Riello F40 won't shut off - need diagnostic help

J-Bone

I returned from a week long trip (It's August) to find that the interior temp in my house was approaching 100 degrees and my oil burner was running full tilt. Candles in wall sconces were pointing toward the floor. My thermostat was set to off, but I pulled it from the wall anyway, which usually stops the burner dead, but the thing kept roaring. I shut off the power to the unit directly, which did shut it down. Anytime I switch the power on, it runs continuously, I cannot get it to shut off without switching off the power. All the information i can find on-line addresses burners that won't start, not those that won't stop.

I have a steam radiator system with a Burnham box. The water jacket indicator tube did not show any water at all, and when I opened the relief valve, steam poured out, then some hot water. This whole unit (Tank, burner, everything) was replaced about 8 years ago (previously a Beckett) after the previous furnace failed to shut off when the water jacket leaked, cracked the tank and practically melted the furnace. It did melt all the guages. Insurance determined that the low water shut off had failed. I seem to have a similar situation, but this time caught it before it burned my house down.

I have two concerns now. How do I determine what is causing this to continually run, and why did the low water shut off not work? My suspicion is that there is some problem with the primary control unit, but I am not sure what a couple of the other components, ( CAD cell eye, igniter, primary relay) do.

Bob Bona_4

You're lucky you're still with us. The second you saw no water in the gauge glass it should have been shut it down/breaker off. Very fortunate nothing triggered an auto feed or other inrush of makeup water any time or when you jostled the relief valve.

Please call a tech. This is too critical to fix over the net.

J-Bone

Not sure I used the correct terminology. By relief valve, I mean the valve below the glass tube that is occasionally used to drain some of the rusty water. Before I call someone in, I want to eliminate possible simple causes, for instance, the hot water thermostat - could that be stuck on?

BobC

40 years ago I smelled something strange, I went down the cellar and found my landlords boiler running with a cherry red hotspot on the side - thankfully it was not facing anything combustible. I shut off the power and the boiler cracked and leaked all over as it cooled - I knew not to add water to a hot boiler.

Has the LWCO been cleaned regularly? If it has been neglected you might as well not have it. It should be cleaned yearly and you should test it yourself to make sure it's working a couple of times a year.

Does the boiler supply your domestic hot water? If the aquastat failed closed and the LWCO was't working that could have caused the boiler to run away.

Bob

Steamhead

Could be a control problem too- the primary control on the burner might have gotten stuck, and not shut down when it should have.

Another possibility is the cutoff valve on the fuel unit (oil pump) sticking open.

The low water cutoff should completely cut off power to the burner so it cannot run at all, even with a stuck primary control. It should not simply interrupt power to the "limit" terminal of the primary control- if that's all it does as currently wired, this is wrong.

Have a competent pro check these two items. Where are you located?

J-Bone

Thanks for replying. i am in the sticks of western mass. What is LWCO? The unit does supply domestic hot water. After replenishing the water jacket, I powered it on again, the water heated to 133 deg and stayed there, but the burner kept running. I shut it off after the hot water temp had stabilized at 133 for 5 min.

Just realized - low water cut off. No, has not been cleaned other than occasionally draining out the accumulated rusty water. Do you mean remove the unit and clean it? As far as I know, when I have had the unit serviced, that was not part of the job.

I may need to call a dealer for service, but I am often not satisfied with the job that they do. I often have to call them back or re-do or complete some of the work myself. Mostly everything in this area is Beckett and it seems that Riello is so reliable that they don't get much experience with them.

BobC

If you are in western mass call Charlie of w mass, he will deal fairly with you. There is no one I would rate higher.

https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating

Bob

Steamhead

BobC said:

If you are in western mass call Charlie of w mass, he will deal fairly with you. There is no one I would rate higher.

https://heatinghelp.com/find-a-contractor/detail/charles-garrity-plumbing-and-heating

Bob

Agreed. Call him first thing in the morning. Keep the boiler shut down till he gets there, unless you're watching it while it heats the way you described.

JUGHNE

You have at least two controls not working correctly, probably more.

Charlie from wmass

Incase you are wondering, yes I work there. It does not matter where you are in Mass, some towns just take more planning than others. I was in Lenox, and Lee MA today and will be in Lee, and Great Barrington tomorrow. Do not let the Springfield address make you think I do not work in your area.