Home owner cleaned boiler questions. PART II

LarryC

Wallies,

 

Home owner here.  I have an oil fired Peerless EC-05 cast iron beauty with a Beckett RWB gun model AFG.  It has a tankless coil and feeds 3 zones of copper baseboard.  It is located in the basement of a 1900's farmhouse in New Hampshire.

 

I moved and rewired the pump relays so I can now remove both the left side and the top to clean the boiler.  I salvaged the white honeywell box o'magic from a discarded L8124L triple aquastat to replace the previous box o' magic that appeared to have a defunct capillary bulb.  The donor aquastat had a burnt open PCB trace.

 

In reading the manual for the triple aquastat, it talks about using the Zc and Zr connections when you have a multizone system controlled by indivdual circulators.  Currently the two zones not controlled by the L8124L are just turning on circulators and I assume the low limit is firing the burner.

 

Is there any advantage running the system the way it is, bouncing off of the low limit to heat the other zones?  Or would it make sense to wire the other zones to fire the burner independently?

 

Thanks for all of the advice that you offer.

 

Larry C

icesailor

ZC/ZR Redux:

There is a correct way to wire this boiler to make it run properly. You aren't doing it. The ZC/ZR terminals are there for a reason. It's best to use them.

Al Letellier_21

wiring zc zr

It depends on what relay you are using for the additional circulators. If a Taco or equal,  or old Honeywell 845s, do use the zc zr terminal. Their function is to shut down the heating circs when a domestic call and heating call come together and the boiler drops below the low limit setting. This gives you domestic hot water priority. If you've had no issues with your hot water, like running out, let it be. Otherwise, you need the priority control that the zc zr give you.

If your relays are R89s, you are out of luck as they don't connect. Replace them with a Taco and wire all three circs into the relay box and connect as the diagram inside the cover shows for tankless application

LarryC

Function of ZC and ZR

I see the logic of shutting off the zone circulator during a hot water call.  ZC does that.  Does ZR turn ON the burner during a zone call for heat?

 

Thanks.

Patchogue Phil_2

Trying to learn

Why won't the R89s work?

icesailor

ZC/ZR Redux

You missed part of that.

The ZC/ZR have another function. The ZC (or ZR) powers the relay from the 8124 (or whichever). When a call comes to the relay, the relay closes and starts the circulator. It also closes a switch that bypasses the low limit operating side of the control, jumps it up to high limit and starts the burner. Which is now running on the high limit. If the operating side drops below the set point, it will stop ALL circulators that are properly wired through ZC/ZR but NOT the burner. If you do not use the properly wired ZC/ZR terminals, the stand alone zones will not start the burner and will run on the operating control temperature. Like, if the high limit is set for 180 and the operating control is set for 160, you only have 160 degree water going into the system and the burner only runs on the differential setting. If you use the circulator relay in the 8124 (or whatever), that is the only zone that will start the burner and run THAT zone on high limit.

If you use multiple circulators and a control with ZC/ZR connections and you then use a control like a Taco ZC-506, and you don't connect the two ZC/ZR terminals, you are not using the control properly. If you want to use that sucky cold start stuff, ignore it all. But if you want a clean and efficient boiler that isn't making concrete or coal in the passageways, use the ZC/ZR and set the "low" at 135 to 140 degrees. It will stop the circulators and stop condensing while the burner catches up..

If you don't understand it, don't expect an electrician to be able to wire it. I have only seen a few who could. I usually need to explain it to them. And then wire it myself. 

icesailor

ZC/ZR

Yes. It turns on the burner. But I can never remember which one starts the burner. It doesn't matter though, if it doesn't start, it isn't wired correctly.

LarryC

Thank you icesailor

Thank you icesailor.  That makes sense.  Now I have to figure out how to put all the wires in the L8124L controller and out to their respective connections and still be able to put the cover on.  Time to make some seven conductor flex. 

 

L1, L2, Gnd, C2, B2, ZC, & ZR

 

Blk, Wht, Grn, Blu, Red, ??, & ?? 

icesailor

R-89's

I think that R-89's are for line voltage thermostats and don't have additional switched contacts.