No central heat - bad wiring?

SteamtoHotWater

Finally got my install mostly finished. Had to spend a couple days chasing down leaks. But it works! Well, it’s outputting DHW like a champ. I have yet to get the downstairs central heat going.
Near as I can tell, the boiler never receives a call from the thermostat and therefore never switches on. The Taco ZVC403 has power. But I’ve never seen the Taco 0015e3 circulator’s power light turn on. As I’ve never done this before, it seems likely that I’ve made a wiring error somewhere. It would be great if the community could take a look and let me know what I’m doing wrong.
I’ve included a photo of the overall install. Closeups of the wires. And I also put up the manufacturer diagrams.

Jamie Hall

What happens if you jumper in that first picture with the thermostat wirers between R and W on the Taco board?

109A_5

Hello @SteamtoHotWater,
Simple answer, Like neither, I would think you would need the 4th wire. So the Zone Valve controller knowns when the end switch closes.

SteamtoHotWater

109A_5 said:

I would think you would need the 4th wire. So the Zone Valve controller knowns when the end switch closes.

Done. There is now a fourth wire.

Jamie Hall said:

What happens if you jumper in that first picture with the thermostat wirers between R and W on the Taco board?

Good things! Everything came alive. Hot water for the central heat started flowing. Does this mean my thermostat is wired incorrectly?

109A_5

Hello @SteamtoHotWater,
Apparently no connection (internal or external) R to Rh terminals at the thermostat.





OR

Jamie Hall

That thermostat wire is a nightmare. Either it's hooked up incorrectly -- or a wire is actually broken.

Jamie Hall

or, some to think of it, it could be the thermostat...

SteamtoHotWater

Okay, I put a jumper between R and Rh - keeping all the other wires the same. No dice.

I don't understand how the second diagram, with the switch relay, applies to the ZV403 - so I didn't try it. Any other thoughts?
The thermostat wire is a nightmare. But it was working for my previous boiler, so hopefully it's still good.

neilc

pull your wire from W1,
jump Rc to W1,
withdrawn

neilc

that Rc Rh jumper would go at the stat, so power could come back to W1,
or with the jumper here, you need another wire to go out to the stat, and come back to W1
withdrawn

pecmsg

The wires in the 1st picture look different than the wires in the later picture!

109A_5

Hello @SteamtoHotWater,

Since the test jumper worked at the Zone Valve Control box. If the wiring through the house is good a test jumper between the Red wire and the White wire should also work when placed at the thermostat. The C wire is only to power the thermostat.

The jumper you previously installed at the thermostat connects the R wire to the Rh side of the thermostat's switch. During a call for heat the thermostat closes the switch Rh to W. Same as the jumper you used at the Zone Valve Control box before.

Do you have a multi-meter ?

109A_5

Hello @SteamtoHotWater,

Be careful jumpering unknowns at the thermostat you don't want to short out R and C like if the wires are spliced wrong in the wall somewhere. A multi-meter is the better way to verify wiring.

SteamtoHotWater

pecmsg said:

The wires in the 1st picture look different than the wires in the later picture!

They're not. For both ends: the red is going to R, the blue is going to C, white is going to W.

109A_5 said:

Hello @SteamtoHotWater,Since the test jumper worked at the Zone Valve Control box. If the wiring through the house is good a test jumper between the Red wire and the White wire should also work when placed at the thermostat. The C wire is only to power the thermostat.

I'll try that.

109A_5 said:

Do you have a multi-meter ?

I do. Though I'm uncertain how to use it in this situation.

SteamtoHotWater

Okay, I jumped the R and W on the thermostat end - no results.

Regardless if the wire is good or bad, what should I be doing?
Is it as simple as?
ZVC403 R <-->R thermo
ZVC403 W<-->W thermo
ZVC403 C<-->C thermo

109A_5

Hello @SteamtoHotWater,

Multi-Meter set to an appropriate AC Voltage range.

At either end of the properly connected thermostat wires, Zone Valve Control box or Thermostat;

No call for heat.
C to R (and Rh), 24 VAC
C to W, 0 VAC
R (and Rh) to W, 24 VAC (Thermostat switch open, No call for heat, system voltage is across an open switch)


Call for heat.
C to R (and Rh), 24 VAC
C to W, 24 VAC (Since now R is connected to W through the thermostat switch)
R (and Rh) to W, 0 VAC (Thermostat switch Closed, Call for heat)

neilc

my apologies @SteamtoHotWater ,
at the thermostat you want the R jumped to Rh, not to W, as I wrote earlier,

but try this first,
at the thermostat base,
voltage meter between c and r,
24v ?
meter between r and w,
24v ?

trying to prove that old cloth wire is still solid, end to end,
if yes, to both,
jump R to RH,

SteamtoHotWater

Okay. Here's what I did.
I took the Tekmar down to the basement.
Using much shorter (much newer!) wires connected everything as such:
ZVC403 R <-->R thermo
ZVC403 W<-->W thermo
ZVC403 C<-->C thermo
Had the thermostat call for heat. Nuthin happened.

neilc

SteamtoHotWater said:

Okay, I jumped the R and W on the thermostat end - no results.

Regardless if the wire is good or bad, what should I be doing?
Is it as simple as?
ZVC403 R <-->R thermo
ZVC403 W<-->W thermo
ZVC403 C<-->C thermo

this jumper, R to W, should have given you a call for heat,
in that it didn't, suspect a broken wire, either the red or white,
the meter test should tell you which,

but plan to replace that old wire anyways,
pull a new 4 wire, or more conductors, 18 ga,

Jamie Hall

OK. If you jumped R to W at the Tekmar and things worked -- you said they did -- but then jumped R and W at the thermostat and they didn't, what does that say? That either R or W is broken somewhere along the line, or... the R or W or both at the thermostat isn't actually the same wire as the R or W, as the case may be, at the control. Just because they are the same colour doesn't mean that they didn't get swapped at some junction along the way. This can be a bit tricky to track down, but it can be done.

A first step[ -- and only the first -- is to disconnect the wires at the control, go upstairs and connect R and W together at the thermostat location, go back downstairs, and measure the resistance between the disconnected ends of the R and W wires. If the wiring is correct and intact, you should get a reading very close to 0 ohms -- a short circuit. Anything else... problem.

109A_5

Hello @SteamtoHotWater,

SteamtoHotWater said:

Okay. Here's what I did.
I took the Tekmar down to the basement.
Using much shorter (much newer!) wires connected everything as such:
ZVC403 R <-->R thermo
ZVC403 W<-->W thermo
ZVC403 C<-->C thermo
Had the thermostat call for heat. Nuthin happened.

Was the R to Rh jumper installed when the Tekmar was in the Basement?

Does this still work ?

SteamtoHotWater

neilc said:

my apologies @SteamtoHotWater ,
at the thermostat you want the R jumped to Rh, not to W, as I wrote earlier,

Oh. No problem. Using the new wire with the thermostat in the basement, I jumped R & Rh while also doing:
ZVC403 R <-->R thermo
ZVC403 W<-->W thermo
ZVC403 C<-->C thermo
And it worked. If the same setup works with the old cloth wire upstairs, that means the cloth wires are good?

109A_5

Hello @SteamtoHotWater,

SteamtoHotWater said:

If the same setup works with the old cloth wire upstairs, that means the cloth wires are good?

Did you not have that already ?

Maybe verify the cloth wires with an Ohmmeter as @Jamie Hall suggests. Although if the Tekmar needs 24 VAC for its power I would think R and C are good and the White is bad.

neilc

so you brought the new thermostat to the basement and mocked it up with spare wire, and it worked?
proof of concept,

yeah, it should work the same upstairs at the end of cloth wires,
But,
you had that jumpered already upstairs, and no love(?), right?

Go back and read @Jamie Hall 's last message where he suspects possible splices not keeping colors correct,
and 109's message also,

or there could still be broken wire, possibly at the stat, is there any slack in the wall that might pull thru? careful, you know how fragile that cloth s, don't make anything worser

109A_5

Another possibility is R and C is crossed in the wall somewhere and White is good.
So with a call for heat the White wire is connected to C which effectively does nothing.
The 24 VAC to power the Tekmar would still be good.

SteamtoHotWater

109A_5 said:

Did you not have that already?

Not with R & Rh jumped. I had R jumped to W.
Anyway, put the thermostat back on the first floor. Wired everything, using the cloth wires. Also jumped R & Rh. The boiler fires up.
Does that mean I'm good?

neilc

does it turn off?

109A_5

" I had R jumped to W. " Theoretically that should have fired the boiler with no Thermostat control. Loose or broken old wires somewhere ?

I'm confused. What was this hours ago ?

SteamtoHotWater

109A_5 said:

I'm confused. What was this hours ago ?

Now I'm confused too. I wonder if I had a loose wire somewhere also. Regardless, the cloth wire with the R/Rh jumper is now working. Presuming that the boiler shuts off when the room reaches temperature, I should be good - no?

109A_5

Hello @SteamtoHotWater,
Yes, if it all works OK and normal, cycles correctly. Maybe a combustion test to verify that is good and establish baseline records.