Pool Mechancial Systems and Solar Pool Heating

Ken Wright is president of Hot Sun Industries Inc, a San Diego based manufacturer and distributor of solar swimming pool heating technology. This blog chronicles the ongoing struggle of one entrepreneur and his noble staff attempting to take a technology approach to solar pool heating…..technology in concert with a swimming pool industry sometimes set in its ways. Hot Sun’s main web site is www.h2otsun.com Welcome to our blog. I trust you'll find our experiences in the field worthy of publication.

Since many of my readers will be our solar dealers looking for on-going training and many solar energy people have no specific swimming pool knowledge it is necessary that we first cover some of the basics of how swimming pools normally work. We all know that a pool mechanical system in its simplest form consists of a pump drawing water from the skimmer baskets and the bottom drain, pumping the water through a filter and returning it through "inlets" to the pool. Its normally all plumbed up with 2" and 1.5" pvc pipe. The pump runs long enough each day to theoretically turn the water over at least once a day. On commercial pools where the health department oversees things generally the requirement is that pools are turned over once in 6 hours. Filters are either sand, cartridge or diatomaceous earth. Sand filters are my favorite. They restrict flow more than the others but they are simpler and easier to clean. "Backwashing" is running the pool water backwards through the filter dumping dirty water to drain. Cartridge filters use a removable paper cartridge so the restriction is minimal when the filter is clean but cleaning requires removal and manual work with a hose. DE filters (diatomaceous earth) are just cartridge filters with a special compound packed in so that the water is treated with the magic earth. These filters also boast of finer particle filtration. Its all nonsense as far as I'm concerned. The job of the chlorine is to oxidize the contaminants into particles that can be filtered out. Pools with sand filters are every bit as crystal clear as pools with DE as far as I could ever tell but then again I've only visited about 15,000 pools in my career. Pool service guys have spent their careers dicking around with this more than we have so if they say DE makes sense in your area I defer to them.

Historically it has been the case that the pool construction industry hasn't been at all concerned with pool pump electricity operating cost. The pool builders are excellent tradespeople. I don't know how to build a pool any better than they know how to configure a mechanical system taking into consideration pressure and flow. Pool builders should not be insulted when an engineer or someone qualified tells them that all they need is a 3/4HP pump for filtering a residential pool but they are. The pool industry is missing oversight. There are no engineers. If I was the engineer working for a major pool company i would specify 3/4 HP or 1/2 HP as the filtering pump power on every pool. My job would then be done because there isn't anything else that requires a mechancial engineering degree. Everything else is pretty much OK just handled by the trades.
Seriously. The idea that you need 1.5HP to filter a residential pool is bordering on the insane. I still fight with pool builders to this day over basic pool pump sizing. Title 20 law in California (Jan 2008) has gone a long way to solve this problem for me by not allowing more than 3/4HP by law. Its a good law. How else can you get past widespread industry misconception? To be fair its just that energy is cheap so why bother trying to save any of it. If one aspirin cures your headache then take 5. That's the thinking and it isn't always the pool builder's fault. He's just not trained to argue it. Energy conservation has only been on the average guy's radar now for a few years.

I spent the first 24 years of my career as a solar pool heating technician, installer, dealer, distributor, manufacturer and consultant spending far more time than I even intended every single day fighting with pool builders over pump sizing. Over my career I saw pool pumps go from 1/2 or 3/4HP to 1.5 or 2 HP on the exact same size pools. The older pools have no trouble staying clear. Its all in the chemistry. Keeping the pump on all day means controlling the chemistry, the scum lines, all day instead of just for the 3-6 hours you end up running a pump if it is oversized. Oversized pumps are noisy because they are oversized. Oversized pumps are expensive because they are oversized. They cost even more to operate than they should usually because they are forcing water through piping not sized large enough for the high power. They fail sooner because of the extra stress from the extra pressure and of course from the solar person's point of view, the pressure is the absolute worst thing you can introduce into a solar heater.

A solar pool heater is a large thin plastic heat exchanger with the sun. When the pool is up to temperature (think hottest time of the year mid summer) the collectors bake in the Hot Sun and the pressure doesn't disappear in every case just because water is diverted away from solar. www.h2otsun.com/pools is a valuable lesson in pressure and solar design to get around pressure. Stagnation temperatures can reach 185 degrees F in the desert. Even in Canada we've seen collectors hit 180F in stagnation. These temperatures are too hot for the pvc pipe the systems are plumbed in and when I say systems I don't mean the solar systems, I mean the existing pool systems. C'mon everyone, let's be real. If you blast a solar pool heater with 30 psi you're asking it to do the job of metals and you can't change the pool plumbing to all copper and you wouldn't want to anyway. We are the only solar company on the face of the planet...except our competitors at Sunbather in Australia that I know of, that accept that we need to avoid collector pressure when solar heating swimming pools. Oh, the big competitors doing millions of dollars a year in sales know it but they are smarter than me. They know that introducing this into the equation requires a lot of extra work and extra training on the part of their dealers. They may have tried but in the end its just not worth the bother. The name of the game is sales not physics lessons. Leave the problems for the pool service industry and keep life simple for the salesmen who boldly install solar and pools faster than they can say, "Will that be cash or charge?" Just sell the damn stuff damn it. I'm being fecicious. I truly believe that there is room in the world for a technology approach to a technology like solar pool heating and I will spend the next half of my life proving it. This blog is the beginning of how we will educate the world on this subject.