Hello, I just added 2nd zone for basement to boiler, but do not know how to wire honeywell r845a relay to control the 2nd circulator pump. I am using flow control valves(manual), not electrical to control flow. First zone is controlled by honeywell L8148e aquastat relay, which came with boiler. Thanks 88ply

 

Follow this link:

R845A relay installation

scroll to the bottom, select the third installation in the list, download it and look at Figure 7 . Didn't you get an install sheet with the relay ?

 

I have this install sheet, but I am unable to translate all of it.
The part I do not understand is the hydronic heating control terminals on fig.7. What are terminals "zc" & "zp"? My boiler is using a honeywell L8148e aquastat relay, which does not have zc & zp terminals.

 

Not much time right now to answer, but if you back up on the Honeywell site, you can also download the install for your aquastat. I'll do same later this evening and see what I can see...

 

You are going to need either another R845 or a 2-3 zone switching relay. If you try to use the single 845, both zones will come on whenever the new zone calls for heat. You have to remove the circulator for zone 1 from the 8148's C1 & C2 terminals. Wiring will be very similar to that shown in Fig. 5 in the instructions for the L8148.

 

I never disagree with Grady! It's not good for ya.

I'll just 'expand' a little. Grady said 'wiring will be very similar'. The only thing that's really different is the designators for the thermostat connection to the aquastat. Where you will have 5 and 6 on each relay wired together, they will to go T and TV on your aquastat. Obviously in addition to removing the circ from C1 and C2, you also need to move the original thermostat from T and TV and wire it to one of the relays. (and just ignore the wiring to the oil burner, as you won't be touching B1 and B2 anyway).

Grady, the E version of the 8148 is for our purposes the same 'functionally' as the J version, with the exception of the vent damper connections, and associated damper proving switches, correct ?

 

No it isn't. My "friends" will break your knee caps.


I do believe you are correct, sir.

 

so what you're saying is I need to purchase another R845A? I was hoping to avoid that. Nevertheless, If that's what I need to do, that's what I'll do. You're help is greatly appreciated. Thanks guys

 

If you can return the R845A you have, it would be much cheaper & easier to use a Taco SR502 or 503 switching relay. The SR503 is very little more than the 502 & gives you a third zone for either backup or a future zone.

 

If you do use the relays, this one is supposed to be a universal replacement for the 845 and is a bit cheaper too.

R8845U $56.00

Honeywell info

I've never used one, just info FYI.

 

I did second zone on Burnham gas boiler fully automatic.Each t-stat controlling own zone not interrupting other. You don't need expensive 503 box or other relay box. Primary zone wiring stays as is. Second zone relay normal wiring: thermostat on T-T terminals, load 1(hot)-2 , circ. 2-3 , jump 1-4, 5-6 terminals now is your "thermostat",it is little tricky find the points where to connect second zone "thermostat" You need read and understand electric diagram. For sample: on Burnham Series 2, model B, you connect to Y and P terminals.
Didn't try on other boilers, but believe it is possible to do.

 

Thanks, but this thread being almost three years old, I'm pretty sure the original poster has finished whatever he decided to do...