Intertherm MAC 1265 Oil Furnace (1980)

Questions about repairs and parts for other brands of furnaces and air conditioners. Please note that our speciality is Coleman and Nordyne products, so our knowledge of other brands may be limited.

Moderators: Greg, Mark

Posts: 1
Joined: Tue Nov 22, 2011 11:20 pm

Hi, initially had problem getting this furnace in our new place to start.Got furnace repair man out, and when he appeared to have no answer got him to check the pipe going into the tank and he found it was too short to access the remaining oil in the tank. After extending the line and bypassing the safety switch, which kicks in after 30 seconds, he was able to restart the furnace. Problem is we attempted to extend the line in the tank further and in doing so seemed to interfere with the pressurized system. It fires up but doesn't seem to run long enough to get the oil pumping properly (rechecked the line and the oil is running through fine). So are thinking we need to bypass the safety switch as was done before to complete the process, but don't know exactly how he did it. We think the pressure is sensitive as the tank recommends lines coming from the bottom, but everything connects at the top. Would like advice as to how by bypass the safety switch as believe it should be safe in this situation. Need advice ASAP as cold out! Thanks.
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Posts: 5696
Joined: Wed Feb 28, 2007 8:01 pm
Location: Weedsport, NY

Hi & welcome. this is old school system so I'll try to help.

First, using the top mount pipe is actually a better system, crud settles to the bottom of the tank and the bottom tubes suck the crud into the filter and plugs the filter (usually around midnight on the coldest day of the year). You need to make sure there are NO leaks in the system, it is like sucking through a straw with a hole in the side if there is.

You should be able to pull the door safety switch out to bleed the system. If the system will not bleed then you are out of fuel, have a leak in the suction to the tank or have a bad pump.

"If I can't fix it, I can screw it up so bad no one else can either."