New TACO zone actuator causing clicking in air handler

researcher

I have a hydronic system with a single zone valve with an air handler in a condo. The 2004 / original actuator head (TACO model ESP075c2-2) wouldn’t close all the way. I spoke with TACO support and they said this is common and the capacitor fails over time and can no longer close.

They no longer make this model, but the replacement is TACO model Z075C2-2. I ordered this unit back in May and it opens and it closes all the way.

Unfortunately, the transformer or relay (inside our air handler) makes a clicking sound with the new model when charging the actuator to open the valve. It doesn’t matter if the actuator is on or off the ball valve or hanging in my hand. In other words it is not a friction issue with the ball valve

When I hook up the old unit the clicking sound goes away.

I have been working with TACO support for several weeks. They suggested I add a 1000 ohm / .5 watt resistor see picture at http://www.taco-hvac.com/tmp/ZoneSentryw_Resistor.pdf.

This didn’t stop the clicking noise.

Now TACO support is suggesting “If you tried the resistor and the relay is still clicking you may have to wire in a separate transformer to power the zone valve.”

I have tried contacting all of the HVAC companies near me and none of them work on hydronic systems. Just forced air. And I have a feeling that this might also not work.

Does anyone have experience with this? Or have any ideas on how best to resolve?

109A_5

@researcher, Please watch the video. Apparently you are not the only one with this problem of incompatible Electrical / Electronic devices causing relays to click. This video is 3 years old. I would think TACO would have a resolution by now.

Testing issues of EcoBee thermostat used with Taco Zone Sentry Actuator
https://youtu.be/t7SdLKTsvTM

Curious, what type of thermostat do you have ?

A second transformer and / or a second relay may solve the problem with the new actuator.

109A_5

@researcher, Apparently TACO uses a electrically noisy Switching method to charge the capacitors in the zone valve instead of a nice quiet linear method. This noise can have a negative effect on other electronic devices in an HVAC system.

To isolate the noise from the rest of the system. I would try the circuit below using an additional transformer and relay. Which may be less expensive than going to a different model or brand of zone valve that uses different technology. This is one simple method using a transformer and a relay to deal with the switching noise, there are others. If you choose to use this method and you are not qualified to work on 120 Volt AC circuits get someone that is qualified to do the work.

researcher

@109A_5 - Thank you, this is brilliant!

I will definitely hire someone for this as I have a cursory understanding of relays, but not enough.

Originally, I thought was just changing the actuator head (that was back in April) and should have been a 2 minute job. That's what I get for thinking..

Question:
You are suggesting a 2nd transformer and relay. Does it need to be an "isolation relay". I noticed this in the YouTube video comments. Or maybe it doesn't matter.

I am asking because I would prefer to be specific when I try to hire someone to fix so they are not scratching their head and guessing. Again, most of the companies near me only deal with forced air systems so I am guessing they have not come across this issue.

Also, any ideas on cost for parts and labor? Just a guesstimate is good.

Thank you again, for all of your help!

109A_5

@researcher, Yes, the transformer and the relay would be new to your system. That way the noise stays local to that new subsystem, so it provides isolation and switching. Many relays and transformers supplyhouse.com for example, and no one specific unit is needed, it is a pretty generic application. The transformer just has to be able to accommodate the load of the zone valve, 20 VA should be plenty for that zone valve at 0.48 Amp draw. And the relay coil needs to be 24 Volts AC to be compatible with your existing system. There are many names for relays, mostly by their basic application Fan, Isolation, switching, etc. All these would work as long as the coil Voltage is correct, the mounting and enclosures may differ. Lately availability may be a bigger factor with the actual choice.

A transformer like this https://www.supplyhouse.com/Packard-PF42420-Foot-Mounted-120-208-240V-Primary-24V-Secondary-20VA-Transformer

A relay like this https://www.supplyhouse.com/Packard-PR370-SPDT-24V-18-Resistive-Amps-Switching-Fan-Relay

A contractor may bring his own flavor devices that they are comfortable with and their markup.

No idea about labor cost, that can vary widely, the job should not take too long.

researcher

Thank you @109A_5.

Also, @Youngplumber says hi. He is the one that pointed me here.

109A_5

Hello @researcher, and Hi back to the young plumber.
I hope it all worked out good for you.

researcher

@109A_5 in case anyone else runs into this. I also found a video where the same guy found that adding the Ecobee PEK (power extender kit) also appears to solve the problem.

I agree that it is disappointing that neither TACO nor Ecobee is solving the root cause (without alterations, extra relays or workarounds).

https://m.youtube.com/watch?v=EzwRLkBZcBg

109A_5

Hello @researcher, yes I did see that video too. The video's author could not explain why the PEK worked, so that method may not work in every situation.

I asked you what type of thermostat you had and received no response to that query, so I did not know if that possible remedy would be applicable to your situation.

The addition of the relay and transformer to your system is a more generic method that most likely provides better isolation of the TACO noise issue.

Presently I think the Transformer and Relay solution is a more robust solution. The apparent filtering or isolation provided by the PEK may fade like the capacitors in your old actuator did.

Without some sort of isolation or noise suppression, the noise (or more accurately stated pulses) impressed upon the power limited 24 VAC system from the charging technique used to charge the large capacitors in that version of the TACO Zone Valve apparently messes with the biasing and / or control of the Solid State output switching with at least the EcoBee, maybe others, so relay(s) in the system momentarily drop out.

In my opinion TACO should of fixed the issue years ago. Since their Zone Valves with that technology are the only units that exhibit that issue as far as I know. Either they did not get enough complaints or the complaints did not get passed along to the correct people to correct the issue or they just don't care, I don't know.

SteveSan

@researcher Thank you for detailing your issue. My name is Steve in Taco Technical Services. We spoke on the phone yesterday with Product Management. Below is the application solution we discussed for this hardware combination.

Our engineering team set up testing with the hardware used in this particular installation and were able to duplicate the issue you describe. It was determined that there is some interference between the components that caused the clicking relay. The clicking relay in your installation can be resolved by adding a small capacitor (P/N: 684MMR100K MFG: Cornell Dubilier / Illinois Capacitor Disc: 0.68 µF Film Capacitor 63V 100V Polyester, Metallized Radial) across the input connector of the Zone Sentry.

109A_5

Here are two vendors that have that Capacitor (no more Radio Shacks around here).

Digi-Key part number = 1572-1179-ND
https://www.digikey.ca/en/products/detail/cornell-dubilier-illinois-capacitor/684MMR100K/5876922

Mouser part number = 598-684MMR100K
https://www.mouser.com/ProductDetail/CDE-Illinois-Capacitor/684MMR100K?qs=BLH6sjKQk%2Bk5C9r2X5pDBA==

In a single quantity order the shipping may cost more than the part.

I would guess a Plumber or a HVAC/R Tech would not have that Capacitor on the truck. I think it is more likely they have a transformer and a relay. The Capacitor is an easy install, you just need the correct size screwdriver.

I hope Taco updates their product, since the EcoBees and the like are probably not going away anytime soon.

Also it would be nice if EcoBee added whatever circuit that is in their PEK unit to their Thermostat unit that solves the problem.

researcher

Ecobee also did some work on the newer thermostats to fix this issue.

The Fast Shutoff circuit was redesigned for Smart Thermostat w/Voice, ecobee Enhanced and ecobee Premium thermostats to eliminate the problem.

The ecobee 4 (and older) thermostats still have the issue.