• If you like antique engines, vintage tractors or old iron machinery, register and join us. When you register on Smokstak, please give complete answers and fill in all blanks. IF YOU ARE ON WIRELESS, GIVE YOUR CITY AND STATE! NO ZIPCODES! We get hundreds of applications, so there is no time to deal with missing information.

Onan: Some oil burner furnace electronics have trouble with un-clean gen power

len k

Subscriber
Last Subscription Date
12/12/2018

Machine and Fab

Subscriber
Last Subscription Date
12/24/2020
It is my understanding that these use line voltage across the flame to ground to sense the presence of the flame, therefore they will not work unless the source is bonded, and the hot / neutral polarity is correct.

Keith
I am in complete agreement with Vanman. Bonding the neutral and ground at the generator will cure the problem. I just recently went through this exercise with my neighbor with his new furnace and his old generator.

Don
 

Zephyr7

Registered
Len, if you have a blower in your furnace, think about an airflow proving switch. Carbon monoxide detector in the basement is a good idea too. Can’t be too careful with combustion appliances.

Vanman and Don: I always recommend bonding the neutral and ground at the genset, especially on portable sets. Usually this is for safety, but it looks like you’ve found a new reason!

Bill
 

len k

Subscriber
Last Subscription Date
12/12/2018
61 year old house, been meaning to buy few CO2 detectors. Would be nice if if they made one with a high CO2 limit that I could shut off furnace with. Don't want nuisance shut off if I'm on vacation and come back to frozen house.

Len, if you have a blower in your furnace, think about an airflow proving switch.
FHW heating

Problem is I've had a no-fire condition with burner motor making air flow and oil mist, but dead ignition transformer , so no spark, thus no fire.

I think it's better to directly check for fire in some way.
 
Last edited:

len k

Subscriber
Last Subscription Date
12/12/2018
Kevin I just read stack switch link you posted.

Looks like ones in link are mounted on exhaust pipe coming off furnace going to chimney.

Mine is mounted on/in furnace itself. If remove 10 inch dia sheet metal exhaust pipe from furnace can look down into furnace interior and see thermal spiral sensor in exhaust flow, ~ 2 inches above cast iron heat exchanger. Guessing it's a VERY OLD design.
 
Last edited:

len k

Subscriber
Last Subscription Date
12/12/2018
Supposed to slide down to a cold 0 degs by morning.

Funny thing , few hours after I went to cellar to read off model # of thermal stack switch the house started getting cold. Was concerned I ran out of oil . so went to cellar to check furnace, it was colder than normal....... then I rememebered I shut off power to furnace., for safty while removing stack switch cover. Turned on power and furnace heated house again.:bonk::bonk::bonk:
 

EICBob

Subscriber
Age
62
Last Subscription Date
07/13/2019
Supposed to slide down to a cold 0 degs by morning.

Funny thing , few hours after I went to cellar to read off model # of thermal stack switch the house started getting cold. Was concerned I ran out of oil . so went to cellar to check furnace, it was colder than normal....... then I rememebered I shut off power to furnace., for safty while removing stack switch cover. Turned on power and furnace heated house again.:bonk::bonk::bonk:
Been there, done that...did NOT get the "T" shirt either :)

-BobC
 

Kevin K

Subscriber
Last Subscription Date
07/12/2019
Funny thing , few hours after I went to cellar to read off model # of thermal stack switch the house started getting cold. Was concerned I ran out of oil . so went to cellar to check furnace, it was colder than normal....... then I rememebered I shut off power to furnace., for safty while removing stack switch cover. Turned on power and furnace heated house again.:bonk::bonk::bonk:
Wouldn't be the first time I forgot to turn on the power after maintenance either.

Here is a picture of the CAD cell and primary control on a Beckett burner. Notice the CAD cell is mounted on the transformer and
looking down the air tube at the flame when the transformer is in the closed operating position. This picture is my spare burner assembly sitting on a workbench.

Burner2.jpg
 

Zephyr7

Registered
I think it's better to directly check for fire in some way.
The time honored way to do that is to look for light and/or heat. A small photocell will do light, a thermocouple will do heat. A simple comparator like an LM393 can check the output and that with a transistor can drive a relay to do whatever you want. Pretty simple and not much to fail.

Bill
 

len k

Subscriber
Last Subscription Date
12/12/2018
Kevin, yours look REAL MODERN compared to mine.

Seeing yours I remember now, I got a burner like that somewhere. I pick up stuff like that from curb to use for parts in emergencys,....... ie 0 degs at midnight on weekends when parts stores are closed. That way I at least have a chance of getting heat for the night.

Little more info on my stack switch. The part of it that shows outside furnace is a box ~ 5x5x6 inch (contains transformer , relay and thermal time delay). The actual thermal spiral inside furnace is ~ 12-15 inch long by itself, ~ 1-2 inch in diameter, and naked ( no shield, so it can be cleaned of ash deposits).

BTW my aquastat looks a lot like this one,
https://www.bing.com/images/search?view=detailV2&id=1B424CDA190196F31D0353841070B5B135FDB92D&thid=OIP.m7yf9JNRoHSQ2Pymv5hFlgAAAA&mediaurl=https://i.ebayimg.com/images/g/r9gAAOSwMTZWRQzl/s-l300.jpg&exph=225&expw=300&q=old+furnace++stack+switch&selectedindex=158&ajaxhist=0&vt=0&eim=0,1,2,3,4,6,8,10
 
Last edited:

BigBlockChev

Subscriber
Last Subscription Date
07/06/2019
My observations on this are that lots of electronics have difficulties with single cylinder non inverter generators. It has to do with the non-symetrecal shape of the sinewaves. As the piston is moving through the 4 cycle process of 2 rotations it speeds up and slows down which affects the slope of the waveform so that it is not a true sinewave , they have a 1-2 cadence which repeats. It seems to be less prevalent in multi cylinder generators. Boiler controls seem particularly fussy. We had one boiler out of 4 with Fyreye flame detection systems which would run fine on utility also on our 1.3MW MTU gens but would crap out on our 240Kw Cummins gen , go figure. Cheers Dan
 

Zephyr7

Registered
Dan, you’re correct about the issue with the non-constant torque as the engine goes around. This is why it’s usually said that “turbines are the best prime movers for generators” since turbines have constant torque.

The actual effect of the non-constant torque from reciprocating engines is pretty small though, but is worst with a single cut Lindee obviously. The effect is half as much with a twin, a quarter as much with a 4 cylinder engine, etc.

The thing is that after that sinewave passes through a rectifier, the capacitor should filter out any issues.

The thing I think is going on is that there are a few devices out there that are sensitive to harmonic currents, which get worse as you deviate from a true sinewave. I suspect the problem devices are using some sort of resonant circuits and that’s probably where the trouble is.

Bill
 

Vanman

Subscriber
Last Subscription Date
07/10/2019
I think you’ll find that a twin is one quarter as much speed variation since not only are there twice as many power strokes, but they’re each half as strong.

I’d bet those fidgety electronics would have a coronary with my single cylinder 1800 rpm plants!

Keith
 
Last edited:

len k

Subscriber
Last Subscription Date
12/12/2018
Just absolutely shocking that heating controls are so POORLY designed.

Not unreasonable to assume the customer would still want furnace to work in 0 deg winter , since many people (and myself) buy a gen PRIMARILY to power the furnace in winter.

Neighborhood behind me was out for 1 WEEK after big NorthEast ice strom.

It's almost trivial to design in a voltage regulator to stabilize DC voltage for the electronics (semi-conductors)
LM317 chip would easily supply up to 1.5 amp , but I'm guessing you would not need anywhwere near that much current.
 
Last edited:

Zephyr7

Registered
I think you’ll find that a twin is one quarter as much since not only are there twice as many power strokes, but they’re each half as strong.

I’d bet those fidgety electronics would have a coronary with my single cylinder 1800 rpm plants!
It depends where the energy goes in. A twin would be half as bad, because you’d have two torque peaks instead of one, and each would be half the amplitude. It’s possible square law might come into play, it would be easy to see with an oscilloscope that had a FFT function.

I can say that our V12 diesel at work puts out a pretty nice sinewave :)

Vanman, you can smooth things out with an extra heavy flywheel too. A flywheel is like a mechanical version of a capacitor.

Bill
 

Zephyr7

Registered
Just absolutely shocking that heating controls are so POORLY designed.
<ship>
It's almost trivial to design in a voltage regulator to stabilize DC voltage for the electronics (semi-conductors)
LM317 chip would easily supply up to 1.5 amp , but I'm guessing you would not need anywhwere near that much current.
Not so much “poorly” designed as “cheaply” designed. It’s not s big deal to design a power supply that can filter out basic line noise. The exact shape of the sinewave shouldn’t even matter all that much. You don’t need an active regulator like an LM317 to do it, either, a simple capacitor and MAYBE an inductor (for severe noise) will do just fine in almost all cases for basic things. An active regulator would be even better for anything really sensitive.

I’d have to see a schematic for one of these sensitive flame sensors to be able to have an idea why they’re so sensitive to line noise. It might, and probably is, possible to build or buy a filter to “fix” the issue with those sensors too. Corcom makes all kinds of line filters, I wouldn’t be at all surprised if one of them would solve the “it won’t run on generator power” problem. You’d still need a ground bond though if that’s also part of the problem.

Bill
 

len k

Subscriber
Last Subscription Date
12/12/2018
From what I hear one type of flame sensor supposedly puts a ~ 120VAC wire in flame to directly measure presence of ionization conductivity to frame. Guessing they measure current. Supposedly those types need a bond between frame and power neutral to work, which seems reasonable.

But it's starting to sound like other types of controls may also have other types of problems on gen power.

Poorly /cheaply ...... end result is the same, cold house.

I designed mil defense equipment. Had to design it to meet specs ALL the time: all voltages, all power noise levels, all temperatures, all vibration levels, all humidity, while subject to EMI, RFI.

My view point is if it doesn't work under conditions it's likely to see then it's poorly designed, and junk. But I hear what your saying..... cheaply designed. Just too bad we are not warned that it's cheaply designed junk.
 
Last edited:

Zephyr7

Registered
Part of the problem is that the consumers don’t know anything, so they buy the “best price”. Then they complain about unreliability later. Manufacturers know this, so they build to the price point that gets their stuff to sell. End result is reduced quality products.

My own experience is the York residential stuff is currently the best. Much more solidly built than most. One of my commercial mechanical contractors at work recommended them so I tried them at my dads house.

Be careful with HVAC brands too: there are only a few manufacturers out there that actually make everything. Many of the “different” brands are actually made by the same company.

Bill
 

Kevin K

Subscriber
Last Subscription Date
07/12/2019
I looked over at the burner site you linked to. Nice site! Anyway the OP posted a picture of his burner assembly, and it appears he is running a Carlin 70200 ProMax or Pro-x CAD cell controller. I never liked Carlin stuff myself, preferring Honeywell and Beckett. This controller is now definitely on my $hitlist. These are not expensive, about $75.

Link to the controller datasheet: https://carlincombustion.com/gas-oil-burner-products/controllers/primary-controllers-oil/70200-universal-oil-primary-control/#tab-1833e411229e7e4883d

He might want to try a few things:

1) Bill had a good idea to try using a line filter. A Corcom 20VB6 looks like it may work. At about $25 it may clean up the generator output enough for the controller to work.

2) He may want to try another brand of controller, say a Honeywell R7284. I don't use it myself so I can't guarantee it will work, especially since I am not on the scene to check the generator output.

https://customer.honeywell.com/resources/Techlit/TechLitDocuments/69-0000s/69-2467EFS.pdf

3) He could switch to an older style non-microprocessor controller that is not quite so sensitive to power glitches. If he can do without the fancy LCD display and does not need programmable functions such as pre and post purge and interrupted ignition. I use the Honeywell 8184G.

https://customer.honeywell.com/resources/techlit/TechLitDocuments/69-0000s/69-0617.pdf

Oil burners use either interrupted or intermittent ignition systems. In an interrupted ignition system, the spark is active for a brief time at the start of the operating cycle, then turns off once there's a flame. In an intermittent ignition system, the spark stays on while the burner runs.
 
Top