Electric is probably the most expensive method of heating that there is. You need to do some serious price investigation before you make this switch.

Boiler is a Burnham RS109. It was serviced late fall, no issues noted. It had been working without issues until yesterday morning. We noticed there was no heat. The blower was on (vented thru wall), but there was no flame. We pressed the relay button and it turned on and stayed on, but last night it happened again. The thermostat call for heat, the blower starts but there's no flame until we press the relay. It doesn't turn off after a while so apparently is no a cad cell issue. It stays on until it reaches the temp the thermostat is calling for. But apparently after some hours, it's unable to turn on automatically as needed. What could be wrong? We checked the cad cell, the electrodes, the motor and oil pump. Could it be the relay? Thanks!

The first issue is why is there any smell from the oil burner. I think there should be none if the burner is operating correctly. The attic fan is pulling the fumes into the house so your nose is more aware of it. I don't own an oil burner, so perhaps those that do can give their opinion on this issue. The attic fan is pulling is creating negative air pressure. That means you don't have enough air coming in through the attic vents. Does the attic have soffit openings and if so are they clear? The attic fan is pulling conditioned air out of your house. This basically negates any savings you are getting from a cooler attic. You need to look into this if you want to run the attic fan in the summer. Does the oil burner need to operate in the summer for hot water production? Keeping the window open is going to let in humid air and your dehumidifier will run constantly. I recommend keeping the windows closed whenever the AC is operating.

I don't think there are many people on this forum who can answer your question. Therefore why not buy the original filter? They are readily available and cheaper than the one you bought and modified.