Heat.....A/C

[The_King48]

I am adding on to my house.... I am putting a master bedroom were my old attached garage was..... Actually the previous home owner did this allready, but lets just say it need updating... I have the whole room gutted down to the 2x4s and part of the floor up because I am moving the bathroom.... Anyway, there are no ducts running into the room. I can see the cold air return in the crawl space. It would be accessable to tap into pretty easy. Would I need to tap into a heat duct so I can get ac and heat in the room. I plan on putting electic heat in the room allready. The house is a 1953 rambler with the furnace on the other end of the house. I don't know if it could push the air that far. Any opinions, or options.... Thanks in advance.

[Roofer]

No one has answered this yet??!!! Come on guys.........

I am not an HVAC guy myself, obviously, but my thought is that your furnace would not handle it. If it can handle it (75K BTU or bigger, depending on your sq. footage)......... besides just the heat ducts, you would have to have some way of recovery air (cold air return or air exchanger). I would look into some kind of alternate heat source and/or possibly upgrade your furnace and AC unit.

[PDOGG]

I don't think you will ever be able to cool the room with the current system. The equipment is usually sized to the original structure and putting extra runs to that sytem will amount to nothing more then, (as my dad would say) a fart in a whirlwind. Electric baseboard is a good idea also look into a Mini-split ductless air conditioning system. They are very quiet and efficient and take minimal provisions to install. Fujitsu and Mitsubishi make nice units. ask your local hvac person about it

[sparcebag]

The heat duct needs to be larger than the flex lines at 8 inches unless you installed two,I would think the forced system would handle it,its higher pressure in the plenum and it will push the air there.You may have to set the thermostat a bit higher for heat and lower for air,but most systems are oversized,they never install a system thats sized exactly for sq.ft.and all the openings have a formula for BTUs Air pressure.And you say your going elec.base so I would'nt worry at least 2 8" insulated flex pipes even a third with control baffles.Go for it!

[PDOGG]

I would definitly not run flex that far! 3 8" runs would be equivilant cfm to almost 2 tons of cooling. I don't know how large your a/c is to begin with but I am guessing it wasn't oversized by 2 tons or you would never have any humidity control. Your furnace may be somewhat oversized but if you where to have an air conditioner that was oversized 2 tons to begin with it would never had ran long enough to remove any humidity from the structure. In the case of a converted garage you have at least 5 sides of that room exposed (3 sidewalls, ceiling, and floor. That room is going to cool in the winter and heat up in the summer way faster than the rest of the house no matter how many flex ducts you run out there. The only way to cool that room properly in that case is to treat it seperatly. Either a seperate unit or zoned off of the exisiting unit.

[sparcebag]

In that case how many Sq.Ft. is the house?Whats the BTU output of furnass,whats the CFM of blower,whats the window and opening factor involved in loss,and the size of air unit & compressor.

An assumption can be made.how long are the suggested 8" flex runs

PDOGG I've been looking for the heatloss factor related to openings and sizes.The equasion.Maybe you can help me?Do you have it or suggest where I can attain it?

[PDOGG]

Give me your email and I'll send you what I use.

[PDOGG]

All I am trying to say and I guess I probably got a little complicated there. Being as you have a room seperate from the rest of the house and having so much exposure. That you will have much better temp control if you treat it seperatly. Will adding some runs in there help a little, yes. But with it being seperate from the rest of the house the T-stat is not sensing the temperature changes it the room, which will be happening at a higher rate then the rest of the house. Thus making that room hotter or colder. Your are already planning on putting baseboard in there which is a great idea. And maybe cooling isn't that big of an issue to you and maybe it's on the north west side of the house so it's inhertingly cooler there to begin with. All factor's in deciding what will work and what won't. I just highly doubt unless it was sized for the room to begin with that the a/c unit is big enough for that much added load even though the furnace maybe. And I would highly suggest against any flex runs longer than 15-20'. Hope that made it simlper.

[sparcebag]

PDOGG Email add is in my profile....THANKS

[PDOGG]

I tried to send it twice not sure if it came through or not it was giving me a strange message if it didn't work let me know I can send it again you just have to print it out and put the #'s in and do the math manually.

[Tima]

might want to think about some extra insulation, or furring

the walls out. 2x4 walls can let alot of cold in.

[sparcebag]

Thanks mike its a OK method but the Manual J is what I'm trying to find.Mnnice if hes here may help,if hes back from vacation.

I shoulda added its for a green room 90% glass & skylites.basically for plant starting in Feb.and porch.

[PDOGG]

I'll try and find what your looking for if no one answers in the mean time.

[PDOGG]

I think I have you hooked up now.