Results 1 to 9 of 9
07-23-2004, 11:04 PM #1
I have a customer requesting a proposal for controls to ventilate an indoor swimming pool. This is, as you can suspect, a very humid room (although a little extra humidity is probably welcome whtn you are in a bathing suit!), with tendencies to be quite warm/cold due to the glass ceiling. There is an Engineered Air Makeup unit with an uncontrolled fully open damper for return air from the conditioned space (this damper has never had a motor so far as I could tell). It has a motorized fresh air damper for mixing return & fresh air (gears broken when I checked it). There is a separate ceiling exhauster which is not interlocked with the Eng Air Unit. The Eng Air unit has no cooling (Canada, eh!) and 5 stages of electric heat. There are a couple of line voltage humidistats (Honeywell SPDT type) and a thermostat for the space. One humidistat has no wires going to it and the both are ancient and in need of replacement. The roof is entirely glass, sloped, and facing north (probably partly why the designers figured they could get away without cooling). Winter design temps around here are about -10 deg F and summer 90F dry bulb & 76 to 78 wet bulb. When I arrived on the site the room smelled like a sewer due to the fact that the makeup air fan was down with a blown fuse and the exhaust fan was going flat out, no doubt assisting in evaporating the water out of the traps in the pool deck floor drains! I got the fan running and cracked the FA damper so at least the room can have some ventilation/pressurization & then had to go on another call. I thought of some comparative enthalpy or humidity stuff to control the fresh air dampers, some interlocking with the exhauster, trap seal primers (if possible!), and some needed upgrades/repairs to the heating stager (old one is one of those ancient cam type units with no cover or model number anywhere to be found--in fact no wiring diagrams or unit model numbers to be found either!).
07-24-2004, 12:35 AM #2
Another guy posted just about the same thing on here about 5 or 6 months ago. Maybe you are dealing with the same customer. Anyway, you have no humidity control - just ventilation plus a little safety control of that ventilation for freeze protection. Hot weather, just 100% outside air. Cold weather = a mixture of return air and reheat with the heaters.
Do a seach on pool ventilations sytems or pool humidity controls and you can read all what we already told the other guy."The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis de Toqueville, 1835
07-24-2004, 12:19 PM #3
The biggest heat loss from a pool is from water evaporating.
When you ventilate you are bringing in dryer air forcing more water to evaporate.
The best solution is a new $y$tem, like a Dry-O-Tron by Dectron in Quebec Eh. This will heat his pool, air condition, heat the space, provide make up water for the pool just be recycling the water that evaporates from the pool.
You want this pool to be under negative pressure. You do not want the EngA LMK unit pressurizing the space.
The way we build has a greater impact on our comfort, energy consumption and IAQ than any HVAC system we install.
07-24-2004, 07:30 PM #4
You most certainly need a new unit designed for the application. Contact equipment reps and let them do the homework. They'll engineer it for you to try to get the sale.
07-24-2004, 09:29 PM #5
I have no idea what you need to do cause I am not that smart, but.
I have worked on several dectron units. Both for High School Natatoriums. Man.
Those units are about the most complicated large peice of a equipment I have ever had the pleasure to work on.
But I learned and relearned many nights on those damn things about humidity. And one things certain, too dry of air is as bad as too much latent load in a pool environemnt. And Fresh air although a must was an enemy of the humidty system.
07-24-2004, 11:57 PM #6
Thanks guys, I appreciate your input. I did some searching and some reading and am beginning to understand what is going on. With the shape the existing equip is in, I am pretty sure the customer will want to go cheap cheap! I could just recirc existing air, maintain a slight negative with the exhaust fan (maybe leave the fresh air cracked open slightly), and heat as required off a thermostat. If the customer gets frustrated and decides to spend some money, I like the new unit idea. Right now the pool is heated off the domestic water recirc loop via a plate HX, so I wouldn't need a unit that heats the pool.
07-25-2004, 12:25 PM #7
Actually with a Dectron set up, you heat domestic and pool water, at the same time control sensible and latent load, all in one unit. All in one box with very little controls work needed.
Thats the reason Dectron exists. They put it in one box. And it is of very high quality, warranty from hell, and also you give your customer total comfort, on top of keeping you away from legality issues now coming to the front with mold and all that other IAQ crap.
07-25-2004, 06:39 PM #8
If I were you, I would not touch this job. The customer has already indicated by his years of lack of maintainance on this system that he just doesn't care.
Once you touch it in any way I just bet he will try to saddle you with every problem he has had, has now and will have (which he will) in the future.
"The American Republic will endure until the day Congress discovers it can bribe the public with the public's own money.
- Alexis de Toqueville, 1835
07-26-2004, 09:39 AM #9
Avoid positive pressure!! Keep the building negative during cool-cold weather to avoid the inside high humidity air from entering the insulation in the walls and attic. How many sq.ft. of exposed water and water/air temperatures to calculate the dehumidification load. Covering pools with plastic reduces moisture load. For load calc. check: