HVAC Help needed ... converting 3 season room?

I have a 3 season screen room that is roughly 350 square feet. It is a 6 sided room, only 1 side shares a common wall to the house. The walls extend up from the floor about 36" and the windows would go from there up to near ceiling level.

The room is NOT insulated. The room is elevated 14' above ground level. There is a small attic above the ceiling but only about 24" of clearance.

I am considering converting this room into a fully insulated 4 season room and would need to heat it for the winter and get AC to it for the summer months. My home's HVAC is maxxed out, so this would need its own HVAC unit. My question is, what type of unit should I use? I used a split unit in my new garage/workshop and like that unit, but don't think it is really attractive enough to use inside a room in a house. Perhaps they have nicer units that can be hidden better? I know they have "heat pump" versions that would be able to provide most of the heating needs, but I'd probably still have to suppliment it with a small furnace for winter use? If so do they make small furnaces that can be tucked into the attic?

Below is a photo of my daughter's playhouse, in the background is my house and you can see the room I want to make into a 4 season room. Not sure how much work it would be, but the big concern right now is heating & cooling. If that is too much grief, or too obtrusive, it would kill the project.

ANY HELP or recommendations would be greatly appreciated!!!

Bob,

Because it is up above ground where cold can get in from the floor I would seriously look at wirsbo for the heat system. You may not be able to get enough Btu's with the wirsbo but make it your main source. You will be much happier if you do. Most forced air systems will keep the room warm but you will always have a cold floor. The wirsbo can even in some states just be tied into your existing hot water heater. Alls you need is a pump, thermostat, solonoid valve and the piping. I do recomend a double wall heat exchanger so you don't mix domestic water with stale water that you get in a wirsbo system that is not being used in the summer.

For air conditioning you could use what is called a PTAC. Packaged Terminal Air Conditioner. You typically see them in hotels. This would eliminate the outdoor condenser that you say will be a problem locating. If you get a good name brand one the noise level isn't bad. Or you could use the split type system like you used in your garage as it will more than likely be quieter. They also have ceiling mount type splits like you purchased for you garage also. Just get it with a electric heat assist but keep your wirsbo the main source.

Hope this helps you.

murph

We use a heat pump for AC & backup heat if we have trouble with our gas well. The heat side works well until it gets below freezing. It probably is good enough to keep pipes from freezing, but it does not heat enough to keep us consistently above 60 degrees when it's below freezing outside. Maybe heat pumps have improved (ours is nine years old) but from our experience I would be hesitant of one as the only heat source. The A/C side works great. If you could supplement the heat with a small propane or gas unit, I think you'd be in business.

Doc - if it's above 32 outside and your Heat Pump still can't heat your house then get a good service guy to look at it.

The first year in our house I was cursing our Heat Pump. I found a good company to service it and it is working great (as long as it is warmer than 32). Our heat pump is 13 years old, held together with duct tape in places but it is still working great.

Bob, there are tons of radiant floor options out there. I'm a little scared of the water based ones - the thought of a water leak (happened to my Dad under a Spanish Tile floor) just makes me not want to go there.

There are more electric options out now that seem fairly easy to install.

Heating or cooling a small area shouldn't be that hard or cost prohibitive.

PBinWA said:

Doc - if it's above 32 outside and your Heat Pump still can't heat your house then get a good service guy to look at it.

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It has been awhile since I had to use the heat pump for heating, but at that time it was fine when the outside temp was above freezing.
I modified my comment in my first post in order to convey that point.

PBinWA said:

Bob, there are tons of radiant floor options out there. I'm a little scared of the water based ones - the thought of a water leak (happened to my Dad under a Spanish Tile floor) just makes me not want to go there.

There are more electric options out now that seem fairly easy to install.

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With the utility rates in my area for electric, that is just not a viable option to use for a long term heating solution. I think a heat pump might be a good partial solution but there would need to be some sort of primary heat for the winter.

thcri said:

Because it is up above ground where cold can get in from the floor I would seriously look at wirsbo for the heat system. You may not be able to get enough Btu's with the wirsbo but make it your main source.

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Murph, one problem that I see is that the water heater is on the opposite side of the house, it would make for a very long run and I wonder if the temperature drop would become a problem?

The floor is held up with 2x12s. My thought was that I'd spray in low expansion foam between the joists, then cover it with a vapor barrier. Top that off with 3/4" T&G plywood. The room would likely be carpeted and would become the new master bedroom, and being a bedroom, it would need to be maintained at a comfortable temperature. I am worried about the cold floor and even wondered if I would be better off with a foam sandwich floor . . . something like plywood, topped with 1" rigid foamboard, topped with another layer of plywood, all over the 12" of spray in low expansion foam insulation???

The existing master bedroom, which is adjacent to the 3 season room, would be remodeled to expand the bath, double the closet space and create a reading room that would be about 12' by 15'. Even with the remodeling of the existing bedroom, there is no way to run air ducts back to the main body of the house because of cathedral ceilings that run full width of the roof in that area. That would be another reason to keep the HVAC set up as its own unit. But it would need to be efficient, quiet, and an unobtrusive installation. I could pull a natural gas line up the side of one of the pillars that support the room and hide it with a chase to provide N.G. for a small furnace.

B_Skurka said:

The existing master bedroom, which is adjacent to the 3 season room, would be remodeled to expand the bath, double the closet space and create a reading room that would be about 12' by 15'. Even with the remodeling of the existing bedroom, there is no way to run air ducts back to the main body of the house because of cathedral ceilings that run full width of the roof in that area. That would be another reason to keep the HVAC set up as its own unit. But it would need to be efficient, quiet, and an unobtrusive installation. I could pull a natural gas line up the side of one of the pillars that support the room and hide it with a chase to provide N.G. for a small furnace.

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I wonder if you could do a NG tankless water heater to heat the radiant floor? It would be a good "on demand" system and relatively low on energy consumption when not needed.

http://www.rinnai.us/

Rinnai also makes some nice direct vent space heaters but they may be to obvious for your tastes.

A small room like that could be easily heated with a NG Stove/Fireplace. Maybe you could consider those. Lots of options and styles these days. Some that are kind of funky and different which might appeal to a trendy guy such as yourself!

I have a propane stove with a fan that I use for backup heat when it gets cold and with the fan on it really can heat up 1000 sq/ft fairly easily. The fan is noisy but this is not a high end model.

Bob - you need to go to the following site:

http://www.hanleywood.com/default.aspx?page=qlsubscribe

Sign up for Building Products and Custom Home magazines. If you pretend you are a professional and click on the right choices then the subscription might be free.

You will get nice shiny magazines with all the latest and greatest stuff for upgrading your home!

B_Skurka said:

Murph, one problem that I see is that the water heater is on the opposite side of the house, it would make for a very long run and I wonder if the temperature drop would become a problem?

The floor is held up with 2x12s. My thought was that I'd spray in low expansion foam between the joists, then cover it with a vapor barrier. Top that off with 3/4" T&G plywood. The room would likely be carpeted and would become the new master bedroom, and being a bedroom, it would need to be maintained at a comfortable temperature. I am worried about the cold floor and even wondered if I would be better off with a foam sandwich floor . . . something like plywood, topped with 1" rigid foamboard, topped with another layer of plywood, all over the 12" of spray in low expansion foam insulation???

The existing master bedroom, which is adjacent to the 3 season room, would be remodeled to expand the bath, double the closet space and create a reading room that would be about 12' by 15'. Even with the remodeling of the existing bedroom, there is no way to run air ducts back to the main body of the house because of cathedral ceilings that run full width of the roof in that area. That would be another reason to keep the HVAC set up as its own unit. But it would need to be efficient, quiet, and an unobtrusive installation. I could pull a natural gas line up the side of one of the pillars that support the room and hide it with a chase to provide N.G. for a small furnace.

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Even with all that insulation I am afraid that you will still have a cold floor. Just my opinion and I guess experience. Remember, insulation will only slow the process down, it can't stop it. If you have room for a NG furnace or can make room do that. And if your master bedroom is at the other end of the house from the water heater then maybe add a water heater at the new end and tie your master bedroom in it. This way you won't have the waste of getting hot water to your master bedroom. Just some thoughts if you can do it.

murph

Any idea how many BTUs of heating/cooling I would need for this 350 sq.ft. room?

With 40% of the walls being glass, and no basement under it, I suspect that it will need more capacity than a conventional room of similar size.

I just put in a Direct-Vent Wall Furnace and according to the big box sitting behind me the 18,000 Btu/h is enough to heat a 529 Sq. ft. room.

Are you considering a stove/fireplace or are you leaning towards radiant?

PBinWA said:

I just put in a Direct-Vent Wall Furnace and according to the big box sitting behind me the 18,000 Btu/h is enough to heat a 529 Sq. ft. room.

Are you considering a stove/fireplace or are you leaning towards radiant?

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I was actually thinking of a forced air unit mounted in the attic over the room. Murph is making me give serious thought to a radiant system, but logistics of installing one might be more trouble than it is worth given the configuration of the room. Again, this would become the main room of the bedroom suite so it really needs to look nice and it needs to be quiet too!

I just checked the blueprints, the room is a bit bigger than I thought and measures 30' long by 16' wide, but because both of the ends are tapered it doesn't measure out to the full 480sq.ft. I expect it is probably about 400sq.ft. instead of the 350sq.ft. that I estimated earlier. But again, 40% of the perimeter is windows which will have minimal "R" value so I expect I need more BTUs than if I were considering a more traditional room with less window coverage.

Below is a photo of ceiling mount split system Heat Pump/AC unit. I still think that a small furnace would be needed for additional heat in cold weather.

Radiant is all the rage these days. If you are putting tile in then Radiant is pretty nice. Nothing like warm tile on a cold day.

If I had the money, I'd go with radiant but it is expensive. Just make sure you get a good installer that is experienced and stands behind their work. I don't trust myself enough to do water based radiant myself - electric maybe.

Bob,

It's 7:30 and still at work. When I get home I am going to find some installation procedures on how to lay the pipe for wirsbo. You can even put it under the floor and between the joist. Then put your insulation under the pipe leaving a 3" gap. That is the why a lot of my house is and it works great. Have you ever been in a house or walked on a floor that has wirsbo? When we built our new house we put it in the lower level (concrete) but not the main level except the two bathrooms on the main level. Now my wife is ticked at me because I did not put it on the main level. I even have it in my garage. Once you have it you would never go back.

murph

Murph, my friend has a radiant floor in his home and it is very nice. My biggest concern with installing it in my situation is that I would have to find a place for the boiler and pump and that place would probably have to be inside the bedroom!?! I suppose I could put in some cabinets and install a small boiler and pump in the cabinet? Exhaust it out the side wall? I was not planning on putting in any cabinets under the windows other than perhaps a low entertainment unit with a hidden TV that rose up out of the cabinet when we wanted to watch it, and that would likely be on the far end of the room and probably would be kept as small as possible (By the way, has anyone built their own entertainment center? Rockler's catalog has all the hardware for lifting a TV, I have the tools, but not sure if I have the skill for that large of a project)

One other concern with a radiant system is I'd still need to have a ceiling mounted heat pump for the AC portion of the solution.

B_Skurka said:

One other concern with a radiant system is I'd still need to have a ceiling mounted heat pump for the AC portion of the solution.

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Yes radiant is more expensive, but you have to look at the comfort level it will give you. With your floor being exposed I am worried you won't be happy. But if you don't have room for a water heater then you may not be able to have it. Combi-Core makes a dual water heater, part domestic, part radiant.


murph

Bob,

Here is what is called Magic Pak and it might be useful in your application. This unit is a complete unit HVAC but does have to be mounted on an outside wall but does not take up anymore room than a closet. It can be gas or electric.

murph