Attaching temp sensor in PVC pipe.

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Dirk said:
PS. You'll notice in my signature a FlowVis Flow Meter. I installed that primarily to fine tune the flow through the solar panels. I was able to very easily adjust my pumps RPMs to optimize the heat exchange. And I can keep an eye on flow throughout the year. It does change a bit, based on the filter's condition, so I can quickly compensate for that by goosing RPMs slightly until the filter gets cleaned. Lather, rinse, repeat. And it's turned out to be quite useful for other purposes, too (I optimized my pool vac's flow, etc). Plus it doubles as the check valve for the solar heater plumbing. There are a few (cheaper) ways to determine heater efficiency and flow, but neither is as accurate as the Vis, and the learning curve for the calculation method was way too steep for me. The Vis was "cheaper" in that regard.
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Hi Dirk,

Out of interest, what kind of flow rate is optimal for your panels? What panels do you have?
I've calculated that I have almost double the manufactures recommended flow rate. I only have a single speed pump.

Thanks
 
I'd have to look up the exact range for my Heliocol panels. But I'm using 5 GPH for each panel, times 8 panels = 40 GPH. The calculation is based on the manufacturer's spec for each panel, times the number of panels. I'd expect that each panel size, and manufacturer, will have its own number. I have a FlowVis, so I just watched it as I adjusted my VS pump's RPMs. Super easy.

If a VS is not in your future, you can plumb a bypass in your system that can reduce the flow of water through your panels. That won't cost much (a valve or two and some PVC). Something like this, though I wouldn't want ball-valves in my system:

dlrauttx33.gif

In this example, the 2 isolation valves are not part of the bypass, only that one horizontal valve is. But before I did that, I might try fooling with the three-way valve that sends water to the panels. They can be adjusted to not open or close fully. So I would set mine, when it's in "solar heat" mode, to channel some water to the panels, and some back to the pool without going thru the panels. That should reduce the flow rate through the panels. Might be worth a try before replumbing anything. What I can't predict is if that will actually improve the heat exchange at the panels enough to compensate for the water you're not heating (the water bypassing the panels). I think it should.

The reason a second bypass valve is preferred is because it's not handy to adjust the three-way. You have to disassemble them and fool with cams inside, then put them back together (plus figure out what you're doing!). So a dedicated bypass valve is much easier to fine tune.

Of course, a VS is the optimal solution. Have you considered installing one? They do pay for themselves over time (and in a lot of cases, not much time). So you'd be able to optimize your heater, and save energy costs whether the heater is off or on.

Does your system have a check valve? There are some brands that accept the guts of a FlowVis. A FlowVIs doubles as a check valve. FlowVis sells a couple variations: one that is the entire assembly, check valve and flow meter and body, and another that is just "the guts" that you screw onto the body of an existing check valve. You might save some dough that way if you're interested in installing a flow meter.
 
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I still think I can make it work. It might not be as efficient as a bigger pump but an extra <$100 panel or two (I'm not going to pay for Helicol) versus running a pump on "high" or "highish" to get the flow might still be a good solution by comparison. Most of the systems I have seen locally would be cheaper to run a heat pump versus the amount of losses in the runs. I am looking to a pump per panel, maybe two panels... and if I go up to the $60 pumps (which in that case I could only run two on a 100W panel) then I am in the range that you are talking about with your pump. If I have to add another 100W photovoltaic cell, that's $85... The flow rates are with tubing the size of the outlet on these pumps, so I think 3/4" tubing off the top of my head. They are bilge pumps so they are supposed to be rated with a small amount of head through a small outlet. The design of the impeller is quite a bit different from a pool pump, and being submerged they are more efficient. I suspect that I will be fine and it's a cheap experiment in any case. If I can run multiple pumps I will have some redundancy in the system as I only expect them to run a year. I will lose capacity but it won't all go down at once.

I suspect that I will at least be able to get readings from this setup to tell me what I need to scale it up to.

Pool pumps (like all pool equipment) are ridiculously overpriced. I think you underestimate the ability of equipment not designed to gouge the consumer. For the four digit price that Hayward VSP that I have is a complete of dung compared to industrial pumps I've seen in the past. It's noisy, poorly built and has a goofy control system on it. The neighbor's Pentair isn't better but it seems a little more quiet. The only equipment in my pool that I have been impressed with is the Paramount stuff, but I think those days are over too.

Again, because of the type of the pump, if I tried to run this more than a foot or two off the ground it would not work.

By the way, in the standard type of system that uses the pool pump, you are putting only a portion of the flow through the panels. If you tried to put all of it you will cause leaks (blow out). The smaller pump will be set to only flow water through the panels, and it will be consistent when it is on. It could theoretically be made more efficient.
 
Hey guys.

I have 2 temp sensors using the sonoff TH16 devices.
They had read the temperature in 1-degree increments only.

The latest version upgrade (3.4.0) now reads 0.1 increments!! Superb especially considering the price.
I would say it would now be useful to install a probe in the inlet and outlet of solar panel tubing as you could read much more accurately the temperature gain.
 
I really like that idea of the PVC clamp. Would love to hear what the experts think. And want to know your experience. I want to use that idea for a stenner injection point.
 
psquare said:
So to swing this thread back to the attaching temp sensor to pipes would something like this work.

1- ½ inch DS10B20 Temp Sensor Probe

2- Spears PVC Clamp

I know the price of the clap is steep but it would prevent me from cutting the pipe. What do you think?
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Well, that is an expensive way to do it, but the reviews are certainly good for it. I am sure it would work, and even if there were leaks, a proper O ring from a hardware store should fix it.

I decided to go a slightly different way. I bought an Ambient Weather floater and display (to get started at least) but I added on two of these sensors: Ambient Weather F007TP 8-Channel Wireless Thermometer with Wet Temperature Probe

Those two sensors are of what is interest for a true DIY project, but I think the floater can be decoded as well.

Those alone would be $27/2 and it gets cheaper for up to 8 of them (they are $11 each after the first one). There is are two projects out there for reading them wirelessly -- one is a Raspberry Pi that uses a RTL-SDR European type TV tuner dongle ($30 or so) to receive and decode the 433 MHz signal (merbanan/rtl_433). The other uses a $2-3 a piece ASK receiver (RX-6) and a Raspberry Pi to read them. (alex-konshin/f007th-rpi). There appears to be an Arduino version as well to for the ASK receiver version. Some have MQTT support which then could even eventually be supported by Alexa, etc.

I plan on using one of the probes on the detached hot tub by running it over the side. For the other I will start with the floater, but I am thinking if I can extend and hide the cable from the sensor somehow I can put the probe into the skimmer on the pool. I don't run my VS Pump all the time, so putting in the line, as tempting as it is would only allow me readings currently 14 hours a day. I suspect that they can be adapted to a pipe clamp like that as well with a little cleverness.

But if you are looking to go wireless easily, this could be a way to do it, and several Ambient Weather displays are compatible with the sensor if you just want a standalone somewhere.
 
I use a Wyze cam ($25 or less on sales) that sits on top of my heater so I can read the temperature display from the heater on my Wyze phone app from anywhere. I put the Wyze cam in a cheap plastic box to protect from the weather. This will tell me the pool temp or spa temp depending on the direction of my valves. Downside is the heater has to be on to "see" the water temp reading. Not a big deal because I can wirelessly turn on my heater for a minute if I happen to want to see the pool temp when not at home.

I have an Engbird bluetooth waterproof temp probe that I located inside my water fill line to get pool temp from inside while at home (BT range). No drilling temp probe just sits in water fill "hole"
 
I'm glad I found this thread. I'm looking to add a temperature sensor to my above-ground pool and have it integrate into Home Assistant, etc.

My biggest concern with a lot of these solutions is the possibility of a leak. I'm terrified that any place a probe could be inserted could eventually leak and I might not notice it for a while. The pool is also next to my house so a leak could cause a very big problem.

Is there any consensus on the best/cleanest approach to adding a temperature probe? (DS18B20 + Sonoff/controller, etc)

Also, is there any GPM sensors I can add to the PVC piping and also detect/record the GPM of the pump?

The Inkbird also looks really interesting. What is the 'autofill' hole that you guys are referring to? Some of the reviews say it can just go in the skimmer somehow?
 
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That looks perfect! Thanks very much!

Are you using the 50mm version of thermowell? Do you just insert a DS18B20 probe into the thermowell?

Do you find it to be accurate? I'm planning to place it directly before my pump. Maybe I can add a second one coming from my gas heater back into the pool but I'm not sure about the purpose of that ...
 
Yes, the 50mm one fits perfectly in the 1.5in pipe fitting. I just stuck the probe in there and it's very accurate. I have a regular thermometer floating in the pool that hangs down a couple feet and it matches exactly. I'll probably take that one out soon, it was just to test accuracy.
 
Thanks again very much! I ordered the thermowell and this probe:

Maxmoral 2pcs DS18B20 Digital Thermal Sensor Stainless Steel Encapsulation Waterproof Temperature Sensor Probe 2m

I think I need 4-5 feet of cable from the pump to the control box (I still need to find a good weatherproof enclosure too) so I had to order the 2 meter length.

Are you using home automation for your pump as well? I wanted to measure current/power output, but I can't find a relay that can handle 1 HP (i.e. 11A motor load). It seems like a lot of people use a standard relay to trigger a contactor that can handle the higher load but then you can't measure current consumption.

Anyways, I'd love to know what other automation you are doing. Thanks again!
 
jmk396 said:
That looks perfect! Thanks very much!

Are you using the 50mm version of thermowell? Do you just insert a DS18B20 probe into the thermowell?

Do you find it to be accurate? I'm planning to place it directly before my pump. Maybe I can add a second one coming from my gas heater back into the pool but I'm not sure about the purpose of that ...
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I have the same setup with the thermowell and it works great. Very accurate. I have it connected into my DIY controller and love it.
 
One of the best things I have gotten out of this forum (one of the threads) when it comes to temperature sensors with pools is to put it in the auto fill well instead of in a flow pipe if you can.
That is my suggestion if it is possible for you rather than putting it in the pump flow.
 
howardtopher said:
No problem. I've gone well off the deep end with the home automation stuff, which I use Hubitat for. I made the temp sensor with a NodeMCU and used the Hubduino project to get it integrated into Hubitat. The temperature is also logged into InfluxDB so I can chart it over time.

I have this for the pump. It supports energy monitoring. GE Z-Wave Plus 40-Amp Indoor/Outdoor Metal Box Smart Switch, Direct Wire, 120-277VAC, for Pools, Pumps, Patio Lights, AC Units, Electric Water Heaters, 14285
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Nice! That sounds exactly what I want to do... NodeMCU (or other ESP8266 device), log into InfluxDB, and graph with Grafana, etc.

I'm also looking at that exact GE device. How does the energy reporting work? It has configuration values for energy reporting but the shortest interval is every 5 minutes. Does it report any quicker if the energy changes? (i.e. if the pumps gets blocked and the energy usage is increased, I'd like to be notified ASAP)

Similarly, I'm looking to monitor my pool heater. It's natural gas, but I was thinking of a separate Z-Wave outlet to detect when it turns on/off. (the GE 14285 can only monitor one circuit energy or the TOTAL of both circuits)
 

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