Hi...

The oil company repair guy was here servicing our old furnace the other
day... He said that it's running at 79% efficiency (however he measured
it). That plus the exhaust pipe from the furnace has a hole about a 1/4
inch in diameter in it. Apparently the former owners had patched it
with quick-dry cement which has eventually dried up and flaked off.

How much more efficient would a new furnace be? And what's a good
material for patching a hole in stove pipe? Obviously it would have to
withstand a fair amount of heat... Probably would be best just to
replace the section but just out of curiousity...

Thanks
-mark

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Not enough info to say anything about furnace, except that many new
units claim far higher efficiency. Better you ask locally, IMHO.
Possibly your existing unit can be made to run more efficiently, too.

Replacing section of smokepipe is possibly very simple, if you know
what to get and length to cut it to, have tools, etc. And, how to do it
safely. Meanwhile, except for light-off surge, leakage at hole had
better be into pipe.

HTH,
J

"Mark Modrall" wrote in message
...
Hi...

The oil company repair guy was here servicing our old furnace the other
day... He said that it's running at 79% efficiency (however he measured
it). That plus the exhaust pipe from the furnace has a hole about a 1/4
inch in diameter in it. Apparently the former owners had patched it
with quick-dry cement which has eventually dried up and flaked off.

How much more efficient would a new furnace be? And what's a good
material for patching a hole in stove pipe? Obviously it would have to
withstand a fair amount of heat... Probably would be best just to
replace the section but just out of curiousity...


The 1/4 inch hole is wher they perform their "test". It's not hurting
anything, but most will swab a little furnace cement or place a bolt the
same size of the hole. Do your have a barometric damper on the smoke pipe?
You know, the "flapper" that's sometimes called a draft regulator? Look how
big the hole is in it! That little 1/4 inch hole is harmless. But if you'll
feel better, get them to close it up. No sense of replacing the pipe.
They'll just have to poke another hole in it the next time they do an
efficiency test. Find a bolt or something that is about the same size and
plug it up. Even a twisted up piece of aluminum foil would work.

79% for an oil furnace is really not that bad. Most new ones get 81 to 86%.
Sure, they make some that get close to 90%, but you'll pay an arm and a leg
for it.

If your furnace is running fine and there are no signs of cracks (or places
that look weak and MAY crack), then I would stick with what you've got.

BTW, when they do an efficiency test, they will first check the draft to see
if it's correct. Then they will checl the smoke output and ajust it as close
to zero as they can. Then they will test the O2 output and then the
temperature and there is a slide chart that tells them the efficiency. It's
not exact, but pretty damn close. You should ask to watch the guy do it the
next time the perform the test. If the company has more money that mine
does, they may have the electronic type that does everything at once and
even spits out a printout of the test.

"Mark Modrall" wrote in message
...
Hi...

The oil company repair guy was here servicing our old furnace the other
day... He said that it's running at 79% efficiency (however he measured
it).

That's 'steady state' efficiency. It's not AFUE (annual fuel utilization
efficiency). If he read a 79% efficiency, you equilivent AFUE would be
around 62-65%.