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[gratefulgary]

I have four zones/thermostats.  One thermostat is connected to the TT terminals on the aquastat and upon a call for heat will start the oil burner.  The other three connect to circulator pumps that are triggered by the other thermostats, but are independent of the oil burner.  The aquastat is a R8182D, which I have wired for cold start.  The oil heating unit is a Burnham V-15A-T.

I want to run that one thermostat independent of the oil burner.  However, I want the oil burner to kick on when the temperature falls below some threshold I determine.  For two reasons, sometimes the OWB cannot keep up with the demand and I want the oil burner to provide a little bump.  And if for some reason the OWB fails to provide heat, e.g., the fire goes out while I'm away and have someone supposedly filling it, or, whatever.

What aquastat, contact type I presume, would you recommend and how should I wire it.  Could I wire it to start the burner at, let's say 115, and remain on to another temperature of my choosing, perhaps 150.  I don't think using a low limit only would serve my purpose.  That is, if my understanding is accurate, that would allow me to use 115, but with the max differential (25) the high temperature would be 130.

Would one of those Honeywell's that I could wire to the TT terminals work?  Or perhaps a Ranco and turn line voltage on/off to the burner, or with a 24V transformer?  How would that be connected?  There is an OWB loop, HX, and house side loop.  Hot water baseboard radiators.

Thanks guys,

Gary

[RSI]

If I read that right, one aquastat just fires the oil burner? Will it work ok if you just put a secondary control on it?

If that will work, just get a strap on aquastat (or you can use a Ranco and strap the probe on to a pipe) and attach it to the incoming OWB line. Then just put it in series with the existing aquastat. You would use the common and NO connections on the new aquastat. If you use a Ranco you will need to supply 120v to it also. No transformer is needed though, just use the common and NO connection.

Doing this will limit the max temperature that the oil boiler will go to, so if you switch over to just oil for a while you would just turn the temperature on the new aquastat higher that the normal setting on the old one it will operate normally.

I think a Ranco can be set to a 30° differential. Mechanical aquastats are available is different ranges but 20° is pretty common.

[slimjim]

A Honeywell 1018-6006C strap on aquastat can be used on the incoming wood boiler line, (copper or black iron ) to interupt B-1, simply install the aquastat on the incoming wood boiler line, set it at about 160 degrees, attatch two wires to the R+B terminals on the aquastat and run them down and interupt the B-1 wire, this kills the burner above the setpoint on the aquastat and when the wood boiler temp drops below setpoint of the aquastat the oil/gas burner returns to normal.

[SOHIO]

A Honeywell 1018-6006C strap on aquastat can be used on the incoming wood boiler line, (copper or black iron ) to interupt B-1, simply install the aquastat on the incoming wood boiler line, set it at about 160 degrees, attatch two wires to the R+B terminals on the aquastat and run them down and interupt the B-1 wire, this kills the burner above the setpoint on the aquastat and when the wood boiler temp drops below setpoint of the aquastat the oil/gas burner returns to normal.

Thanks for the clear description of how to do this, I just been pulling B1 to kill the burner but wanted to have a oil burner backup!

[slimjim]

You do understand then.

[SOHIO]

Yep!

Just have to get around and buy the stat. I'm going on vacation next month and leaving my teen son in charge of the OWB and want some peace of mind.

My oil boiler aquastat [Honeywell L8148A] is not turning on my circulators, I think the circuit board has a bad solder joint. I need to pull it out and repair/replace it.

[slimjim]

The only circ that it should turn on is the C-1 circ which is usually used in primary secondary plumbing or as a loop pump for zone valves, all zone circs should be off a switching relay, seperate from the boiler aquastat.

[SOHIO]

Its a loop pump for zone valves on my oil burner. Not the OWB.

[Tree_Killer]

attatch two wires to the R+B terminals on the aquastat and run them down and interupt the B-1 wire

When you say interrupt B-1 wire, can you clarify that?  I understand what happening and how the aquastat makes it kick on...just not how to wire it into the b-1 connection.

probably having a brain fart moment

[Tree_Killer]

Duh. Got pass the brain fart, and figured it out.

[slimjim]

Isn't it nice when it all comes together in your head.