Surging

SEPA

Elderly parent with OLD Ducane oil furnace.

A month ago it quit. Called tech who said it was losing prime. Did some stuff, nozzle, replaced compression fittings with flares, oil filter housing, something to the pump, etc.

It ran okay for a few weeks then when the cold snap hit it began this surging thing where it sounds like the pump coming off and on for a second. Bucking, sounding horrible. Then it would catch and run fine until the house reached temp. Next time it would fire up just fine and after a couple of minutes it would begin the surging thing again. Initially it was for 10 or 15 seconds but got longer and longer until it would smooth out.

I took Mom out of there and shut it off and secured the plumbing.

Tech came and spent a few minutes and fired it up. Thought it might be a loose wire.

It ran great-ish for a couple of days and then i noticed it again.

I went through all the wires, checked them etc. The only thing I didn't have an answer for was a wire going into the transformer that has some insulation missing.

Turned it on and it ran great-ish for 48 hours again.

Now its doing this surging thing again.

If I crack the bleed screw it smooths right out. Close it and it instantly starts the surge thing.

Ducane furnace. 1978?

2 line system

Suntech A2VA-7016 pump

Honeywell control R8184M 1051

Franceformer


I know a new furnace is in the near future but I need safe heat now.

thanks in advance
SEPA

EBEBRATT-Ed

Check the oil pump coupling, it could be partially broken or cracked.......spins the pump sometimes sometime not.

You can remove it to check by removing the burner motor or the pump. Motor end is easier

SEPA

I will definitely do that. I changed it years ago. Might as well do it again.

While I was waiting I was messing around in the garage and found a new thermostat. Changed it out and turned it on. Things seemed to work right until the house came up to temp.

We'll see what happens

thanks

Big Ed_4

What type of oil tank set up does Mom have ?

SEPA

Inside. 20' away in a separate room. 2 lines from top of tank running under the floor.

SEPA

I haven't ghosted. Apparently New Years is a problem getting stuff.

I pulled the motor and coupler and it seemed a little sketchy like maybe it was skipping.
But I put the ends on and twisted as hard as I could and they didn't skip. Turned the tube backwards and reinstalled and things ran perfectly this first run. Now back to the nonsense.

Pulled the motor and just ran it sitting on the floor and it seems fine. Checked the ohms still and turning the fan by hand, seems good.

Turned things on and shined a flashlight in the housing and it ran but if I moved the light just a little it would die. Move it back quick and it would start up.

I put a dot on the green pump adapter and reassembled. when its acting up I can peak in the air slide and see the coupling slowing and one time coasting to a stop before kicking on again.

It feels like the 120V is being interrupted but honestly you couldn't get any more seat of the pants amateur testing.

The control is 3 years old.

Tomorrow I'll grab a new coupler and maybe a CAD and we'll go from there.

thanks again

Dave Carpentier

There are 120v testers that work via induction/proximity. You could tape that to a 120v wire to monitor the presence of supply voltage while you watch this faulting happen.
Afaik, at least on my primary-control, a condition like running out of oil (actually running out, or maybe plugged/collapsed pickup tube in tank ?) will cause the cad to see poor light from the fire. After a short bit, the primary will shut down the burner motor. But until that short bit of time expires, the burner motor will keep running normally.. not slow down or stop and restart. Once the primary does lock out, it wont spontaneously restart.

EdTheHeaterMan

Turned things on and shined a flashlight in the housing and it ran but if I moved the light just a little it would die. Move it back quick and it would start up.

I'm trying to picture this in my minds eye and can't grasp it. I assume "it runs" means the motor runs. How is the flashlight shining in the housing? Thru the Air adjustment or is the ignition transformer opened? I don't get the connection of shining light the housing and "it would die" when moving the light. If it were light sensitive, the Cad Cell flame detector would take at least the 15 or 45 second safety timing to stop the motor electrically.

Can you give a more detailed description of this test? Is the flashlight touching a bare wire? what model oil burner is it. I am assuming a Beckett or Carlin where the Ignition transformer is on top and on a hinge to open and access the internal burner parts. If it is the Ducane burner that came with those 1970's furnaces, they also open by way of the top transformer on a hinge.

EdTheHeaterMan

I went through all the wires, checked them etc. The only thing I didn't have an answer for was a wire going into the transformer that has some insulation missing.

It sounds like the insulation on the old wiring is failing and beginning to crack and fall off. My guess is that there may be some old wire nut connections from the R8184 to the motor and ignition transformer that are compromised. Poor electrical connections with deteriorated insulation can be a real problem. If your condition continues, you may need to secure these bare wires with heat shrink wire covering wherever there is missing or cracked insulation. Then re-dress all the wires and install new wire nuts.

SEPA

So I had the motor out just sitting on the floor of the furnace, still hooked up. I noticed if the transformer was open it wouldn't start and thought if its closed I have a complete setup to run without pumping oil into the furnace.

So I shined a small flashlight into the opening where the motor goes and it would not start. But if I waited 5 or so seconds the motor would start normally. I kind of reflected it off of where the blast tube leaves the housing. Its kind of tight quarters with a motor and fan running etc.

I noticed if I just moved the light 1/2" up so the Cad cell got a bit more light it would stall.

I noticed that if I turned the light away it would do the 45 second thing and lockout as it should.

I was able to time it for 2 minutes running before I got tired of hold a light next to a spinning fan.

By the way anytime this this is acting up it never locks out. When you look at it it certainly looks like it should be locking out. The relay is rattling and the led is flashing green, but it will go and go until the house reaches temperature. It does lockout under other conditions when messing with it so that does work (maybe).

It does look like a Beckett setup. We'll call it Bobo Beckett.

SEPA

By the way both the tech and I have bled it and not seen a problem. Maybe traces of foam but no real shots of air like you might normally see. On the advice here I got a tube and bled it until I got a half gallon.

MaxMercy

SEPA said:

.

By the way anytime this this is acting up it never locks out.

The way these things work when things are working properly is that the cad cell doesn't affect burner performance - it's purpose is only to tell the control whether a flame is established. If the flame is not established or insufficient, the control will lock out the burner.

The burner won't start with the transformer swung open because the control watches the cad cell resistance to make sure there is no light before start. If the transformer is swung open, the cad cell is seeing light causing the resistance of the cell to drop and the burner won't start. The reason for this is because someone might jump out a cad cell to prevent nuisance lockout. Since a jumped cad cell tells the control there is light before the flame is supposed to be there, the control knows there should be no light when the burner is off, so it won't start (good).

If the burner reads the cad cell as open (very high resistance), it knows there is no light in the blast tube and also that the cad cell isn't jumped out or internally shorted, so the burner will start with the cad cell reading open. After the burner starts a flame, the control watches the cad cell to ensure the resistance drops below 1500-1600 ohms or so.

If, after 45 seconds (or whatever your control is programmed for), a no light or insufficient light condition raises the cad cell's resistance to above 1500 ohms give or take, the burner will lock out.

But during the time the burner is running, the cad cell should NOT stop or otherwise cause run issues like surging. It's function is binary - if there is no or insufficient light, the burner shuts shuts off and lock outs, if the the burner flame is sufficient, the burner continues to run. The burner will run until the programmed 45 second period elapses if there is a problem even if the cad cell is removed, so shining a light inside shouldn't change anything until the lockout period counts down.

The cad cell's function is binary - it either causes the burner to shut down and lock out or tells the burner the flame is OK and to keep running - but it won't affect *how* the burner itself performs.

If your system is doing anything other than that, replace the control.

SEPA

Put in a new coupler. No love.

It ran about 10 or 15 minutes and started acting up.

My Supplier has been bought by Northeastern Supply. Today! A lot of the inventory was missing. They had no Cad cells or kits.

They had only a Honeywell R8184G-4009 control.

Its a simple box with just TT FF. My old box was the same but old. When he put in the new control 3 years ago I noticed a C wire and a G wire were added. I asked him and he said it was for cooling which I don't have. But its been fine.

If I use the simpler model what do I do with those two wires?

They currently run from the control to a little box on the floor where power comes out of the 4x4 box above the motor and up to the limit switch.

Big Ed_4

Two pipe oil Ine running under the floor ? Run a new oil line , single new pipe and instal a tiger loop at burner ... Done

EdTheHeaterMan

SEPA said:

Put in a new coupler. No love.

It ran about 10 or 15 minutes and started acting up.

My Supplier has been bought by Northeastern Supply. Today! A lot of the inventory was missing. They had no Cad cells or kits.

They had only a Honeywell R8184G-4009 control.

Its a simple box with just TT FF. My old box was the same but old. When he put in the new control 3 years ago I noticed a C wire and a G wire were added. I asked him and he said it was for cooling which I don't have. But its been fine.

If I use the simpler model what do I do with those two wires?

They currently run from the control to a little box on the floor where power comes out of the 4x4 box above the motor and up to the limit switch.

I believe you have a L4064W Fan Limit control that was discontinued. The 2 wires from the R8184M that ran up the the fan control were a way to make the furnace a smidge more efficient by making the blower start sooner. They called this feature a timer. The two low voltage wires were connected to a small heater in the Fan Limit Control to make fan start to run within 90 seconds (+/-) of the call for heat even if the plenum temperature was not hot enough to make the fan temperature probe start the fan. They came up with better ways to do that and discontinued that control. If you want to connect those wires,

You can connect them to the L8184G4009 in this configuration. . the middle T on the primary control is equal to W and the outside F on the primary control is equal to C. On the old R8184M primary control the W could be used to power the fan control timer along with a C wire connection. In the diagram the Blue and Red wires are connected to the Fan Control timer and the primary control at the green arrows.

Hope this helps.

EdTheHeaterMan

This however sounds like someone has fired the parts cannon in hopes of tripping across the problem. Can you get an intelligent oil burner technician there? The oil company that delivers the fuel should have someone, or at least know someone.
You need to know what the fuel pump vacuum is during the "Surging". You also need to know the fuel pump pressure to the nozzle during the surging. This will let you know if it a fuel line or fuel pump or other fuel related problem.

If there is no change in the vacuum or pressure during the surging, then there could be contamination in the fuel, condensation, or other problems related. If the vacuum changes during the problem, then the oil filter, oil line, or valves may have restrictions that need to be corrected. Just throwing parts at it, especially electrical parts, is not going to solve a fuel problem. Ask me how I know this.

mattmia2

What would happen if one of the cad cell wires is shorted to the burner(or maybe some other wire) as the resistance of the cell changes?

EdTheHeaterMan

mattmia2 said:

What would happen if one of the cad cell wires is shorted to the burner(or maybe some other wire) as the resistance of the cell changes?

Lets see... if the resistance reading translated to the F F terminals on the primary control were high enough to simulate a flame signal, the primary would not start. If the resistance was below the flame signal threshold at the F F terminals on the primary control, then the reset button would pop out after the 15 to 45 second safety time elapsed.

If it were on a 120 V hot wire and it were to have a short circuit and melt something in the control then the circuit breaker would trip.

Either way, the burner would stop operating in a Safe Mode… OFF = no flame.

Dave Carpentier

The comment about watching the painted on green spot on the rubber shaft and witnessing the motor slow down then speed up, and once coasting to a stop before spinning back up..
Has me thinking supply voltage , motor wire from controller to motor (but they've been checked), controller, or motor itself.
Would intermittent supply voltage cause the primary-controller to lock out ?

SEPA

Both Eds,

I'm not glossing by the stuff you're telling me. I'm reading closely.

I've been in the trades 40 years and am very meticulous about my work as are the techs on here. But I think you have to concede the realities on the ground. Finding a real oil burner man is tough. Imagine calling around to get your car fixed and asking if they have any wrenches. Not only do they not have wrenches, they don't know how to use them and don't know anyone who does.

Very discouraging and very cold.

If you knew what I paid to not have the parts gun fired at this thing you would come out of retirement.

STEVEusaPA has been conspicuously absent in this thread. That's someone I would trust to do it right and I probably drove right past his house last night going to get this part.

I put the new primary on and it has run several times without issue. I'm not calling this a fix yet and I'm not leaving it run unsupervised just yet.

I left the C and G wires off with a meter but then realized the signal would be coming the other way and I can't wrap my head around what might trigger a signal out of this or any primary since there is no cooling and no fan or cooling switches on the thermostat.

I read about the heater in the fan switch you talked about but I'm almost certain (kind of) I don't have that Fan/Limit switch. But those wires are there for a reason. maybe I'll hookup them up like you showed and see what happens.

The Fan switch seems to be operating well. When I first started it up I noticed the temp continued going up after the fan came on and was concerned. Read something about restricted air flow and Mom said "Oh yeah, your brother came by and shut the vents in the rooms not being used".
Opened everything up and now the fan comes on at 140 and the temp goes up another 10 degrees and sits there rock steady. Shuts off when it should and kicks back on for residual heat.

I don't have any misconceptions that this burner is set up as it should be. I've never seen any combustion analysers or vacuum gauges used here. But I kind of feel like the problem was on the electric side and that's only half as scary as the oil side.

There are certainly things to deal with on the oil side whether its this furnace or a new one and I'll try to figure out who I can get to handle it.

I appreciate the time everyone has taken to help me think through this. I've learned a lot and that I really still don't know much.

Hopefully this issue is resolved. If not I'll be back.

thanks much