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[murph]

I don't know if anyone out there knows anything about oil furnaces but here is my problem. It seems that every once in a while(maybe thats all I've been noticing) when one of my house thermostats calls for heat my oil furnace will come on for about 3 minutes and then shut off. This is happening even though the water in the oil furnace is over 175 degrees and is not set to come on unless it gets down to 140. Is there anything I can do to not have the furnace come on ? I'm not sure why the oil furnace wants to come on. Has anyone else had this problem?

Thanks
Murph

[charlie]

Murph,
 Go to "HEATING HELP.COM". Post on there. Click on "WELCOME" at the top. Next you will see"THE WALL". Read that paragraph , it will tell you how to post a question. They will get back to you in a few hours. Hope this helps. Might just be the thermostat going bad. Charlie

[yoderheating]

 It may be a heat senser in the oil furnace is doing that.

[ckbetz]

Your thermostat inside the house tells the furnace to kick on.  It really doesn't know how to keep the oil burner from kicking on unless you have 2 thermostats.  The thermostat wired directly to your oil furnace will tell the entire system to kick on as a back up.  It will be set a couple degrees lower than a new one put in just to tell the fan or pump of your inside system to kick on.  You really need two thermostats to keep your oil furnace from kicking on unless you turn the oil burner off and just let the fan work.  But, some systems won't work unless the burner is left in the on position.

[murph]

ckbetz,    I have 4 thermostats and I have forced hot water (baseboard). I'm not sure what difference it makes but I thought the oil furnace turned on when water temp in oil furnace got to a specific set point, which happens to be 30 degrees lower than the water actually is. Its strange but it only happens once in a while and the oil furnace only runs about 2 -3 minutes. Do you think its a specific thermostat that may be causing this to happen when its calling for heat? Also, I can't just shut off oil furnace without shutting off the circulating pump at the oil furnace.

Thanks

Murph

[willieG]

im not familiar with these types of systems but it sounds like your thermostats (you say you have 4) should be operating zone valves that control the flow of water not the temp of your water? i would look to (perhaps) an aquastat that is going bad? from your description, sounds like your furnace is shutting down the boiler at the proper temp but starting early (sometimes) if i was in this situation and i was going to trial and error my own fix (not willing to pay the licensed expert and probaly save money) i would start with the aquastat

[ckbetz]

Wow Murph, 4 thermostats.  It sounds like you have a fairly complex system with different zones.  I would think it would have to be something in the backup thermostat calling for heat from your oil furnace but without knowing your system it would be very difficult and only supposition on my part.  Charlie had a great idea about going to "The Wall" on heating help.   I've spent hours on the wall trying to make my system run better and more efficiently.  http://www.heatinghelp.com/

Before anyone there answers your question they'll asked you specifics about your system like what kind of thermostat, how many zones, what kind of oil furnace, etc.  Be ready for that.  Let us know here what you come up with.  That will also help grow this site since there isn't really a great source for information specific to the OWB world.  Good luck.

[sstan]

Just for info .. I also have this problem (unless I disconnect the burner) .. oil burnner has 4 zones (one for domestic HW) each with it's own pump.  The zones thermostat does notihing but turn the pumps on or off.  There is a sensor in the burrners water jacket that was set at 180 deg...  In my set up there is no pump in the oil side that runs constantly .. only when one of the house zones ciome on does the water circulate through the heat exchanger to pick up heat... if no zones are calling for heat .. no pumps run .. no heat picked up and eventually the temp of the water in the oil burner goes low enough to kick on the oil burner.  first year for my set up so you'll have to ask at the end of the year on how it works!!

[MD20/20]

How is it working many years later?  I have a similar set-up.