options for heat in a 3rd floor attic master suite

mjp82

So after a year in our new home my wife got the idea that we need a master suite, That means either an addition over the garage or finishing the attic. So far the attic looks like the winner, but my new concern is getting heat up there and also ac. The home is a 1925 Victorian with about 850-100 sqrt of attic space depending on how I lay it out. That will include a bedroom bathroom and walk in closet. The home has forced hot water currently (ng) but I don't think I can expand that much more to the existing boiler, and I don't want to replace it, as its only a few years old.

So the question becomes what type of system would be best suited for this. I'd ideally like some thing that I could use for both heat and ac, but I also has the idea that if I had a separate AC I could duct it into the other bedrooms below.

Everything now I'd very conceptual right but this is the one part of the project that I,m the most unsure of a direction. Also we would want gas for heat as our electric cost are very high.


Thanks in advance.

Bob Bona_4

Lots of options. If you can chase up 2 pipes from basement, perhaps do some period radiation up there or gasp...some fin tube baseboard as a zone. Get creative and follow a chimney up or in closets for a chase? When the contractor does a heat loss calc, and you weigh in zoning factors, your current boiler may be sufficient. Should get a whole house load done to verify anyway, if the current boiler is right sized.

you could do an inverter heat pump, they are very energy efficient but totally electric...heard you on the high electric rates. They still are way better than electric resistance baseboard. Then you have your ac covered. Up there anyway.

You could chase up piping like said before and put an air handler in a knee wall and do hydro air with ac. With maybe some drops to feed the second floor as another zone, or not depending on space.

the ac lines could chase down to basement or worst case be sleeved on the exterior to ground.

another thought would be a gas furnace up there, 90-95 percent AFUE, chase a gas line up from basement. This is not my first choice though- more complex.

Those are my initial thoughts.

BobC

Tell us what brand and model boiler you have and how many radiators you have. A heat loss will have to be done so you will know if you have any excess capacity in that boiler. Also how well insulated is the house now?

Bob

mjp82

Bob Bona: getting a gas line isn't a problem I have a 1/2" black pipe running to the dryer on the second floor right now.

Bob C: my only issue there is even if it is large enough to accommodate the added zone, right now the 2600 sqft of living space is on one zone. Without busting into the living space I would only be able to run one set of new water pipes to the attic, without really tearing into the first and second floor living space.

Bob Bona_4

That's a plus. You'd have to check the pipe size to see if it can carry the dryer and a furnace to the dryer part. A good heating guy can do this. I'd figure 30- 40k input btu dryer and a 40k input btu furnace (they don't come much smaller and I can't imagine a residential typical attic needing over 25k).

I would favor some kind of hot water radiation over hot air if possible for better comfort and efficiency.

There's always the air option.

mjp82

I could even replace the dryer line with 3/4" if needed. Now if I can run a hot water line and return from the basement boiler can I run several priced of baseboard off that and just tuck it behind the knee walls?

mjp82

Basically can hot water baseboard be run as one bog loop around the attic?

EBEBRATT-Ed

Yes you can do the attic in one loop. Have a heat loss and heat gain done by someone that knows how or download the Slant Finn app (for heating) and do it yourself.

You will realize that you won't need that much more heat. Your attic has no heat now which means the first floor has a "cold " ceiling. Now the attic will have a warm floor below it--your just moving the cold ceiling up to the attic if you can picture that. You only need to have enough additional heat to offset the heat loss through the attic walls and windows and a little bit more for the pitched roof.
Most likely you will find your boiler is large enough

mjp82

That would be great if I could do it as one loop, to save the money of having to install a desperate heating system.

Now it's onto the AC, anyone have experience with or know of what brand / type of system would work to provide multi zone AC, for the new attic master and 3 bedrooms below? I'd prefer the type that just has the small round outlets, but I don't any any experience with central Air systems. In reality the current bedrooms are not that bad with the whole house fan, except for those few extra muggy nights, but if I can run what I need behind the knee walls to provide those bedrooms with AC why not. I just want to be able to control what rooms are on and what rooms are off for the sake keeping it efficient.

I can't say enough how great this site is, since i found it, I've learned so much, and been able to make well informed choices about things.

EBEBRATT-Ed

Have to do a heat gain calc for the AC. 600 sq ft /ton is a very rough guess not to be used for sizing. You could use ductless mini split with multiple evaporators.

I will let others comment on "Space Pak" the small duct system as I have no experience with it. I have herd it is a good system runs with low evap. temps.

Bob Bona_4

Hot water bb sounds like a good plan. Or cast iron rads if you are into keeping the vintage flavor. The small round ducts are part of high velocity ac setup like Spacepak or Unico. An exotic proprietary setup that requires mixing and matching their specific air handler to another brand of condensing unit. I have yet, in 26 years, had to resort to this. Where you would see one typical supply register you would need 3-4 of the small round ones. Plaster and lathe ceilings? Oh joy.

I envision a typical air handler preferably variable speed, in the kneewall. Two parallel trunks come off it. One for the attic, one for the second floor. The second floor room ducting can run in the floor joist bays to reach room ceilings on the second floor. The attic supplies can be taken off the other trunk. Motorized dampers in the two trunks create your 2 zones. Return air can be split into some from attic, some from the second floor common area? Build your knee walls 4 foot or better for equipment space and have full access to the air handler and zoning components.

wogpa67

Hi-velocity if installed correctly is a good system. Make sure you have 6-7 outlets free of the diffusers per ton. I prefer not to use a central return. Have them install a merv11 filter.
You most likely would only have to do the attic and second floor.

On the heating side look into finding matching radiation that is period correct to the home. You can fish the supply and return lines up from the basement. Then pull up the floor to go from Rad to Rad and back home. That way you have no heat lines in unconditioned areas.

kcopp

I am a Hydronic guy through and through...but a Ductless mini split is prob your bet. All in 1 and they are pretty quiet.
Mitsubishi...

Bob Bona_4

Yes they are good Kev, but not sure if this attics going to be a big open space and he still wants to ac the second floor. Multiple heads get fussy...

Mits/fuijits/sanyo...seem to be all from the same mother

mjp82

The other option is the new above garage addition, which might be the route ought we take depending on how the attic measure. I'm hoping for this mainly because then I get a balcony looking over the house behind US to the river.

That would actually be much easier to run the utilities through as it would be almost a split level between the first and second floors. That however still ends up with me finishing part of the attic as offices (she works at home 100%, me 25% of the time) and a nice big play area for the kid(s)

EBEBRATT-Ed

Well, sounds like you have some nice options

JUGHNE

I have done remodels using Multi-mini split heat pump/AC . It worked out to put the inside units on inside walls with the linesets run up in the closet behind the indoor unit, or gracefully boxed in. One outside unit can easily run 3 inside coils, (some do 4).
One thing I always try to do is bring the condensate drain for EACH inside unit to daylight out side thru the rim joist. IMHO the condensate drip is the best indicator of cooling working well. (and obviously the drain is not plugged; if it is you can carefully back flush with a garden hose ).
You have to adapt to the inside units being in your older décor.
But you have individual control for each indoor unit and the advantage of cheap heat during the shoulder seasons of heating, keeping the boiler off. You still need the hot water heat installed for cold weather.
You could price this versus ducted system/zoning/ losing space in the knee walls/access door to air handler & insulating ductwork and air handler room.
An advantage to inverter variable speed compressor drive is that you can oversize the cooling somewhat and use that oversizing to your advantage in the heat pump mode.

icesailor

I would be extremely surprised if your boiler isn't more than large enough to handle the additional load. PEX can be a wonderful thing. You can insulate it and it "fishes" just fine. If you want AC, put in a Mini-Split.

Be sure to do an accurate heat load calculation on the room. In fact, do it on the whole building. Also, be sure that your building codes will allow living space in a Victorian attic. Codes are specific about headroom/livable space. It could be tough. The Garage might be a better choice because of access.