Can High Winds Effect 90% Furnaces?

Dairon421

I live in Michigan and because of the winter storm we been having high winds. I had 3 service calls on 90% furnaces and they all did the same thing. The burner will kick on (not a flame sensor issue ) and run for like 3 minutes and then all of the sudden the flame will kick out and turn back on. I had constant 24v at terminals W and C on the control board so I don't expect no switches to be open. These are new furnaces that my company installed . The pvc vent pipe is at the side of the house and the wind is blowing toward it direction. I did many boiler service calls and the draft spill switch was open because of the strong winds so I suspect the same issue is with the furnace maybe?

Constantin

In a prior life, I had to design a vent terminal for a atmospheric outdoor gas water heater. It had to survive all sorts of install locations and 40+MPH winds without affecting combustion. Designing a zero-delta P intake/exhaust for that application takes a lot of care (about 4 months).

Forced combustion gives the designer / installer a lot more options re: flue terminals. But high winds can wreak havoc by creating the kinds of delta-Ps that inducer fans may not be able to overcome. Either spills (i.e. flames going the wrong way) or just enough flame lift-off at the flame rod that the controller freaks out occasionally.

Condensing boilers typically use forced combustion and following gas valves that may be more resistant to this - as the back pressure through the exhaust goes up, the air flow reduces, followed by the gas flow reducing also. The more expensive boilers have separate gas and blower controls using the flame sensor for combustion feedback (lambda sensor) that should also do an even better job.

Appliances that vent into a chimney may fare better in high wind conditions even if they have inducers because the wind speed at chimney height is usually higher, causing a draft and hence at worst causing excess air through the appliance as it attempts to operate. No such luck with a lot of condensing furnace which frequently feature non-concentric side vents with just PVC pipe to save money.

Does the furnace OEM perhaps have a approved exhaust terminal that is more resistant to wind issues? For example, I like concentric terminals for the simple reason that they should experience less delta-P as wind hits than separated intake and exhaust pipes.

However, I assure you that there is a lot of devil in the details. I was moving holes in 1/8" increments until the combustion analyzer was always happy, regardless of wind direction, water heater location, and so on.

Emergency wind breaks may be another option. Not sure that would pass muster per the manual so I would not use that option unless approved by the OEM. But as a HO w/o heat, I'd at the very least try it.

EdTheHeaterMan

@Dairon421 High wind can most definitely affect the way a 90+% burner/heat exchanger/vent system interacts with the control system. There is most likely a combustion fan proving switch of some sort. This is usually a pressure switch with a hose attached to some place in the exhaust vent of the appliance or somewhere near combustion the air intake of the appliance. Pipes leading to the outdoors for air intake and exhaust are connected to this appliance close to the pressure switch operating hose location.

Any little change in the air pressure in that pressure switch may cause the flame to drop out. In some cases the flame can come right back on once the pressure switch engages again. In most cases the open switch will cause the burner to go thru the complete start-uip sequence. Every manufacturer has a different idea. on how this should work.

mattmia2

It would be worth it to put a manometer on the gas supply and make sure that is ok, with it being around 0 and very windy this is probably a bigger load than record low temp.

JUGHNE

Here in Nebraska, where 25-40 wind is common, we had several days with -12 to -18 degrees overnight and -1's during the day.

That weather usually does not affect cond venting very often, maybe a few freeze ups.

But this year with that wind speed and "mist", weather site calls it "haze".
Usually at very cold temps any snow is dry, this was an exception.
And the angle of the wind was different than previous years.
New snow drift locations etc.

The most problematic was the concentric design, even going thru the roof.
The roof approach was usually trouble free.
I had 2 concentric wall exhaust free over solid.
Other companies were climbing on the roofs to chop ice.

Sewer vent pipes thru the roof were also froze over.

My ModCon boiler which vents horizontally out a north wall had no problems.
It is the side by side flat plate design that is shipped with the boiler.
Some curse it as being the most trouble but has worked for many years.

On some furnaces the inducer fan, after a few years, is border line on moving air.
Had issue with outside "periscope" risers, it seems during off cycle cold air will enter the exhaust vertical and drop down the riser into the horizontal section.

The mouse powered inducer could not move that slug of cold air and close the pressure switch.

Sometimes one had to do the start fan-then jumper switch to get the unit firing until the piping warmed up----temporarily of course.

HomerJSmith

It may surprise many that we are surrounded by air pressure. At sea level it is 14.5psi.
It is the pressure differential that is the problem. I am not a user, take that as a fan, of concentric venting. I have always been concerned with gas reversion. It would probably be ok on the leeward side of a building, but I think problematic on the windward side.

I don't know how your venting installations are. But a solution might be to alter the terminations. If it is a straight pvc pipe out of the wall for the exhaust you might want to try a pvc tee or a 90 deg up leg vertical termination. Rheem and Ruud have a pvc baffle that can be cemented on the exhaust termination to mitigate winds affecting the exiting exhausting gases. Something along that nature might be helpful.

captainco

Terminating with a swing tee works great in the wind and helps the condensate drain outdoors better preventing freeze ups. An open tee on the combustion air pipe indoors helps also. Doesn't matter if the intake gets plugged and it helps temper the combustion air for more stable combustion.

JUGHNE

I have been piping the combustion inlet pipe with a wye installed in the horizontal run near the furnace. Put a clean out plug in the wye pointing towards the furnace.
Drill a 1/4" hole in the plug for moisture draining if needed. This will also collect any dirt in the CO part of the wye.
Some homeowners can manage to remove the CO plug if outside air is plugged.
Makes for easy troubleshooting from the basement.