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-   -   Tx shop being cooled&heated looking for info on ducting and heat strip sizing (http://www.diychatroom.com/f17/tx-shop-being-cooled-heated-looking-info-ducting-heat-strip-sizing-160927/)

zman1969 10-23-2012 01:27 PM

Tx shop being cooled&heated looking for info on ducting and heat strip sizing
 
I am buillding a 30x30 garage/workshop and I am planning on a 3 ton cooling unit and a heat strip for warmth during winter. I dont need it 80 degrees but at least 60, and was recomended a 10KW strip which i was thinking was kind of small? this will not be a heat pump so all this will have for heat is the strip just wanted to be sure that its enough. I am also planning on doing the ducting and was wondering my options - I was thinking about a suspended metal duct with about 4 outlets along about a 25' length i have no idea where to source this stuff from-Lowes/Home Depot? or? Thanks ahead for your suggestions/tips :thumbsup:
Rich in DFW

SeniorSitizen 10-23-2012 02:12 PM

Since you are looking for suggestions/tips let me suggest if you are building a concrete slab floor put PVC pipe duct under the slab and be done with it forever. My 1,800 sq. ft. house is in a similar environment and is cooled with a 2.5 ton unit and the insulation isn't all that great. Sure there are days when another ton would be better but not that many and my unit runs longer on those days for better efficiency and moisture removal. 10K of heat is plenty for a work environment in a well insulated building unless you will have 20 ft. ceilings and this comes back to warming the floor with in floor ducting. Some systems like the water loops for heat are better if you care to go that route.

notmrjohn 10-23-2012 02:19 PM

10 kw should do the job, if insulated adequately. perhaps a 5 kw auto-matic back up strip, or auxillary space heater near glue, paint, etc storage, for the few really cold nights we get.. How many windows and are they double glazed? Consider also sun on garage.

Big boxes have ducting, vents etc. or AC supply house. DYI with duct board from AC supply house, not as sturdy as metal, and will need more hanger straps, ( get roll of hanging strap at Big Box.) but easy to work with and self insulating.

Reconsider heat pump. we replaced 2 1/2 ton AC, electric heat with high SEER 3 ton heat pump, electric bill had dramatic drop. Haven't had to use heat yet.

notmrjohn 10-23-2012 02:29 PM

Just saw fairviews answer, don't know what part of area you are in, but if you are on gumbo soil, you know problems with slab foundations around here. i would avoid putting anything in slab, including water and drain lines. if you are on stabler soil, it may be worth considering, warm floors are real nice, and once heated concrete slab is great heat battery. Be sure and insulate full depth of slab footing with foam panels.

Controllable two speed fan in airhandler is nice. High speed to get rapid cool down or heat up, then slower to just circulate air, makes it feel cooler and warmer. Unit actually cycles less once room reaches temp..

zman1969 10-24-2012 08:35 AM

Fairview, are talking about heated concrete? the cold isnt that bad I'm in North Texas not North dakota :) I will have 12' ceiling in it
notmrjohn - Hello neighbor! I'm in Lewisville, the A/C im looking at is a 14 seer and will have insulated doors walls and ceiling I guess for the little cold here the heat should be fine. my contracter wants me to go with his a/c guys 4k estimate I believe I can get this done for around 2k. this all will only be used 3-4 days a week not 24/7. he said I needed a pro to install a package unit and would install my unit for the difference of the 4k - I will pass on that offer

joecaption 10-24-2012 10:07 AM

I'm heating and cooling an 850 sq. ft. home with just a 2 ton mini split. In VA.
Very easy to install, no duct work, very low power usage, quiet. If I remember right it was a 16 seer.

beenthere 10-24-2012 03:23 PM

What kind of work are you going to be doing in the work shop. That will also have a bearing on what size A/C you need.

notmrjohn 10-24-2012 06:22 PM

I installed everything on new 3 ton heat pump, except brazing the lines,vacuuming lines, a squirt of coolant, and final connection of power lines to units.

Most of it, coolant lines, duct work was there. I ran heavier power lines, extended coolant lines to new location of condenser/pump and had to make sheet metal conversion from size of new air outlet to plenum. Most of actual installation job is grunt work. I could have done brazing but didn't have hot enough torch.

I have relatives in Lewisville, no point in saying Hey to them for me, associating with me is sure fire way not to get invited to their house. You may even be one of them. Does Buffalo Gap have any significance to you?

zman1969 10-25-2012 10:16 AM

Quote:

Originally Posted by notmrjohn (Post 1037242)
I have relatives in Lewisville, no point in saying Hey to them for me, associating with me is sure fire way not to get invited to their house. You may even be one of them. Does Buffalo Gap have any significance to you?

Giggle sorry no I'm a damn Yankee and a car guy I will have an above ground lift, compressor, bead blaster, welder and I have tools to fix tools :)
I am prett sure I want to do a package A/C 3 ton with heat strip. my building is wood and brick and what I'm really not sure about is what type of hole do I need for the 14" inlet and outlet ducts to pass thru the wall 16x32 or? and hoiw do I seal up around them? the ducting I can figure out sorry I am a little ignorant here :huh:

I think the heat and cool will be ok just needing some info on how to do this

beenthere 10-25-2012 05:31 PM

If your going to run the duct up the wall, and then 90 it to run across the ceiling for another 20 foot or so. You'll want to be at least a 16" round.

You can either cut round holes through your wall and then caulk them to seal them. Or make up metal flashing, and insulate the side toward the shop.

zman1969 10-25-2012 05:50 PM

Quote:

Originally Posted by beenthere (Post 1037882)
If your going to run the duct up the wall, and then 90 it to run across the ceiling for another 20 foot or so. You'll want to be at least a 16" round.

The a/c unit is like 1200cfm so that sounds right 16" and i will run this below the ceiling instead of in the hotter attic - wont look as good but less heat losses

Quote:

Originally Posted by beenthere (Post 1037882)
You can either cut round holes through your wall and then caulk them to seal them. Or make up metal flashing, and insulate the side toward the shop.

well i need to plan this because its going to be bricked - suggestions?
3'x20" rectangle then wood trim it around the tubes?

Doc Holliday 10-25-2012 05:58 PM

I'm in Houston if that matters. On package units we ALWAYS install them on the roof. One side is a return and one side supply, the usual. Open return box (filter in units) and drop down duct work either metal or duct board trunk lines. If open ceiling than all you need are registers directly on the trunk line. If closed office type than flex duct take offs to registers as well as one or two return runs with the filter(s) in the ceiling grid.

I guess what I'm asking is if the unit is on the roof or outside on the ground? I've never seen one package unit on the ground in Houston.

zman1969 10-25-2012 06:00 PM

it will be ground/foundation level

Doc Holliday 10-25-2012 06:07 PM

Have you considered the roof? Is it open ceiling? I don't believe there to be any operational difference in ground or roof location but duct work is easier to run. You're going to need the ducts up there anyways. Is that an option?

beenthere 10-25-2012 06:14 PM

On the outer sides of the pipes, they can brick around it, makes it look nice that way.

Wood trim on the inside.


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