More c-wire fun. Gas-Steam-Probe LWCO

JohnNY

I came across this yesterday. Williamson CGA boiler wired for Ecobee. by connecting TT as you normally would and just connecting a C-wire to the thermostat.
Customer called and said there was no heat and the thermostat lost its display but it used to work fine. The problem turned out to be a bad water feeder. In this boiler, the thermostat gets its power from the B terminal on the LWCO. Can't have that. I know I read somewhere that Weil-McLain or maybe it was Burnham uses a factory relay to make this happen but I can't find any part numbers right now for some reason. Maybe use a basic RIB?

mattmia2

Looks like it is installed with a fan center but the relay isnt installed and everything is just connected to the xfmr terminals. I bet there are wires to the relay socket and terminals that aren't shown.

mattmia2

Let's think about how this would normally be wired.

G would go to the end of the relay coil not connected to C.
You would close G-R to close the relay and turn on the fan.

Y is a terminal to splice the control wire from the tstat to the condenser contactor.

W is a terminal to splice the thermostat to the safety chain and the gas valve.

C is the end of the xfmr that connects to the control coils directly.

R is the end of the xfmr that is switched to control things.

I think you can install the relay, use the leads from the relay contacts in the junction box to connect Y and the wire connected to the lwco currently connected to G to make the heat call. Remove that wire connected to the lwco from G and connect it to one contact of the relay. Connect the other relay wire to Y.

Connect the Ecobee-fan center
C-C
R-R
W-G

Does that make sense?

JohnNY

So then maybe I can do this and make it look like its belongs there by using a Honeywell R8222D relay.

Matt_67

Using the R8222D would look better but it would need a little diagram for a future tech. If I walked up to it and it had a RIB it would be easier to troubleshoot.

mattmia2

Definitely leave a diagram. Or bring a printout of the diagram and mark it up.

I don't know why they used Y instead of W for heat. Super confusing.

EBEBRATT-Ed

I dont know.

Rib RIBU1C.

Rib contacts (NO) to Y & G on the fan center remove the stat wires from Y & G. Wire ecobee to R & C on the fan center along with the Rib common coil wire to C. W on the Ecobee to the hot coil wire on the RIB

JohnNY

EBEBRATT-Ed said:

I dont know.

Rib RIBU1C.

Rib contacts (NO) to Y & G on the fan center remove the stat wires from Y & G. Wire ecobee to R & C on the fan center along with the Rib common coil wire to C. W on the Ecobee to the hot coil wire on the RIB

Thank you, my friend.

Steamhead

@JohnNY , on these boilers, I use the R8222D, but mount it separately from the transformer plate.

Connect a NO contact on the relay to the existing factory-original thermostat leads.

Assuming the thermostat cable is wired in the usual manner: Run a red wire from the R terminal on the transformer to the Red wire in the thermostat cable. The White wire in the cable goes to one side of the R8222D's coil. The other side of the coil, and the green wire in the thermostat cable, connect to the C terminal on the transformer.

This method gives you a completely independent thermostat power and control circuit, while not altering the boiler's factory wiring.

The Burnham Independence has this relay already installed. Not sure if the new SteamMax does.

JohnNY

Steamhead said:

@JohnNY
The Burnham Independence has this relay already installed. Not sure if the new SteamMax does.

Hey, amigo. Yeah. Finally a good reason for that noisy relay on the Independence. I've installed a few Williamson boilers recently. They're new to me. There's not a word anywhere in their literature about 3-wire thermostats. Thanks for chiming in. I'm going to do this myself Monday.

EBEBRATT-Ed

Williamsons are Weil McLain's as far as I know

ChrisJ

It's been a few years, but I believe my EG series was the same as that and it was slightly modified so the LWCO broke the connection after the roll out switch instead.

This made it so the tstat never lost power and no need for a relay, just an extra wire.  

HVACNUT

Can you designate a separate Rc, Rh on the Ecobee? Got an extra wire?
You can power the Ecobee Rc and C.
Wire G on the boiler to Rh on the Ecobee. W on the Ecobee to Y on the boiler. 

JohnNY

HVACNUT said:

Can you designate a separate Rc, Rh on the Ecobee? Got an extra wire?
You can power the Ecobee Rc and C.
Wire G on the boiler to Rh on the Ecobee. W on the Ecobee to Y on the boiler. 

That's interesting. I'll take a look. Thanks a lot.

JUGHNE

I had 2 boilers on a 2 stage tstat.
Thought of some how jacking around with the relay socket, (none was installed, FWIU the relay is for circulator if that boiler used for HW heat).......
but that would leave a mystery for the next guy and any diagram will most likely be lost or ignored over the next few years.

I added a transformer at the remote tstat location in the boiler room.
Used the 2 pole RIB. So this is an obvious modification, should get some attention from future HVAC dudes.

And the 2 LED indicators tell you at a glance which stage is calling.

Also a 24 volt Led was mounted in the top corner of each boiler. It is wired to the gas valve terminals so you can see which is firing. 3 boilers and pump in the room, and the boilers are quiet running so pilot light is handy.

EBEBRATT-Ed

@JUGHNE

That's why I like RIBS. That little idiot light save time

HVACNUT

EBEBRATT-Ed said:

@JUGHNE That's why I like RIBS. That little idiot light save time

They certainly have their place but this situation only needs a switch. Use Rh and W at the thermostat to G and Y at the boiler. Factory wiring doesn't change and that's better than an idiot light.

JohnNY

Well, that worked out nice. Thanks for the guidance, everyone. I've never done that myself before. I'd post a pic but it looks like the worst spaghetti ever.

HVACNUT

JohnNY said:

Well, that worked out nice. Thanks for the guidance, everyone. I've never done that myself before. I'd post a pic but it looks like the worst spaghetti ever.

You've never done what before? Did you add a relay?