Oil Burn Delay

GordoB

I recently installed a outdoor wood boiler at my house. Previously the main heat source for the house was a Buderus G215 oil furnace controlled by a Honeywell L7224A,C aquastat and a Taco SR503 switching relay. The system runs forced hot water through old steam radiators. I have the outdoor boiler plumbed through a heat exchanger located on the water return pipe to the oil furnace, so water entering the oil furnace is heated by the outdoor unit. The high limit on the Honeywell aquastat is set at 140F (the lowest possible setting) The outdoor unit cycles between 140F and 185F. My intention is for the oil furnace to only come on if the outdoor unit is not producing sufficient heat (below 140F). This should also protect the outdoor unit from freezing if the fire were to be out for an extended time, because the warm return water (after passing through the radiators) would go through the heat exchanger and heat the loop for the out door unit. This system seems to be working with one glitch. The oil furnace runs for a few minutes every time the thermostat calls for heat, without the zone circulator pumps running, the water in the oil furnace drops below the high limit (140F). After the zone pump has been on for a couple of minutes the oil burner shuts off. My question is: Is it possible to delay the oil burner until the zone circulator has been on for say, 5 minutes? That way the oil would only kick on if it is really needed.

iix

http://www.icmcontrols.com/TIME-DELAY-RELAYS-DELAY-ON-MAKE-DOM-Prodlist.html