garage heater question
 

On windy days my heater keeps relighting because the burners keep going out. I assume it's because the exhaust flue is like pictured where it exits out a side wall.

I figure turning it so it exits up and adding a cap will fix the issue but how long of a vertical run should it have?

1 foot? 2? none?

What kind of heater do you have? Gas heater with the blower in the back?

yes.

Mr. Heater brand made in China. Works ok as long as it's not windy

I'm assuming its natural draft, it should be pointed up and should be vented with type "B" gas vent.

B vent isn't required with it.

Should go at least a couple feet above the eaves.
A cap helps, but oddball wind gusts seem to outsmart the best of caps.

I have a Mr. Heater 80,000 BTU unit as well in my small pole barn. The flu exits through the roof with a cap. It is sensitive as well and goes out and relights in certain windy/rainy conditions. It also doesn't light at all due to the pressure switch in the draft portion when there is snow on the roof sometimes. I have just learned to live with it after 4 years. Not the most reliable deal out there.

Ask a HVAC company. Not a bunch of car guys. Lol

There are guys here with HVAC experience, but thanks for your insight.

How many BTU heater is it? Alot of these units use 4" Stainless Steel venting now. Also venting goes up above roof line. Looks like you have 6" Heating duct and pointing down!. From what I understand here in Canada, some of these units came with 3" exhaust outlet from the manufacture which was suppose to be a minimum 4". Not sure what the out come of that has been. My 100,000 BTU Reznor has 4" Stainless piping horizontal to outside with a Vent cap. Has to extent past the building a certain length. Also has a Wall thimble installed for fire rating.

Category 1 vertical, category 3 horizontal venting
https://www.mrheater.com/50-000-btu-...ater-1336.html

If its a natural draft heater the horizontal run shouldn't exceed 70% of the rise. Example, 10' of vertical means no more than 7' of horizontal. If its a fan assist some of those run the vent slightly downhill and have a cap directly outside. The downward slope to outside allows condensation to run away from the heater. Manufactures specs overrule these. B vent does several things, along with providing closer clearances to combustibles it also helps the flue gasses retain heat which helps with the exhaust process. Single wall vent exposed to unconditioned air will also rust out much faster.