Screen over exhaust pipe?

sunlight33

Do people usually put a varmint screen over exhaust pipe of a mod-con boiler? If the holes are sufficiently big enough (1/4'' by 1/4'') there shouldn't be any issue with ice formed from condensation right?

kcopp

Screen is a requirement....
Ice should not be an issue....
hence the reason you should pitch the vent back to the boiler.

GW

We've had issues with blocked intake in cretain winter conditions with 2" pipe. Very cold and snow flurries and blockage can happen. I've seen in several times.

kcopp

GW said:

We've had issues with blocked intake in cretain winter conditions with 2" pipe. Very cold and snow flurries and blockage can happen. I've seen in several times.

GW said:

We've had issues with blocked intake in cretain winter conditions with 2" pipe. Very cold and snow flurries and blockage can happen. I've seen in several times.

What sort of conditions? How far off the ground?

GW

Well above the snow line, I'm not talking snowed in. Super cold (single digits and lower) and moist conditions (snow), and we are on it. "Can you please walk out to the pipes outside, see if the pipes are free of frost buildup? Ok, do you have a screwdriver or something to pry the screen out? It should pop right out. Ok press the reset button. Are the numbers starting to climb? "

It's a pain. Our furnace installs don't have screens.

ced48

At -10, even with a back pitched pipe, my WH55 had some ice build up in the bottom of it's 2" exhaust, not enough to be a problem, but there. I doubt the screen was the cause, just so darned cold.

kcopp

So do think that keeping the vent and intake to 3" is the way to go?

ced48

Only if the boiler calls for 3", if it calls for 2", you should use 2".
These boilers require a certain amount of pressure to operate correctly, using larger pipe opens the door for problems.

kcopp

Most give you both options.

Jason_13

I have also seen the air intake freeze over which is normally caused by cross contamination.

kcopp

Jason said:

I have also seen the air intake freeze over which is normally caused by cross contamination.

Hence the reason I hate concentric venting.