SPST Wiring with 24v Transformer wProblem - Troubleshooting / Wiring - Rachio Community
SPST Wiring with 24v Transformer wProblem
post by Cindy on Jun 19, 2024
I have installed two Rachios in the past with no problem but they didn’t link to a pump. This time I am trying to replace a Rainbird controller (with a 220v 1 HP pump and Hydrotek 1000 pump start relay) with a Rachio 3. I kept getting the wiring issue error and searched the forum.
I found the instructions from DLane to use a SPST and 24v transformer. I bought the ones he suggested from Amazon (link) but I am getting a repeated clicking (I think at the pump start relay) about every second or so when I try to run a zone.
I have the Rachio M & C wires connected to the coil leads (#1 & 3) and one wire for the Pump Start Relay is connected to the 24v transformer. The other pump start relay wire is connected to the SPST. The second wire for the 24v transformer is connected to the SPST. I must have something wired wrong?
Can someone please lead me to a working solution before my lawn dries up? I don’t want to have to reinstall the Rainbird. I can attach photos if needed, but nearly all the wires are white so it is difficult to follow from the photo.
Thanks in advance for any assistance you can provide.
post by ady624 on Jun 19, 2024
can you draw a schematic? the control pins of the single pole single throw (1 and 3) should connect to M and C of Rachio. The other two (2 and 4) pins need to be inline with the pump start relay and the transformer - what power does the pump start relay need to operate? 24VAC? Pump model?
post by Cindy on Jun 19, 2024
Hi ADY624
Thank you for trying to help me. Per the drawing from DLane, the M and C link to the coil connections on the SPST. That is correct, right? the pump start relay is a Hydrotek 1000. How can I tell how much power that needs? The pump model is unknown. It is buried and we have been told you can’t bury them anymore. I know the pump is a 220v 1 HP pump because there is a shut off for it. Please ask more questions. I really appreciate you trying to help!
post by ady624 on Jun 19, 2024
The only thing I could find is this HYDROTEK 1000 INSTALLATION & TROUBLESHOOTING MANUAL Pdf Download | ManualsLib is yours a controller or just a pump start relay? is there any diagram whatsoever on the hydrotek? can you provide some pictures?
post by Cindy on Jun 20, 2024
I apologize for not responding more quickly. My husband just had rotator cuff repair surgery and he needed assistance; then I forgot to come back to you.
The Hydrotek 1000 is only a pump start relay. The controller was a Rainbird ESP-M. Here is a link to its manual, but I didn’t see anything in it that would help. Rain Bird ESP-Modular User Manual
There is also CentriPro Model CB10412 control box that is attached to the Hydrotek. Here is the manual link. 548671_1_Goulds+Quick+Disconnect+Control+Box+Brochure.pdf
But I used the M and C wires from the Rainbird to wire the Rachio (and then the SPST) and those came out of the Hydrotek so I don’t think the CentriPro matters?
I have sketched a schematic. I am no artist, and it’s not to scale but hopefully it helps. I will upload it from my phone.
post by Cindy on Jun 20, 2024
post by Cindy on Jun 20, 2024
Inside of Hydrotek 1000
Outside of Hydrotek 1000
Centripro
post by ady624 on Jun 20, 2024
I am sorry to hear about your husband and wish him a speedy recovery!
Forgive my messy, slanted drawing, pretty good for just having woken up!
Divided it into low and high power sides. Without touching wires, can you confirm this is what you have? Rachio is plugged into N and L1 via the power block, not shown. The 24V transformer you just purchased is also plugged into N and L1 (110V). Voltage across L1 and L2 is 220-240V.
Let’s start with basica, if you unplug the new transformer and disconnect either pin 2 or 4 from the SPST, then turn a zone on for say 3 minutes, you should hear a single click from the SPST when it starts and a single click again when it stops. Is that what is happening?
post by Cindy on Jun 20, 2024
Good morning. Excellent drawing for just waking up!
Thank you for the good wishes for my hubby. It’s going to be a very long recovery.
So - Yes, what you show for the low power is what I have and I believe what you show for the high power is what I have. The high power was working fine before Rachio - and I have changed nothing there. I have the M terminal set to Well or Pump Start Relay.
post by ady624 on Jun 20, 2024
So what do you get when turning a zone on? Unplug the transformer so we isolate things, you have a SPST and a DPST (that Hydrotek 1000 is internally a GE double pole single throw relay).
One click for start and one click for end? Or many, many clicks?
post by Cindy on Jun 20, 2024
I get many clicks as currently wired. I will go unplug the transformer and see what happens.
post by Cindy on Jun 20, 2024
Interesting. I don’t get the repetitive clicking, which is wonderful. But the sprinkler also doesn’t run. I tried a couple of zones.
post by ady624 on Jun 20, 2024
well yeah, it is expected to not work, you are not triggering the hydrotek relay. Wire it back up, is the hydrotek the one doing the many clicks? or the pump controller? do not touch wires, those two work on higher voltage that is dangerous.
post by ady624 on Jun 20, 2024
if you cannot determine where the sound is coming from (components too close to each other), you can use a funnel to figure it out, much like a stethoscope- watch your ears though. Top of the funnel against the device, listen through the funnel neck but don’t stick it in your ear, it may be loud. Another way is with touch, but given the high voltage, am skeptical of asking you to touch things in there.
Loudest clicker wins.
post by Cindy on Jun 20, 2024
the HydroTek is loudest
post by ady624 on Jun 20, 2024
I think I know why. According to this link the coil is 110V, not 24V. Let’s inspect ye old controller, was the hydrotek plugged right up into the COM and M/V ports? I am looking for other sources to confirm that DPST relay is 110V driven, not 24VAC. I believe the enclosure may take 24V and drive the relay.
post by Cindy on Jun 20, 2024
Yes, the old controller had them in the MV and COM ports.
post by ady624 on Jun 20, 2024
I believe that web page is wrong, others say min voltage is 24V. It looks like either that is now broken, or has a higher energy requirement to keep the coil and switch engaged, and the transformer is not providing it, voltage drops and relay disengages, then repeat. You don’t happen to have a voltmeter, do you?
post by Cindy on Jun 20, 2024
Like a multimeter? My hubby has one of those…
post by Cindy on Jun 20, 2024
On the cardstock/paper in the Hydrotek it says 5-HP24V
post by ady624 on Jun 20, 2024
Yeah, that part is long discontinued, cannot find any exact reference, I expect the coil is 24V. The question is, how much power does it draw. Which transformer did you purchase? What is its advertised VA power?
post by Cindy on Jun 20, 2024
post by ady624 on Jun 20, 2024
with the multimeter, you’d want to set it to 200V~ (alternative) and measure the voltage on the two wires going to the HT1000 - do not measure inside the box where there’s 110/220V present - just the wires going to it, one should come from the SPST and the other from the 24V transformer. Only do this if it is safe, please. If not, I’d suggest you get an irrigation guy to take a look at it.
If the HT1000 is broken, you might as well buy a recommended pump start relay and then not need the SPST and the transformer, but we don’t know if it’s broken yet.
post by ady624 on Jun 20, 2024
ok, so the transformer suggests it can put out 1A - when Rachio complained, did it mention any amperage being used? Struggling to find any reference on power need for that HT1000 coil
post by ady624 on Jun 20, 2024
the closest I could find is the new series 1500 from K-Rain - they suggest the coil resistance is either 155Ω for the lower powered ones and 5.6Ω for the higher powered ones. That’s about a 70VA in rush current on start up - which your transformer would not be able to withstand. Nor would the Rachio. Explains the clicking.
post by Cindy on Jun 20, 2024
When Rachio complained? Do you mean the error message? I haven’t gotten it since I started with the SPST work around but it was saying there was a wiring error. I will try to check those wires you requested.
post by ady624 on Jun 20, 2024
I think we need a bigger boat. Sorry, transformer!
post by ady624 on Jun 20, 2024
yeah, that initial error message, did not say anything about amperage? I have never seen the message myself. Assuming it was suggesting a short?
post by ady624 on Jun 20, 2024
Before measuring voltage (which will fluctuate so fast you may not be able to discern the low and the high) - can you fully disconnect the HT1000 from the transformer and SPST - power down the high voltage L1 L2 from the breaker (assuming you have a breaker box nearby) - then switch the multimeter to ohms and measure the resistance of the HT1000 coil.
post by ady624 on Jun 20, 2024
Looking at that transformer, it is a 24V DC transformer, you need 24VAC for the coil. Running it off a 24VDC (continuous current, not alternative) would make the coil overheat because it has a low resistance - impedance no longer plays a factor in limiting the current - this may cause the transformer itself to trigger its overcurrent protection, causing the clicks. We need a 24VAC transformer, I just don’t know how much VA yet - let me know when you have a measurement on the resistance of that coil please.
post by Cindy on Jun 20, 2024
OK, and when I measure the resistance, do I use the same two low voltage wires coming out of the Hydrotek?
post by ady624 on Jun 20, 2024
yes, the same two wires, one coming from the transformer and one coming from the SPST - but it is important the wires are disconnected from the SPST and the transformer in order to measure just the internal resistance of the coil, not the whole circuit. And I cannot stress this enough, all power off please.
post by Cindy on Jun 20, 2024
The numbers jumped all over the place and then ended up at zero. FYI one of those wires still had a 1/4" quick disconnect fitting on it so I just put the probe in that. I am not sure what to tell you…
post by ady624 on Jun 20, 2024
if you removed all power and nothing else is attached to the two wires controlling the hydratek 1000, and the multimeter is on its ohm position, then the number should be pretty stable - I don’t know what ranges you have on the multimeter, but start high, say 20k ohm and go down until the number is in range and not over - maybe 2000 or 200 ohm range. Depends on what ranges you have.
post by Cindy on Jun 20, 2024
We have 20M, 200K, 20K, 2000 and 200
post by ady624 on Jun 20, 2024
start at 20k or 2k and if the result is below the next lower limit go lower, I suspect you’re ok with the 200 range
post by Cindy on Jun 20, 2024
Ok, at 200 it was 5.5
post by ady624 on Jun 20, 2024
Cool, that is in line with the document I shared earlier, for the higher powered coils.
Double Pole, Single Throw
Inductive: 40 AMP
Resistive: 50 AMP
Input: 120V AC - up to 3 H.P.
240V AC - up to 5 H.P.
post by Cindy on Jun 20, 2024
So we are making some progress?
post by ady624 on Jun 20, 2024
yep, at 5.5Ω and a DC transformer @ 24V you are asking that transformer to provide 24/5.5=4.4A - when it can only give you 1A. You need a AC transformer. Give me a minute to figure out VAs.
post by ady624 on Jun 20, 2024
Alright, 60VA in-rush (this is the instant current when turning on, but lasts for a brief moment) - and a 7VA when stabilized. The transformer I pointed to above should get you going. It’s actually overkill, let me see if there’s any 1A, but if that’s fine for you, go for it.
post by ady624 on Jun 20, 2024
This will definitely work:
Make sure whatever you buy is 24V and outputs AC, not DC.
post by Cindy on Jun 20, 2024
So if either one will work, should I get the over-kill one you found first? It is only a dollar more. And I will get AC - I didn’t realize I was getting a DC one earlier. Or does it truly not matter if I get the 40 vs 50 VA?
post by ady624 on Jun 20, 2024
If using DC voltage on an AC relay coil, you’re essentially overloading the coil - in the DC world, the current is voltage over resistance - you have a 24V and 5.5ohm requirement, so you’d need a staggering 4.5A - assuming you get a 24VDC@5A transformer, it will work but you’re now spending over 100W to drive a solenoid - the power dissipation or lack of thereof will make it melt and potentially catch on fire. We don’t want that, that relay was not designed for DC currents.
In the AC world, when the power turns on, the rush current will show up but as the electromagnetic field is formed in the coil, a new, inductive resistance appears, which, along with resistance, results in a higher impedance - current in AC is voltage over impedance, with impedance being much higher than the 5.5ohm resistance - this causes the current do immediately drop down to about 292mA (7VA used, at 24V means about 7/24=292mA). i believe Rachio reserves about 250mA for each of the max of three valves it can drive - this being over 250mA may explain why Rachio complained right away. Hope the explanation helps (confuse you more LOL)
post by ady624 on Jun 20, 2024
between 40VA and 50VA (note in AC we don’t use W watts, we use VA volt-amps) - I would pick the 50 if the price diff is irrelevant - they both are over the stable 7VA, but it’s likely the 50VA will handle the in-rush split second 60VA power draw at start up easier than the 40VA. We don’t know their in-rush current ratings, but they both should be way over that 60VA. We’re talking about 20-50ms of in-rush currents, they can handle it.
Get the one that arrives faster? LOL
post by Cindy on Jun 21, 2024
Thank you so very much! The new transformer arrived tonight and I hooked it up - and we had water! I really appreciate your time and knowledge getting me on the right path! Have a wonderful weekend!
post by franz on Jun 21, 2024
Nice job @ady624 ! Holy cow.
post by ady624 on Jun 21, 2024
Glad I could help! Finally got to use my electronics license, though I am more of an embedded engineer!