Help with ZVC404

CraigWest

Info: i have a zvc404 with priority and a slantfin vsph90 boiler with honeywell aquastat. Originally hooked it all up and everything seemed to work, thermostats were calling for heat and boiler and circulator came on. Then my 4th zone starter to flicker and the transformer burnt in the zvc404. I later noticed that the thermostat in zone 4 melted a part of the circuit board behind the wire connections. I installed a new transformer (not knowing about the thermostat) and pop it went again. Could the blown thermostat have caused this?

The transformer was all black and charred on the 120V side so i have my doubts????

Also i have the erie zone valves(4 wire). The isolated end switch is connected to the aquastat TT connections. I have not used the dry contacts on the ZVC404 or the pump end switch becuase i have it wired to the boiler instead. Is this ok? seeing as it is just a switch i dont think i would have to use it??

I had the green wires connected to the C terminal on the zvc404 and the thermostat which i now know is not needed for a heat only system so i will disconnect those but seeing as they are just a common i dont think they should cause a problem?? I am a newb when it comes to heating if you cant already tell.

Any help would be greatly appreciated!!



Craig

Zman

The manual?

Do you have it wired anything like http://www.taco-hvac.com/uploads/FileLibrary/102-090.pdf ? It sounds like you do not.

Carl

Paul48

hmmm

Sounds like 120v to the thermostat?

icesailor

Wires:

And I'd be pulling the bad thermostat wires off of both ends and checking to see if the wire is shorted by the insulation melting and the wires are shorted together.

CraigWest

Yes

I have it all wired as the diagram shows...mine is new so there is an updated diagram but basically the same.



After more testing i found that there is voltage comming from the boiler tt contacts back to the ZVC404 and shorting out the transformer...

Do i use an isolated relay or something? anyone seen this before?



(i am pretty sure the boiler tt terminals can be used to power zone valves and thermostats so i think i need to stop that voltage from getting to the ZVC)

Paul48

wiring

The TT on the boiler is wired to the end switch on the zvc404?

Zman

Wiring

It sound like you have 120 volt where it doesn't belong. You may have competing transformers on different phases.

The boiler TT should be wired to the main end switch terminals.

The t-stats to the TT on the taco.

All four wires of the zone valves go to the corresponding 1234 terminals.

The only line voltage should be to power up the control or on isolated switches on the bottom left.

Carl

Alan (California Radiant) Forbes

It doesn't sound

as though you have it wired correctly. 



1) The 4 wires from each zone valve should be wired directly to the ZVC.  Terminals 1 & 2 on the ZVC send power to open the zone valve and terminals 3 & 4 are connected to the zone valve end switch.



2) Wire the isolated end switch (dry contacts) on the ZVC to the boiler TT terminals.



And wire your thermostats to the R and W terminals at the top of the ZVC.  The C terminal is only used on thermostats that require 24 volts to operate.



And per icesailor: "And I'd be pulling the bad thermostat wires off of both ends and

checking to see if the wire is shorted by the insulation melting and the

wires are shorted together."

CraigWest

All correct

i do have the 4 wires on the zone valve all connected properly.

I have replaced the thermostat and checked that the wire was good.

The end switch on the controller is hooked up to the TT terminals on the boiler. My thermostats are electronic and do require 24v to operate so i had to hook up the C terminal to make them work...learning as i go here.

Also the surge was getting back to the transformer in the controller somehow through the end switch terminals because that is the only thing connected to the boiler. If i take off those wires there is no more surge...

talked to slantfin and they said there is no way there should be any voltage spike comming from the boiler but by process of elimination thats where its comming from. Unless there are some bad connections in the controller...

Also when i unhooked the wires from the TT terminal on the boiler to the controller the lights on the controller just flicker and make a pulse (kind of clicking)sound...

I will take some pics and upload tomorrow.

CraigWest

wiring

Carl - This is whats confusing me because it doesnt seem like voltage should be able to get from the isolated end switch on the controller back to the transformer on the controller.... as far as i know there is 24v to the thermostats, which when calling for heat will activate the end switch and complete the circuit to the boiler tt terminals... is this correct?

Paul48

Enhanced

I couldn't find any "C" terminal, until I went to Taco's site. That is considered an enhanced ZVC.I guess by enhanced,they mean it is going to transform itself into a melted pile of garbage on the floor. Sorry....Just kiddin'.

Alan (California Radiant) Forbes

Thermostats

What is the make and model number of your thermostat(s)?

Paul48

volts

Disconnect the wires from the end switch. Make sure there is a call for heat, and check for voltage to ground at each of the terminals of the end switch. If there is voltage, the zvc is toast.

Zman

Sequence

Once the TT terminals on the Taco close , the controller will apply power across the zone 1,2 terminals to the zone valve. When the zone valve opens it closes the 3,4 terminals. Once this happens the dry switches on the bottom left will do their thing.

The only place you should be introducing power is the 120v to feed the controller and anything you want controlled by the 3 switches in the bottom left.



I would be surprised if you melted a t-stat at 24v. I would pull all the wires and test their voltage to ground.



Carl

CraigWest

Thermostats

they are heat link 46443 electronic thermostats

CraigWest

voltage to ground

i will try this tonight and report tomorrow

CraigWest

good plan

i will probably disconnect everything and test/hookup one zone and thermostat at a time to see if i can eliminate some things here...

CraigWest

SOLVED

so as promised made  a rookie mistake....

the problem turned out to be wrong wiring on the controller. I had the motor wires for the zone valve going to the end switch and the end switch wires going to the 24vac terminals....

I should have read deeper i just assumed that the red wires on the erie zone valve would be for the motor.... and i was wrong!!

glad its fixed though thanks for the help!!!

Alan (California Radiant) Forbes

Thanks for getting back to us.

I'm glad you fixed the problem!



But I'm still wondering why you fried the transformer.  If you connected the end switch to 24 volts, nothing will happen since the end switch is open.  Just sayin'.