floor furnaces

i know they still make them, and i've looked at a few models, but the question i have is are there any that are relatively efficient? i've seen thermal ratings at 70 something percent but then operating is like 55 or so. how is that even possible anymore? seems like they've gotten somewhat of a handle on the surface temp issues, but how come these things aren't in at least the 80% range? or are there ones that run on par with a standard furnace?

 

As far as I know, any furnace made today has to be at least 80% efficient. I checked one manufacturer's web site & strangely enough they didn't list the AFUE. Maybe some kind of exemption. I dunno.

 

I think the ratings are going to be lower cuz there is no blower to "push" the heat away from the heat exchanger.

 

jay : so the inefficiency lies in the fact that its a gravity system? i thought the efficiency ratings were based on combustion alone? either way, it begs the question as to why there aren't blowers then on gas units? are there add on blowers out there maybe?

grady : its all rather odd. i expected there to be high efficiency units, perhaps direct venting or condensing even. whats the deal here? i found this off the gama website :

EMPIRE COMFORT SYSTEMS, INC. Empire 3588-(2,3) Floor Furnace Gravity Type Natural Gas or Propane Input (Btu/hr) 32500 Heat Cap (Btu/hr)22750 56.0%

EMPIRE COMFORT SYSTEMS, INC. Empire 5088-(2,3) Floor Furnace Gravity Type Natural Gas or Propane Input (Btu/hr)45000 Heat Cap (Btu/hr)31500 57.0%

EMPIRE COMFORT SYSTEMS, INC. Empire 7088-(2,3) Floor Furnace Gravity Type Natural Gas or Propane Input (Btu/hr)65000 Heat Cap (Btu/hr)45500 57.0%

WILLIAMS FURNACE COMPANY Floor Furnaces by Williams 4505622 Floor Furnace Gravity Type Natural Gas Input (Btu/hr)45000 Heat Cap (Btu/hr)31500 57.0%

WILLIAMS FURNACE COMPANY Floor Furnaces by Williams 6005622 Floor Furnace Gravity Type Natural Gas Input (Btu/hr)60000 Heat Cap (Btu/hr)42000 58.0%

 

Here's one I found. They don't even list the output.
http://cozyheaters.com/pdfs/products/spec_sheets/ChallengerFF.pdf

 

grady :
i've seen the cozy model, and i'm going to try to find somewhere that lists its output/afue. odd that it isn't on the gama list.this is one of the williams models models...

http://67.114.233.34/images/Specification%20Sheet%20Floor%20Furnace%20Page%202.pdf

can you explain the thermal vs. afue % and what it means?

also, if you or anyone knows, what are these considered in terms of heating. are they considered furnaces like any other? essentially, are they categorized as permanent heating units or are they considered "heaters". its something i'll take over to the insurance forum if i must, but i'd be surprised if folks here didn't know.

 

Actually years ago there was a floor furnace with a blower. Not an add-on, factory. I would venture a guess it was probably late 30's early 40's vintage. I've probably seen 6 or 8 in my career.

 

One of the major differences is in AFUE, heat generated by the pilot is considered (and for the most part is) lost. There are a lot of other factors but this is the biggie.
I believe floor furnaces are considered furnaces, like any other, for insurance purposes. Many mortgage companies do not consider them as central heat & will not grant a loan on a property which has one.

That link wouldn't work for me.

 

so, i guess the key is to find one with an electronic ignition...gonna guess fat chance on that.

thats weird about them being furnaces like any other, yet insurance companies don't consider them central heat. kind of odd, considering its just a furnace with no ducts. they'd probaly okay a furnace with just a plenum pumping out air though...

 

And they have been around forever......"Pipeless gravity"

 

I said many mortgage companies don't consider them to be central heat. Not sure about insurance.

 

my mistake. sorry.

 

I've made the same kinds of mistakes myself. Darn, I wish I was goof proof.

 

Assuming these units are fairly efficient, I kind of like them - and don't care for electronic ignition. I have a Sunair wall furnace in my condo where I have lived 20 years now (40 year old wall furnace) and it has been very reliable, just needing a few simple parts. As it nears replacement, I like the idea that my furnace will work during a power failure just fine, without having to be home and "light" it, as with electronic ignition models - unless they have a battery back-up feature.
We also had a great floor furnace in our 50s house, when my parents upgraded to central heat and air, the face plate was taken off the old burner - it was still clear after all of those years of burning -
To me, many of these old style appliances are such workhorses that I would consider keeping one in an old house, and just supplementing the heat if needed in some rooms. It seems that with a few simple parts on hand for repairs you were pretty much set during cold winter storms, knowing your furnace would not likely break down, and would work during power failures.
I read so many repair nightmares with modern furnaces, as a newbie to them, it scares me to trust them totally for my heat source in a cold climate - if I move to one!

 

No, they are not efficient at all for our long winters. For the mild area like CA where heat is not needed much may be fine.

Also these floor furnace don't heat evenly in the house. Far end house is cold, and risk of freezing pipes.

It has been 15+ years since I've seen a floor or wall furnace used in a home here in Minnesota.

 

Around Seattle, old floor furnaces are still fairly common. Often they are fifty years old or more. Seeing one that has been installed recently would be very rare.

And for the right house, they can do a good job of heating. This needs to be an older house that is built around a one or two story core, rather than ranch style house that sprawl out horizontally.

With that compact, vertical structure, floor furnace heat on the main floor often does a good job of heating the seond floor as well.

Figure a nominal 75-76% efficiency when the furnace is operarting, with a somewhat lower AFUE rating since pilot light operation year round counts against efficiency. Of course you can turn off the pilot during the summer and sidestep those losses.

Pretty much any gravity vented furnace is going to limit out at about 75-76% efficiency, since the exhaust gasses need to be kept pretty hot so they will vent out the chimney and water in the moist combustion gasses wont condense into water.

Higher efficiency furnaces have inducer motor that use electricity to move the combustion gasses, and avoid use of standing pilot lights.

Make sure you house is suitable for heating with a floor furnace or you may be unhappy.

 

Is there a reason these floor furnaces could not be made relatively efficiently? As I am also considering replacing my 40 year old gas wall furnace, I have asked Williams products what changes have really been made in the last 40 years - especially since I really don't want electronic ignition, unless it has a battery back-up of some time, so it can re-light unattended.

 

Power is needed for higher efficent system. Here are things that are used for furnace to get higher %.
-Hot Surface or spark ignitior. (no standing pilot)
-Inducer or draft fan.
-Chimney dampers (older furnaces)
-Secondary heat exchanger (90%)
-Fan to move the heat away from the heat exchanger.

With out these items above, you are not going to get a higher effcients ratings.

 

Jay11j has some good explanations.

To the best of my knowledge, about the most efficient self powered gas heating equipment are direct vent gas fireplaces and stoves.

They use a fairly tightly engineered venting system that brings outdoor air to the equipment for combustion and then vents it outside without using a motor. And they extract about as much heat from the combustion gasses as possible short of causing condensation in the equipment.

Many have pilot generator systems that generate a small amount of electricity to operate the fireplace from a standing pilot. Other use an electric ignition system that plugs into the wall, often time backed up with a battery system that can be used if the power is out.

 

Very interesting - as a average joe, I would think the "simple" floor furnace would be efficient, since heat rises =

 

Hear rises --- that's the problem! Combustion gasses don't rise UNLESS they are hot. Take too much heat out and the combustion gasses wont rise throuigh the heat exchanger and out the vent and chimney, and thus there wont be fresh air to burn the gas.

"Gravity vented" furnaces rely on the combustion gasses being hot enough for them to move on their own. Often they are 450 degrees Fahrenheit or so to insure that the venting system works properly.

"induced draft" furnaces use a fan to force the combustion gasses through the furnace. So you can take out more heat --- combustion gasses in induced draft furnaces are usually around 350 degrees F., But again, there is a problem --- take too much heat out and the steam formed when the hydrogen in gas burns will condense into liquid water. So the combustion gasses can't be cooled down much below 350 degrees.

Condensing furnaces are designed to condense that steam into water, and then get rid of the water properly. The combustion gasses of condensing furnaces can be 90-120 degrees or so, vented through plastic pipe. Not only do you get heat from further colling the combustion gasses, but additional heat is produced from condensing the steam into water.

 

So the more efficient gas furnaces would also be less dry air, since it is not being heated so much?

 

Not on the "Not being heated as much", most 90% furnace has two pipes. One PVC is the exhaust, and other is the intake.. They both run outside, and uses 100% outside air, and that means you are not pulling the already heated air from your house to the burner and up the chimney, and that air needs to be made up , so it comes in from leaky windows/doors. With the air leaking into the home, that makes the home drier than a home not leaky.

The air flow is still hot from teh system, just not going to waste.

So, A 95% furnace, 95% of the heat is put into the home, and only 5% goes to waste.

Where a standard vent system, maybe 60% going into the home, and 40% going to waste.

 

The air can be just as hot from a high efficiency furnace as a lower efficiency furnace. A large part of that is how much air you pass over the heat exchanger.

Lots of air (high speed fan setting) lower temperature.

Moderate amounts of air (low or medium fan speed) higher temperature.

And of course the old floor furnaces had no fans. You could get toasty warm standing over that big grate!

 

I was just thinking about the different model floor furnaces I have encountered over the years, AND:

Does anyone one here, especially S/P remember the old Electro Gas model that used a spark plug for ignition? The power source was a Model T (I think, if memory serves me) battery box. You would always find them nailed next to a floor joice. I have no idea how long the battery would last.

To my knowledge that was the first electronic ignition device.

 

Never saw one of those, mbk.