New OWB attachment to indoor Fuel oil Boiler

[gregk]

Just got done last weekend connecting OWB to indoor fuel oil boiler,and I am trying to figure out how to keep Honeywell L8148A aquastat from kicking on.I bumped the dial down to 160 degree on the dial.I have 3 zones with 3 thermostats,and 1 circulating pump.I am using 2 brazed plate heat exchangers.1 for hot water tank,and 1 for fuel oil boiler.Hot water is circulating through both plate exchangers from OWB all the time.Any suggestions on what to do to keep aquastat from firing when zones are not calling for heat,and water temp.drops in fuel oil boiler?

 

[peakbagger]

I just put a relay on the power feed to the burner. The oil burner aquastat may ask the burner to fire but if it doesnt have juice to run it will not fire.

 

[gtmci84s]

Following.

I'm new to outdoor wood boilers this winter.

I just unplugged my burner but with some of these really windy days, I would like it if my oil burner kicked on when the wood boiler can't keep up.

Sent from my SM-G955U using Tapatalk

 

[maple1]

Need more info about your plumbing. Pics might help. If you want heat to get into your oil side when zones are not heating, the oil side of that Hx would need to be able to flow in a loop through the boiler when zone valves are closed. A separate loop.

 

[E Yoder]

I usually use either a temp controller (Ranco) or a 3 way light switch to either send the power going down to the oil burner directly to the oil burner or to a pump that circulates from ports on the oil boiler to the flat plate heat exchanger.
That way you have an either/or option. Temp controller sensing incoming OWB water temp makes it automatic.

 

[gregk]

I can get pictures this evening after work.I saw a video where i could install a T where my pressure relief valve is,and install a small strap on aquastat and install a small circulating pump to go back ahead of the return going back through the oil boiler side of my plate exchanger so that the strap on aquastat would kick on the circulatating pump to just loop back to boiler while no zones are calling for heat.does this sound like the easiest way to resolve the issue?I still want my boiler to kick on if the OWB would happen to run out of wood,or some problem with the OWB.

 

[maple1]

Something like that sounds reasonable. That new stat would feel the temps of your OWB line, and whenever it is hot, it would run the new pump.

 

[gregk]

Here are pictures are what I have plumbed in.I would like to know the best way for me to make a loop,or circulate the water in my boiler through the plate exchanger so my aquastat at the fuel oil boiler does not kick on unless the wood boiler goes out.THANKS for any,and all help.

 

[btarby15]

Just got done last weekend connecting OWB to indoor fuel oil boiler,and I am trying to figure out how to keep Honeywell L8148A aquastat from kicking on.I bumped the dial down to 160 degree on the dial.I have 3 zones with 3 thermostats,and 1 circulating pump.I am using 2 brazed plate heat exchangers.1 for hot water tank,and 1 for fuel oil boiler.Hot water is circulating through both plate exchangers from OWB all the time.Any suggestions on what to do to keep aquastat from firing when zones are not calling for heat,and water temp.drops in fuel oil boiler?

I set my high limit on oil boiler to 140 and low limit at 120 and oil burner doesn't kick on. But it can depend on your system. I have cast iron radiators which can still distribute decent heat at 140, if my OWB goes out.

 

[gregk]

I set my high limit on oil boiler to 140 and low limit at 120 and oil burner doesn't kick on. But it can depend on your system. I have cast iron radiators which can still distribute decent heat at 140, if my OWB goes out.

So my aquastat is only a high limit from what i read about the Honeywell L8148A,and it sounds like it has a 8 degree difference or something.So if I just set my aquastat to 140 I should be good to go even if the wood boiler goes out.I have hot water baseboard units.Do you have any issues in the spring and fall when you have warmer days,and no zones are calling for heat.I guess it is not a bad thing to have the fuel oil boiler kick on once in a while to make sure it still runs ok also.

 

[E Yoder]

I don't see a picture of the boiler drain. But I've teed the relief valve and boiler drain, then used those ports to pump a loop through the flat plate. Pumping out the cooler drain and putting heated water back into the relief valve tee at the top. It's kind of like it's own zone that heats the boiler.
The power going down to the oil burner can also be split (with a temp controller or aquastat, or 3 way light switch) and one leg rerouted to the new pump.
This way it keeps the oil boiler hot just as before (so it doesn't run), but heating from the flat plate.

There's more than one way to do it though.