Oil Burner in Vacant House

I don't have much experience with oil furnaces [only coal] and have a vacant house that I am selling with one in it. I am trying to maintain just enough heat in the house to avoid frozen pipes. I am assuming? the furnace will continue to run to keep the boiler temperature up for domestic water, regardless of the thermostat setting.

Is there a way to adjust the furnace, aquistat, etc, so that the furnace will only run if the thermostat calls for heat?

Thanks for your help.
Dave

Dave,
if the house is vacant, there won't be any domestic water demand so the unit should only run to satisfy the thermostat. Any standby loss will be insignificant. You could turn down the aquastat some to save alittle oil. It's probably at 180-190 for DHW. Try 160.

Inherited Axeman 130 wrote:I don't have much experience with oil furnaces [only coal] and have a vacant house that I am selling with one in it. I am trying to maintain just enough heat in the house to avoid frozen pipes. I am assuming? the furnace will continue to run to keep the boiler temperature up for domestic water, regardless of the thermostat setting.

Is there a way to adjust the furnace, aquistat, etc, so that the furnace will only run if the thermostat calls for heat?

Thanks for your help.
Dave

No, it needs to maintain the water temp. You can turn the settings on the aquastat down to 130*-150* for the low and high setpoints, I would go no lower because when it gets real cold it may not be able to keep up. What you really want, and will probably be a cheap and easy fix, is a thermostat that can go down to about 35* or 40*. That way it will run the minimum amount to keep everything in the home from freezing. I would set it at about 40* for starters and check the house out on a very cold day. A 25-30* drop in the homes temperature setpoint will be a HUGE savings.

If the boiler is set up for DHW with an internal coil it will always want to maintain temp within some window (controlled by the aquastat) However if you don't have a DHW coil you can set it up as a "cold start" boiler and it will only run when a heating thermostat calls for heat and stop when either the the heating thermostat or aquastat reaches temp. When I installed my boiler I had the option to wire it as a cold start boiler...
Bryan

I would offer a caution--assuming that you have not drained the supply pipes and put anti-freeze in the drain traps--you don't want to lower the thermostat to a point that you get freezing temperatures under sinks located on outside walls or in pipes located in or near an outside wall. The temperature setting needed will vary depending on the insulation in outside walls, the tightness of the house, and the specific location of pipes. If pipes are poorly located, there are significant air leaks, and/or insulation is poor lowering the temperature only 20 degrees or less might result in frozen pipes.

Thanks for all your help. Have a great day!!

As per the manual, I disconnected the "low limit" wire inside my aquastat to make it a cold start boiler. Now it only runs with the thermostat calls for heat.

markviii wrote:As per the manual, I disconnected the "low limit" wire inside my aquastat to make it a cold start boiler. Now it only runs with the thermostat calls for heat.

Is that relatively easy to do?
Thanks

My opinion on this issue would be not to go below 40 for a room temp set point, and also I wouldn't go below 140-150 for a low limit setting on the boiler due to the risk of condensation which can waste a boiler quicker if its cast iron. Also if you set it up for cold start you will loose the heat in the boiler area and possiably risk freezing lines.... the little bit of heat loss may save your lines. I can tell you my Honeywell controller won't go below 40 because of built in freeze protection that also runs the all the pumps and boiler on high fire for 2-3mins if it's been over 3 hours for a call for heat.