Adding C wire to Burnham 2 wire boiler

Reply

  #1  
Old 01-14-21, 06:41 PM
R
Member
Thread Starter
Join Date: Jan 2021
Posts: 4
Received 0 Votes on 0 Posts
Adding C wire to Burnham 2 wire boiler

Just ran a new 18/5 wire to connect a C wire to the nest 3rd gen. I connected it to the c terminal on the boilers transformer and I am still getting a no power warning. Anybody have any Idea why this could be or could help me with my specific system?

Transformer

Wiring diagram
 
  #2  
Old 01-14-21, 08:44 PM
D
Member
Join Date: Apr 2014
Location: us
Posts: 1,041
Received 41 Votes on 39 Posts
At Nest terminals try switching wires that go to Rh and W1.
 
Rhino298 voted this post useful.
  #3  
Old 01-14-21, 09:51 PM
R
Member
Thread Starter
Join Date: Jan 2021
Posts: 4
Received 0 Votes on 0 Posts
Cool

Update: I added some additional pictures so hopefully I can figure this out because it is driving me crazy. I have a 2 zone system and based on further research I believe I need to complete the circuit with the C wire to a connection on the zone valves. Another thing that is confusing me is that from the zone valves to the boilers transformer there are three wires white black and green. White is connected to C terminal, Red to R terminal and the green is connected to the G terminal on the boilers transformed.

2 zone valves

Full wiring diagram

wires coming into boilers transformer
 
  #4  
Old 01-14-21, 09:55 PM
R
Member
Thread Starter
Join Date: Jan 2021
Posts: 4
Received 0 Votes on 0 Posts
I tried switching the white and red at the nest terminals and I think that would work if I didn't have zone valves.
 
  #5  
Old 01-14-21, 10:52 PM
R
Member
Thread Starter
Join Date: Jan 2021
Posts: 4
Received 0 Votes on 0 Posts
One more better picture of the zone valve wiring

Better picture of zone valve wiring
 
  #6  
Old 01-15-21, 05:44 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Location: United States
Posts: 5,001
Received 89 Votes on 84 Posts
Hi, do you have 24 VAC between your “C” conductor and red at the Stat? Do not change any other wiring yet! Bare in mind that Nest does not have a great track record.
Geo 🇺🇸
 

Last edited by Geochurchi; 01-15-21 at 06:29 AM.
  #7  
Old 01-15-21, 08:36 AM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,306
Received 35 Votes on 34 Posts
It looks to me like post #6 on this thread shows the connections :

https://www.doityourself.com/forum/b...dd-c-wire.html

green is connected to the G terminal on the boilers transformed
.

see what you mean. a little different.

I’m no expert for sure, but it looks like connecting C on the Nest to C on the transformer should work. I guess what Geo said is best – see if you have 24v from R to C.
 

Last edited by zoesdad; 01-15-21 at 09:13 AM.
  #8  
Old 01-15-21, 11:40 AM
Z
Member
Join Date: Jan 2008
Location: Southeastern Pennsylvania
Posts: 3,306
Received 35 Votes on 34 Posts
from the zone valves to the boilers transformer there are three wires white black and green. White is connected to C terminal, Red to R terminal and the green is connected to the G terminal on the boilers transformed.
Did you really mean White,Red, and Green - and not White, Black, and Green?
 
  #9  
Old 01-15-21, 12:23 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 61,369
Received 1,397 Votes on 1,294 Posts
You have to follow certain wiring logic. It's not critical when there are only two wires. It's extremely important with three wires. I see what looks R connecting to two yellow wires and two red wires at the zv's. R cannot go to the zv first. You could use the wiring as it is but it's too confusing.

I've modified two of your pictures. The wiring is now very basic. You now have white two wire thermostat cables. That is where your new ones needs to connect...... at the valves.

Turn power off. I would open all connections at the zone valves.
1) Connect one red wire from each valve to R. Connect the red from thermostats to same R(red).
2) Connect the second red wire from each valve to G(green) and cap off.
3) Connect one yellow wire from each valve to C(white). This is also C to your stats.
4) Connect white wire from t'stat cable to yellow of proper zone valve.



 

Last edited by PJmax; 01-15-21 at 12:41 PM.
  #10  
Old 01-16-21, 08:34 AM
D
Member
Join Date: Apr 2014
Location: us
Posts: 1,041
Received 41 Votes on 39 Posts
Understanding the basics circuit is key to trouble shooting. It is easy to get lost with terminal labels and wire colors.

The thermostat needs 24 volts on C and RH for power.

at call for heat RH is connected to W. That may just connect TT terminals on something or provide other side of transformer 24 volts to start it.

Zone valve needs 24 volts on motor, yellow and orange to open. When open valve end switch closes connecting red wires use to start something.

Would start by connecting RH and W to see if valve opens. Then connecting zone valve red leads to see if circulator starts.

Rather than wire nuts these terminals make reliable connection and are easy to use, adding or changing wires. Cut off number needed from strip. ​​​​​​https://www.allelectronics.com/item/...l-block/1.html
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: