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MagiicAir
MagiicAir, HVAC Technician
Category: HVAC
Satisfied Customers: 110
Experience:  20+ years Commercial and Residential Systems
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Ive been working on a Carrier 58MVB060-F-12114 Furnace for

Resolved Question:

I've been working on a Carrier 58MVB060-F-12114 Furnace for the last couple days. The furnace would fire just in, nice straight blue flame with no hickups. After about 10-15mins the furnace would cut out and the board would show (LED) a "code 34 - Ignition Proof Fault." This problem will repeat and even fail on a code 14 eventually.

Gas pressure is acceptable to nameplate and componets all appear fine. Ground was fine, and even relocated. The unit is only 1 maybe 2 years old. Flame sensor was checked and even cleaned. I spoke with 3 Carrier service reps on the phone. First person told me to replace the board. The board was replaced and it failed again. Another told me to replace the electrode, so I replaced the flame sensor and still unit failed.

I had to pack up and do some research and ask some of my seniors. The next day I returned and tried a couple other things. I monitored the unit for 2 hours and it didn't fail once. Several hours later I got called back from the customer and the furnace was doing the same thing again.

The furnace is undersized for the buildng for 1, but shouldn't be a big deal, just take longer to heat the space. I live in BC, and lately it's been getting below 0'C and it almost appears that the unit fails when the ambient temp goes below freezing, otherwise I have no idea what the problem could be as it is intermitten. I suspect that it may not be the actual unit, but the venting that could be causing the problem.

Like I said, it runs fine for a number of minutes even hours and then will cut out all of a sudden and show an ignition fault. Can you give me any suggestions?
Submitted: 6 years ago.
Category: HVAC
Expert:  MagiicAir replied 6 years ago.

MagiicAir :

ill see if i cant assist you here.

MagiicAir :

two possibilities here

MagiicAir :

one and most common, is the roof cap for the exhaust vent is gone and wind is causing ill effect on the pilot sensor.

MagiicAir :

the second is the polarity of the wiring from the breaker panel is wrong. Sometimes you can switch the power leads comming in to that furnace and solve the problem

MagiicAir :

most techs dont bother to check polarity and this becomes evident as the unit gets older

Customer:

hi there! The exhaust actually is actually exhausting out horizontally, but come to think of it, it didn't have any cap or anything to prevent wind

Customer:

wind could be pushing the flu back into

MagiicAir :

ok, there is your problem exactly

MagiicAir :

you need to buy a proper side discharge cap for it

Customer:

I don't want to use that as an excuse though, but I'll see if I can put something over it and see if it solves the problem

MagiicAir :

if that vent is open, it requires a cap by code here in the states

MagiicAir :

and yes that will definately cause your issue

Customer:

it has a guard over it

Customer:

but no cap

MagiicAir :

you mean like a mesh?

Customer:

I don't do any residential really, but I imagine the rules are the same here in Canada, I'll have to read up on that

Customer:

yeah mesh

MagiicAir :

is this pvc pipe?

Customer:

yes

MagiicAir :

i would suggest you add a 90 downturned elbow

MagiicAir :

and then cover that with the mesh

Customer:

yeah the problem seems intermittend

Customer:

almost like whenever it went below freezing it would drop out

Customer:

but I would just find it very odd that the unit would run for a good period of time, and then fail on ignition

MagiicAir :

not uncommon at all

Customer:

well that's great to hear

Customer:

I figured it was something to do with the venting

Customer:

the unit appears ok

Customer:

and I don't think it's the supply voltage

MagiicAir :

stick a 90 on that pipe and i bet your problem goes away

Customer:

I'll give it a shot.

MagiicAir :

and its not a matter of voltage really, its the polarity of that voltage

Customer:

Thanks so much for your time

Customer:

even single phase?

MagiicAir :

one side is hot which should connect to the black wire, and the other side is neutral and should be on the white wire

MagiicAir :

single phase is the only place you have this issue really

Customer:

yeah that's how it's wired

MagiicAir :

in 3 phase it just affects direction of flow

Customer:

yeah

Customer:

ok well I'm pretty sure it's the venting

Customer:

but if not, I'll try the polarity

MagiicAir :

im inclined to believe the same thing. vent

MagiicAir :

may even have a critter that is dead inside the pipe

MagiicAir :

thats another issue i see on those systems

MagiicAir :

rats

Customer:

and they would get into the pvc even with a mesh cover?

MagiicAir :

but with the mesh thats kinda unlikely

Customer:

I don't deal with residential, only commercial and industrial

Customer:

awesome

Customer:

I appreciate your input

MagiicAir :

i normally do ems systems and Lieberts

MagiicAir :

amd good luck

Customer:

Thanks!

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