Oil Boiler as backup (control help)

[u4015]

I have my oil boiler set as my backup boiler to my PB-105. The general configuration is the PB goes into the input of the OB, then through output of the OB to my Taco zone valves (7), returns to the main manifold and goes to the input of the PB. There is one Taco circulator that is tripped by the call of any of the 7 zone valves to circulate the water. The problem is whenever my t-stats call to trigger my zone valves my OB is tripped. I can get around this by using a bypass switch to the OB burner, but then obvoiusly it won't function as a backup.

This is what I've done to date: - created a bypass for the OB burner only (temporary)
- set my min to 120 and max to 140 on the OB
- set my min to 145 and max to 165 on the PB-105
- set my Buderus S-120 HW storage heater to 135

Is there a jumper or something for the Honeywell T8182D 1145 (RS & RMS) TT on the oil burner, so it will only trip on water temp not a call from the t-stat.

Thanks

Bob

 

[RJP Electric]

I had a tipple aquastat control too. I put a toggle switch in because there was no way I want the oil to kick on automatically.
In your case the PB-105 pumps water through your oil boiler until up to temperature correct? If I was going to do it this is what I would do, I would return all the temperature settings you listed above to original normal settings and do this. Disconnect B1 from from controller and run a 2 wire switch leg and connect a strap on aquastat on a pipe near PB-105 and set the desired temperature (Honeywell L6006C1018) . If PB runs out of fuel, the pipes cool down, aquastat closes and the oil fires.

 

[u4015]

I found out there is a 3 wire connection to the Diff portion of the honeywell controler. If you remove the center wire (blue) it disables the DWH setting on the tankless coil. In theory this should bypass the instant call to the TT and solve the problem. I've had time to do a couple of checks and the zone valves are able to call with out the oil boiler firing. I'll keep you posted.

My fingers are crossed this is too easy an answer.

As a side note the outside air temp sensor on my PB-105 was disconnected and I appear to be getting normal temp readings and the status light will now go out (less pellets consumed). I don't understand the concept of 3 independant controls, feed rate, outside air temp and min and max on the control board. This seems like asking for trouble.

Thanks
Bob

 

[RJP Electric]

OK, I see what is going in now. By cutting that blue wire also disables the low limit and will turn your it into a cold start controller too. Just keep the HI on the oil lower than the LO on the PB. Good luck! I seen pellets as much as 350 a ton up here, I hope it saves you $.