Using condensate pump to shut off Maytag MGF1RC furnace

Dave_61

We just moved into a house with a Maytag MGF1RC100C furnace. It is AFUE 92.1%. Looking at it, I noticed the condensate pump is wired so that if the pump malfunctions, it will cut power to the thermostat and shut off everything.



The basement is unfinished.



I have a couple questions. Is this a condensing furnace? Does it produce a fair amount of condensate when heating? Our Aprilaire 400 humidifier that should not normally drain water into pump.



I don't want the entire heating system to shut down if the pump malfunctions. If we were away in winter, I would not want heat to shut off and potentially freeze pipes. Is there a better way to wire it into control board of furnace? Maybe in series with Y wire from a/c?



Would a/c be the main contributor to condensate?

Thanks

Jamie Hall

I can't find

that particular furnace.  However... if it is rated at 92.1%, then it pretty well has to be a condensing furnace.  And if it is a condensing furnace, it will indeed produce a fair amount of condensate when it is running.  Comparable to the amount of fuel it burns, in fact.



You don't want that condensate to back up somewhere -- it has to drain to something, and if it can't drain by gravity, then you have to pump it somewhere.  Therefore, if the pump quits, you really do want the thing to shut down before it floods itself.



Welcome to the wonderful world of condensing furnaces and boilers.



What type of system is this?  Hot air?  Hydronic?  If it's hydronic, you can at least protect the heating system, albeit with some nuisance and complexity.

Dave_61

Pump

Jamie,

It is forced hot air. I like the idea of the safety, but we go away in the winter, and the thought of the heat going out due to a bum condensate pump scares me. I would rather have water on the concrete floor than frozen water pipes.

Jamie Hall

Well then...

can't say I totally blame you about being concerned about the heat going out when you are not there -- although there are a number of other, much more likely reasons why it might do so than a condensate pump failure.  I would very very strongly recommend that if you are going to be away in the winter for a significant length of time that you either have a trusted individual who will (really will) check your house for such problems on a daily basis, and do something about the problem if there is one -- and figure out what to do when there is a power failure -- or that you drain the house plumbing and shut off the water when you go away.



If the condensate can freely drain -- for instance, onto the floor -- without backing up into the breaching or the combustion chamber, I suppose you could get away with it.  I would not be willing to bypass that particularly safety (or any other safety for that matter) and I'd be kind of surprised if you could find a contractor who would do it, either.



I might point out that the resulting puddle would be pretty strong acid, and would not be good for the concrete floor, to put it mildly...

Dave_61

That makes sense, but

What if I instead interrupted just the wire for the heat and allowed thermostat to function if pump shut down? My reasoning is that I have a wifi thermostat that would send an alert if heat was out. So, if pump malfunctions, furnace does not run but thermostat stays powered. Of course, this would do nothing to shut things down if a/c was on and pump died.