How to wire a Hydrostat 3250

seized123

My new Weil-McLain WGO came with an already mounted Hydrostat 3250 high limit/lwco etc. Boiler’s not installed yet, but I’d like to have my ducks in a row ahead of time. Photos below.

Question 1 (dumb maybe but I want to be sure): The Hydrostat came with two nice metal flex cables one of which goes to the circulator, the other must go to the primary control; it has that plastic connector at the end.

I assume I have to provide 120V via my own metal flex conduit (which I have on the old boiler). I guess I have to use a knockout on the box for that.

Anyway, inside the Hydrostat I see L2 with nothing attached; I assume the white wire from my 120 goes there. L1 has a red or pink wire that goes to the primary control, also at L1 is a black wire that curves over to a switch at upper right of photo (the Hydrostat also acts as a service switch.) From the other side of the switch (bright red connector upper right of photo) is a black wire not connected to anything. I assume that goes to my 120 via wire nut (it’s braided wire but I assume that’s okay?).

Question 2: The Hydrostat gives you all these options if you have an indirect hw heater. They involve hooking the indirect hw heater’s zone valve wires to ZR and ZC and clicking a switch to “I”. They even say if you have multiple zones you need a separate dpdt relay switch (#6 in the instructions below)? My indirect is currently hooked up to all the other zone valve wiring, with just two wires going from them to TT in my current limit control. I have enough to worry about, so I figure it’s okay to leave it that way for now and pick option 1 in the instructions, treating the indirect as just another zone for now. Does that seem okay?

It’s a 5-zone one circulator system, which includes one zone for the indirect which is currently not separated from the other zones, in that they are all connected together before going to TT, so any one of them activated sends a signal to the limit control. Honeywell 8043E zone valves.

In the photo, just below the yellow coil it’s L1 L2 C2 C1, the row to the right of that is B1 B2 ZC ZR. You can see B1 (Bk ) and B2 (W) and ground (Gn) and L1 (R or Pk) going to the conduit at lower left, which’ll go to the primary control ; C2 (W) and C1 (yw) to the other conduit.

I include pictures for the manual for those who’d like to give themselves a headache.

leonz

I have had 2 of them fail and 1 will never allow them to be used in my home. The system has a single bulb that is also used as the low water cut off sensor.

The Honeywell L8124L mechanical triple aquastats are still available and so are direct immersion low water cut off sensors from Bell & Gosset; the model I have is the RB122-E LWCO. My thermocouple bulb is immersed in the Honeywell paste and I have had no issues with either the L8124L triple aquastat or the RB-122-E LWCO in 7 years of use.

My thoughts anyway as a plumber friend told me the digital triple aquastats are not reliable as yet.

HVACNUT

You can leave all as is and wire it like diagram 1, bringing the Reds to TT.

You need to turn the Economy setting to Off, though. If Economy is on, boiler temperature might not be high enough to meet the demand of the indirect.

Like you said, you can do it later. A RIB relay mounted right at the 1900 box on the boiler, and little 4 conductor thermostat wire, and done.

And this new boiler will be commissioned by a pro, who has everything a pro should have to test the boiler and burner?

What did you wind up getting, WGO-3? New burner or existing?

seized123

@leonz I have read recently that there have been problems with the Hydrostats.

With an indirect hw heater is it true I don’t need the low limit, and does that mean I don’t need a triple aquastat? I have an L8148A on the old boiler, it’s been fine forever and I won’t throw it away. I don’t think it has any kind of low limit. But I’m sure it doesn’t have an lwco and I’ve been wanting one. I looked at the RB122-E and saw you can mount it to a riser. Cool.

Since this Hydrostat came with the new boiler I’ll use it at least to get things up and running, with an option to switch to something else later.

@HVACNUT thanks, yes I’ll put Economy on Off. I think I also set the low limit to zero, or Off. or whatever.

Well, I don’t know what a RIB relay or a 1900 box is, but I’m sure I’ll be looking it up if I ever do that stuff.

Got the WGO-3 which is now sitting in my garage and I just started detaching the old one. I’m keeping the old burner as is; it has new stuff on it and will get more. What I ordered was called a WGO-3R which turns out to be exactly the same as a 3; if you choose to use a smaller nozzle and appropriate head it “becomes” a 3R. For now I’m leaving things exactly the same, so 3.

What I may do if I make it through all the hurdles and obstacles of installation is then replace the old nozzle with an identical new one (.85 70B), clean and gap the electrodes and then use my new old wet kit I got last year to test for smoke, draft and CO2 (but not CO) and try to adjust things and after doing all that feel like a total hero if it’s good.., but even if it’s good then call in a pro to check with the real analyzer and tweak if necessary. That’ll happen no matter what.

I might start a thread to show how it’s going and of course ask the occasional question.

HVACNUT

You can turn the Low to Off, but enable Circulator Hold Off for condensate protection.