No heat/hot water on new install by others

adamkirwan1994 · October 18

Taco 506 circ zone board- found system wiring like this on arrival. The thermostat terminals have no voltage on board but have 24 v on end switch. The indirect aquastat wiring also seems incorrect but wanted to get some insight from more experienced technicians. When adding 24v from separate source to t stat terminals it activates the circs/zones. (Indirect on zone 6)

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Photos for reference.

pedmec · October 18

Just to clarify are you using zone valves?

adamkirwan1994 · October 18

he has circulators

tcassano87 · October 18

no zones turn on at all?

Have to checked the Fuse on the Relay Box?

Is the In-Direct wired to the Taco Relay or the hyrdostat? Because wiring would be different for both

adamkirwan1994 · October 18

fuses all fine, indirect control wired to zone 6 on board, I included pictures in post as well. They used a jumper wire on the indirect control instead of a dedicated 24v which is not an option in the manual

adamkirwan1994 · October 18

also no idea why they wired the white wire to the C terminal on all heat zones

Jamie Hall · October 18

Can you make a circuit diagram of how it is wired now?

109A_5 · October 19

" The thermostat terminals have no voltage on board but have 24 v on end switch. "

Ummm… Why are all the White wires going to the C terminals for every Zone except Zone 6. W means White not C. I'm assuming the 'End Switch' you are referring to is at the Orange arrow (image below) and there are no Zone valves in the system. Since there is no active call for heat (Yellow box), there should be 24 VAC across the Main X-X 'End Switch'. That 24 VAC comes from the boiler or the boiler's Aquastat.

The way it presently looks, the SR-506 is wired wrong, on any call for heat from any Zone 1 to Zone 5 when the thermostat closes it would short out R and C of that Zone's 24 VAC. The thermostat's R and W should connect to R and W on the SR-506.

Is there 24 VAC from R to C of any of the Zones ? If not check with all the thermostat wires disconnected and after the SR-506 is Powered down for a few minutes then re-energized. The Green power LED is lit, however I'm surprised the main glass fuse was not blown. Maybe the device at the Blue arrow is a PTC (Positive Temperature Coefficient) Fuse protecting against incorrect wiring, and also saving the day.

I would imagine the reason that Zone 6 does not work even though it appears to be wired correctly is due to the thermostat 24 VAC is missing on all Zones due to the PTC Fuse is overloaded.

Closing R to W is a call for heat. R and C is for powering thermostats that need power to operate.

Also the Indirect should be on Priority Zone 1, not on Zone 6. Set the "Priority ON" DIP switch to ON.

Assuming nothing was damaged (which would be amazing). Shut off the power (the PTC Fuse needs to cool down), correct and verify the thermostat wiring with the power off, and hopefully it should work when the power is restored.

So a contractor did a new system install and then gave up due to incorrect wiring ? What else is messed up ???

tcassano87 · October 19

wow didn’t realize that, above comment 100% right all the thermostats are wired wrong to the “C” terminal. You need to be on the R & W

109A_5 · October 19

This Fuse is Good ? If it was blown I would expect the Green Power LED to be out. However the fuse looks a bit odd in the middle. Maybe it is a little beat up from the abuse but still holding.

HVACNUT · October 19

The curly Qs on the control wiring is more important than knowing how to wire. Presentation trumps performance. Jumping power to the N.O. contact on the water heater is fine.

adamkirwan1994 · October 19

I appreciate all the insight! The customer got very “weird” when I was asking about who installed the system and that if something is potentially damaged internally on the board that they should warranty it but he wanted no part in even contacting the installer. Whoever installed it looks professional and it’s an extremely clean organized plumb/level job even secured all piping/MC cable to a nice painted board which is even more confusing as to why they did the wiring this way.

I did research after I left that night (no service or WiFi on site of course ) that like someone mentioned previously there is a safety that activates in board to prevent any damage to the circuitry and it requires a cool down period before turning system on again. I had 24v on the end switch on board consistently throughout. But yes very odd how the white thermostat wires were all on C terminal on zone board. Hoping that this didn’t cause permanent damage.

GGross · October 19

as long as the customers check clears i suppose they can keep their secrets lol. I too am usually surprised when someone doesn't want to go into details about a job like this. in my experience basically everyone wants to tell all about this stuff even when its not very relevant.

109A_5 · October 19

Maybe the home owner did the install.

Since there is no active call for heat (due to the wiring errors), there should be 24 VAC across the Main X-X 'End Switch'. That 24 VAC comes from the boiler or the boiler's Aquastat, not from the SR-506. Main X-X 'End Switch' on the SR-506 are just relay contacts.

No heat/hot water on new install by others

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