Cost to re-plumb furnace exhaust

[Raswan]

So the people we bought our house from built a new deck over the current natural gas furnace intake and exhaust and neglected to re-route them. Somehow the inspector missed it, and of course I missed it. The result is that during the coldest months of the winter the warm exhaust air gets trapped between the deck joists and condenses, slowly freezing up the exhaust and tripping the furnace off.

So: how much can I expect to pay an HVAC guy to re-plumb these? Would have to run ~20 feet along the interior of the laundry room and punch out the north side of the house. $300? $500? $750? The nearer I get towards $1k, the likelier I am to try this myself and die from carbon monoxide poisoning mid-February.

Thanks.

 

[herm0016]

be sure to check your furnace manual, as most have a maximum lenght of vent. other than that, i would just do it myself. its just pvc pipe. use the right glue and you should not die in feb. could you just put a big grate over the area to promote airflow?

 

[Raswan]

be sure to check your furnace manual, as most have a maximum lenght of vent. other than that, i would just do it myself. its just pvc pipe. use the right glue and you should not die in feb. could you just put a big grate over the area to promote airflow?

I think maximum length is something crazy like 50 feet. But I'm wary of cutting the hole in the side of my house and getting the pitch right. In reality we're talking a half day on a weekend, but my wife and I are training for a marathon and I'm disinclined to do it after a fifteen mile run.

The grate is a good suggestion; I'd considered it, but then have to look at a grate forever. Still, it might be the simplest solution.

 

[WilliamM2]

50 feet is not that hard to reach. Check the furnace manual. Mine states to add 3.5 feet for each 90 elbow, and 1.75 feet for 45 degree elbow. What looks like 25 foot of pipe actually works out to be 55.

 

[Greenman]

Is it a PVC vent or steel? More to the point, you probably have options with the prior owner. It all depends on disclosure and permit laws in your state. Here in CA you could go after the prior owner, the contractor that did the work, the inspection company, and the listing agent.

 

[bbhaag]

If you do it yourself it would be super cheap. A couple of ten foot sections of pvc pipe, some couplers, and a few elbows should be all you need. Grab a small can of pvc cement and primer and that should be it for pvc supplies. Grab an appropriate sized hole saw for your drill and that should punch through the side of your house with no problem. Don't forget to buy a tube of caulk to seal around the perimeter of the pipe leading out of the house.
I bet this is a $200 diy job but that is just an estimate without seeing it in person or pics. Take half a day break from training and you could easily do this yourself.

Or pay an hvac guy to come in and do it for you. Ballpark estimate would be between $600 and $900 for the job.
I guess you could also sue the prior owner, the contractor that did the work, the inspection company, and the listing agent but I don't have an estimate for what the lawyers fee would be for that. You would have to call an attorney. I'm guessing it would probably cost more than just either doing the job yourself or paying someone else to do it.

 

[Raswan]

50 feet is not that hard to reach. Check the furnace manual. Mine states to add 3.5 feet for each 90 elbow, and 1.75 feet for 45 degree elbow. What looks like 25 foot of pipe actually works out to be 55.

Good looking out. I'm only looking at a single 90-degree and then about 20 feet straight.

 

[Raswan]

Is it a PVC vent or steel? More to the point, you probably have options with the prior owner. It all depends on disclosure and permit laws in your state. Here in CA you could go after the prior owner, the contractor that did the work, the inspection company, and the listing agent.

It's PVC. I'm 90% sure they built it themselves. I am a little miffed that the inspector didn't pick up on it, but I'm not sure it's worth the hassle.

 

[Raswan]

If you do it yourself it would be super cheap. A couple of ten foot sections of pvc pipe, some couplers, and a few elbows should be all you need. Grab a small can of pvc cement and primer and that should be it for pvc supplies. Grab an appropriate sized hole saw for your drill and that should punch through the side of your house with no problem. Don't forget to buy a tube of caulk to seal around the perimeter of the pipe leading out of the house.
I bet this is a $200 diy job but that is just an estimate without seeing it in person or pics. Take half a day break from training and you could easily do this yourself.

Or pay an hvac guy to come in and do it for you. Ballpark estimate would be between $600 and $900 for the job.

I guess you could also sue the prior owner, the contractor that did the work, the inspection company, and the listing agent but I don't have an estimate for what the lawyers fee would be for that. You would have to call an attorney. I'm guessing it would probably cost more than just either doing the job yourself or paying someone else to do it.

Part of the problem is the setup in the mechanical room. There's a cinder block utility shower in the corner I'd exit that reaches about ten inches from the ceiling. Plus an air return sitting between the joists just before I'd exit the house. It definitely means one 45-degree elbow to get up there and another to straighten out. I think I could get the slope, but it would be close.

A grate on the deck is the simplest by far, but I have to believe that it's not a great idea in Minnesota to exhaust warm, moist air in sub-zero temps under your deck, grate or no.

 

[NetWareHead]

Read the manual for the furnace and it should have the exhaust piping specs including slope per inches, maximum length of run, size/type of pipe etc... Pay attention to where you punch out the side of the house. Most code demands you are within x feet away from any windows/entrances etc...

 

[Raswan]

Read the manual for the furnace and it should have the exhaust piping specs including slope per inches, maximum length of run, size/type of pipe etc... Pay attention to where you punch out the side of the house. Most code demands you are within x feet away from any windows/entrances etc...

Roger that. Thanks.