Oil Hot Water Boiler Cycling

Burntoacrisp

1st post! Hello to all. I have a low volume oil hot water boiler, Dunkirk DPFO 3 section.

My question is currently, when there is a call for heat it will run for approximately 5-6 minutes before it hits the high and turn off. It will then fire again after water temp drops to set point for approximately 5 mins again to hit high. Is this acceptable? Should I drop a nozzle size to enable longer runs for more efficiency. It is my understanding that long continuous runs are more efficient. This is a newer well insulated home, outside temps 10-15 degrees during the cycles described above. Finned baseboard.

Thanks in advance to all who post!

Jean-David Beyer

Should I drop a nozzle size

I am a homeowner, not a heating technician.



While reducing the nozzle size will probably reduce the cycling rate, there are a couple of things to be concerned about.



Unless you are a skilled technician, in which case you would not be asking this question, you should not monkey with the nozzle size because you will need a digital combustion analyzer, and the know-how it takes, to readjust the oil burner for safe efficient operation.



The other thing is that if you make the nozzle size too small, you may not get enough heat on design day.

STEVEusaPA

Maybe you can

Depends. How is it set up now? Which burner? Nozzle size, which head, low fire baffle in? Also are you sure it's a DPFO 3, or a DFPO3T? If you have the boiler piped to protect from low temp return water, you might be able to lower the reset curve.

But based on what you posted, it's bouncing off the high limit for a few reasons--boiler oversized, too many zones, wrong size or failing circ on boiler loop.

Can you provide more details and post some pics?

Edit: it's also possible you could benefit from a buffer tank.