My Industrial Cabin Build

[ROUSTABOUT]

So I need 28 tons of A/C? Or is it only the windows in the front? That would be 13. 14 if you count the doors.

How much does that cost?

Prices going up daily now.

 

[EddieWalker]

One ton of AC extra for each window.

I don't understand this. From what I understand, HVAC sizing is based on the volume of the building. Ducts are placed to deal with the heat loss of windows, but I've never heard of increasing the size of a unit by how many windows you have.

The HVAC Contractor should have been consulted before construction started. He will size the unit and create a plan for the ducting, along with electrical requirements before anything was framed. Then when the house is sealed in, he shows up and installs everything after the electrical is roughed in, and before the sheetrock happens.

In my opinion, it's better to go with a unit that is slightly undersized, so it runs longer, then a bigger unit, that is always turning on all the time. Kind of like a car. You use less fuel when driving at a constant speed than you do when accelerating from a stop.

 

[ROUSTABOUT]

I don't understand this. From what I understand, HVAC sizing is based on the volume of the building. Ducts are placed to deal with the heat loss of windows, but I've never heard of increasing the size of a unit by how many windows you have.

The HVAC Contractor should have been consulted before construction started. He will size the unit and create a plan for the ducting, along with electrical requirements before anything was framed. Then when the house is sealed in, he shows up and installs everything after the electrical is roughed in, and before the sheetrock happens.

In my opinion, it's better to go with a unit that is slightly undersized, so it runs longer, then a bigger unit, that is always turning on all the time. Kind of like a car. You use less fuel when driving at a constant speed than you do when accelerating from a stop.

Well you build yourself a greenhouse, and an insulated house with no windows. Size your AC according to square footage, and see which one is livable. Build both the same size with same amount of AC.

 

[ovrszd]

Well you build yourself a greenhouse, and an insulated house with no windows. Size your AC according to square footage, and see which one is livable. Build both the same size with same amount of AC.

I think accuracy is somewhere between your theory and Eddie's. I don't think I need to add a Ton of AC for a bathroom window for example.

 

[murphy1244]

That's why the HVAC guy does a heat loss-heat gain study first before the building is even built.
Its not really how many windows you have but the quality and the install of them that counts.
AS they say"Install is everything".

 

[Carl_NH]

I have to agree, a ton of AC per window would mean we need 25 ton of AC! Never heard of this - its about the building heat loss (for heating) and similar for cooling. Our HVAC contractor calculated for heating we needed 75-78K BTU at 5* F so we installed a 72BTU FHW boiler 11 years ago and never had an issue.

On the AC side, we have 2 Mitsubishi Mini Splits a 12K and a 9K, so not quite 2 Tons and this cools the house fine in the summer. Of course this is NH, so in the south or warmer climates more cooling will be needed, but most typical houses are a 3-5 ton units.

I think David is going with Mini Splits for cooling mainly in the BR's and main living area, at least that was the plan.

 

[ROUSTABOUT]

I think accuracy is somewhere between your theory and Eddie's. I don't think I need to add a Ton of AC for a bathroom window for example.

I just built houses for a living. I don't know nothing.

 

[ovrszd]

I just built houses for a living. I don't know nothing.

Never said you didn't know anything. Just looking for middle ground. My Builders were awesome. But they let an HVAC expert design and install our system.

 

[EddieWalker]

Well you build yourself a greenhouse, and an insulated house with no windows. Size your AC according to square footage, and see which one is livable. Build both the same size with same amount of AC.

You got jokes. I misunderstood and thought you were being serious. I get it now.

 

[WoodChuckDad]

[QUOTE="Carl_NH, post:

I think David is going with Mini Splits for cooling mainly in the BR's and main living area, at least that was the plan.[/QUOTE]

That is still the plan. I have been doing my calculations based on area, btu output, and making adjustments for high ceilings, tight building with full insulation, and thermal mass of the floors. It’s gonna be fun.