Modine unit heater issues

[Bretny]

I got this used heater about 2 years ago. Its had small issues. Randomly i will find it blowing cold air with the fan on or the pilot light out.

I cleaned it last year and it seamed to help but only for a short while. I did turn up the piot a bit and aim it at the thermocouple better. It also makes this horrible humm noise on cold start up.

What issue should i tackle first and how?

Its hooked to a 100lb bottle with 10ft of 1/2in black pipe and 12in of yellow flex line.

 

[D45]

Any blinking fault codes on the panel?

Are you certain the heater has been converted to propane?

 

[Bretny]

I think this unit is to old to have blinking codes. Yes it was bought at a green house that i know the area didnt have NG.

 

[polexican23]

my dad has a couple of those in his greenhouse and the old thermostats are hard to come by that will last a season for some reason.

 

[naturalgas]

Turning the pilot up will only make it burn lazy and yellow creating a sooty mess. You need to take the pilot out and clean it good.Or sometimes you can get away with disconnect pilot line at valve and blow compressed air through the pilot line. The pilot should be sharp and crisp for lack of another word to describe.


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[LS6 Tommy]

A lot of them hum on a cold startup. Clean the pilot like described above and replace the thermocouple.

Tommy

 

[Bretny]

That is how i cleaned the pilot. Even poked the hole a bit with a piece of copper stranded wire. This pilot has a flame cup over it so it is better directed at the thermocouple. Turning up the pilot just made the flame bigger not any more yellow.
The thermostat is just a regular 24v home one.

 

[naturalgas]

Ok so the pilot is on and thermostat is calling for heat, check for 24v at gas valve. If you have power to gas valve and not opening the gas valve is no good. If no 24v at valve follow the path from transformer and see where you are losing the 24v. Start with jumping out the thermostat to see if that is your problem


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[naturalgas]

That is a pretty basic heater with a standing pilot. Not much going on there.


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[Bretny]

Thank you.
Once restarted the pilot the heater works normaly.

 

[bobbyjean]

so..... could it just be a bad thermocouple? may be worth a few bucks to try and change out

 

[naturalgas]

Yes you need a new thermocouple. They will get weak and hold the pilot on for awhile then drop out. Eventually it will not hold the pilot on at all. Change it out and you should be good .


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[Bretny]

Ok thanks guys

 

[Bretny]

I replaced the thermostat last week with a t87 or what ever that round one is. I wanted to do this anyway due to the programable one not working in cold temps...well that wasnt the problem. It did run fine for about a week until i came into it blowing cold air.
I have a thermocouple im going to put in tonight.

Is there any other reason for this to have the fan on and blowing cold air with the pilot out? Possibly got snuffed out on start up and the time delay for the fan still went on as if it was hot?

 

[Bretny]

New thermocouple installed. This time i was in the garage when it went out. What it sounded like was a small explosion that put out the pilot and the fan still comes on. So could this thing be setup for natural gas and still run like this on propane?

 

[Bretny]

Anyone know what could be going on with this heater? Not getting out of the teens this week and colder at night.

 

[ljhhontx]

Could be preignition gas that blows the pilot out, in other words for some reason the pilot is not able to light the burner until gas has built up in the combustion chamber, it could be the regulator built into the combo valve on the unit or possible the reg at the propane source. It is a momentary problem, the reg will flow the correct pressure normally but will creep up in pressure when the unit is off, sometimes this is intermmittent and hard to diagnose.

 

[naturalgas]

That’s delayed ignition. Gas is building up in unit before pilot lites it off. Boom! Will knock pilot out. Take all the burners out clean them up, dump the **** that’s build up inside them make sure you have the right size orifices for burners and pilot. Then a good clean unit and pilot it should run nice and smooth


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[Bretny]

Thanks guys il check that tonight. I dont think i have ever cleaned the actual burner tubes. Only the pilot tube.

 

[walta]

Sounds like 2 separate faults to me

1 Carefully inspect the heat exchanger near the pilot you may find a hole that allows the fan to blow thru the hole and put out the pilot.

2 If the fan is running and the heat exchanger is less than 120° the thermo switch for the fan is bad.


Walt

 

[Bretny]

As far as i can tell this is a modine pa50. It uses a time delay relay and not a thermo switch to turn on the fan.
I blew out the burner tube while it was still in the unit. I got alot of **** out of it so most likely the problem. Il remove it from the unit in the next few days to give it a proper cleaning.

 

[naturalgas]

That’s right fan is on time delay. Will come on whether burner comes on or not. You should take the burners out and put them vertically and you’ll be surprised at all the **** that will fall out.Then vacuum the end of burner.


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[Bretny]

Got the burner removed last night and it looked good until i took a light and looked down in the burner that connects all the main tubes. The ones around the pilot were prety much clogged with rust. I took a small drill and cleaned them out. That burner looks alot more healthy now. If it fixed the problen idk yet. The outside temp was 3* this morning so after work i will check.

 

[Bretny]

Heater is fixed. Must have been the rust clogged secondary burners.

 

[naturalgas]

There you go nicely done


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