circumventing domestic hotwater and installing hotwater heater

I have a Burnham oil burner that supplies base board heat and domestic hot water.  To save money, due to the high price of heating oil, I circumvented the domestic coil and installed a electric hot water heater. I teed off ot the cold water line, cut and capped the hot water outlet of the domestic coil and took the hot water output from the electric water heater to the house supply line.

It now appears that the burner won't respond properly to thermostat calls for heat.  The thermostat input at the Aquastat controller is registering the state changes of both thermostats but the boiler won't stay on long enough for the temperature to rise to the thermostat set point. On a call for heat, shouldn't boiler stay on, providing heat until the temp reaches the set point.

The boiler will come on for about a minute and will then go off for about 8 minutes.  It seems to be doing this continuously. I think that the boiler comes on until the little remaining water in the domestic coil quickly heats up and then won;t respond to calls for baseboard heat from the thermostats. Is there some setup for the Aquastat or the Honeywell boiler firing  controller.  Yes, I installed the electric heater myself, I'm not a plumber but I am an electronics technician.  I would appreciated any advice.