Gas furnace/insert?

[jimmiller2]

High efficiency propane furnaces as I understand it are so efficient that they have only a pvc chimney pipe as the heat out the stack is very low. Are there any units available with this type efficiency that could be built in like a fireplace insert where you can see the flames?

Thanks

 

[DAKSY]

If a fireplace insert was as efficient as your furnace, you would only see blue flames,
Not very natural looking, IMHO.

 

[Later]

Google Empire stove mantis or if you have high speed internet try this link http://www.empirecomfort.com/ and download the brochure.

 

[jimmiller2]

I found the empire site and their insert has a 90% efficiency rating. This type unit will do exactly what I was looking
for as a major heat scource used in conjunction with a heat pump. I plan to build a very small retirement size home that will
be very open and easy and cheap to heat. I have a Yukon Big jack furnace that I recently installed in my present house but
in the next 10 years I may have had enough wood cutting.

 

[Don2222]

Hello

Yes, we had no fireplace in our living room so we built an LP Gas fireplace in with a 46" flat screen above it. We also had 2 built-in hutches on each side made to house the Yamaha 7.1 surround sound receiver and network Blu-Ray player. That is the way to go! We got a Heat & Glo SL-550TRSD http://www.heatnglo.com/Browse/Fireplaces.aspx with auto ignition. That saves $1.00 per day in gas over a standing pilot!

 

[jimmie ray]

High efficiency propane furnaces as I understand it are so efficient that they have only a pvc chimney pipe as the heat out the stack is very low.

Gas furnaces or boilers that are certified to use PVC pipe are almost always of the condensing type, where the flue gasses are normally cooled to below 140* F, and a condensate removal system is required. The amount of excess air for for combustion has to be limited also, to reach the dewpoint at a lower temperature - in order to attain the high efficiency. The maximum allowable temperature for PVC pipe in this application is 158* F. CPVC is rated higher, but there may be future requirements for only permitting installation of certified piping systems made of these materials.
A gas insert would then require a large heat exchange area, presumably with turbulence for the flue gas and room air flow, coupled with a burner that (as mentioned above) is designed primarily for a very rich air / fuel ratio.
Not sure if the insert exists, just some info on how the boilers and furnaces operate to accomplish this...

 

[jimmiller2]

What would probably work best for me is a fairly efficient unit that can use a horizontal stub type exhaust pipe that goes from unit horizontally thru the back wall using a stainless steel pipe. A unit with a reaonable eficiency and resonable cost.
Any suggestions for this type of gas (Propane) insert that I could in new construction.

Thanks
Jim Miller

 

[DAKSY]

Most DV gas fireplaces (you don't want an insert) can be converted to LP, so it's a matter of what style you want & how you want it to look...
Heat n Glo, Heatilator, Regency, & Jotul are the brands I'm familiar with & any one of them (or OTHERS) may suit your needs.
Most can be vented horizontally, although I don't think you'll need Stainless.
Aluminum, galvalume or galvanized steel are more common venting materials & less expensive...
Browse this forum to get ideas & then visit your local hearth shop.
Bottom line is what you want to see on Christmas or New Year's Eve when you're sitting near the fire with your SO & your favorite beverage...
HTH...

 

[Highbeam]

Don't get all crazy over the last 10% efficiency improvement between a forced air furnace and a fireplace. The NG furnace is very efficient at making heat but it then pumps that heat into ducts where huge losses occur. Your fireplace has no duct losses plus it acts as a zone heater to heat the room you live in while not wasting heat in bedrooms. The headaches of designing a condensing gas fireplace are not worth the efficiency improvements.

 

[vvvv]

Don't get all crazy over the last 10% efficiency improvement between a forced air furnace and a fireplace. The NG furnace is very efficient at making heat but it then pumps that heat into ducts where huge losses occur. Your fireplace has no duct losses plus it acts as a zone heater to heat the room you live in while not wasting heat in bedrooms. The headaches of designing a condensing gas fireplace are not worth the efficiency improvements.

why is a furnace typically ducted so that the heat vents are located under windows?

 

[Highbeam]

Windows are excellent conductors of heat relative to the walls of the room. The cold glass will sap away the heat from the air and cause a waterfall of cold air to pour down from the glass. The vent located at the window is supposed to counteract this and provide a more uniform room temp.

The duct losses are due to leaky ducts and locating the ducts in unconditioned spaces such as crawlspaces, attics, and basements. The ducts are poorly insulated and just loose heat.

Now if you can make that furnace ductless by just dumping the heat into the room then you can get mucho heat for your dollar. It'll be like watching a refrigerator run though.

 

[jimmie ray]

Since furnaces and boilers are not typically located within the design heating space, their radiant jacket losses are factored into the efficincy calculation as waste heat. If you happen to have your boiler / furnace and piping / ductwork within spaces that you desire to be heated (finished basement), and already has a high efficiency design, you would theoretically be actually getting close to 100% out of the system.
A stove or fireplace design, however, relies on radiant heat emmitted for it's efficiency. It is considered a plus, since the product is within the living space. But you wouldn't want condensing to occur on any of these surfaces, or the venting system, for many reasons.

 

[Highbeam]

Modern gas fireplaces do NOT rely solely on radiation to emit heat. They have huge heat exchangers to provide convection just like the furnace does. These modern glass front gas fireplaces are much more like a mini furnace than they are like an open fireplace. Many folks choose to upgrade their gas fireplace instead of replace a dead furnace, the fireplace can be a primary heat source.

 

[jimmie ray]

Agreed, most of the heat output of a gas fireplace is from convection. But any additional heat from radiation, however small, goes in favor of the efficiency. The difference in rating a boiler or furnace is that any heat from radiation (of it's outer surfaces) goes against the efficiency. The heat exchanger is considered solely responsible for the usable heat output.