD to build this system but I would be using a number of relays and other components from my tub's original control system as part of this system.

If people are interested to know how I would've done this they should let me know and I'd be happy to describe how I would've done it. Hopefully, people might be able to suggest where there might be opportunities to improve the safety of the system by adding fuses or whatever here or there. If no one is interested then that's fine too. I'll keep my ideas to myself and not ask for anyone's input on it until I'm ready to go ahead with installing and implementing the DIY system at some unknown point in the future.
 
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RDspaguy

In The Industry
Mar 21, 2020
1,098
Cabool, Mo
@DangerBoy , you clearly know alot more about electronics than I do, which isn't tough to accomplish since I know next to nothing on the subject. Sorry to be down on your ideas, I have seen some fairly catastrophic results of control system malfunctions, and watched the progression of added safety features, over the years. I wouldn't want you (or anyone) to cause damage to anything or harm to anyone. Maybe you could build that from scratch your way, I wouldn't know, but you should definitely consider the possible outcomes before doing so. Maybe I was a bit melodramatic, but I wanted to get my point across, not just to you, but to the next guy too, who may not share your know-how. So I apologize for my negativity. In my defense, your forum name does not inspire a great deal of confidence. ;)