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Blodgett DFG

Originally Posted by mwright

OK now I have my own mystery. Had a complaint the oven was getting up to temp then they put cold food in and it would drop. Normally it would take a few minutes to come back up but now it's not recovering at all.
Example: heat to 325 put in 5-2'x3' sheets of bacon and it would drop to 260. It wouldn't recover to 325 or would take 20 minutes.
I took it all apart and cleaned the flame sensor and HSI. Cleaned and blew out the flame tubes. Checked gas pressure and it's at 3.8 and specs call for 3.5. Just can't figure out what's causing it not to recover.
Any suggestions or insight would be greatly appreciated.
Model number is DFG-100

Thanks!!

MWRIGHT...what was the verdict for this oven? I am having the same experience (unpleasantly).
Would certainly appreciate your input on this.

ECtofix
Thanks for the list of things to check. I don't work on these very often so I don't know of "all" the things that can effect these ovens. I'll look into these things.

Originally Posted by mwright

OK now I have my own mystery. Had a complaint the oven was getting up to temp then they put cold food in and it would drop. Normally it would take a few minutes to come back up but now it's not recovering at all.

Is it calling for heat when it drops in temp?

If it does, are the burners staying on?

Is the flue vent clear/free of any debris/blockage?

Is the blower motor rotating the proper direction?

Is there anything (foil, etc.) caught in the blower wheel vanes and therefore affecting convection airflow?

Are the doors sealing properly (metal gaskets)?

Just some ideas. These are things I always check anyway when I look over a convection oven.

If you're still stumped, calling Blodgett may help. (802) 658-6600 or (800) 331-5842.

Blodgett DFG1XL/AA

OK now I have my own mystery. Had a complaint the oven was getting up to temp then they put cold food in and it would drop. Normally it would take a few minutes to come back up but now it's not recovering at all.
Example: heat to 325 put in 5-2'x3' sheets of bacon and it would drop to 260. It wouldn't recover to 325 or would take 20 minutes.
I took it all apart and cleaned the flame sensor and HSI. Cleaned and blew out the flame tubes. Checked gas pressure and it's at 3.8 and specs call for 3.5. Just can't figure out what's causing it not to recover.
Any suggestions or insight would be greatly appreciated.
Model number is DFG-100

Thanks!!

Gas Blodget ovens have these problems, generally in this order:

Pilot/Ignitor related issues- dirty flame sensor, pilot orifice or air mix holes clogged- flame doesn't hit rod fully, loose or cracked wires.

Spark module- overheating, melted blue box on the older style, and I've seen the new open ones fail a bunch too.

Motor- capacitor in the models that use it, *motor air intake clogged* (oven runs for hours, shuts itself off, comes back on all by itself in 20 minutes or so), centrifugal switch not making.

Temp potentiometer- loose shaft making for erratic temps at best.

Temp probe- after heating up a bit it might go way out of calibration, check for frayed wires at wall opening.

Door switch- always a problem on any oven.

Ive so far found that the cooling fans were CAKED with grease and dust, im going to clean them first. And follow up with all your suggestions. Thanks!

I think that this unit extinguishes its pilot when the door is opened (if memory serves me). So…you did THAT, which therefore reset the ignition module. You closed the door, it retrialed and worked properly thereafter. So…the ignition module might’ve locked out.


As stated above by ECtofix, opening the door makes the flame and also the fan to go off. The is a micro switch by the bottom corner of the door. When you open the door this switch opens cutting power to the flame and fan. This switch is sensitive and starts to get out of adjustment. Sometimes just bumping the oven can cause this switch to fail. Check it out and make sure its staying closed. Hope this helps.


Sent from my Nexus 7 using Tapatalk 2

The high limit safety is a good place to start , take your screw driver and tap on the high limit ,if your pilot drops out ,then your high limit is weak, another thing to check ,is while the unit is on start to wiggle wires around and see if the pilot goes out then ,if so you have a bad connection on the wires. Hope this helps.
Regards

What sucks about these intermittent problems is you will have 12 different techs offer you up 12 different solutions. I myself have had problems with gas valves not shutting the pilot off completely when the door is opened - so when the customer closes the door to engage the module, the module doesn't sense that the flame went out and goes into lockout mode - meanwhile the pilot will finally go out, the customer will open and slam the door, which is basically resetting the module, and turning the oven back on. Thats when the customer says, "I had to slam the door shut to make it work", throwing you on a wild goose chase, looking for broken or loose wires, door switches, etc.

I feel your pain, though. Let us know what you've found. All the above answers are correct, too. Module, flame sensor, flaky centrifugal switch, gas valve - any one of these could be causing the problem.

im not sure on the type of oven you have but from my experence, you may want to check the blower motor centrifugal switch if everthing else check out.

Originally Posted by generaltech1

Ill check into that.

Does it spark an unusually long period after the pilot has already relit? That's a sure sign of impending problems. Here’s why I ask…

I think that this unit extinguishes its pilot when the door is opened (if memory serves me). So…you did THAT, which therefore reset the ignition module. You closed the door, it retrialed and worked properly thereafter. So…the ignition module might’ve locked out.

I’m not certain, but I think that oven also relights the pilot upon every call for HEAT. That’s allot of relights in a cooking session. A poorly performing pilot flame or flame proof circuit is bound to show itself. Initially it’s often intermittently.

So the ignition module might not be proving flame on occasion. Look for anything that may be affecting the flame sensor circuit. I expect you already checked the gas pressure to the unit and then at the main burner. If those were good, then inspect for:

1) A clean pilot burner and proper pilot flame.

2) Clean and tight GROUND connections.

3) Clean and tight flame sensor lead connections.

4) A clean, unoxidized flame sensor electrode. I replace these vice cleaning, to be sure. They’re relatively cheap.

If all of the above looked good, then check the flame current to see if it meets the threshold value specified by Blodgett (I don't have that info handy at the moment). If you did all of the above and the flame current is still weak, it may indeed need a new module.

Ill check into that.

Probably the spark module is going bad

Blodgett DFG1XL/AA

S/N 092107RI0492-Ive had numerous calls on this unit, but I cant ever find a problem with it, yes the dreaded intermittent problem. Although the last time that I was there I set it to 350F, and babysat it for almost two hours while I did other things in the kitchen. At one point, about an hour into it, it did drop to about 290f, I opened the door, it relit then continued to cycle around 350F. Im not comfortable with just shotgunning the unit, Im hoping that maybe someone here might have seen the same problem and has solved it and can pass along the fix. Or if someone can pass along a service manual for this unit, that would be great too. Thanks in advance.