Issues with furnace flame cutting in and out

DarrylMiller

A liitle bit of a back story in short form: We had oil delivered in November and it was not winterized. The tank was 1/4 full during the summer (yes bad on me for condensation). We had a first cold snap and the furnace started cutting in and out. Assuming the fuel was gelling I added another 60L of dyed diesle with anti gelling agent. Since then it was going strong but the last few days it started cutting in and out again and looks like the Tiger Loop is pulling out some air. Assuming maybe the oil filter had been gummed up I replaced it but now it seems like it is pulling air more frequently and every time the furnace comes on it cuts out and starts again (it does finish the heating cycle). 

When I remove the oil filter I can hear the air seal break so I am assuming it is on tight enough. I turned it 3/4 after the rubber seal hit the tiger loop as directed by filter manufacturer. Is there something I am suppose to put on the rubber seal or could my problem be elsewhere? I checked the Cad Cell and it seems very clean. The furnace was also serviced and inspected by a tech in November.

Lastly there is also a gauge before the firo-matic valve that has always sat at zero since it was installed 2 years ago, not sure what this is for. The furnace is a Riello BF3 pulling from a 2 year old Roth tank that draws from the top of the tank.

STEVEusaPA

Are you in Canada? What kind of oil line is that?
That appears to be a pressure gauge. A vacuum gauge would be better. Sounds like you have a restriction, or a vacuum leak.
One of the main ways to solve oil problems is with a vacuum gauge, plus you'll need other tools, training and know how.
Time to call in a competent pro.

DarrylMiller

Yes I am in Canada in Thunder Bay are so we some frigid nights around -25C. Not sure what kind of line but it is a flexible non copper based line so I was not able to apply heat to the line outaide wen I thought ot gelled up in November.

Jon_blaney

The issue seems to be related to the fuel level in the tank. I believe there have been issues with the pickup system with Roth tanks.

STEVEusaPA

Jon_blaney said:

The issue seems to be related to the fuel level in the tank. I believe there have been issues with the pickup system with Roth tanks.

I wouldn't think that but I would lean to maybe a pinhole in the pick up line.

Dave Carpentier

I saw a video of a tech displaying a "soft" pickup line on a Roth. As they age, they can get soft and collapse under the suction ?
Also, apparently, if the Roth is installed with the house line and the level gauge on the same end, it can cause issues ? On mine, the house line and the fill pipe are on one end, with the gauge and whistle on the other end. Fortunately, my pickup line is hard copper.
If you move ports around, mind the rubber gaskets for the big "nuts".

DarrylMiller

I will have to checkout the pick-up line

DarrylMiller

Dave Carpentier said:

I saw a video of a tech displaying a "soft" pickup line on a Roth. As they age, they can get soft and collapse under the suction ? Also, apparently, if the Roth is installed with the house line and the level gauge on the same end, it can cause issues ? On mine, the house line and the fill pipe are on one end, with the gauge and whistle on the other end. Fortunately, my pickup line is hard copper. If you move ports around, mind the rubber gaskets for the big "nuts".

Yeah. That is the way mine is set up Fill valve and line on one side and on the left are my whistle and level gauage.

EdTheHeaterMan

I am not a fan of the Roth flexible floating pick up line. I would change that to a hard copper tube about 3" from the bottom. Copper will not collapse.

Dave Carpentier

When you say its cutting out and back in, the burner's motor is going during that period ? Like, just a flame out then back on before the primary control faults the system off ?
Are you seeing foam in the tigerloop when it's running ? Mine swirls, but no foaming.

Re the possible condensation from leaving partial load of oil in tank during summer.. the water would collect at the bottom of the tank. Your pickup is at some level above the bottom. It seems unlikely you would have enough water in a 2 year old tank to be an issue.

DarrylMiller

No foam aside from the initial run after removing and replacing the filter. Yes, the burner pump keeps going but the flame dies out for a few seconds. Usually this happens near the end of the furnace run cycle. I would say within 1 minute of it shutting off when the desired heat is achieved.

Dave Carpentier

(Btw, Im nearly your neighbour (out by Kakabeka) and have used about 850 L this season. Cant really apples-apples houses, but just for a sanity check..)

If its a 2 year old tank, maybe it wouldnt have one of those flexible pickup lines. Surely Roth stopped using that idea ?
You could do a water check by drawing some oil via the bleed point at the burner, get it into a clear jar like a mason jar, then let it sit for a while. If there's water, it will separate visibly.

Is the whole furnace 2 years old ?
If it was an old furnace upgraded to Roth, how about;
- the inlet screen at the oil pump ?
- the rubber drive shaft/hub between the motor and the oil pump ?

DarrylMiller

Hi, sorry I did not mean to abandon post. Caught up with work. The furnace has been running but the flame still goes out near the end of the cycle and cuts back in 2 times for reaching desired heat. You can put a stop watch to it and it happens at the exact same intervals. I checked everything mentioned above aside from checking for leaks and all seems good. If we set the heat to 73 it does not happen but then it is too hot in the bedroom. If I drop it back to 69 then it starts and stops at the end of the cycle again.

Thinking I might have to ride it out for the season and call someone out.

Dave Carpentier

Found a manual online that shows a Reillo where the Tstat causes the flame to go out but the motor continues in a post-purge for 2 mins before it shuts down.
If your Tstat is calling again within the 2 mins, it should relight, I would think.
Is it possible that you always have a 2 min post-purge , but are only noticing the ones with re-lights ?
Bad Tstat maybe ??

Big Ed_4

Floating line , They made a tank gauge with a flexible line .. The hose used for the flex line would develop leaks ... How old is the tank ?

Air foaming in the Tigerloop indicates a suction leak .. A plugged line would increase air being sucked in ..

DarrylMiller

Thanks Dave, I replace TSTAT with a basic honeywell as I had an ecobee. The problem persisted though. So I am going to switch back to ecobee tomorrow. 

Big Ed, The tank is 2 years old. The only time I see air bubbles is when the flame is cycling on and off and a more noticeable buzzing niose can be heard from the Riello BF3 pump. 

I had a reputable company come out today and checked for vac leaks, airflow and ran diagnostics on the furnace and it is 100% working and holding pressure. I now know it is not the t stat or the furnace and it comes down to the oil tank. 

Funny thing was that while the tech was here the sun was out and still minus 15C but worked perfectly. It ran for 30 minutes with no issues. As soon as the sun went down it started up again with the issues. 

I think at the beginning of the season before I put the antiwaxing agent into the tank the line going from the tank outside to inside already gelled enough to create a restriction and not a full block. My thought is that with the sun beaming down on the outside lines the oil is thin enough to pass through the restrictions, but without the heat from the sun the fuel thickens up a bit (gelled fuel in the walls of oil line). Does this make sense?

I think I might have to abandon the line or try to clear it out somehow, maybe disconnecting both ends and pouring diesel 911 through, then run through with oil before reconnecting...

Lastly looking inside the tank the oil seems fluid and not gelling in any way. When I did add the antiwaxing agent I also added 60L of home heating oil to help mix it up and used a long clean piece of wood to mix up the tank hoping to disperse it around the tank.

EdTheHeaterMan

If you believe there is a restriction in the fuel line you might try this:

I would use a hand operated pump to put the fuel treatment in the tank form the oil burner end of the fuel line. This makes the fuel treatment flush out the line and push anything the may be gelling back into the tank and mix it with the chemical that will reduce the gelling. This practice never failed me when I encountered a frozen fuel line. The chemical ended up at the bottom of the tank near the fuel pickup line. That is where you need it the most. Then a few pumps of air through the fuel line would agitate the chemical with the fuel. This will not work if the fuel line for some reason has a check valve. (The chemical will not pump back against the check valve)

If you don't have a hand pump perhaps you could fill up an air hose with the chemical and hard pipe a flare fitting to the air hose. Once it is connected to the fuel line you can turn on the compressor and force the chemical out of the hose into the tank. I would not let the compressor pressure to the tank get higher than 20 PSI.

However... I'm with @Dave Carpentier on the 2 minute thing. The fact that it happens at the end of a cycle and for 2 minutes "You can put a stop watch to it and it happens at the exact same intervals." ...makes me think it has something to do with the thermostat getting close to being satisfied and electrically shutting the flame down, then the post purge, then during the post purge (even within a fraction of a second) the burner will retry for ignition and since there is no reason for it not to light, the burner will relight.

To test this theory you will need to place a test meter or test light on the wire to the solenoid wire to the pump to see if there is a break in the circuit to the valve, that might cause the valve on the pump to drop out. That might save you from looking at a faulty fuel line that isn't at fault.

Here are some examples of where you would place your test light or meter leads

STEVEusaPA

Big Ed_4 said:

Floating line , They made a tank gauge with a flexible line .. The hose used for the flex line would develop leaks ... How old is the tank ?

Air foaming in the Tigerloop indicates a suction leak .. A plugged line would increase air being sucked in ..

High vacuum also foams.

DarrylMiller

Thanks for the detailed response EdTheHeaterMan! Could I use my multimeter to run those tests jist checking for continuity?

As for clearing the oil lines I will have to see where I can get a push pull pump and try as you have instructed, makes sense. 

DarrylMiller

Well I believe you are right Dave and EdTheHeaterMan, I have been listening to the furnace and it kicks on and does the pre purge, fan runs strong while flame is going and as soon as the fan slows down and sounds like it is going into a 5 minute post purge. That is when the flame cycles on and off for the whole 5 minutes and I start to get the smoke from the burner. A couple minutes later furmace turns on again amd runs fine until post purge happens.

Dave Carpentier

Smoke from the burner ?
Describe whats happening

CLamb

DarrylMiller said:

As for clearing the oil lines I will have to see where I can get a push pull pump and try as you have instructed, makes sense. 

I bought a pump intended for inflating balloons or balls from the dollar store and disabled the check valve to convert it into a push pull pump. It wasn't durable at all but as a home owner it lasted long enough for my use.

MaxMercy

Lock-out was never mentioned. I suppose it could be possible that an oil delivery problem might be bad enough to cause a flame out but not bad enough to exceed the lock-out threshold before flame is reestablished, but since the T-stat was subbed to no effect, I'd be looking at the primary controller next.

In the meantime, I'd connect a pressure gauge to the pump and see what's going on with the fuel during the flame out.

DarrylMiller

Would this be a good pressure gauge to go with? Also, I am going to take a video tonight to show what is going on.

DarrylMiller

CLamb said:

As for clearing the oil lines I will have to see where I can get a push pull pump and try as you have instructed, makes sense. 

I bought a pump intended for inflating balloons or balls from the dollar store and disabled the check valve to convert it into a push pull pump. It wasn't durable at all but as a home owner it lasted long enough for my use.

Thank you for the tip

DarrylMiller

Dave Carpentier said:

Smoke from the burner ? Describe whats happening

I will take a video tonight. Appreciate the follow-up help.

EdTheHeaterMan

EDIT

This is the pump I used as a professional https://www.patriot-supply.com/products/showitem.cfm/WESTWOOD_T30

If you have a tire pump or an air compressor, you can do the flush with that. you need to get your air hose and pour some of the oil treatment into the hose. Then you need to get a fitting that will go from the 1/4" hose connection to a 1/4" flare fitting connection and put them together with a 1/4" pipe coupling.
Connect the air hose that is charged with the chemical and pump it thru the fuel line. You can set it up with these fittings and your existing air hose.
EDITI just looked at your non copper flexible fuel line. The above drawing I made will not help you. You will need to use the fitting that is attached to the tiger loop (in the yellow circle) to adapt to the compressor hose or the tire pump. You could just pump the chemical thru the air hose fitting the green arrow is pointing to with the firomatic valve closed.


If you don't have access to a compressor, I would not go to the expense of purchasing a pump that will only be used once. But that is up to you.

DarrylMiller

Here is the video. this is starting 10 seconds after furnace started up. It sounds like the flame should have been done around the 2 minute mark. After 9 minutes of cycling the furnace will run again in about 5 minutes. I feel like this should only be a 2 minute run cycle then post purge as it is only running to increase temperature by 1 degree C. The end of the video is where furnace reached desired temperature, the blower fan also stops so heat is left in the furnace.

https://youtu.be/dKRDf-hCRvw

Dave Carpentier

Cool video.
There didnt seem to be a "whump" or "boom" during that off and on situation. Thats a good sign, if there was then it would signify that oil is being sprayed into the combustion box during those off periods.
There seems to be some kind of an intermittent squealing noise that to me sounds like a rotating part.
The pros should be able to nail this one down from that video.

Do the bubbles in the Tigerloop get worse towards the end of this odd cycling or is that the most you see ?

Jon_blaney

Early on you mention some relation between the sun up and sun down. Could there be an electrical issue? is there something else on the furnace electrical circuit that is activated when the sun goes down?

EdTheHeaterMan

There is a whine noise when the oil valve is open (flame is on) that stops when the valve closes. This may be an indication that the fuel pump is pulling a high vacuum. Since the fuel pump is moving fuel when ever the motor is operating, that does not make sense. The only difference in the amount of fuel that the fuel pump is moving from valve open to valve closed is the firing rate of the nozzle, then the high vacuum noise may be a result of a defective tiger loop.

When the fuel pump gear set is connected with 2 fuel lines (2 pipe) the fuel enters the inlet of the pump and builds pressure. The high pressure fuel is sent to the nozzle when the valve is open. The unused fuel is sent back to the tank (or in this case the tiger loop). When the valve is closed ALL the fuel thru the gear-set is unused. When no fuel is going to the nozzle to burn, then no new fuel is needed from the tank. The fuel is just recirculated thru the pump gear set back to the tiger loop reservoir. The float valve inside the tiger loop that connects the fuel line from the tank is closed, because no new fuel is required to replace the fuel leaving via the nozzle.

As soon as the fuel valve on the burner opens (burner fires) the float in the tiger loop drops to allow more fuel into the reservoir. This is when the high pitch whine noise kicks in. To test this idea I would place a Tee fitting with a vacuum gauge in line, on the inlet side of the fuel pump and see if there is excessive vacuum between the tiger loop outlet and the fuel pump inlet. If this happens then the valve mechanism inside the tiger loop may have a restriction that is only apparent when the float is partially open to the tank.

Net result is the fuel line vacuum is increasing incrementally during the burner operation to the point where the gear set can not develop enough pressure to sustain combustion and the valve closes perhaps as a result of the cad cell flame sensor. The fuel in the tiger loop then closes the float valve from the tank and the vacuum in the fuel pump normalizes to a point where the primary control does a trial for ignition and the flame lights, only to open the float valve in the tiger loop and cause vacuum and the flame to extinguish again.

I know… that idea is way out there but… I thought Tiger loops were infallible and spent 3 days diagnosing a fuel problem, I replaced fuel lines and fuel pumps and added check valves and replaced firomatic valves …all to no avail. The only part of the fuel system that was untouched was the tiger loop. I replaced the tiger loop and the problem was solved. That was my one and only warranty tiger loop replacement

Hope this helps

mattmia2

Did anyone check combustion and draft? There could be more draft in the vent when the house is warmer.

You could inject chemical by getting a pipe nipple big enough to hold the chemical, adapt one end to the oil line, the other to a Schrader or air coupler and use a compressor or bike pump.

STEVEusaPA

EdTheHeaterMan said:

...I thought Tiger loops were infallible and spent 3 days diagnosing a fuel problem, I replaced fuel lines and fuel pumps and added check valves and replaced firomatic valves …all to no avail. The only part of the fuel system that was untouched was the tiger loop. I replaced the tiger loop and the problem was solved. That was my one and only warranty tiger loop replacement..

I had one on my burner at my house. Started to hear some whining. Of course I ignored it. Noticed the burner off on reset at midnight. Had to go get the service van. The problem ended up being the firomatic partially failed enough that it created the super high vacuum (whining noise), and killed the fuel pump.

Back to my first post...a competent tech needs to diagnose the problem, and should start with a vacuum gauge.

HVACNUT

The level of oil in the reservoir looks low. I might start looking for a restriction between the Tiger Loop and the oil tank. 

Dave Carpentier

HVACNUT said:

The level of oil in the reservoir looks low. I might start looking for a restriction between the Tiger Loop and the oil tank. 

My Tigerloop typically has about that much oil or maybe a tad lower. It's only my first year with it, but the burner seems to be running fine.

Grallert

It sounds like the solenoid valve is closing and opening? I think I hear a click. On riello BF burners I've found that too much air will change what the cad eye is seeing and the control be very touchy will disconnect the vale briefly. Has the combustion been ch3ecked with a digital analyzer?

Grallert

near the end: motor bearings? restricted pump?

Grallert

quiets when the flame(pump?) cuts out.

DarrylMiller

Grallert said:

It sounds like the solenoid valve is closing and opening? I think I hear a click. On riello BF burners I've found that too much air will change what the cad eye is seeing and the control be very touchy will disconnect the vale briefly. Has the combustion been ch3ecked with a digital analyzer?

The tech that game out used a device to measure a few different things through a hole in the exhaust vent coming from the furnace and set the amount of air it the furnace was pulling in. Not entirely sure of all the values he was checking but he also had a hand pump that had a piece of paper checking the color of the the air coming through the exhaust. Everything was spot on from what he could see.

DarrylMiller

Grallert said:

near the end: motor bearings? restricted pump?

That is what I am thinking. In the spring I am going to pull the line and check everything over. Season is almost done, but the pump screen was virtually clear of any debris or gunk.

DarrylMiller

So after all the farting around I can confirm the issues are from the pressure gauge on the line. It has to have a minimum of 8 psi and it pressurizes the line as a safety in case the line is compromised. It was gradually losing air over the winter and I just had to add more air to it. I had the original installer make it back out and check over everything - Tank, lines, furnace and all is good.

Apparently to meet code here in Canada this valve is necessary when tank is located outside.