Long conversion question

[ideliver]

I apologize in advance for these questions. I was a longtime reader and occassional poster at TPF but I have been lurking here for a few months. I see most of my "friends" and respected pool owners have migrated here, so I will post my problems only here.

I have a "Utopia" pool that is unique in its filtration and pump system. The pool is approximately 25,000 gal vinyl liner. You can go to http://www.desjoyauxusa.com/index.htm for some more information.

The short story is that the pump is in a self-contained unit that sits under the deck. It really works well with a few noticable exceptions. The filtration is done via bags that get cleaned/washed/changed weekly. I have three pairs of bags so this is not a big chore. The only problem is that the AFT can flood. There is drainage from the AFT but if I get forgetful when filling the pool, it can overflow and flood the AFT where the pump is. This has happened on a few occassions and I have had to replace the pump, which is expensive ($800.)

A back story is that the pool manufacture now has very little US presence. The pulled out of the States few years back.

I am considering converting the AFT/bag filter system to a convention sand filter. The pool builder has done this a few times with no problems. In addition, I had a brief exchange with a previous TPF user and he had no problems after his conversion.

If I were to convert, what size filter and pump should I use? The PB wants to sell me a single speed 2 hp pump with 300# sand filter. This does not seem correct to me. One issue is that there are only the two skimmers (one) in the AFT and one return line. But everthing is 2 inch pipe. The volume of water that runs though this AFT is fairly impressive. I have had absolutely no problems with clarity.

The next thing is my heater. I have a 7 year old Raypak RP2100. I believe that there is a design defect with the heater. My control panel has been replaced multiple times due to warping from the sun. See the pictures linked below. After much ado, Raypack put a new style control panel on the heater. But, this was done at the end of the season and it kept throwing error messages and did not work correctly. I suspect that another sensor was bad, but I grew tired of hassling the PB because they did the whole thing for free.

So, my heater may not be working either. I am considering a AquaCal heat pump. But, WOW are these things expensive. I never really thought that I had to do a ROI on pool equipment.

Finally, while I am throwing money around like water...I am going to get a SWG. Obviously the Pool Pilot is my only choice. Can I have this thing control my pump/heat pump on a timer without concern about everthing going off and on?

My PB tells me that I will need some type of "fireman switch" ?? so that went the pump turns off, the hot water does not accumulate in the pipes and cause them to warp. Very confusing to me.

So, I guess my question is...If I were going to convert to a sand filter/pump...how big a pump is needed?

Should I replace my heater at all...or try to get it to work...or get a heat pump (if so which model)...or just a new heater??

Can the Pool Pilot control everything...SWG cell, pump/filter and heater/heat pump???

My gas is $9.42 mcf and electric is 6.3 cents/kwh. I live in Northeastern Ohio and have kids that like to swim...early may til mid october...

If I were to do all of this, I would also have to move some serious landscaping also...so I need to think hard on this one...

Some pics at http://gallery.mac.com/anthony.desalvo

Please feel free to ask for more information...because it is difficult to be clear with so many issues...

 

[JasonLion]

The general rule of thumb is that you want a small pump and a large filter. For pumps the question is how much do you want to spend up front to save electricity in the long run? Your electric rate is fairly low but over the entire life of the pool you could still save from a two speed pump. In single speed pumps, something like the Pentair WhisperFlo full rated 3/4 HP would be fine. THe WhisperFlo line is particuarly wonderful and is available in a high efficiency verision which is worth getting even with your low electrical rates. When looking at other pumps check for full rated, max rated, etc. If not full rated then perhaps a 1 HP pump. With a two speed pump it is often simplest to go to a full rated 1 HP because the available choices in 3/4 HP are not ideal. The price bump isn't that large and there will be electrical savings on low speed. Going for a variable speed pump is a more difficult call with electrical rates that low, I believe you would still save money over the entire life of the pool, but it isn't as clear cut as if your electrical rates were higher.

For filters, I would go up to a 600 lb sand filter at least, and larger if you can. The larger filter will simplify taking care of the pool in the long run, fewer backwashes, less resistance to flow, and generally fewer problems. Of course it is physically larger and more expensive but not dramatically more expensive.

The AutoPilot Digital model can control the pump and I don't see any complications with going that way with a simple pool as you describe. The issues get more complex with a spa or waterfall. For a simple pool the pump timer in the AutoPilot is ideal.

The need for a fireman switch depends both on local electrical code and the particular heater you get. Some heaters are completely fine without a fireman switch and others will tend to melt the pipes without one. Even then you can use a higher grade of pipe for a couple of feet after the heater to avoid problems. Sometimes electrical code requires one in any case.

I would think hard about a heat pump. Your electrical rates are low so a heat pump would save you money on heating in the long run but they are far more expensive up front. Running a gas heater can really add up. It all depends on how much heating you really do.

 

[ideliver]

Thanks for reply

The general rule of thumb is that you want a small pump and a large filter. *snip* If not full rated then perhaps a 1 HP pump. With a two speed pump it is often simplest to go to a full rated 1 HP because the available choices in 3/4 HP are not ideal.

Thank you for the reply...and I have read the sticky...and links...

With my 25,000 gal...8 hr turn over...give MIN flow of 50 gal/min
2 inch pipe...max flow of 73 gal/min
I have NO spa or features...
Max Flow of filter in the 100gal/min range (30" filter)

Assuming 50 - 60 feet of head (I have no idea if this is correct or how to calculate on my pool)

1 hp would be ideal...

SO, would I have to run this 24/7...I think yes because I would only be getting 3 turn overs a day and I usually have a very high bathing load...3 boys aged 5 to 8 and all of their friends...we have a very fun, kid friendly 'hood and the pool is used almost non-stop

AND....why do PB insist on overpowering the pumps...it can't just be money can it...with this conversion I am looking at $6000 of equipment...I mean...we are talking about an additional $50 to $100...what are we seeing that they are missing...why is their experience telling me to go with a 2 hp pump???

 

[JohnT]

Re: Thanks for reply

AND....why do PB insist on overpowering the pumps...it can't just be money can it...with this conversion I am looking at $6000 of equipment...I mean...we are talking about an additional $50 to $100...what are we seeing that they are missing...why is their experience telling me to go with a 2 hp pump???

Because the bigger pump costs them very little extra, and people have a perception that "bigger is better" and that a bigger pump will keep the pool cleaner. By throwing in a bigger pump, there is a perception that you are getting more for your money. There are times that having a little bigger pump can help, like when cleaning up a real mess, but you pay for that every second the pump runs. A two-speed pump gives you that option, but allows a more reasonable cost for normal operation.

 

[JasonLion]

The other consideration builders have is that if the pump is too small they have to come back and replace it, but if the pump is too large it doesn't affect them at all. By the time you see the electrical bill they are long gone. So they much prefer to err on the large side. Also new pool owners really like to see some dramatic water movement. A properly sized pump will hardly move the water and a novice might feel that something is wrong.

A two speed pump solves things nicely. It has high speed to move water dramatically and in special situations while low speed is far more energy efficient for day to day usage. The extra cost of running an oversized pump on low speed is nothing compared to the extra cost of running an oversized pump on high speed.

Calculating TDH is tricky. I tend to use 40 feet as my default guess, but it can vary rather dramatically depending on the distance from the equipment pad to the pool, how many pipe fittings end up being used, etc (in addition to the more obvious issue of pipe diameter).

A design goal of three turns a day is plenty. I usually aim for 2 to 2.5 turns a day. A two speed pump on low speed might well need to be run 24 hours a day in the summer, but on high speed there is no way you will need 24/7 pump operation even with the bather load you describe.

 

[ideliver]

Thanks for the information

I just located the original pool manual. The current pump literature states:

"The Utopia Pool two speed pump motor operates within the following electrical and hydraulic parameters: Note: The Utopia Pump is a medium head system using a closed face impeller, and ceramic shaft seal. a) 230VAC b) High speed = 2.2 hp @ 9 amps draw for 207 gal per/min turnover c) Low speed = 1/3 hp @ 2 amps draw for 114.7 gal per/min turnover."

I believe that the pipe is 2 inch. The run from pool to the equipment is about 14 feet. So what would be a good guess on the head?

In previous seasons, I only used the low speed (except for sweeping and opening). Should I try to replicate these numbers with the new pump...or do I need something different? I am interested in a two speed pump.

I ran the AquaCal program and looks like possible savings of $850/yr...so this thing will pay for itself in a few seasons...

 

[Poolsean]

The Pool Pilot is capable of controlling the single speed pump, and even a two speed pump (but in this mode it is continual run - no off mode).
The Heat Pump will need to be on it's own circuit breaker as the installation requirement calls for its own disconnect box. However, the heat pump operates off a pressure switch and does not need to be wired/interfaced to the Pool Pilot.

If you select the two speed pump, I would recommend using a separate 2-speed pump time clock if you want an off mode.

If you stay with the gas heater, as Jason mentioned, some still require the firemans switch, most do not. A heat pump will definately not need it.

Regarding the pump specifications, something doesn't sound right....
High speed for a 2 hp circulating in excess of 200 gpm, and Low speed (1/3 hp) in excess of 100 gpm is very, VERY high.

The 8 hr turnover is standard practice for a residential pool. Therefore, 50 gpm would be the minimum flow rate of your pump. Higher HP pumps mean quicker turnovers. While this is not bad, it does tend to consume more electricity for daily operation. What is important is that the filter is also sized appropriately to handle the flow.
With Cartridge Filters, 1 sq ft of filter area = gpm, that is, a 100 sq ft filter can handle 100 gpm
With DE, 1 sq ft of filter area = 1/2 gpm.
With a Sand Filter, 1 sq ft of filter area = 20 gpm filtration, but more important, backwash mode recommends providing 60% of the design flow rate (as per Hayward) for proper cleaning.

Cartridge and DE allows for the "Bigger is Better" philosophy, all the time!
Pumps? You can oversize the pump, but make sure you also size the filter accordingly.

 

[ideliver]

Thank your for all of the advice so far.

Having done as much homework as I can comprehend...I am confused about 2 speed pumps...

I have calculated a min flow of 50 gpm and have guessed at a total head of 40 to 50 feet.

The two speed pumps seem to have flows in the 40 range at 10 feet of head on the low setting. Could this work for me?

Also, my current pump is turning 114 gpm with 1/3 hp at 2 amps with 230 VAC. That is .46 kW. I cannot find the wattage for the low speed on the hayward or pentair pumps.
I checked the pipes...the return lines and skimmers are 2.5 in. The pipes that go to and from the heater are 2 inch.

Any suggestions for a 2 speed pump that would work...or should I just stick with a correctly sized pump?

 

[JasonLion]

Two speed (and more so variable speed) pumps cost more up front but can save you lots of money in the long run. You want a pump that will give you two to three turnovers per day. A turnover is pumping the amount of water in the pool. So a 25,000 gallon pool should have a pump that is between 35 GPM and 52 GPM (on high speed). Low speed will move half as much water, and so only provide one to one and one half turns per day.

Even though your pump should be capable of 2 to 3 turns per day, you normally only run it for part of day and actually only get one turn per day. By running on low speed for 24 hours a day you can get at least one turn a day, which is normally sufficient. And when low speed isn't enough you can go back to running on high speed.

The reason it is worth it is that low speed moves half as much water but uses noticeably less that half as much electricity, somewhere around one third as much electricity. 1/3 as much electricity, running for twice as long means 2/3 total or a savings of 1/3 off your electric bill. Variable speed pumps can do even better than that.

 

[desjoyauxpools]

ideliver: I just wanted to let you know that Desjoyaux has been re-established in the USA and now has a flagship store in Atlanta with a technical, parts & services team. You can order parts online, download parts manuals and request technical assistance here: http://desjoyauxpools.com/tech-assistance

This thread/question is several years old, but if you require any further assistance with our pipeless filtration system, please let us know!