Ventilation Problem With An Indoor Pool

 
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Old 02-03-2007, 01:15 PM   #1
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Ventilation Problem With An Indoor Pool


I am looking for some help explaining a roof issue that I encountered yesterday. I will start off by saying that an indoor pool in my area (Central Michigan) is a rarity for me to find and I have really no experience with the unique problems associated with them. So what I am looking for is a bit of expertise that can help cure this homeowners problem.

I visited this gentlemans house yesterday evening and the ceiling (in the pool enclosure)was stained from one end of the enclosure to the other and from the top to the bottom. The pool has been enclosed according to the owner since well before they purchased the home (over 6 years ago) and was OK until recently. The recent occurence was the fact that the heat had went out leaving only the pool with heat. This was supposed to have only been for a few days but the ceiling is completely destroyed and brown stains are running down the walls.

Here's what I found;
* The roof pitch is a 4/12 and was shingled with a 30 year laminate shingle a week after they purchased the home (6 years ago).
* A ridge vent was installed by the roofers and the owner does not know if there was one before they re-did the roof.
* The roofers did strip the roof to the bare sheeting and installed ice and water shield on the eves only.
* The roof system is a cathederal trussed framework with 1/2" plywood sheeting.
* There is no insulation in the ceiling other that 1 1/2" styrofoam sheets nailed to the bottom (ceiling) of the trusses.
* There are 3 apparent intake vents on the east side of the pool that seem to be thermostatically controlled to work in conjunction with a large gable fan located on the west wall which must circulate the moist air out and is controlled by a thermostat.
* I removed a peice of the styrofoam and found that the entire underside of the roof sheeting is a sheet of ice and now that the heat is back on it is melting and leaking through nearly every seam in the styrofoam.
* With no insulation in the ceiling and lanced soffit the airflow circulates perfectly from eves to the ridge vent.

He wants to know if this isolated occurance has caused this problem and what can be done to solve the issue for good. The big issue is that the new heat pump in the pool enclosire is a gas boiler type and when the circulation system starts up to move out the moist air it sometimes blows out the pilot to the heater which caused the problem from the start.

Does anyone have any experience with this type of situation and I certainly do welcome any suggestions that could solve this issue.

One suggestion given to the owner was to remove the ceiling entirely and spray foam the roof solid, which sounds reasonable to me but I would like to gather as much info as possible.
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Old 02-03-2007, 01:36 PM   #2
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Re: Ventilation Problem With An Indoor Pool


Any indoor pool space that does not have a "Desert Air" or similar system installed is asking for trouble. He needs to get up with an HVAC man.

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Old 02-03-2007, 03:40 PM   #3
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Re: Ventilation Problem With An Indoor Pool


Before you going out and having the homeowner spray insulate the roof decking, solve the problem first. That is only a band-aid for the symptom.

Wow, too many things going on. Did you say gable vents in addition to a ridge vent. Theory says that wil cause a short circuit of the exhaust ventilation flowage, ie; rather than the fresh air getting sucked in from the intake vents, upwards to the ridge vent system, it will "short cirduit" and be supplemented by taking the path of least resistance and poceed inward from the gable vents rather than the lower eave soffit vents.

Are the soffit vents 100 % continuous and of sufficient NFVA to supply the required exhaust potential. Alcoa states that 95 % of al ventilation problems are due to an inadequate capacity of fresh air intake ventilation.

What is the rafter distance from eave to ridge or the horizontal plane from wall to wall. Their is a certain distance where the distance diminishes the functionability of the complete ventilation system.

Decrease the indoor relative humidity. Ask HVAC techs on how to properly achieve that in this scenario.

Option. I have read about a power actuated ridge ventilation product. I can not recall if it was solar or A/C current. Just throwing this thought out in the wind.

Insulation? There is only a minimal amount of R-Value from the rafter beams. This changes the rafter bay temperature dynamics from bay to bay.

I hope this gives you a place to start.

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Old 02-03-2007, 03:52 PM   #4
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Re: Ventilation Problem With An Indoor Pool


The gable vent on the west side is more of a humidistat controlled power vent than a gable vent and the east side vents are thermostatically controlled to open up when the humidity reaches a certain level. As I see it this system (which supposedly worked well for many years) removes the moisture below the styrofoam insulated ceiling.

It does have ridge and soffit vents also but these seem to ventilate the roof deck above the styrofoam barrier.
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Old 02-03-2007, 04:02 PM   #5
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Re: Ventilation Problem With An Indoor Pool


Thats what the ridge vent and soffit vent combo is supposed to do.

On a side note, does the ridge vent contain an esternal baffle, as in the Shingle Vent II, by Air Vent and several other manufacturers. The theory is that even a minimum of external wind creates a vortex, they call it the "Bernoulli Effect", which creates additional air exhaust from the external wind dynamics.

In your scenario, its all about expelling the internal humidity and why and how does it reach such an inordinate level?

Ed

Call Paul Scelsi, at 1-800-AIR-VENT and see if he can assist you with better information from an engineers point of view. See if he remembers me, Ed from Right Way Roofing Company. Tel him I am the contractor that redesigned or modified their SV II for usage on a mansard wall ventilation system to jog his memory.
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Old 02-03-2007, 07:08 PM   #6
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Re: Ventilation Problem With An Indoor Pool


Well, it is a pool of water...this provides moisture.

You have a gas fired heating unit...this produces a ton of moisture simply by burning.

The systems were all working until the heater went out. There was a ton of condensation collecting from the warm pool onto the cold roof structure.

If it were mine, I would in fact foam the underside and finish it with waterproof materials with weep holes back to the pool area, and make sure to include the Class A fire rating on the exposed finish material.

If this happens again, then the moisture would be trapped in the pool area instead of hitting the roof deck and destroying the non-waterproof finish materials.

Thats just me.
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Old 02-04-2007, 12:42 PM   #7
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Re: Ventilation Problem With An Indoor Pool


The real issue is the pool water (and I do have an indoor pool, have build several, and consulted on others). The warm pool water evaporates rapidly then is absorbed by the sheetrock (or whatever the coverings are) and condenses in the cold.

Because the heating system was off, the ceiling and wall surfaces got colder than normal and likely had substantially more condensation than normal. It is quite possible the the minimal ceiling insulation installed provided enough heat into the cavity that the moisture would ventillate out but the colder surfaces allowed the moisture to freeze then thaw and drip.

The pool water will evaporate rapidly to warm a cool room, creating many gallons of condensation daily.
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Old 05-27-2009, 06:56 PM   #8
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Re: Ventilation Problem With An Indoor Pool


From what you said, everything was fine until the heat cut out. This may or may not be the case. The ridge and soffit vents also changed.

I think the moist warm air from the heated pool is condensing on the underside of the roof. This is true with the heat on or off. Is there a vapor barrier between the heated space and the roof deck? Is the styrofaom board insulation acting as a vapor barrier and is it sealed along the rafters to act as avapor barrier? Probably not.

Therefore, you have a warm moist interior space, which can condense on the roof deck above the insulation. The lack of heat allowed it to ice up. Perhaps when the heat is on, it woudl not could be is why there are brown stains running down the walls ---- from past molding....?

Gable vents should not disturb the soffit to ridge flow, since you said that path was behind the insulation board. I also understand these vents are only opened as needed by temp and humidity sensors.

I think your home owner has had vapor barrier issues for years, and have only found them when the heat cut out. It may also have been exacerbated by the ridge vent, which now allows the potential for warm moist air to pass over the roof deck underside.....

These are some possibilities....?
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Old 05-27-2009, 07:38 PM   #9
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Re: Ventilation Problem With An Indoor Pool


Quote:
Originally Posted by mdshunk View Post
Any indoor pool space that does not have a "Desert Air" or similar system installed is asking for trouble. He needs to get up with an HVAC man.
Finally someone who gets what is involved with an indoor pool especially in Michigan thanks for the post.
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Old 05-27-2009, 07:45 PM   #10
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Re: Ventilation Problem With An Indoor Pool


Quote:
Originally Posted by VPOPP View Post
From what you said, everything was fine until the heat cut out. This may or may not be the case. The ridge and soffit vents also changed.

I think the moist warm air from the heated pool is condensing on the underside of the roof. This is true with the heat on or off. Is there a vapor barrier between the heated space and the roof deck? Is the styrofaom board insulation acting as a vapor barrier and is it sealed along the rafters to act as avapor barrier? Probably not.

Therefore, you have a warm moist interior space, which can condense on the roof deck above the insulation. The lack of heat allowed it to ice up. Perhaps when the heat is on, it woudl not could be is why there are brown stains running down the walls ---- from past molding....?

Gable vents should not disturb the soffit to ridge flow, since you said that path was behind the insulation board. I also understand these vents are only opened as needed by temp and humidity sensors.

I think your home owner has had vapor barrier issues for years, and have only found them when the heat cut out. It may also have been exacerbated by the ridge vent, which now allows the potential for warm moist air to pass over the roof deck underside.....

These are some possibilities....?
Better late than never I suppose.
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Old 05-27-2009, 08:16 PM   #11
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Re: Ventilation Problem With An Indoor Pool


OK guys and gals here is what is going on

The room temperature of an indoor pool needs to be at least 10 degrees warmer than the water temperature. Gas fired heat or not this should not make a difference as the moisture is in the flue gasses and these should be expelled to the exterior and not the interior so ght moisture in the fuel is not the issue. What is going on here is an owner who had the heat go out on them or turned it off. the building got cold and the pool water turned to vapor when exposed or continuously. I had a job at Ted Kennedy's former house replacing skylights and the interior of the pool room due to mold and rot etc. After looking at Job saw that a climate control system was installed ( Not Desert Air but similar with all the features.) Asked if it was operational and was used during the heating months. Owner said yes to all questions. First winter comes along and in February I get a call that there is mold on everything. I go out to look and yes there is mold on everything. I ask owner to demonstrate how pool is used (
Room is 50 degrees at time.)

Owner takes solar blanket ( bubble wrap ) off the pool and the entire room fills withsteam ( Pool is kept a t 90 degrees)

Had to tell him to F**k off as our contract stated that the pool room was to be kept heated and to accepted standards IE desert air conditions for warranty.

If you don't know what you are doing with anindoor pool stay away or get and experienced HVAC guy to advise.
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Old 01-11-2014, 08:29 PM   #12
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Re: Ventilation Problem With An Indoor Pool


The first thing that comes to mind after reading the posts, most standard construction materials will rot or have mold issues when they are exposed to high humidly and warm temperatures. So pool enclosures made from standard materials will sooner or later have issues no matter how much sealing and protecting you do and HVAC systems will definitely help but over time you will lose the battle and start to repair/replace items.

Pool enclosures should be made from materials like aluminum, stainless steel, polycarbonate, glass, and acrylic. Not only will these materials not rot or get moldy. But can be easily cleaned with just water. All the installs we have done over the years never had rot or mold issue.

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