Natural Gas Venting Option

[Scooter Scott]

I wanted to get everyone's thoughts on my propose position and venting for my natural gas Mr. Heater (Menards Special) 80k heater. I have a 20x30 garage and unfortunately my only access to NG will be on the interior wall. All walls are insulated. The garage door isn't insulated yet. Ceiling is part of the house so it is also insulated.

What are your thoughts on my horizonal venting option? I will essentially need to do a 135 degree bend to get a straight shot out to the exterior. The total length of pipe should be under the 25' which is what the manual reads. Vertical venting is out of the question since I have a bedroom directly above it.

Also is anyone aware of in Indiana if I can use B vent or if I need Cat III?

 

[theoldwizard1]

Contact your local inspector.

 

[Gizzi]

Since it is horizontal venting, and not vertical, you'll need Cat 3 rated vent pipe. Looks like it will get really expensive at 20 plus feet.

 

[Scooter Scott]

Since it is horizontal venting, and not vertical, you'll need Cat 3 rated vent pipe. Looks like it will get really expensive at 20 plus feet.

That's what I was afraid of....has me thinking if I do electric instead

 

[Firstram]

Look into footage equivalence for bends to calculate length. A typical adjustable 90 is the same as 15 feet of straight pipe.

 

[Jackfre]

Your install manual is the key here. Follow it. Also given you have a bedroom over it and cannot go up, look at the closet location in the BR. Perhaps you could go vert if you could get into a corner of the closet.

 

[Scooter Scott]

Look into footage equivalence for bends to calculate length. A typical adjustable 90 is the same as 15 feet of straight pipe.

Manual says with 2 90 degree bends I can have up to 20ft of straight pipe

 

[Walkers]

Why not put the heater close to the door and blow the heat the opposite direction? Then you just have a few feet of vent.

 

[Scooter Scott]

Why not put the heater close to the door and blow the heat the opposite direction? Then you just have a few feet of vent.

I can most certainly do that. I was trying to follow where it says to blow the heat toward the cool source (door)

 

[Showkey]

I can most certainly do that. I was trying to follow where it says to blow the heat toward the cool source (door)

In your situation blow direction has little to no benefit………vs……….venting cost.

 

[HoosierBuddy]

Agree with the above. Reconfigure and shorten the vent. Seems like a pain, i'm sure...but the operational costs AND heat output of an 80K btu heater would be difficult to match for heat output with electric and the energy cost would be 3 to 5 times as high.

Assuming 80% efficiency for your heater, you'd be looking at 18,750 Watts for an equal performing electric heater. That's almost 80 amps at 240 volts. Goodness.

 

[Scooter Scott]

The beautiful thing is that I am going to run new gas line for this anyways so I can put it wherever I need to along that interior wall

 

[engineer2]

Why not put the heater close to the door and blow the heat the opposite direction?

Our company OH door and most loading docks I've seen are set up this way.

 

[Scooter Scott]

So you guys are proposing to do this instead? Is 80k overkill for a 20x30? Should I be getting a 50k instead?

 

[engineer2]

A rough estimate is 10,000 to 12,000 BTU per car space (~160sq-ft) assuming a snowy climate, full insulation, normal height ceiling.
Assuming those things, the upper estimate puts you at 45,000 BTU.

 

[Scooter Scott]

I can't hang it from that location over the door. There is a section that is built down for utilities and looking at the pics of when the house was built, they are not structural whatsoever. F

 

[Showkey]

30-50k more than enough. I run 50k in 1000 sqft in a much colder climate.
That distance to the right of the door to the wall is that 18” ?

Could you move it to the left of the steel beam ? Yes, The exhaust would be more visible. Also remember the exhaust will drip water and might form ice below the xhaust.

 

[Scooter Scott]

Here is a picture of the last position suggested above the garage door:



Here is the opposite side of the steel beam




Here is the original spot that I proposed where you can see the ceiling isn't built down for hvac/utilities

 

[charliev]

I would hang it just above the garage door motor and vent out that wall.

 

[PoorUB]

So you guys are proposing to do this instead? Is 80k overkill for a 20x30? Should I be getting a 50k instead?

50K is overkill! the 80K is ridiculously over kill!

My neighbor heats a detached 24x36 foot garage with a 35,000 BTU in North Dakota!

You could probably heat that 600 square feet with 15,000 BTU.

Also consider you have no heat loss through one wall and the ceiling beings there is house above and adjacent. I would return the 80K and look for a 30,000 BTU, which is still way to large!

 

[PoorUB]

A rough estimate is 10,000 to 12,000 BTU per car space (~160sq-ft) assuming a snowy climate, full insulation, normal height ceiling.
Assuming those things, the upper estimate puts you at 45,000 BTU.

That is a pretty rough estimate!!

When I worked for a heating contractor and later, sales for a HVAC supply we would go 25 BTU per square foot in a well insulated garage, or 15,000 BTU in this case. We were never undersized, and still usually well over sized, in North Dakota. We sized heaters for green houses at 35 BTU per square foot, no insulation! Granted they didn't use them in severe cold, but well below freezing in some instances.

I heat a 900 sqft detached garage with 45,000 BTU and it is plenty.

 

[gmcgeo]

I have a 120k btu modine in my 35x35 8' high celling's. why? because i got it free.

heats from 35 deg to 70 in less than 5 min lol. unless you are getting this 80k for free i would stick with a 45k btu unit

 

[u3b3rg33k]

food for thought. for Indiana, a 36k minisplit will get you plenty of heat and also humidity control and AC in the summer.

 

[D45]

Friend has the same size garage

Drywalled and insulated.......we installed a 45k and its works very well

 

[danski0224]

Can't use B vent in a horizontal application.

There may be vent location issues if that's the front of the house (nosy neighbor, building inspector, other ordinance that doesn't allow certain locations). There are also minimum clearances to things like roof overhang, soffit or windows.

 

[yeldogt]

How about a NG cabinet heater? That's what I use -- they mount on the wall and come with everything you need. Drill a hole to the outside for the included vent -- another smaller for a 1/2 gas They are sealed combustion -- plug it in.

How are you going to use the space ? I typically put them so they blow in front of the cars ....

They are more money up front -- but they come with everything.

 

[Scooter Scott]

Hopefully I don’t regret this but I ended up installing a 7500 watt electric heater from Rural King. The venting thing was really bothering me as I don’t have a great location to vent. Under $300 installed for this guy.

I appreciate everyone’s input on this. It gave me a lot to think about. With the garage being on the front or the house I didn’t have much of an option for venting and the wife refused to let me stick a vent on the front side of the roof (I don’t blame her).

I know this will cost me more to run but it will atleast give me heat when I’m out there.

 

[PoorUB]

The vent in the front of the house reminds me of a garage heater I installed in a development. I cut a hole in the roof and run the venting up. About that time the owner of the development, (that happened to live right down the street), came by and told me we were not allowed to run the vent on the front of the house as it didn't look nice. I asked him what about your place? He looked at me funny and I pointed to the heater vent coming out of the roof of his garage. He stood there for what seemed like forever, then said, "Strange, I never noticed it before!", and told me to carry on!

People get all bent about roof penetrations in the front of their houses, but unless there is a bunch of them, or some strange color most people never notice. When I did HVAC work I tried to avoid them, but sometimes you can not.

 

[u3b3rg33k]

Hopefully I don’t regret this but I ended up installing a 7500 watt electric heater from Rural King. The venting thing was really bothering me as I don’t have a great location to vent. Under $300 installed for this guy.

I appreciate everyone’s input on this. It gave me a lot to think about. With the garage being on the front or the house I didn’t have much of an option for venting and the wife refused to let me stick a vent on the front side of the roof (I don’t blame her).

I know this will cost me more to run but it will atleast give me heat when I’m out there.

you may want a ceiling fan or something to get the cold air off the floor and mixed up with the heat. otherwise you'll spend a lot of money heating your ceiling and still be cold.

 

[Scooter Scott]

you may want a ceiling fan or something to get the cold air off the floor and mixed up with the heat. otherwise you'll spend a lot of money heating your ceiling and still be cold.

Yeah I'm going to figure out a way to keep air circulating in there. Either a wall mounted remote control fan or something.

 

[yeldogt]

Vents are always an issue .... I try and hide them as much as possible.

That's why I use the cabinet type --- the vent is right out the back and all you see on the side of the house is a small round SS concentric.

 

[u3b3rg33k]

Yeah I'm going to figure out a way to keep air circulating in there. Either a wall mounted remote control fan or something.

I've found a cheapo fan sitting on the floor is pretty functional, just aim it up. it doesn't take much.

 

[yeldogt]

Yeah I'm going to figure out a way to keep air circulating in there. Either a wall mounted remote control fan or something.

Most of those fan forced heaters have rather strong fans. In an open space with typical ceiling height a ceiling fan on low can be nice as any heater up high is going to have a harder time heating low in the room ...

Sort of hard in a garage with the openers >

 

[u3b3rg33k]

Most of those fan forced heaters have rather strong fans. In an open space with typical ceiling height a ceiling fan on low can be nice as any heater up high is going to have a harder time heating low in the room ...

Sort of hard in a garage with the openers >

I've found the little electric ones to be very much otherwise. the gas ones yes, strong and loud.

 

[yeldogt]

I've found the little electric ones to be very much otherwise. the gas ones yes, strong and loud.

Really? .... I have always bought the Qmark 220v (think that's right name ) .... good throw on them.

 

[u3b3rg33k]

his looks just like mine, only a different color and brand (but out of the same factory). the fan on mine isn't going to blow air down to the floor and stir it up.

 

[D45]

Hopefully I don’t regret this but I ended up installing a 7500 watt electric heater from Rural King. The venting thing was really bothering me as I don’t have a great location to vent. Under $300 installed

I am very skeptical that this will effectively heat the square footage without running nonstop

 

[The Cobbler]

80k way over kill and it will very likely cause erratic temps that you wont be happy with

 

[jlv03]

I am very skeptical that this will effectively heat the square footage without running nonstop

On very cold days, probably. Other days, it will likely be good enough. 2 of the 4 walls are shared with the interior, so that helps.

It looks like the garage door isn't insulated, so that might be something to take care of sooner rather than later.

 

[Scooter Scott]

On very cold days, probably. Other days, it will likely be good enough. 2 of the 4 walls are shared with the interior, so that helps.

It looks like the garage door isn't insulated, so that might be something to take care of sooner rather than later.

Yes, 2 walls are shared. The other wall I insulated. The ceiling is 80% below the house and fully insulated, the other 20% I am going to blow insulation in. The garage door will either be insulated or I am going to buy a new door. I haven't decided that yet.