Furnace in shop

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Forum topic by AkBob posted 12-02-2014 05:41 PM 1254 views 0 times favorited 15 replies Add to Favorites Watch
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201 posts in 1970 days

12-02-2014 05:41 PM

The house we are in now has forced air. The garage, which is soon to be my shop has the gas furnace in it. In the attached image you can see a pvc pipe that is an intake of some sort. I placed my hand over this opening while the furnace was running and did witness a vacuum occurring. So, a couple of question for you jockers with this set up.

What is this intake for? I assumed that it was a sealed unit. and…

do I need to cordon off my furnace from the shop to avoid wood dust damaging the unit? I do have a door near the furnace that can supply fresh air, I think.

sry the image is sideways

15 replies so far

View Fred Hargis's profile

Fred Hargis

3848 posts in 1916 days

#1 posted 12-02-2014 05:46 PM

I would think that to be the combustion air intake, and it wasn’t piped outside. If that’s true, I would pipe outside like it was intended. That would also keep shop fumes/dust from getting into the combustion chamber.

-- Our village hasn't lost it's idiot, he was elected to congress.

View daddywoofdawg's profile


1006 posts in 998 days

#2 posted 12-02-2014 06:00 PM

it’s the intake for the furnace don’t block it!if you pipe it outside put a screen over it to keep bugs and critters out of it and make sure the outside pipe is above any snow line drifts will get or it may block the opening.

View AkBob's profile


201 posts in 1970 days

#3 posted 12-02-2014 06:17 PM

Thanks for verifying what it was for me. Always helps when you call a contractor with the right terminology, even if you don’t know what your talking about.

Anyway, I found the number on the furnace for the contractor who installed it. Called him and asked if it should be piped outside. He stated that it should be if I am going to be creating wood dust and he would be happy to pipe it for $400. I politely ended the call and thought, I bet he would be happy :) Looks like a trip to the big box store for me. Thanks again all!

View Jim Jakosh's profile

Jim Jakosh

16810 posts in 2528 days

#4 posted 12-02-2014 06:19 PM

If you have forced air heat in the shop, the heat coming out has an intake of air from the shop ( not combustion air) to keep it circulating and that will have to have a filter that is changed frequently to allow good efficiency of your furnace. I agree with the first two statements on the combustion air.


-- Jim Jakosh.....Practical Wood Products...........Learn something new every day!! Variety is the Spice of Life!!

View AkBob's profile


201 posts in 1970 days

#5 posted 12-02-2014 06:23 PM

In this case I think the filter you are referring to is in the house Jim? The square one on the ceiling? Tell me if I am wrong. I figured I could plum the combustion intake to the outside to just below the exhaust one.

Garage is not heated, the furnace is just in there. One of the things I am going to miss dearly from my old shop. sadly enough.

Any recommendations on heating the shop?

View Fred Hargis's profile

Fred Hargis

3848 posts in 1916 days

#6 posted 12-02-2014 06:25 PM

$400???? (rolling on the floor laughing my arse off)....for something he should have done in the first place.

-- Our village hasn't lost it's idiot, he was elected to congress.

View AkBob's profile


201 posts in 1970 days

#7 posted 12-02-2014 06:32 PM

He was keen to let me know that that included the tax though :)

View LakeLover's profile


283 posts in 1362 days

#8 posted 12-02-2014 06:37 PM

That should have been piped in during install. Hack job period.

Look at the install maunel, there are only so many feet and elbows allowed.

Did that job get inspected ? If it did it should have been noticed or fixed at no expense to you.

View bigblockyeti's profile


3581 posts in 1143 days

#9 posted 12-02-2014 06:52 PM

$400 seems about right in my area, but I worked for an HVAC outfit for 4 years to insure I’d never have to pay for someone else to do work for me. If the guy didn’t do it right the first time, he’s already given you a physical resume of the kind of work he does, he’d be the last guy I’d let touch my stuff. This: is what I used to install on 90% efficient furnaces, done properly they should outlast any furnace.

View MrFid's profile


793 posts in 1327 days

#10 posted 12-02-2014 08:07 PM

Yeah I’d definitely be writing him a bad review on Angie’s List or whatever service you might use (Yelp?). If someone had done shoddy work for my house (not too many things I don’t do myself at this point, but you never know), admitted that it was done wrong, and then charged me to fix it, I would have made more of a stink than you did. I would say you were very polite, and you were definitely right to reject his offer. Good luck! In our old house the intake got blocked by snow once, which is exactly when you need the heat the most.

-- Bailey F - Eastern Mass.

View Fred Hargis's profile

Fred Hargis

3848 posts in 1916 days

#11 posted 12-02-2014 08:38 PM

It sounds like it was that way when you bought the place, but just so you know, workmanship like that (or worse) is quite common around my area. That includes the highly rated “certified/licensed/bonded/whatever the hell other description you can think of” ones that do business. This is largely an unincorporated area, so very little ever gets inspected. That doesn’t even begin to cover some of the DIY improvements some houses have…...

-- Our village hasn't lost it's idiot, he was elected to congress.

View johnstoneb's profile


2105 posts in 1595 days

#12 posted 12-02-2014 08:42 PM

Check your code. When my furnace was put in the there had to be at least 3 ft separation between the exhaust and the intake.

-- Bruce, Boise, ID

View AkBob's profile


201 posts in 1970 days

#13 posted 12-02-2014 09:21 PM

Thanks for the heads up Johnstoneb, I’ll be sure to check it out.

I hear you Fred, I moved from where there was no code or inspectors. In fact I still own a home there. I have seen some pretty scary self built cabins/homes that people lived in. Most of these folk were truly good people, just totally unaware and severely underfunded. I also found that these were the same people that would offer you anything they had, if it would help you and weren’t afraid to lend a hand.

I think I’ll do the repair myself as the cost is nominal and pick my battles with the HVAC guy. Especially as the furnace and central air are under warranty right now and I might have to hold him to a larger repair.

Thanks guys!

View OSU55's profile


1039 posts in 1412 days

#14 posted 12-02-2014 09:43 PM

I’m able to heat my shop/garage with a 120V 1500W small portable space heater, about $30 at the box stores (well insulated attic and attached to the house, in Missouri). I use a Lux WIN100 Heating & Cooling Programmable Outlet Thermostat (Amazon) ~$48 to keep the temp where I want it. I keep the shop ~60-63° all the time, so I’m only dealing with a sustaining heat load, not trying to warm things up. Many are tempted to tap into the home HVAC to heat or cool a shop, which is not a good idea for a lot of reasons. Recommend against an open flame heat source in a wood shop if you sand much and particularly if you use solvent based finishes. Walling off the HVAC unit from the shop would be a good idea.

View Jim Finn's profile

Jim Finn

2390 posts in 2345 days

#15 posted 12-02-2014 11:31 PM

Whether you wall off the furnace, or not, it is a good idea to install a space heater of some sort just for your shop. It will keep a lot of the sawdust out of your house if you do this. It will also give you very good tempature control in your shop.

-- "You may have your PHD but I have my GED and my DD 214"

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