How to deal with doors opening and closing -- letting in hot air?

[KWBum]

So, I'm in the process of re-thinking my A/C. I may simply be replacing a unit (one of three), or just re-designing the whole darn thing.

Hence, I'm asking all sorts of questions.

I'm a slightly strange homeowner -- HVAC problems actually keep me awake at night!

In any case, and this is a question I've pondered over the years, here goes...

How does one best deal with an area in a house that gets a lot of exposure to the outside?

In my own house I have three such areas. This is South West Fla.

1) A laundry room, right off the kitchen, that leads to the garage. We are going in and out constantly. At times, we go in and out so often, that the door might as well be open full time.

2) A living room. Very large, 20' X 20', but communicates with the pool area. So, when the pool is in use, the kids are in and out non-stop.

3) A bedroom. Right by the pool. Less use but still, the door is letting in a lot of outside air.

In short, we live a very indoor/outdoor lifestyle.


I've thought of two solutions:

1) Just install an additional, large, regular A/C return over each entrance.

2) Over each often-used entrance (inside the house, I mean), for example in the laundry room foyer, I could install an in-line fan. It would be exhausted to the outside. I would run it at low CFMs, say 20-40CFM -- but constantly.

Negative pressure is not a problem, because we're coming and going so often. But, if each area that get open to the outside all the time, has an exhaust fan, less of the hot, not-conditioned air gets into the house. Or so I'm thinking??


Thoughts?

And all input is always very carefully considered, and much appreciated!! (And will keep me awake...considering...things...)


b (Thanks!)

[Frank-0]

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[genduct]

so you can get some cold water and pick coils that can handle the high latent load. Pool that communicates to living space with kids splashing around and you have AC and expect residential equipment to do the job...

Good Luck

[Frank-0]

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[Frank-0]

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[jpsmith1cm]

Frank-0

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[KWBum]

so you can get some cold water and pick coils that can handle the high latent load. Pool that communicates to living space with kids splashing around and you have AC and expect residential equipment to do the job...

Good Luck

Hmmm...

Sounds a bit hopeless.

But, at the same time, I'm thinking that I can't be the first homeowner in Fla to have this problem.

Also, I'm not sure what a small chiller is?

Installing an extra return in foyer, over the door to the garage that gets a lot of use was actually the suggestion of a pro who came to service my A/C.

And the idea of continuous, low CFM exhaust was my own idea.

I'm kind of leaning toward the continuous, low CFM (25 or so) idea.

What I'm thinking is that exhausting at low CFMs to the outside won't affect the A/C too much. But, it will pull out the hot, humid air that rises to the ceiling.

I mean, the door opening/closing itself dumps all sorts of air in and out.

A return over that area would mess with the balance of the A/C more, I would guess.

And air curtain would be nice -- or any other commercial solution. But, I don't know if that's realistic for me at this point...

Any thoughts?

[BNME8EZ]

Have you given any thought to an air curtain? Very uncommon in residential but would help slow down air transfer through the openings like they edo at freight doors.

[skippedover]

You need a good contractor who's not afraid to install one of the new modulating heat pumps. If you were my client, I'd recommend a zone control system, coupled with an over sized heat pump such that when high load demands are present, the system has the capacity to do the job. By over sizing you'll also be able to get very efficient heat at colder temperatures than a normally properly sized HP but at the same time, being able to reduce to 30% of maximum output will make sure the system isn't over sized for summer cooling and so can do a great job of dehumidifying your home. The ducts will need to be re-worked to accommodate the areas that are currently problematic due to outdoor air infiltration but a sophisticated zone system can easily handle the variable needs of each zone. We're a Bryant dealer so I am most knowledgeable about the Carrier/Bryant line. In keeping with that, I'd recommend a Bryant Extreme heat pump, Evolution zone control system and re-work of ducts as needed to accommodate the system over sizing. You'll be pleasantly surprised at the new found comfort and overall substantially reduced operating costs. You'll also be surprised at the sticker price so please be sitting down when you get the quote. It's going to cost but the results are well worth it. To get things into perspective, I'd say the costs to acquire a properly designed and installed system will be on the order of the cost of a small Lexus auto or less.

[motoguy128]

+1 on either a modulating heat pump like a Carrier Greenspeed, or replace all 3 with a single VRF system with 3 indoor air handlers such as those by Mitsubishi or Daikin.

The 2nd option since it's a larger home that needs 3 systems and has high humidity and varyign loads, is putting in a chiller with 3 or more seperate fan coils possibly with hot water reheat as well off of a hot gas reheat system making hot water or a natural gas wall boiler. You can even use the chiller to heat the pool water as well with a seperate heat exchanger.

FYI - a chiller is just like a air conditioner, but instead of cooling air, it cools water. All larger commerical and industrial that need cooling and are designed correctly and effciently, use chillers in warm and hot climates.

That beign said, chillers, while prviding better year round comfort and dehumidification, and lower overall operating costs on larger systems, are not cheap. The Bryant and Carrier Inverter drive system like the Greenspeed and Extreme, might be more econimical overall.


I wouldn;t specifically modify the ductowrk. IF anything I'd add a supply near and exterior exit, not a return. A return will increase the amoutn of air that leaks into the home when the door is open and could cause mold in the return ductowkr. A supply on a system that runs continously at low speed will help pressurize the space to keep the hot humid air out. However, you may also get some sweating on the registers too. I would use plastic registers if possible in thseo locations.

[Shophound]

Just put one of these over each door that gets heavy use:

[motoguy128]

Hmmm commerical air curtain. Nice idea.

[energy_rater_La]

I thought air curtain also.
as did poster #8, 11 & 13.

limit numbers of doors used to buy less air curtains.

best of luck.

[vstech]

a poor man's air curtain would be to have a return set outside to positive pressure the house. it's commonly called fresh air makeup.

[genduct]

A living room. Very large, 20' X 20', but communicates with the pool area. So, when the pool is in use, the kids are in and out non-stop.

3) A bedroom. Right by the pool. Less use but still, the door is letting in a lot of outside air.

The POO: makes this a situation with a latent load that is offf the charts and more of a commercial application
A chiller produces cold water and you can select coils that will deal with the high latent load whate "standard equipment will NOT

Sorry to mention this but everyone in Fl has a pool that communicates with their living space, if I understand your post

[Frank-0]

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[jpsmith1cm]

Frank-O

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[wanttosee]

What if you positively pressurize the house? Any door open would push cold air out instead of hot air in.

[AtticAce]

Why not build an addition over your pool area bringing it inside.

[KWBum]

This has been very useful. If for no other reason than this...
Of the 4-5 pros I've had look at the house, only one offered the Bryant Extreme, and at a fairly reasonable price.

But the idea of air curtains really makes sense -- short of redesigning the system.

My question about that is, do they have to be mounted on the inside? I've looked at some sites, and they all seem to be inside mount. Trouble is, all the door in my house open to the inside. Is that a problem?

Thanks!