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Burner won't stay running when real cold

To my knowledge we have not done any testing with a power vent. The use of a power vent is similiar to a chimney. The draft is created by the fan in the power vent and adjusted to provide the proper breech (outlet) draft.


  • Ken_50
    Ken_50 Member Posts: 2
    Burner won't stay running when real cold

    I'm thinking about last season already, but when the outside air approaches 10F, the burner won't stay running. It will start sometimes 10-15 times but not stay running. I have a Buderus boiler and a Riello burner with the outside air intake. Someone told me they now install the damper at the ceiling level instead of just before the burner (at the floor). Is changing this enough to ensure the air is warm enough at the burner? Are there other fixes required?
  • Jim Davis_3
    Jim Davis_3 Member Posts: 578

    Not a good idea to pipe cold air to an oil burner ever. If you have a 2-line system that will be problematic with cold oil which may be your main problem. The oil in the lines indoors gets warm during the off-cycle but on a 2-line system it is sent right back to the tank and replaced with cold old. Oil never has chance to heat up in pump gears.
  • Ken_50
    Ken_50 Member Posts: 2

    The Riello oil burner is the model with the outside air intake. The entire boiler is in my basement - unheated except for the duct losses (the boiler output goes to a hydro air unit).

    The boiler/burner seems to run fine when the outside air temp is above 10F. It is only when the outside air is 10F or below that it won't stay running. It'll fire and stay on for a few seconds then quit.
  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
    This is the ....

    achilles heel of direct venting( I presume its a direct vent)especially w/ 3 pass boilers. I have tried many things. nozzle heaters, lenghtenig the intake run, concentric vent hoods, pulling the intake off....anything to warm up the intake air and thereby the oil can atomize properly...The thing I have found the work the best is putting the boiler in a smallish room that is heated so no wide open cold basements, this esecially worked well in a home that had a ICF foundation...

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  • Tim_41
    Tim_41 Member Posts: 153

    I have a burner at my house which I piped a 4" intake to the burner. I used a carlin intake assembly that hooks right on the burner. Same thing. When it got really cold the burner would lock out or really make some bad noises. I removed the intake pipe and left it next to the intake of the burner for the winter. It ran fine. The cold air density at below zero is quite a bit different than above zero.
  • Noel
    Noel Member Posts: 177
    An old timer showed me this fix

    He had taken a 30" section of 8x20 ductwork, and put two endcaps on it. He put 4" starter collars on it's side, one near each end cap. He fastened the duct to the back of his boiler to warm it, and he ran the cold, outdoor air into the bottom collar, and the warmed air from the top collar to his burner air inlet. Every time the burner started up, it had a box of warm air to use before any cooler air got to it.

    It worked pretty well, but it wasn't UL listed.....

  • Jed_2
    Jed_2 Member Posts: 781

    Call Buderus. It's their application, they own it, they gotta fix it. Is the direct vent kit a separated exhaust/intake type, or a co-axial (one termination hood outside)? Separated direct vent kits can be be problematic in cold climates, as the intake air inlet is seperate and provides direct outdoor ambient air to the burner. The co-axial arrangement takes the combustion air through the same termination hood as the the exhaust gases, thus tempering the incoming air. The aerocowl termination hood design seems to work fine on the boilers I have specified.
    Haven't had a complaint to date in the last 2 years (I'm in Maine)

    Don't know what Buderus specify's, but my Biasi's are working just ducky.

  • Darrell
    Darrell Member Posts: 303

    We have tons of burners that work just great with direct air at minus 35 degrees. I'd look further than cold oil. Air density could be a factor but you'd have to have the burner adjusted awfully tight at higher ambient temperatures. Use a Tiger Loop to preheat the oil, and push up the pump pressure after sizing down the nozzle. Ten degrees isn't that cold. Do you have a motor that tighens up after it runs for a couple of minutes? Do you have a pump that tighens up after running a couple of minutes of cold oil? Is your oil gelling up on you at lower temps? If you have a long run of supply piping thicker oil will raise, (lower), the line pressure below the point where the oil will strip and cause a lock out.

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  • Joe@buderus_2
    Joe@buderus_2 Member Posts: 302
    Ignition Issue

    It is suggested to have the burner technician adjust/install a "vacuum relief" on the fresh air intake, adjusted so that anytime the burner runs the damper opens. Drop nozzle size and increase pump pressure (better atomization of oil), set CO2 for 10.5%, check electrode spacing. Have the technician contact our technical support if there are any questions. Checking for other issues such as "cold oil" is also great suggestions.
  • steve_29
    steve_29 Member Posts: 185

    I'm with joe , you got good advice to install the vacuum beaker where the pipe enters the structure.
    I also like to open it to allow warm basement air to mix with the cold outside air. I've also found that Riellos on Buderus tend to favor higher CO2 levels 12.5-13% Please don't set these levels when it's extremely cold use Joe's settings
  • Bob_102
    Bob_102 Member Posts: 16

    Riellos have this problem with cold oil and cold air because there is no ignition carryover, the ignition shuts down at the moment that the flame is detected. I had asked a beckett trainer why they don't do that and was told that they have 10 seconds of ignition after the flame is detected to give it time to warm up in there and stabilize the flame. Carlin also has a 10 second carryover. In the meanwhile I would do what others have sugessted with the damper bringing some room air and see what happens.
  • Leo
    Leo Member Posts: 770
    Joe Have


    Have there been any tests using power venters to see if there is better performance than direct venting?

  • captbuderus_2
    captbuderus_2 Member Posts: 23
    Buderus/Riello and cold air

    I have numerouse DV combos out and I to have had retention issues with cold air. My "fix" has been to set up the CO2 "high" in normal conditions. I set it @ 12.5- 13% (making sure you maintain a "zero" smoke). And opening the vac braker when it gets cold to temper the outdoor air a bit.When the temps drop the co2 drops also (due to air density) If you are lean during normal temps. you will possibly loose retention when the temps drop. All mine are the seperate intake/ exhaust type.
  • Gary P
    Gary P Member Posts: 14

    I had the same problem with Weil Mclian Ultra OIL, Direct vent aplication. Beckett NX Burner. Burner running to lean to support fire. Off on Flame failure on cold nights only. Removed air intake, and take combustion air from boiler room, Increase pump pressure and reduce nozzle size. Boiler still running, but it wants to run smokey, have to open air to maintain smoke, but not to far to blow out fire.We can only get 82% EFF. Beckett ruled it cross contamination from direct vent kit.We Have checked direct vent kit with CO detector and there are no sighns of cross contamination. They have called me back and said they would like to look at it again this winter.
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