Need help with 3 zone TACO valve heating

[Mike Fern]

Hi – I have gas boiler with 3 zone baseboard heat. One zone hasn’t worked for several years insofar as I need to keep the valve open to manual if I want to get heat to that zone – if would not open and close based on the thermostat settings. The problem is that zone would obviously get too much heat even if you just wanted one other zone to work. A friend suggested that the valve head may be bad.

I replaced with a brand-new valve head (careful to copy and match the wires exactly as they were). However, it still does not seem to be working.

I have to admit, looking at the wiring, it looks awfully ‘over complicated’. I could be wrong about the complication, maybe it just needs to be that way.

I have a PDF available here with pictures everything, hopefully enough for someone to see if it is functioning properly.

I would have drawn a diagram with colors, but I am colorblind and so I took the photos. Hopefully they are clear enough.

Picture:

https://www.dropbox.com/s/r7ww4tl1a3taonq/valves.pdf?dl=0

In the picture, the non-functioning zone is Zone 3 – Middle Level


My level: extreme novice

I did make sure new batteries are in each of the thermostats.

Much appreciated if anyone can provide guidance on how to get that zone3 to work.

In some picture you will see what looks like a blue wire next to Zone 3 not connected to anything, I think it was always that way.




Thanks

Mike

 

[Stuff]

The wiring looks normal and correct for a 3 valve system.

Sounds like it is a thermostat or wiring issue now. I would first check at the zone 3 thermostat - pull the cover off and connect the two wires together and see what happens.

 

[Sponsor]

 

[Dana]

What Stuff said- the first thing to check when a zone it's responding to the thermostat is the thermostat wiring.

 

[Mike Fern]

Hi again, it's been a while.

I haven't really paid much attention to things, but it's getting colder now in the Northeast .

So it still appears that the 'problem' zone is still sporadic.

After some testing, it seems like when Zones 1 and/or 2 are running Zone 3 will not open. If I shut off at the thermostat all 3 zones, then turn on zone 3 only, it opens and closes as normal and works.

Any thoughts on why that is?

Thanks

 

[djdavenport]

Just a guess, but do the thermostats go through a controller? Sometimes there is a priority setting in the controller that will lock out certain zones until the other zones are satisfied and quit calling for heat. It's often times used when you use the boiler for an indirect DWH. If somehow z 1 & 2 had priority, it would lock out z3 as long as the other two were calling for heat, which is the situation I think you are describing.

 

[Dana]

There doesn't seem to be a zone controller in any of the pics.

It's possible that you don't have enough transformer output power to open all 3 zone valves at once, or perhaps one or more of the zone valves are pulling more current, so the last to be called can't quite open or close. If zone 3 is the first to open, will either or both of the others open while zone 3 is active?

If the wiring connection to zone 3 is bad it might be on the edge of not working. They draw the most electrical current when opening, and should draw next to nothing when fully open. What model number zone valves are those?