4 terminal Taco 570 series hack

archibald tuttle

I must have been on mushrooms. I thought TACO actually finally relented and made a 4 terminal version of the venerable if vulnerable 570 style wax motor zone valve. But no, so I had to do it myself.

on yet one more job where multiple transformers for multiple relay systems for boiler and pump operation are cross talking to the point of incoherence because of the 3-terminal design. the standard line at TACO was "it's been that way for 80 years and they work" to which I say "except when they don't". And if 3 terminal was such a wonderful efficiency that the rest of the industry should have adopted, then they could have repeated that on the Sentry line but it has, you know, an independent end switch.

Despite the old school affection for the 570s and I think TACO still moves quite a few, it is orphaned technology so I guess they were never moved to make a 4 terminal head despite my vociferous complaining to Jr and his father for that matter (revealing my age status).

So, I made my own 4 terminal heads for this job:




and I learned one more thing about these valves from john barba while I was busy hacking them. I couldn't figure what the break in the motor circuit when the plunger reaches its full extent between terminals 1 and 2 was for (vs. the end switch between terminals 2 and 3). It is a power saving trick so as not to overload the transformer with continuous operation allowing multiple units that actually close a little and then reengage the heater for the wax motor. from their perspective this allows multiple zone valves to run on one transformer which would theoretically exceed the amperage allowance for a 40VA transformer. So then I ask, what happens if several 570 series valves still end up heating at the same instances and apparently there is impedance protection on the transformer that lowers the output voltage in those circumstances so you get slower response. But I guess the whole thing is a stochastic game in which generally speaking everything works for up the 3 valves.

I would install sentries, or caleffis anyway these days but still service a lot of the 570s and get called in when 570 installs aren't working from the get go, as on this job, going back to their 3 terminal design.

I can usually solve these issues also by reversing the phase on one of the transformers involved but it feels more like necromancy than science so I'm just working out this hack as my preferred solution. if I was really on my game i'd have some kind of little bushing that fit the hole I made but otherwise functional.

FWIW thought I'd throw this out there cause it's todaze deal. thoughts. better workarounds. am i prisoner of imaginary ouijas and one side of a transformer will be theoretically unaffected if it encounters one side of another transformer, which some folks have tried to convince me (despite my 'lying' eyes seeing any inexplicable 570 anomalies in complicated multi transformer applicates fixed by going the independent end switch route).

brian

mattmia2

I'd get a phoenix connector you can mount on the housing and do it that way so it plugs in like the zone sentry ones do and is far easier to terminate.

The disconnection of the heat motor keeps it from overheating, there have been posts about people cooking the motor and having wax boil out when they couldn't open enough to open the switch to disconnect the heat motor.

The difficult to solve issue with multiple transformers comes up when they are all grounded so they can be shorted through the ground.

hot_rod

I have timed it at about a 17 sec cycle where the operator over-strokes, breaks the switch and allows the wax to cool. When a thermal motor can draw 1.1 amp, any "power savings" helps.

I don't think you want to run a thermal actuator unless it is connected to the valve body. Or not for long

EdTheHeaterMan

archibald tuttle said:

I must have been on mushrooms. (That would explain a lot) I thought TACO actually finally relented and made a 4 terminal version of the venerable if vulnerable 570 style wax motor zone valve. But no, so I had to do it myself.

on yet one more job where multiple transformers for multiple relay systems for boiler and pump operation are cross talking to the point of incoherence because of the 3-terminal design. the standard line at TACO was "it's been that way for 80 years and they work" to which I say "except when they don't". And if 3 terminal was such a wonderful efficiency that the rest of the industry should have adopted, then they could have repeated that on the Sentry line but it has, you know, an independent end switch.

Despite the old school affection for the 570s and I think TACO still moves quite a few, it is orphaned technology so I guess they were never moved to make a 4 terminal head despite my vociferous complaining to Jr and his father for that matter (revealing my age status).

So, I made my own 4 terminal heads for this job:

Photo excluded


and I learned one more thing about these valves from john barba (he was messing with you) while I was busy hacking them. I couldn't figure what the break in the motor circuit when the plunger reaches its full extent between terminals 1 and 2 was for (vs. the end switch between terminals 2 and 3). It is a power saving trick so as not to overload the transformer with continuous operation allowing multiple units that actually close a little and then reengage the heater for the wax motor. from their perspective this allows multiple zone valves to run on one transformer which would theoretically exceed the amperage allowance for a 40VA transformer. So then I ask, what happens if several 570 series valves still end up heating at the same instances and apparently there is impedance protection on the transformer that lowers the output voltage in those circumstances so you get slower response. But I guess the whole thing is a stochastic game in which generally speaking everything works for up the 3 valves.

I would install sentries, or caleffis anyway these days but still service a lot of the 570s and get called in when 570 installs aren't working from the get go, as on this job, going back to their 3 terminal design.

I can usually solve these issues also by reversing the phase on one of the transformers involved but it feels more like necromancy than science so I'm just working out this hack as my preferred solution. if I was really on my game i'd have some kind of little bushing that fit the hole I made but otherwise functional.

FWIW thought I'd throw this out there cause it's todaze deal. thoughts. better workarounds. am i prisoner of imaginary ouijas and one side of a transformer will be theoretically unaffected if it encounters one side of another transformer, which some folks have tried to convince me (despite my 'lying' eyes seeing any inexplicable 570 anomalies in complicated multi transformer applicates fixed by going the independent end switch route).

brian

You may not have the full story on the brake of the motor circuit and you may also be interjecting philosophic ideas that don't really apply, in an effort to understand the reasoning for this. It is really quite simple. (it’s a high limit) It all comes down to Hydraulic pressure. Try this on one of the hacked heat motors. Connect R from a 24 VAC transformer to terminal 1 and the C to the wire connected to the cam switch as shown in the diagram.
That will leave the cam switch out of the circuit. Let us all know how long it takes for the heat motor to warm up the wax in the valve chamber enough to cause a catastrophic seal failure from the hydraulic pressure piston. I always wanted to see that happen. Maybe @ethicalpaul can film it with you and post it on his youtube channel. That would be a great video.

Nothing to do with transformer overload or theoretically exceed the amperage or even imagined impedance protection. It is just to keep the wax from getting too hot, plain an simple.

hot_rod

EdTheHeaterMan said:

archibald tuttle said:

I must have been on mushrooms. I thought TACO actually finally relented and made a 4 terminal version of the venerable if vulnerable 570 style wax motor zone valve. But no, so I had to do it myself.

on yet one more job where multiple transformers for multiple relay systems for boiler and pump operation are cross talking to the point of incoherence because of the 3-terminal design. the standard line at TACO was "it's been that way for 80 years and they work" to which I say "except when they don't". And if 3 terminal was such a wonderful efficiency that the rest of the industry should have adopted, then they could have repeated that on the Sentry line but it has, you know, an independent end switch.

Despite the old school affection for the 570s and I think TACO still moves quite a few, it is orphaned technology so I guess they were never moved to make a 4 terminal head despite my vociferous complaining to Jr and his father for that matter (revealing my age status).

So, I made my own 4 terminal heads for this job:




and I learned one more thing about these valves from john barba while I was busy hacking them. I couldn't figure what the break in the motor circuit when the plunger reaches its full extent between terminals 1 and 2 was for (vs. the end switch between terminals 2 and 3). It is a power saving trick so as not to overload the transformer with continuous operation allowing multiple units that actually close a little and then reengage the heater for the wax motor. from their perspective this allows multiple zone valves to run on one transformer which would theoretically exceed the amperage allowance for a 40VA transformer. So then I ask, what happens if several 570 series valves still end up heating at the same instances and apparently there is impedance protection on the transformer that lowers the output voltage in those circumstances so you get slower response. But I guess the whole thing is a stochastic game in which generally speaking everything works for up the 3 valves.

I would install sentries, or caleffis anyway these days but still service a lot of the 570s and get called in when 570 installs aren't working from the get go, as on this job, going back to their 3 terminal design.

I can usually solve these issues also by reversing the phase on one of the transformers involved but it feels more like necromancy than science so I'm just working out this hack as my preferred solution. if I was really on my game i'd have some kind of little bushing that fit the hole I made but otherwise functional.

FWIW thought I'd throw this out there cause it's todaze deal. thoughts. better workarounds. am i prisoner of imaginary ouijas and one side of a transformer will be theoretically unaffected if it encounters one side of another transformer, which some folks have tried to convince me (despite my 'lying' eyes seeing any inexplicable 570 anomalies in complicated multi transformer applicates fixed by going the independent end switch route).

brian

You may not have the full story on the brake of the motor circuit and you may also be interjecting philosophic ideas that don't really apply, in an effort to understand the reasoning for this. It is really quite simple. (it’s a high limit) It all comes down to Hydraulic pressure. Try this on one of the hacked heat motors. Connect R from a 24 VAC transformer to terminal 1 and the C to the wire connected to the cam switch as shown in the diagram.
That will leave the cam switch out of the circuit. Let us all know how long it takes for the heat motor to warm up the wax in the valve chamber enough to cause a catastrophic seal failure from the hydraulic pressure piston. I always wanted to see that happen. Maybe @ethicalpaul can film it with you and post it on his youtube channel. That would be a great video.

Nothing to do with transformer overload or theoretically exceed the amperage or even imagined impedance protection. It is just to keep the wax from getting too hot, plain an simple.

But if you had say 3 of them on a 40Va constantly pulling 1.1 amp, how would a transformer handle that load?
Va=. VxA. 24V x 1.1a= 26Va


So 3 valves at 1.1 draw would be 79.2 Va.

So I believe breaking that draw occasionally does have multiple purposes.

Most of the thermal actuators you see on manifolds and zone valves are 800 milliamp now, so they can be constantly powered. That 800Ma inrush is just on the initial warm up. Depending on how cold the actuator is when it gets powered is how long it takes to warm sufficiently to open.

Here is a look at how 3 different types of zone valves power up. The thermal actuator, blue, spring return, and ball valve, red that powers open and closed.

mattmia2

Most heaters are a PTC thermistor to one extent or another so I'm curious at what point in the operation the 1.1 a is measured.

EdTheHeaterMan

hot_rod said:

But if you had say 3 of them on a 40Va constantly pulling 1.1 amp, how would a transformer handle that load?
Va=. VxA. 24V x 1.1a= 26Va


So 3 valves at 1.1 draw would be 79.2 Va.

So I believe breaking that draw occasionally does have multiple purposes.

Most of the thermal actuators you see on manifolds and zone valves are 800 milliamp now, so they can be constantly powered. That 800Ma inrush is just on the initial warm up. Depending on how cold the actuator is when it gets powered is how long it takes to warm sufficiently to open.

Here is a look at how 3 different types of zone valves power up. The thermal actuator, blue, spring return, and ball valve, red that powers open and closed.

Agree. I just like to mess with Brian ever since I met him in person at the trade show. L O L

I still think an exploding 570 would be something to watch.

EdTheHeaterMan

mattmia2 said:

Most heaters are a PTC thermistor to one extent or another so I'm curious at what point in the operation the 1.1 a is measured.

At the T87F mercury thermostat heat anticipator. But only when the cam switch between the #2 post and the heating element.

Otherwise you will get some pretty interesting short cycles on that zone if you leave it at the factory setting.

Not the answer you wanted ... was it?

archibald tuttle

@EdTheHeaterMan you may not have nixon to kick around anymore, but you got me. youse guys are killing me. pretty soon we'll need relays to run the 570s that will trip relays to run the pump that will trip relays to run the boiler. well, come to think of it, it kinda comes down to that anyway. i'm not going to tattle names out of school but it was TACO what said they use the break to limit constant amperage in the interest of transformer capacity, but i see your point about heating the wax. i guess i thought maybe the way it moves slowly that there was some kind of logical high limit that was acheived if the thing was left on, but your point is well taken. i've never dealt with one that was stuck on that i'm aware of, or if it was it didn't result in wax ejection.

i was always intrigued that it must take some pretty hot heat to get the wax going because once circulation starts, the valve body itself could be seeing like 180 degrees depending whether its on the feed or return and the aquastat setting and i wondered why the valve didn't necessarily stick open given that, but guessed that the instantaneous temperature needed was higher. i guess this all goes to lack of availability of small cheap stepping motors back in the day. to be fair, had some honeywell elpitical ball zone valves on fan coil units in a building and they were pretty much junk after 15 or 20 years and trane had made no provisions for practical service (guess they wanted to seel me more fan coil units). i just elimnated the zone valves altogether and went to temperature setback to run that building with constant circ to all units in season.

i do think you'd have some interesting cycling through an old heat anticipator stat, that's for sure. And not sure how any of this would affect those old scavenging states that ran a clock off a two wire stat catching the potentional through the load in the basement i guess and it still had enough umph to run the clock which must have a had some ohms to prevent it from accientally signaling thermostat closure.

all goes to my general idea that we ought to separate these functions rather than do them all off one leg of the thermostat loop. . . . just sayin.

of course there is no wax in the thermostat so we can't watch that melt but i did once accidentally hook up 24v to a robert shaw remote thermister and man did that thing glow.

archibald tuttle

@mattmia2 phoenix, maybe, but how to mount one side on the head. do they make those with a couple screw holes molded on ears off the side on one of the plugs?

if the damn insulated board were like 3/8" longer I could just fit another terminal on there.

mattmia2

There are versions of male phoneix connectors made for panel mounting. I suppose you could use a finer pitch terminal strip too.

Are these UL listed?

EdTheHeaterMan

Really? You need to have the end switch separate from the common side of the transformer of the other circuit? You know, if you just get into the habit of wiring the 570 head properly EVERY TIME!!! then you would not have this problem.

I determine what side of the transformer that is powering the zone valve is the R terminal. (Many times it is labeled R) Then always connect that to the R on the thermostat.

The W on the thermostat ALWAYS goes to the #1 terminal on the 570 motor.

#2 terminal on the 570 ALWAYS goes to the C on the transformer.

If that is the way you ALWAYS wire a taco 570 motor, then all the end switch #3 terminals get put together.

Since all the #2 terminals are already connected to the C from the zone valve transformer, all you need to do is use the C and the #3 terminal wires that are connected to every end switch in an identical way, you will never have a problem.

Where you have a problem is when someone tries to wire one of the zone valves with C on the transformer to W on the thermostat. Then R on the thermostat to #2 terminal on the 570. Then #1 on the 570 to R on the thermostat. It is amazing to know that this will work on one zone valve perfectly. The problem is that you hardly ever have only one zone valve on a heating system... Funny how that works.

When you take the alternate wiring and try to connect it to a system that has the wiring connected as i stated originally. You will always let the factory smoke out of one or more of the transformers in the system. There is a detailed comment on this topic here: https://forum.heatinghelp.com/discussion/comment/1785090#Comment_1785090

Good habits yield good results, Bad happets yield smoke from transformers.

archibald tuttle

@EdTheHeaterMan this is nice in theory and it is what I believe has caused problems on jobs in the past however to take your diagram of the WRONG mix of R and C uses



not all transformers label R & C. Now maybe it doesn't matter with AC, as long as you designate one or the other. but I don't read a potential between any of the terminals on one 24V transformer and another which tends to vindicate TACOs approach as not required a phD EE to put hook up the wires. But my experience in the field has been otherwise. I do observe the conventions you indicate (As do most people by, you know, convention) that the same side of the transformer goes to all the Rs on thermostats. Because you generally take all your thermostat red leads and wire them to one side of the transformer.

According to my meter there is not 48 volts between the transformers but you have to be creating a circuit as you diagram, I'm just not convinced its 48 volts, (and it isn't a short circuit because the transformer is a long wire creating some resistance or load). So the one transformer is trying to 'transform' (sorry) the load side of the other into the power side. I would have to be more of a double E to know, if the other side has no load but is live, what happens? I wouldn't think smoke is out of the question. But weird stuff like the one or the other circuit not working, i.e. not opening the zone valves or not start the circulator or boiler has been more my experience.

But the green 'shortway' you indicate in that WRONG diagram would not exist on a 4 terminal zone valve, regardless if you shifted an R&C in function as you depict. And I know of no other 3 terminal zone valve than the 570. Some engineer 80 years ago decided to save a little space and a half cent terminal and maybe that has been largely fine; but, for the life of me, I can't feel good about crossing over the two control circuits at terminal 2. So for saving a half a cent, you get my 2 cents that runs to as many paragraphs as yours.

Maybe, metaphorically speaking, this dual function efficiency out of one terminal is akin to gas control circuits that switch the ignitor to become the flame sensor. An interesting concept and I guess with todays digital switching I don't really recall that control strategy presenting more repair headaches although my instinct is to separate the functions.

Even though I would decide on an "R" if not labeled and observe the conventions, I always slept better with an independent end switch on all these applications. Ergo my hack. But I'm going to look at the wiring carefully to see if it is out whack as you depict. I didn't wire it to begin with.

brian

EdTheHeaterMan

@archibald tuttle I use the term 48 volts as an indication that you are creating a series circuit. If you were to break any one of the wire and place a meter on the two ends left you would measure 48 volts, like placing 2 nine volt batteries + to - together would over heat and burst open and the acid ooze out, batteries in series Add voltage together. Batteries in parallel add amperage together voltage stays the same. And I use Just "make 48 volts" as a expression like "Wake Up Dead" might indicate what happens after sleeping in a home with a blocked exhaust vent.

hot_rod

EdTheHeaterMan said:

@archibald tuttle I use the term 48 volts as an indication that you are creating a series circuit. If you were to break any one of the wire and place a meter on the two ends left you would measure 48 volts, like placing 2 nine volt batteries + to - together would over heat and burst open and the acid ooze out, batteries in series Add voltage together. Batteries in parallel add amperage together voltage stays the same. And I use Just "make 48 volts" as a expression like "Wake Up Dead" might indicate what happens after sleeping in a home with a blocked exhaust vent.

Such a wordsmith