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Hot topics: Planning of garage HVAC

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Original Post: Garage Conversion HVAC

GGPHD Member

Hello everyone,

I am currently converting my garage to a residential area and I will add a HVAC line for this rooms from the main side. I have some questions and I have pictures to follow them:


. Appendix 1: Supplies for the rest of the house cross the entire feed section of the oven so I can't draw a new line directly from the oven. Can I draw the line from Annex 2 (before fork) or Annex 3 (after fork)?

2nd What should the diameter of the new line take into account the fact that both supply and exhaust lines have to pass through a 9 "x 12" opening in a crawl space (Appendix 4)?

3rd After the crawl space, there will be an opening under the floor (between concrete and subfloor) into the garage for the new supply line between one row of radar and for the new exhaust line between another row of radar (Appendix 5 – only delivery line shown). The opening dimensions of the rule are 4.5 "x 14" (Appendix 6). Given this, what should be the dimensions of the channel line through here? What would also be the transition between the average line and the floor line?

4th In the garage there will be spray foam insulation in the floor. Do I still need to have insulated ducts for the supply and exhaust pipe considering that the insulation can be sprayed under the duct? Appendix 7

I really hope I didn't make it too complicated and if you have any other posts I would appreciate it. Thanks!

  oven system diagram

  new HVAC system diagram

  new HVAC system diagram

 oven system diagram

  new HVAC system diagram

  new garage hvac system drawing [19659017] new garage hvac system drawing

roughneck77 Member

The ductwork is dimensioned via a room of room manual J and manual D.

If your current unit has enough capacity for to properly condition the garage?

Someone didn't like you with that channel. It's pretty messy.

Have you considered a mini split heat pump? Just for the garage area.

airman.1994 Member

Mini split! You will never be able to get enough air to cool even the smallest garage.

GGPHD Thread Starter

I considered a separate plumbing unit for the space but the budget is the limiting factor. The current unit has enough capacity to add to this room.

I will check the channel size tables that you recommended.

Do you have input on my other questions? Thanks!

roughneck77 Member

There are no charts.

There must be a manual J and manual D calculation to determine channel size.

What size is the garage?

These openings are not sufficiently large channel.

GGPHD Thread Starter

I don't know what manual D and J are but I will check.

The garage is only 20â & # x20AC; & # x2122; s.

GGPHD Thread Starter

I question how I got a quote from two different contractors for this job before I decided to do it myself. Why didn't they tell me that the opening is not big enough?

roughneck77 Member

In reality, it is impossible to say exactly how much opening you need, how large a channel you need to run or if your current equipment is large enough for the extra load.

Manual J calculates heat loss / gain.

Manual D is used with a room in room manual J for channel size. [19659005] Do you run flex channel or metal channel?

Here is a free manual calculator J.

airman.1994 Member

20×10, have no idea where you are, what type of insulation, sun, etc. Id say at least 10in flex for delivery and 12in for return.

GGPHD Thread Starter

I live in CT and the insulation will be spray foam. I do not know if I will use flex or hard channel but I may use a rectangular cross section, which means hard channel.

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