You need to explain yourself clearer. You probably have the boilers in series and it should have its own triple aquastat. Tell me more. I have the same system.

Yes they sit side by side/in series.

I have added a switch so that I can turn off the oil burner, in order to use wood heat only.

I would like to add an aquastat in order to monitor the oil boiler water temp and shut off the circulator when the water reaches a specified temperature.

Right now the circulator will just keep running and will reduce the oil boiler water temperature to a very low temp..

When I get up in the morning and restart a wood fire I have to again bring the oil boiler water up to temp-which is a slow process.

Hope that helps.

Does the oil boiler supply hot water to your heating zones and does the wood boiler supply hot water to the oil boiler in a continuous circulation setup?

If so, your problem is that the circulator doesn't shut down on the oil boiler when it reaches a low limit??? or does the circulator never shut down?

Does the wood boiler shut down when it reaches its low limit?

1-yes /yes..continuous circ setup.

2-no/yes it never shuts down

3yes wood boiler circ. shuts down at it's low limit

Does the wood boiler have two aquastats? One will control its own circulator and the other will control a circulator or zone valve on the oil boiler as a "dump" zone?

The oil boiler's aquastat is supposed to shut down its circulator when the water temperature goes below the low limit. What is the model number of your oil boiler's aquastat?

What is the model number(s) of the wood boiler's aquastat(s)?

YES...Yes

oil= #L6000A 1145 (turns burner off when water reaches preset temperature)

both Wood aquastats are the same number= #L4006B 1007

On the wood boiler, the one B aquastat turns ON its circulator on a temperature rise. The other B aquastat controls a zone valve OR an (oil unit) circulator, (possibly thru an R845 relay) The first B should be set around 160; the second B should be just slightly higher. It will then shut down the zone valve, which in turn will shut down the oil boiler circulator and preserve the oil boiler water at about 160.

First you have to determine what that second B aquastat's function is. B aquastats always allow power on a temperature rise and stop power on a temperature drop. To calibrate the second aquastat, turn the knob so that it clicks internally, a minute after the first aquastat B shuts off the wood boiler circulator on a temperature drop.

This is a dump zone and a safety feature. If the aquastats use more than 24V, get an electrician to adjust them.

More later.

Your oil boiler has a single A aquastat? An A aquastat loses electric upon a temperature rise. This would work to shut down the oil burner when the desired boiler temperature is reached. I assume there is no domestic water coil in the boiler because that requires a B aquastat and I have no idea what controls the oil boiler circulator. There must be another B aquastat somewhere. If you added a B aquastat, it would shut down the circulator upon a temperature drop.

So, with both aquastats, the oil burner shuts down at a certain temp, let's say 160 and the circulator shuts down via a B aquastat at 150, for example.

yes-one aquastat on the oil boiler.

correct-no domestic hot water coil in the oil boiler.

where would i look for another aquastat on the oil boiler?

how do i set up a b-aquastat to shut down the circulator on water temp drop?

http://www.inspectapedia.com/heat/Honeywell_L6006A_Aquastat.pdf

Read the link above to understand the operation of your oil boiler's 6006A. Page 3

At the setting on the degrees wheel your burner will shut down on maintenance or keep running if the thermostat is calling for heat. At the same time the circulator will start.

When the water temperature in your oil boiler drops below the dial setting, the circulator is supposed to stop and the burner should still be running.

If you have disabled your burner, the circulator should start at the dial setting and stop 10 degrees (differential) below the setting. This process continues whenever the water temperature is in that zone.

So, if your 6006A aquastat is set at 160, the circulator should stop at 150 and resume at 160. If it doesn't, the aquastat is not wired correctly, the probe isn't inserted into the well correctly, the well has contaminants on it that prevent the transfer of heat to the aquastat bulb or the aquastat is bad.

The second aquastat on your wood boiler. Is it used as a dump zone to force open a zone valve in case your thermostats are satisfied and the wood fire continues to make heat? If so, that's why it's set a little higher than the first aquastat. Set it about 5 degrees higher than the first aquastat.

I have my first B aquastat set at 150 to start circulation between boilers. The second B aquastat is set at 160 to activate my dump zone, which is really a safety, but it can be set at 200 so that it is truly a dump zone. As long as it's higher than the first B aquastat.

At my oil boiler, I have the aqustat set at 140, so that the circulator shuts down and allows hot water for my domestic coil. In your case, it just keeps the boiler from falling below 140.

Just started reading your latest post and the link to the aquastat data.

I will email the temp setting on all 3 of my aquastats when I get home to see where they are set. You may have a suggestion to change the current settings?

One thing I am confused at is that the aquastat on the oil boiler should also now be turning off the circulator at a preset temp to maintain water temp in the oil boiler.

It is not doing so and I don't understand where the setting is in the aquastat and how to change it , if necessary??

Does the fact that the burner is switched off have anything to do with the circulator not shutting off?

No, I suspect the problem is the setting of the dump zone second B aquastat. Try the settings I use and I think you'll solve the problem. If not, there is a wiring issue.

Back home and checked the 3 settings:

-oil boiler aquastat-175 degrees

-wood boiler circulator-173 degrees

-wood boiler dump-200 degrees

we set the wood boiler settings up higher this season assuming that the higher temp in the wood boiler would help keep down creosote buildup and give us a warmer chimney and a better draft flow. Seems to be working.

What are the 3 settings that you think would be ideal?

And, thanks!!

Try adjusting the oil boiler aquastat as per instructions in the pdf. Turn the dial until the circulator stops to see if it shuts down at ANY temp. The wood boiler settings are OK. If this problem started when the two boilers were joined, your oil boiler aqustat is bad or the wiring is wrong.

I will do that this evening when we fire up the wood boiler.

Correct me if I am wrong. I am assuming that once the boilers are up to full temperature and hot water is circulating, I am to use a screwdriver and slowly and progressively turn the dial to lower temeratures to see if at anypoint the circulator shuts off. Is that corrent?

I did not understand the setting with the paperclip in the pdf instructions. Was that to calibrate the aquastat itself?

What do you advise for a setting for the aquastat on the oil boiler? It's now set to 173 degrees.

Also what do you advise for the differential setting on the same oil boiler aquastat?

Is there a test for the differential setting, as well?

Yes, turn the dial till you hear a click and see what happens. I would disconnect the wires to the zone valve that the dump zone is hooked to just to test if it corrects the problem. Build a small fire during the test so the water temp doesn't go very high.

Differential can be at 20-25 without a coil.

Let the oil aquastat alone.

Think we may be getting to the source of the issue. Just took cover off the aquastat on the oil boiler. There are only 2 wires connected-black to top screw, and white to center screw. The bottom screw has no wire attached to it.

Via the pdf, it appears to be wired wrong??
Is this something I should attempt to correct?

Looks as if the first thing needed is a metal shielded cable with red, white, black and ground wires?

R-W operates the circulator. R-B operates the burner. So if the wires are hooked to R-W, your circulator should work. But if there's no wire in B, the burner must work off some other control or the installer removed the wire from B.

You're dealing with 120V possibly at the aquastat, so somebody with experience should be making the changes or troubleshooting.

I think I may be able to do this. Just looked at the wiring and have a couple of questions.

Should I be using the upper wiring diagram on pg3-figure #3?

It shows W, R, and B in decending order-is that how they need to be rewired?

Currently the black/top wire goes to the switch (that I added in last winter)that shuts down the burner and the white (center)goes to a cluster of white wires. When this burner switch is in the off position for winter, does that shut off power to the aquastat, as well?

I need to add a red wire into the aquastat. Can the red go from the bottom screw on the aquastat and be attached directly to the black wire coming from the circulator?

Will there be power to the aquastat?

I think I may be able to do this. Just looked at the wiring and have a couple of questions.

Should I be using the upper wiring diagram on pg3-figure #3?

It shows W, R, and B in decending order-is that how they need to be rewired?

Currently the black/top wire goes to the switch (that I added in last winter)that shuts down the burner and the white (center)goes to a cluster of white wires. When this burner switch is in the off position for winter, does that shut off power to the aquastat, as well?

I need to add a red wire into the aquastat. Can the red go from the bottom screw on the aquastat and be attached directly to the black wire coming from the circulator?

R being 120 V power in from the fuse box or another control. W being circulator. B being the burner. The control will make and break at the setting as shown in the upper diagram. The letters themselves are marked on the aquastat.

This aquastat only uses hot wires. Whites are usually neutral but not necessarily. That's why you need someone qualified to work with this. You shouldn't find a white wire inside there unless it's a hot wire and they usually aren't unless they're marked with black.

I am challenged by this and would love to complete the task, if possible.

The black wire going to the burner has been connected to the top/R position. It should be moved to the center/B screw?

Move white wire from the center screw to the top/R screw?

Add new wire going the to circulator to the bottom/ W screw?

Does that sound as if it will work?

On a 6006, the wire from the electrical panel or some other control box goes to screw R and is either directed to screws B or W depending upon the temperature of the boiler and the dial setting. On a temperature drop below the setting, the power is applied from Screw R to screw B, which is usually hooked to the burner and the burner turns on.

At the same time, power to screw W is dropped, shutting off the circulator. If I only wanted to use the circulator when the temperature was above the dial setting, I would only use the W screw with a wire to the circulator.

The orig wiring has the burner wire going to R,
and the white (coming from a cluster of white wires tied together) going to B. And no wire to W.

Do I need to move the 2 wires?

I tried running a wire from W to the wire going into the circulator and did not hear the circulator shut off.

I hooked up the temporary W wire, turned the oil boiler on and ran up to temp., and then turned the oil boiler aquastat dial with a screwdriver both up and down when the therostat was turned up and the the circulator was running. Circ. did not shut off.

That wiring must be coming from the primary control on the burner. You'll need somebody experienced in electricity to figure out your wiring by coming to your house and looking at it.

If you want to use that oil boiler aquastat to ONLY turn on and off the circulator, you have to either install a second aquastat or rewire the existing one. 120V Power in from the panel to R and power to the circulator from W. One black wire in and one black wire out.

Will a tech be able to rewire this oil boiler aquastat to handle both the burner and the circulator without adding a second aquastat?

Thanks so much for all of your help-greatly appreciated.
Will call in a tech to help with the wiring, as suggested.

I'm not sure why you have a white wire going to B. Anyway, is there voltage at W when the burner shuts down and the water is warm? And is there no voltage at W when the water is cool? If so, you can hook the circulator to W.

What turns on the circulator anyway? Trace that wire back.

You also have the option of an L6006C which will strap on to the supply pipe. When the supply pipe off the oil boiler is hot, the circ will start and when it is cool, it will shut down.

Will a tech be able to rewire this oil boiler aquastat to handle both the burner and the circulator without adding a second aquastat?

Thanks so much for all of your help-greatly appreciated.
Will call in a tech to help with the wiring, as suggested.

Yes, as long as he can figure out the wiring.

How did you make out on this?