Modine, Modine what to do?

[Jeff Ivers]

Back in 2011, I acquired a Modine PD30A0111 off of a CL ad for a couple hundred bucks and installed it in my shop.


I have loved having this in my shop. I like the location and I like the feel of the warm air blowing across the shop.

Unfortunately, when I was in the shop a couple days before Xmas, I noticed a loud metallic noise when the unit was kicking on. Since it seemed to be kicking on and heating, I ignored it for the time. Then, a couple days after Xmas when I went out to the shop, the unit would not kick on. I could hear the sound of the thermostat activating and I verified the pilot was lit.

When I lowered the bottom panel (as shown), I found about a cup of soot. Even though I have the original installation and maintenance manual, I am having trouble trying to diagnose the problem and determine if it can be put back into service or if it is time to replace. A call to a service company to find out if they could service it resulted in no return call. I am assuming I need to remove the pilot and the burners to inspect and clean as a starting point, but am not clear on how to remove these items.

Any suggestions on how to proceed? Is this likely repairable by a DIYer?

Since I have more than gotten back my investment, it may be time to replace. Should I consider infrared rather than a similar replacement unit? My shop does get dusty when I do woodworking and may be a contributor to the failure. Is a 30,000 btu infrared unit just as effective as a 30,000 btu circulated air like the unit I have?

Any other things I should consider? Thanks, in advance, for any help.

 

[The Cobbler]

I would attempt to figure out what you have first . the burners & pilot assy probably comes out from the back of the unit . some screws holding in place probably . you may have to disconnect the gas valve to get it all out. metallic sounds? is the fan motor spinning freely? noisy bearings? . looks like you're quite tight to the back wall by the picture . do you have room to get back there?
the soot may well be sawdust as nat gas burns fairly clean , if it's burning properly.
I don't like radiant overhead heat , where it shines is in big hard to heat places IMO .

 

[htmdude57]

Soot is caused by lack of air to completely burn the fuel. When I was in the oil burner business, I saw a couple of times when someone sawed some 2x4s, and the furnace started producing soot. Due to the sap sticking to the blades of the squirrel cage fan in the oil burner. Cleaning the blades cleared up the problem. This might work for you, but you should also check that the chimney pipe is clear.

Oh, another bad thing is to have a clothes dryer running in the same room while the furnace is burning (causes exhaust to get sucked DOWN the chimney pipe)

 

[fitter30]

First look at the heat exchanger from the front. Between the sections for hair line cracks top and bottom with a flash lite. Then from the backside fan side. Any cracks your done need a new furnace. Ever pull and blow out the burners and pilot? Look at the flue on the roof?

 

[Jeff Ivers]

I finally figured out how to remove the pilot/burner assembly:


The above pins get punched out from the outside of the sides.

From the hole near the top of the above pic. This is the lower right side (as viewed from the front) and there is one on the other side. This allows the rear of the burner assembly to pull down and slide to the rear to remove.

This is the burner assembly before cleaning.



Would this be considered a crack in the heat exchanger that means my Modine needs to be put to rest?

 

[fitter30]

I finally figured out how to remove the pilot/burner assembly:


The above pins get punched out from the outside of the sides.

From the hole near the top of the above pic. This is the lower right side (as viewed from the front) and there is one on the other side. This allows the rear of the burner assembly to pull down and slide to the rear to remove.

This is the burner assembly before cleaning.



Would this be considered a crack in the heat exchanger that means my Modine needs to be put to rest?

Yes it's a crack

 

[Git]

That looks like a crack in the 'bracket' that holds the burners in place. Can you tell if the end of the burner tubes are sealed or could gas leak out via that crack?

 

[toyotadriver]

I would replace that heater ASAP. It's old and worn out. Do NOT use it ever again!! It's dangerous now.

New heaters might be a little more efficient than that one too.






Nothing in this post should be misunderstood, interpreted, misinterpreted, or construed to be of a political nature.

 

[The Cobbler]

sadley, it's days are over .

 

[htmdude57]

Ok. Nevermind my answer in the #3 reply, regarding dirty fans. Your heater is naturally aspirated. It doesn't have a fan to blow air to the flame.

 

[BillK]

I have an almost identical Modine heater at my business and I lower the bottom panel and blow the whole thing at least once a year. It gets quite a bunch of **** buildup.

If the crack you showed is in the burner assembly that you pulled out then it shouldn't be a problem. That isn't the heat exchanger. A friend of mine that has done commercial HVAC his entire life told me the best way to know if the heat exchanger is cracked on one of these heaters is to see if the flame changes when the blower fan turns on. He said if the blower affects the flame then it is probably cracked.

Those units are pretty bulletproof, mine is almost 30 years old. I would give it a good cleaning and see what happens.

 

[Git]

I don't know if this helps or not - I pulled this parts diagram off the web - I have no idea if it is the OP's heater or not, but you can get a pretty good idea what part is which

7 - is the actual heat exchanger
8 - is the burner box
9 - is the burner
10 - is the 'burner 'bracket'

 

[BillK]

I don't know if this helps or not - I pulled this parts diagram off the web - I have no idea if it is the OP's heater or not, but you can get a pretty good idea what part is which

That one is totally different. It is the newer style with a powered draft and electronic ignition. I have the information for the type op has but it sounded like he had it already.

 

[Jeff Ivers]

I have completely disassembled my Modine PD30 that had quit working.


The above picture is of the bottom of the heat exchanger unit before any cleaning. All welds are intact and tight and I can only find the one tight crack that runs from the right side of the picture to the nearest exchange duct. The burner assembly and other parts of the heater appear to be in great shape except for the need for some cleaning. So, my question is why could this crack not be welded up and the heater re-assembled, assuming one determines the cause of the failure and corrects that?

 

[PoorUB]

You can weld it up if you want. I wouldn't bother as it will have no effect on operation.

 

[The Cobbler]

I'll probably get flack for this, but, since it's in a workshop and no one is sleeping in there, I would probably weld it up and use it . just keep an eye on it and even install a CO detector

 

[klassenl]

I'll probably get flack for this, but, since it's in a workshop and no one is sleeping in there, I would probably weld it up and use it . just keep an eye on it and even install a CO detector

Me too

 

[toyotadriver]

I'll probably get flack for this, but, since it's in a workshop and no one is sleeping in there, I would probably weld it up and use it . just keep an eye on it and even install a CO detector

I would replace the entire heater. So it really depends on what the OP wants to do, how much he wants to spend, and what his risk tolerance is.


Nothing in this post should be misunderstood, interpreted, misinterpreted, or construed to be of a political nature.

 

[4x4Pete]

Welding is considered a big no-no on these types of heat exchangers. Replace the heat exchanger or the unit. If the existing pictured crack is irrelevant to the operation of the unit, where did the soot come from is the question you need answered. There is more than likely another crack somewhere.

 

[American Locomotive]

Really I thin the only thing that could cause soot like that is if the stack were restricted? Are you sure there isn't a birds nest in the chimney?

 

[Sturgeon]

Now that it's public knowledge, where's the insurance company stand. There getting pretty stringent with there policys, as for me my insurance company said no way for installing wood stove. Good luck.

 

[Jeff Ivers]

Welding is considered a big no-no on these types of heat exchangers. Replace the heat exchanger or the unit. If the existing pictured crack is irrelevant to the operation of the unit, where did the soot come from is the question you need answered. There is more than likely another crack somewhere.

I agree that the question of where the soot came from is the number one question to be answered. As someone else posted, my manual indicates the cause of soot is incomplete combustion caused by not enough air for the fuel present. The next diagnostic for me is to disassemble the vent stack and check for obstructions. The vent stack has the appropriate vaned top on it and no way a bird could get in there. I am wondering if mud daubers might have got thru the vanes and caused the problem. Right now it is too cold to work in the attic on disassembling the vent, but will get to as soon as possible. When the gas regulators on these units fail, does the gas flow increase?

My curiosity about welding is wanting to have a better understanding of cause and effect, as I can't understand how this crack would really have any effect on operation (other than possible CO release into work space). Air comes thru the bottom of the unit to the burners that create the hot air that rises thru the heat exchanger tubes attached to the base plate (with crack) that separates the burner from the area above where air is forced past the heat excahnger tubes to enter the building. The heated air form the exchangers goes up the vent and out of the building. It seems the only possible cause of the the soot would be blocked air intake, blocked air exit, and increased gas flow. If the problem was blocked intake caused by soot buildup, what caused the soot to be created in the first place?

When I installed this furnace, I installed a CO detector in the shop (since replaced with a new one). I once ran the kubota in the shop long enough to verify the CO detector worked. The detector has never gone off as a result of the furnace.

Really I thin the only thing that could cause soot like that is if the stack were restricted? Are you sure there isn't a birds nest in the chimney?

Absolutely no birds nest due to proper vent topper, but maybe mud daubers - will soon find out (when it warms up a bit)

Now that it's public knowledge, where's the insurance company stand. There getting pretty stringent with there policys, as for me my insurance company said no way for installing wood stove. Good luck.

I am not sure I understand your post. I have just received a replacement Modine HD30 Hot Dawg. My questions about the old unit are trying to gain a better understanding of what went wrong to avoid with new unit and to determine if there is a salvage value for the old unit. I have heard of these units going 30+ years and this one (although made about 1999), has only been in service for 13 years.

 

[Jeff Ivers]

Today, it finally warmed up enough I could get up in the attic and disassemble the flue. Confirmed there is no obstruction of any type in the flue.

The good news is that clears the way for installation of my new Modine Hot Dawg.

The bad news is I still don't have a clue what caused the old unit to start sooting up.