Direct Vent Fireplace

[JimD]

We need additional heating in our old, underinsulated, house when the temperature goes below freezing. The heat pump cannot keep the great room, roughly 25x25 with 16.5 foot ceiling, warm. When it was in the teens, the GR didn't get to 60. So I'm looking at a direct vent fireplace insert to use for supplemental heating. Fuel would be propane.

Anybody with experience to share? Propane company will provide either a 120 gallon tank or two 100 gallon. If I run out with the 100 gallon tanks I am supposed to switch to the other tank and call them to replace the empty one. They check the 120 gallon and fill it, hopefully before it runs out. Which do you think is better?

[capncarl]

Jim
In my neighborhood everyone uses small tanks, I think they are 80 gallon tanks. Every one of them whines and carries on what a pain they are to transport, especially when full. The larger tanks would be better but the yards here are large and the driveways are longer so the propane company will not drive their truck on customer driveways. I'd check with the propane supplier to see how long of a hose they can handle and see if they can refill a large tank in your yard. That would be the deciding factor for me, and may even go with a larger tank, like 250 gallon and fill in the cheaper off season.
capncarl

[JimD]

Jim
In my neighborhood everyone uses small tanks, I think they are 80 gallon tanks. Every one of them whines and carries on what a pain they are to transport, especially when full. The larger tanks would be better but the yards here are large and the driveways are longer so the propane company will not drive their truck on customer driveways. I'd check with the propane supplier to see how long of a hose they can handle and see if they can refill a large tank in your yard. That would be the deciding factor for me, and may even go with a larger tank, like 250 gallon and fill in the cheaper off season.
capncarl

Thanks

[Knottscott]

We put in a Heatilator brand natural gas (not propane) insert in our GR a few years back, mostly for the novelty of having a fireplace, but the extra heat is nice in the dead of winter around here for when it gets to say -11°F. IIRC, ours was 25K BTU unit...the 48K BTU was quite a bit more expensive, plus I was concerned about too much heat when we wanted to have a fire when it wasn't bitterly cold out....the lowest setting on the bigger unit had more output than the high setting on ours. One thing we have noticed is that the heat spreads throughout the dining, kitching, and den area too, but often prevents the furnace from kicking on unless I turnup the thermostat to compensate,...otherwise upstairs gets pretty cold!

We had to get permits from the town...one for the fireplace, another for the bump out addition for the chase. Dunno if that's true in your area.

http://lumberjocks.com/projects/24145

[JimD]

Your installation looks nice. I did something similar a long time ago in Omaha, Neb. We had that house built when mortgage rates were about 12%. I left the fireplace out of the FR but had them put in the foundation but stop one block short so it wouldn't be visible until I was ready for the install. Mine was a woodburner. We moved about the time it was finished. I burned some softwood scraps just to have used it.

Thanks for your feedback, it seems like you are happy you did it.

[Condoman44]

When we moved to our current home we had a corner FP installed with an 80 gallon tank and direct vent. I finished the surround and modified the baseboard heat to complete the install.

The supplier installed the piping (CSST instead of black iron) and I provided the required #6 gauge copper ground back to the main breaker panel. You can search for all the reported issues and legal challenges for ungrounded CSST.

A few years later I changed suppliers and wanted a 120 gallon tank. They confirmed it would meet code of 5 feet from the nearest window. A DOT tank can be used which allows 4 foot if needed.

I also wanted a remote gauge which I installed later because the tank gauge was "remote ready". Since we have a "will call" account I read the gauge each week so we never run out.

The fan on the FP is powered by an inverter/charger in the basement below. This is a backup for out heating system if needed.

In this current chilly weather we run the FP each night while watching the evening TV shows.

[capncarl]

Does this inverter allow you to use this fireplace in the event of a power outage? My goal was to be able to operate a house heater with the power off. When you are able to operate off the grid even though you are normally on the grid you have a good advantage in adverse conditions. Kerosene lanterns are also a nice touch.
capncarl

[Condoman44]

Yes it will operate with the power off for about 8 hours. It uses a deep cycle marine battery. When the power fails it takes over if the fan is running. I also plugged in my broadband modem since it was in the same space.

[RAV2]

Pellet stove or insert. 'Propain' is expensive. Pellets come from a variety of sources and suppliers without a contract.

[vaking]

Jim,
I replaced central heating/AC system in my house couple years ago and did some research at the time. Heatpump is a tricky thing. It works by transferring heat from outside to inside (AC in reverse) and its effeciency depends on tempereture differential between inside and outside. When the differential is less than 15 degrees F - heatpump is very efficient, it is more efficient than any other source of heat. However, as tempereture differential increase - efficiency of heat pump rapidly drops. When differential reaches 30F - heatpump becomes useless. For this reason when people install heatpumps - they usually provide "emergency heat" if there is any possibility of outside temperature being 30F colder than what you want inside. In places like SC such low temperatures are infrequent and emergency heat can be electric. I am in Northern NJ, I installed a full blown gas furnace as emergency heat. When temperature outside drops to about 40F - smart thermostat automatically shuts off heatpump and switches to furnace.
I do not have experience with directly vented fireplaces, I am simply saying that you might not have a problem with "underinsulated house". When temperature outside is in teens - no heatpump will bring temperature inside to 60 even in the properly insulated house.

[Condoman44]

When we moved here we decided the time would come when moving pellets was not going to be an option. Prior to the move I enjoyed 13 seasons of Harmon pellet heat instead of electric furnace. It was a great way to heat and we loved it.

[woodturner]

Jim,
When the differential is less than 15 degrees F - heatpump is very efficient, it is more efficient than any other source of heat. However, as tempereture differential increase - efficiency of heat pump rapidly drops. When differential reaches 30F - heatpump becomes useless.

Heat pumps work more efficiently with higher ambient temperatures - it's not really elated to temperature differential. However, air source heat pumps begin to lose efficiency below ambient temperatures around 40F and the efficiency drops significantly below about 15F. Ground source heat pumps overcome essentially all these issues and are more efficient due to the constant 50F or so ground temperature.

This link discusses the sizing issues that can cause an improperly sized unit to be less efficient:

http://www.lacool.ws/heat%20pump%20tutorial.htm

For this reason when people install heatpumps - they usually provide "emergency heat" if there is any possibility of outside temperature being 30F colder than what you want inside.

A properly sized heat pump can readily maintain 70F temperatures when the outside temperature is 15F or above. Emergency heat is provided as a backup in case the heat pump fails or when the outside temperature drops below 15F. In addition, at the colder end of that range, a heat pump will take longer to increase temperature, so setting back the temperature during the day can increase operating costs, as the emergency heat may be used to decrease the time required to reheat the home.

As a practical matter, heat pumps are pretty efficient and are used throughout the continental US for that reason. In an area where temperatures are regularly and consistently below 15F though, a heat pump may not be the most efficient option.

[vaking]

Woodturner,
I agree with some of your statements but not all.
Let's start with the code.
Heating system is essential part of the building. Every building has it and it is sized to maintain comfortable temperature (70F) inside when outside temperature can be as low as 6F. It means heating system must be able to maintain 64F differential between outside and inside (that is in the national code).
Air conditioning is not required by code - it is a luxury. Not every house has central AC and even when they do - central air system is typically sized to maintain temperature differential of 15, may be 20 degrees. Central AC will maintain inside temperature of 70F only if external temperature is below 90F. Beyond that - nothing is guaranteed. In my area typical house will have a furnace with capacity 80KBTU/H paired with AC system with capacity 36KBTU/H (3 tons). So typical for my area is to have furnace more than twice the capacity of AC.
Heat pump shares compressor and other parts with AC, so it has same capacity as AC. That means it is fully expected that heat pump alone will be able to maintain at most 30 degrees differential, so it will need help when temperature outside drops below 40F. All the "inadequately sized" heat pumps are all heat pumps that are sized based on needs of AC - that is probably 90% of all heat pump based systems. In all such systems people fully expect that when temperature outside drops below 40F - heat pump will need help. All these installations have additional sources of heat - either furnace or electric strips. That is not a backup if heat pump fails - it is a code requirement when (not if) heat pump is not enough.
Ground source heat pump is definitely a nice idea. But it requires that source of heat must go at least 13' deep into the ground. Most residiential houses do not have basements that deep, don't think this is a common setup.
I agree with you that heat pumps are widely used and overall efficient. I live in northern NJ, my system is programmed to switch from heat pump to furnace when temperature outside drops to 40F. With all that my furnace gets turned on probably 30 days out of a year (this year might be an exception). Anybody living south from me will have even less use for emergency heat. I have seen my heat pump fail many times trying to heat the house with outside temperature being below 40F. Is it because my heat pump is too small or because below 40 heat pump becomes ineffecient? I think it is the second, but to be honest - not 100% sure. For me it is not important because I know my heat pump is not too small for what it was meant to do. I know that I need to use furnace when temperature outside drops below 40F and I believe Jim's problem is because he does not have another source of heat besides that heat pump.

[woodturner]

Ground source heat pump is definitely a nice idea. But it requires that source of heat must go at least 13' deep into the ground. Most residiential houses do not have basements that deep, don't think this is a common setup.

It may be one of those things that differs with local practice. Ground source heat pumps are fairly common around here. The normal practice is to drill a "well" into the ground 50 feet or so and place a loop of pipe down the hole - that is the ground source. Doesn't require a deep basement, it's all just in a hole outside. Many water well drillers are equipped to do this, it's essentially like drilling a water well, and cost is fairly reasonable.