NOOB hello with a venting question

[larrym]

Howdy, new here from Richland, Washington, moved from Alaska after 40 years to Austin, TX, too hot, so two years of that, here I am in Washington. I grew up in the Seattle South end, Burien, right on the sound, Three Tree Point, leaving in 1964 for the Marine Corps. NOw retired with a T-Bucket hot rod in a cold garage!

I just received a new Modine Hot Dawg 75k gas unit for my garage and plan to install it myself then have it inspected.

It will vent through the garage wall, do I need double wall exhaust vent piping? It will pass through a thimble, 3 inch system, and extend about one foot to the outside.

I'm not sure, reading the instructions, what type of vent cap I need...it does get a little windy here, but my exit location is relatively protected.

I'm sure this has been covered in this forum and will continue to search, but any input is appreciated. Thanks, Larry

 

[03protege]

Welcome to the forum, I have no clue on how to answer you question but just wanted to say hello.

 

[larrym]

Well hey, and thanks for the welcome. I'm finding a few clues searching the forum, curious about the wall thimble install, does the vent pass through it, stuff like that.

Have a great weekend!

 

[dave67fd]

All residential, horizontally vented Category III heaters must be vented with an agency certified (UL1738) Category III venting system. Agency certified Category III venting systems are available from your local vent pipe distributor. Follow the agency certified Category III vent manufacturer's instructions for installation.

Also follow the Heaters installation instructions for recomended lengths. For 3" your max length is 4.5'.
Learn what codes you need to adhere to for your town or juristiction as they take presidence over anything else. In the absence of any town codes you need to follow manufactures installation for the vent and the heater. Your heater manual has all this info. Read it carefully and several times.

Make sure you mount the heater in an area that will accept the vent system properly and mount it so it blows the heat to the area that has the most cold air intake (ie..garage doors) consider the gas piping route as well as electrical connection and thermostat location.

You don't need a special circuit for the heater as long as it isin't on a switched lighting circuit.

 

[larrym]

Thanks Dave, and yes, some of that information is in the manufacturer's package. I'm curious what the specific codes call out for the agency Catagory III vent systems, such as B-Vent (double wall), through an insulated outer wall, etc. Buying an entire system is a great idea, were it not for the price, two and three hundred dollars to run about 3' of exhaust.

Thanks again

 

[dave67fd]

Correct. Unfortunately they recently changed horizontal venting catagories. Class III vent systems as i understand it are completely sealed. When using a horizontal vent system with these heaters, only one single length is allowed, thats why their short, typically 3'.

With my heater i purchased the recomended kit. My town codes required the permit to be pulled and installed by a licensed contractor. They won't issue permits to home owners installing a gas fired appliance. I installed the heater and wired power and thermostat. Before i located the heater i made shure all the clearances and vent lengths would fit within the code. Your vent kit has more stringent requirements than my did as it was manufactured before the code change.

If you can purchase the required length of b-pipe thru a wall thimble to the termnation cap with the minimum elbows required and all other specifications are met i think you will be fine.

 

[Jackfre]

Category III means your stack temps will be 140* above dew point temp and that your vent system is positive pressure. B-vent is a Cat I negative pressure system & 140* above dew point temp. I haven't installed one of these and so cannot advise. What specifically does the manuf call out for vent material?

Cat II is negative pressure, corrosion resistant vent system, stack temp can be below the above 140*. Due to the corrosion resistant vent without the hi efficiency of non-condensing No manuf made a Cat II appliance. That bit of info is a few years old, soo...grain of salt with that.

Cat IV is positive pressure, condensing (high efficiency), corrosion resistant vent system. People typically use PVC although, and this is absolutely correct, PVC is not an approved vent material. Many in the industry look at PVC vents to be the next big recall in the heating industry. We'll see.

 

[larrym]

Got it guys, I do plan to use a single run of B vent, I assume the 3 inch wall thimbles are pass-through and will accept the 3.5 inch diameter of 3" B vent pipe. I will check with local agencies to ensure I am able to DIY.

Interesting bit about the PVC vents, the home I just bought here in Richland, WA has that system. The home inspector was curious whether it would fly in the future...

Dave, looked at your build, what a great space! Thanks, Larry

 

[dave67fd]

Got it guys, I do plan to use a single run of B vent, I assume the 3 inch wall thimbles are pass-through and will accept the 3.5 inch diameter of 3" B vent pipe. I will check with local agencies to ensure I am able to DIY.

Interesting bit about the PVC vents, the home I just bought here in Richland, WA has that system. The home inspector was curious whether it would fly in the future...

Dave, looked at your build, what a great space! Thanks, Larry

I think PVC's are typically used in very high efficiency systems.
Thanks for the kind words.