HVAC questions

[spazegun2213]

While not for my garage I'm thinking about putting a shed dormer across the back of my 1940's cape cod. One thing I've not thought about is how the addition of ~300sq/ft will affect the need for heat/AC on the top floor. Are there many good places to read about sizes of units (to see if mine is up to snuff) and what flow rates need to be and size of ducts, etc?

I'm 90% sure about what is needed for framing, electrical, and plumbing, but I know nothing about HVAC.

TIA guys!

 

[thooks]

Screw all that worrying about adding on to a conventional HVAC system.

Throw a mini-split or ductless split up there and have no worries.

Daikin is king. Cry once. Do it.

Then you will be wanting to re-do the rest of the house.

 

[spazegun2213]

Screw all that worrying about adding on to a conventional HVAC system.

Throw a mini-split or ductless split up there and have no worries.

Daikin is king. Cry once. Do it.

Then you will be wanting to re-do the rest of the house.

I've thought about ductless, but part of the 300sq ft is a bathroom and a walk in closet. Would ductless work for all of that space?

(sorry if these ?'s seem silly, lol)

 

[aandpdan]

First thing, insulation.

You know you're going to be bringing it up way above what it has (or doesn't) have. That will help reduce your heating/ac demand. Include the rest of the roof while you're at it.

You may need some changes in distribution but more than likely your heating system is oversized, most are. To do it right, have a heat loss calculation done.

 

[thooks]

There are some ducted mini-splits and some cassette models that allow you to take a 6" round duct off to serve another room (such as a bathroom).

 

[Mike N]

Mini splits are excellent. Look at the Mitsubishi Mr Slim line. It may be overkill for what you need but they work extremely well, are very quiet and don't cost much to run. I have a 12,000 BTU unit in my detached garage and am very happy with it.

 

[lzenglish]

For your small space, I would consider a combo heat/cool thru the wall, or window unit, with a remote control. Your talking around 500 bucks for an LG, or like brand, and you won't need to run a line set and mount a remote condensing unit, like you will with a mini split. Don't get me wrong, I love Mini Splits, and have installed many of them, but it might be overkill in this situation. There are several good sites for sizing info., but I think a 6 to 10k btu unit will do the job for you.

Good Luck,

Wayne