Old Gas Furnace: Replace or Keep Until Dead?

[fdcg27]

Your furnace dates from an era when these things were still built to last about forever.
You need not be in a rush to replace it, although you may be able to take advantage of various federal and state tax credits when you do.
We did so when we replaced our boiler, although whether it really was qualified for the energy tax credit I don't know.
The dented duct that you show is actually the flue to the chimney, not an inlet.
The filter size is obviously wrong.
Find one that fits or engineer something with the cheap media you bought and maybe some cardboard and speed (duct) tape.
No need to be in a rush to replace the old dear.
Cooler temperatures upstairs are pretty much a standard feature of any multi-story house. To overcome this requires a sophisticated and expensive control system with mulitple zones, not just a single point themostat.
Good looking hardwood floors, incidentally, which were still standard back in the day, unlike the underlayment covered with wall-to-wall carpeting you'd find in a typical condo of more modern construction.
Was your building originally built as an apartment complex and later converted?
That used to be all the rage and was a real money maker for building owners wanting to sell out at a healthy profit.

 

[gathermewool]

Thanks for the help, bubba.

I'm sorry for not being clearer; the part that I'm talking about IS the inlet. The return duct sits atop the box shown in the fourth picture, upstream of the gap where the filter is. It's not really clear in the pics, but the box has been pushed down a bit, which I think has also caused the gap where the filter goes to expand from an original ~ 1" to 1.5"+

Cut-to-fit filter: I wasn't sure if there was some easy way to install the filter, but I guess I'll have to jury rig something with cardboard.

Hardwood is a few years old, installed by the previous owner.

The complex was built back in the 60s as a condo complex.

 

[raytseng]

I am not an expert,

but I would say just get an expert to come by to take look at your thing.

Then you can ask him all those questions directly, including the small fixes that he might say are good to do, or won't make a difference.

At least around here, the checkup is actually free from the utility to tune up the system, let us know anything that is beyond his scope and should be fixed, and also encourage us to save energy.

Basically the same as like the "Free oil change and check" from the dealers; but without the hard push for a sales agenda

 

[Thermo1223]

The pics are typical of what my grandmother's monster looked like.

Cast Iron is great for a inside wood stove/coal stove but not for a forced air heater.

It takes a lot longer to heat up so that is wasted fuel before the air handler kicks on. Is very prone to cracking with age especially with short cycling.

Apparently even in the late 70's as with my house undersizing the return ductwork(filter is now) was still standard practice.

The return should be as big and depending on the system bigger than the supply. Yours is basically choking it self, mine is somewhat similar. You get a lot of noise from air movement because you are basically sucking air through a straw in comparison to what it should be. However they didn't think about building science like they do today. The various holes don't help either as instead of cycling conditioned air in the living space you are pulling in basement air.

My neighbors is similar and his return actually sucked in and would pop the ductwork because it was pulling such a large vacuum.

Just out of curiosity can you pull any numbers off the unit?

Like I said prior you should ultimately replace it but the not right way. Get a manual J/heat load calc done, odds are that return will need to be increased in size. Stick with an 80% efficient model unless you can easily duct PVC outside and have a drain near buy. If money warrants it look for 2 stage unit which means it may run constantly but only at 50% of capacity so your comfort level is increased. The same goes for getting a variable speed blower, a tiny bit electrical savings and not so much for efficiency but comfort level. These days no matter what you buy they all are pretty efficient the add-ons will greatly increase your comfort in the house though.

Not hearing a loud blower, but a quiet ramp up to speed. Constantly even heat throughout the house not the wild temp swings you get now.

It is not typical of a 2 story home to have a colder upstairs, all rooms can be the same temp without zoning. In fact it is more typical depending on the layout of the upstairs to be warmer. It just takes more work to get it that way. Zoning just makes it easier but zoning can create it's own issues unless done my someone who has installed them before with success.

I would get quotes and be smart about it but let ride this winter and worry about it next winter. Your utility company may even give you a tax credit or the state my offer an interest free loan. I know PA was doing that for a while.

 

[Cujet]

You've got a couple of minor issues to fix there.

The sag may be able to be addressed with an adjustable post. I did exactly that in my system with a similarly poor design. I had to drill a hole in the lower duct to allow the post to rest on the floor. But it was really no big deal and should have had some support built in anyway! I used a piece of EMT tubing, a 1/2 inch threaded rod and a 1/2 inch nut. In a male-female arraignment.

The filter needs some form of carrier if you plan on using the "cut to size" stuff. Might not be a bad idea to configure one that fits and seals in that opening.

A little bit of TLC and sealing will go a long way towards satisfactory operation. Don't be afraid to caulk up the small stuff and tape up the larger gaps. It can be done with care and skill for good results. I like aluminum tape, pressed down, nice and neat, with a tongue depressor.

And, I'll bet a dollar that a new furnace installation will eventually develop similar duct problems. At least, the local craftsman are "quality consistent" !!!

 

[gathermewool]

I got tired of the squeaks, rattles and poor-fitting filter, so I sat down and stared at the darned thing for a good five minutes. Remember the picture above, where I asked about whether the cover should have a gap at the bottom where access to the motor and blower is? Well, I pulled that cover off and the one above it and noticed that they were swapped. When installed correctly, there is no gap. I taped up the edges with silver tape and it doesn't make a peep now!

I also bought two cut-to-fit filters for a reason; to practice on one to see what I could do. I cut it to fit very snugly horizontally, and to rise above the plenum by a couple of inches. I was looking for some way to brace it when I realized how stiff the cut-to-fit stuff is. I used a very long straight-edge I have on either side of the filter to guide it snugly into the bottom stop and it was seemed very secure.

I then man-handled the inlet plenum and moved bent/shifted some of the ducting before taping the [censored] out of it. I may have wasted a bit of tape, but the darn thing is sealed tighter than a sphincter now. I actually ran downstairs a few minutes after hearing the thermostat click, because I couldn't hear the darned thing and wanted to make sure it was actually running.

Not to brag or anything, but I'm pretty sure I just added 30-40% efficiency with the job I did, and extended its life out another decade.

 

[Thermo1223]

You honestly might have...is the thermostat located near any heating vents?

Try opening all the vents now and see if it made an improvement in air flow.

 

[gathermewool]

Haha, I was just being silly. The thermostat is situated in the middle of the 1st floor; the vents run on either side of the 1st floor.

I'm going to leave the spare bedroom covered, since we don't use that room at this time, but I'll remove the magnetic vent cover from the 1st floor vent to see what affect it has.

The furnace doesn't seem to run all too frequently, honestly. With the temperatures so low outside, however, it is running more frequently than before, when temps were in the 20s F at night. Because of this additional run time, the upstairs seems to have risen in temperature for the same thermostat set point.

 

[zzyzzx]

Originally Posted By: dishdude
Every 2 story I have lived in is like this, if you have central AC wait until summer, you'll be sweltering upstairs. From what I can tell, it's a combination of factors that a new furnace won't help - lack of proper sized air returns on the second floor, duct work that wasn't sealed with mastic (this was pretty common up until Energy Star rated homes came out) and of course being the farthest rooms from the furnace.

The proper way to fix it is to replace/seal the duct work and install a zoned system. Not at all worth it IMO. I was fine in the winter, but actually installed a $99 window AC to supplement the central unit in the summer.


I agree with this and I do the same thing. I have a bedroom window A/C unit (upstairs) that I use a lot, but I don't run my central A/C much.

 

[Quest]

@ OP:

Is your thermostat the mercury switch type? or digital (electronic) type?

Being forced air heater furnace type: you may be able to gain additional efficiency by having it on programmable style: drop the temp by a few degrees overnite and weekends (unless your wifey complains and/or the shi-zu started to complain about chilly feet, *grin*).

Even with my hydronic in-floor radiant heating (with boiler, heating that big slab of concrete below our feet on lower storey): I manage to save 30% by means of replacing those 3 dreaded honeywell mercury thermostats with ritetemp.....set it to be constantly @ a fixed temp...

Good luck.

Q.

 

[gathermewool]

Ritetemp digithermo (energy star-rated) is what we have. I set it to 64F overnight and 68F during the day. The wife would rather have those numbers swapped, so now i've got the thermostat set to 64F all the time