Taco zvc404-4 4 zone limit and gas hook up

Frankiefiggaro

I have a old boiler with old DOLE zone valves. I replaced all the zone valves with new Taco zones and a Four Zone Taco relay. All wiring to the 4 thermostats, zones, and circulator pump are complete. On this model I have no idea where to wire my limit switch/aquastat, and th/tr s from the gas valve to get them to communicate. I know they work because I tested them when the old zones were. I just need to know where these go in this model so it will fire up and heat. Please help as its cold in the house and fire woods getting expensive. I have pics, specs and everything to help solve this issue.

Paul48

You use the aquastat to control the functions of the boiler and circ. The end switch on the ZVC is used to close the T-T from the aquastat.

Alan (California Radiant) Forbes

Do you have an aquastat relay on your boiler? It looks something like this:

http://www.supplyhouse.com/Honeywell-L8148E1265-High-Limit-Vertical-Mount-Aquastat-Relay-15F-differential-5478000-p

Frankiefiggaro

So does my feed line to the aquastat get 120v to power (supply line) or 24v power to operate?

Paul48

To replace the zone valves and add a ZVC, none of the wiring on the boiler itself needed to be changed. The new ZVC does not feed power to the boiler. It merely acts as a switch. Check out the instructions that came with the ZVC.

Zman

Your low voltage wiring looks reasonably good. It is a good idea to strip only enough insulation to make contact with the terminal. Exposed bare wires are a liability. Also, be sure to add grommets and secure the wires coming from the bottom.

What is connected to the terminal on the bottom left of the 404?

Your original configuration should have had a low voltage wire to the boiler. It may have been attached to terminals labeled "T-T".

Frankiefiggaro

First of all thank you guys for your input. Really appreciate it as the holiday has been a nightmare to get someone out or get parts for that matter. The original configuration in the boiler before the zvc had 2 transformers in it originally and was a mess inside see attached pic. Unfortunately as for the wiring guide on the zvc this model has been upgraded but the intructions and wiring diagram have not. The extra end switch isnt even on the instructions and the labeling is different as well so thats whats been hanging me up. If im understanding correctly the limit/aquastat needs 24 volts then goes to the th/tr terminals then from there to the end switch on the zvc? Or should I Add a transformer on the boiler and wire it independently from the zvc? If I do, wire it independently then how does the boiler cimmunicate with the circulating pump? In essence I just have 2 wires left, 1 from the limit/aqua and one from the T terminal on the gas cock. Thanks I'm hoping to get this running today with your guys feedback!

Frankiefiggaro

The end switch on the bottom left is the circulator pump if that's which wires you were referring zman

Zman

You boiler has a transformer. It is sending power through one of the "T-T" terminals and wanting the end switch on the 404 to close the circuit with it's end switch. This completes it's circuit and tells it to fire. Do you have a picture of the low voltage connections on the boiler?

Zman

One of your pictures may show the terminals. I am not familiar with that model and cannot read the terminals.

Alan (California Radiant) Forbes

I don't know if the boiler has a transformer. I asked Frankie if the boiler has an aquastat relay and he never responded.

Alan (California Radiant) Forbes

So, Frankie: I'm not telling you to do it this way and I'm reticent to draw a diagram, but I want to help you out. This is the way I would wire it if I were there and was able to confirm that there is no boiler aquastat relay.

I'd like to hear from others here to make sure it's right. Please see my moniker below.

Frankiefiggaro

The boiler had 2 transformers hooked up originally. I have extra transformers but wasn't sure if it was needed since the zvc404 had a transformer already. Currently this is what's left but I can add whatever needed. I thought the limit switch was the aquastat if I'm wrong then, no it doesn't have one. See attached photo as to what I have left to hook up

Frankiefiggaro

Here is closer pictures of them.

Zman

There doesn't happen to be a wiring diagram on the back of the door is there?
Can you take the model number and find a diagram. Alan likely has a workable drawing, I would want to see a schematic for the boiler or the gas valve before I would put power to it.

Do be sure to fix shorten the amount of exposed wire on the pump terminal before wiring low voltage right next to it. Lot's of smoke will come out if those touch.

Frankiefiggaro

Heres the back panel. Thanks Alan for the draw up, my issue with the drawing is that the transformer on the 404's 24v lead wires they are already in the circuit board. I have a 2 spots open on the extra end switch on the 404.

Alan (California Radiant) Forbes

Yes, those wires power the circuit board. Leave them there and add the new wiring as shown, just clean up the wiring with no exposed bare wire.
The only caveat is with all four zones calling for heat, will there be enough power to open the gas valve. What kind of Taco zone valves did you use? Can you show us a picture of one of them?

Frankiefiggaro

Here's the taco zone valve

Alan (California Radiant) Forbes

So, these Taco zone valves require 11.4 watts while charging and only 1.44 watts while on. All 4 charging at the same time would require 45.6 watts, slightly exceeding the capacity of the on-board 40 VA transformer in the ZVC control which may just mean that it takes a little more time to charge the zone valve capacitors vs. burning out the transformer. Once the zone valves are open, voltage consumption drops to 1.44 watts per zone valve which should mean there's plenty of power to open a gas valve, no?

Frankiefiggaro

Alan So from the gas valve back to the transformer, I'm tying that to the neutral (white) wire returning the voltage back to the transformer?

Alan (California Radiant) Forbes

Oh dear, no! That is your line voltage coming in. It will fry your gas valve.

Do you see the terminal block at the upper left hand side of the circuit board? There are two wires there; red and yellow. That is where you want to tie into the 24 volts to power your gas valve, with switches at the "extra end switch" and limit as shown on the diagram.

DO NOT proceed unless you are confidant of what you are doing. Wait for a professional to do it properly.

Frankiefiggaro

I didn't think so, ok I will try it this way, makes sense. Thanks for your time and insight. I will follow up with the results but, I'm sure the way you explained will suffice now that it will be tied into a power source after the transformer.

Frankiefiggaro

Hey guys thanks for all the help. I actually brought a certified tech out to fix the issue and he couldn't figure it out, I got frustrated and used your guys feedback and used a seperate transformer to power the boiler and alans diagram and the puppy is firing on all four zones nice and smooth, it opens and closes valves when the heat is called and kicks off when the temp reached. Can't believe the service tech that came out he used a volt tester on the end switch which I told him was a dry switch. When i politely told him that the end switch wont have power until power is given, then he questioned if it needed 110 or 24v ........after that I was done. If it wasn't for your guys help I woulda been one cold S.O.B. Thanks fellas. Much appreciated.

EdTheHeaterMan

Did you tell your Pro about this website?

In the old days i would always replace a transformer and put a fuse on the R terminal
.

Now with the new fuses you can get one of these


But in a pinch you can make one.


seems that we all have these items on our service trucks today. pc boards with 3 and 5 amp fuses and all.

This was a good series of posts!