Reducing hot air oil burner temperature overshoots set

[bdymnjm]

If I set the thermostat up say for example from 68 to 72*F the temp will go to 80. Its a hot air oil burner. I hear the burner shut down but before it finishes the cool down the temp keeps rising. It isn't a new problem I just wonder if I can make it less drastic. I did try swapping to the old manual Honeywell thermostat from a cheap programmable and it didn't make a difference that I could notice. Today its 40* and sunny. Sunny makes it worse.

Jim

 

[ctfjr]

try lowering your fan & limit settings, both the fan (so it turns on at a lower temp) and the high limit (so it doesn't let the heat exchanger get as hot).

 

[pstnbly]

The heat anticipator setting on the thermostat needs to be adjusted.

 

[Rookie2]

The heat anticipator setting on the thermostat needs to be adjusted.

ditto

 

[bdymnjm]

Thank you for the advice, I will try something when I get time. I see we are going to have warm temps this week. The fan settings are about 100, 140, 200 I think. The settings on fan and thermostat probably are the same as set when furnace was installed.

 

[ctfjr]

The heat anticipator setting on the thermostat needs to be adjusted.

Good pickup. But it would be hard to believe the gross amount of overshoot is due to the anticipator setting. In the worst case if you had no anticipator you might get 1 or 2 degrees overshoot. Sounds like he is getting >10 deg, a boatload.

With the settings he has now the fan doesn't turn on until 140 and the high limit is 200. He may actually be getting to 180, who knows but that's pretty damn hot. His fan isn't turning off until it drops to 100. That's going to drop a lot of heat into the space on burner shut down.

I would wonder if his furnace isn't over sized to boot.

 

[LS6 Tommy]

The heat anticipator setting on the thermostat needs to be adjusted.

I've never seen a fan/limit cause more than a few degrees overshoot. The stat should shut the burner off LONG before you hit the limit


^^^THIS.^^^

Tommy

 

[pstnbly]

Good pickup. But it would be hard to believe the gross amount of overshoot is due to the anticipator setting. In the worst case if you had no anticipator you might get 1 or 2 degrees overshoot. Sounds like he is getting >10 deg, a boatload.

With the settings he has now the fan doesn't turn on until 140 and the high limit is 200. He may actually be getting to 180, who knows but that's pretty damn hot. His fan isn't turning off until it drops to 100. That's going to drop a lot of heat into the space on burner shut down.

I would wonder if his furnace isn't over sized to boot.

I would tend to agree with all your statements, but you need to start somewhere.

 

[bdymnjm]

Thank you all for the replies! I didn't change anything yet. I do think the furnace is oversized. What are the typical fan limit settings?

Jim