Intelliflo VF question from down under

[OzPool]

Hi from Sydney, Australia!

Firstly, I want to say how valuable troublefreepool.com has been to me - what a fantastic source of information on all things pool.

If I may, I have some questions related to the Pentair Intelliflo VF pump, which has recently become more widely available in Australia. I am in the market for a variable speed pump, having inherited a pool with an energy hungry 1.5HP pump and paying very high energy costs here in Sydney. It seems the most commonly sold variable speed pump here is the Hurlcon EVO 320 (http://www.astralpool.com.au/products/v ... -p320-pump). This looks like a decent pump, but the Intelliflo is a similar price and offers quite a few additional features. As many of the users on this forum have an Intelliflo pump I am interested to hear whether the additional complexity of the pump has led to failures or reliability issues (eg. controller, VSD, flowmeter, LCD display) that would not have been a problem with a standard pump.

My pool spec is as follows: 45,000L concrete (pebblecrete) pool, Davey PM250 pump, Hurlcon VX9T salt water chlorinator, Waterco 21" sand filter, 40mm PVC plumbing throughout, Polaris 3900 Sport cleaner with dedicated booster pump.

I've read all the posts on this site regarding the Intelliflo VF and I've also read the manual. I think I've got a pretty good handle on how it works and the potential energy savings, but I still have a few questions:

1. Does the flow figure come from a flowmeter that is incorporated in the pump or is the flow derived by the controller?

2. Does the pressure figure come from a sensor that is incorporated in the pump or is it derived by the controller based on the pump curve?

3. The Intelliflo is the only pump I have seen that measures pressure and flow. Has anyone experienced problems with the flowmeter or pressure reading?

4. Has anyone experienced failures related to the controller other than those caused by extreme temperatures, accidental closing of valves or other equipment malfunction?

5. If hypothetically I find that, for my pool, the most effciient operating point for the Intelliflo is at 1000rpm and I want to set it up to run close to that point, but still retain all the features of filter mode (ie increase speed as flow drops and still have all alarms and pump protection active) then do I need to fudge the scheduled hours/pool volume such that the pump target flow rate corresponds to 1000rpm? Alternatively, it seems I can run the pump in RPM mode, but then I lose some of the features of filter mode? Hope that made sense :?

6. I assume the Intelliflo will run ok with 40mm plumbing? My pool is a suspended concrete construction on a rock shelf so all the plumbing is accessible. I plan to upsize to 50mm and get rid of 90 degree bends, but probably not right away.

7. The maximum flow on the Intelliflo is very high and I'm not sure my system would cope with it. It seems you can set a maximum flow limit, but has anyone had any problems with the pump exceeding this limit?

I hope that isn't pushing my luck too much for a first post. Any help would be very much appreciated.

 

[Bama Rambler]

1. I think the flow comes from a calculation and not an actual flow meter.
2. I think the pressure comes from an actual sensor.
3. I haven't seen any issues being reported.
4. There have been a few failures reported but most of them appear to be power surge related.
5. I'm not sure about the programming but I think you can set the rpm and it will compensate for the increasing pressure.
6. 40mm is about 1½" our size and the Intelliflo will be fine with it. While 2" (50mm) would be better, 40mm will work ok.
7. The flow rate is limited by the plumbing and you won't damage the plumbing with the pump.

 

[JasonLion]

Welcome to TFP!

1) There is a flow meter, though it doesn't work the way a typical mechanical flow meter works and does appear to make use of knowledge of the pump curve. Internally it is measuring the current used by the motor, and figuring out what is going on from that. That is a flow meter, though the slightly unusual design means different quirks than other flow meters you might be familiar with.
2) While the pump does model what the pressure must be, it doesn't appear to actually have a pressure meter. You calibrate it's concept of what the pressure is by setting your clean filter pressure and apparently it models the pressure change from there.
3) The flow meter is not reliable at the low end of it's range. It seems to work just fine at the upper end of it's range.
4) The speed controller occasionally fails for no apparent reason (presumably power surges), though this is rather rare. In the US Pentair has been good about replacing them for free when that happens. Other variable speed pumps seem to have similar issues.
5) You can play with the settings when you are using flow rate mode so that the RPM number is around 1,000 RPM when the filter is clean. However as your filter gets dirty the motor will increase in speed to maintain the same flow rate. There isn't any way around that. A dirty filter reduces system efficiency regardless of what you do.
6) Sure.
7) The pump won't exceed it's limit, but it might refuse to start if it "thinks" that exceeding the flow limit is the only way to properly achieve prime. Some people have had significant problems with that, leading some people to recommend you get the VS instead of the VF. The VS will also limit the max speed (if you set it up that way), but it doesn't actually "know" if prime is achieved or not, so it won't shut down.

Hum, Bama and I disagree about 1 & 2. Pentair doesn't actually say, so were are both guessing a little bit.

 

[Bama Rambler]

There was no doubt I was guessing, based on things I had read different places, so don't take that as fact.

 

[OzPool]

Thanks guys for your patience and great responses.

Regarding 1) and 2) - my guess is that the flow is metered and the pressure is derived. Both can't be derived from the pump curve because Intelliflo would need to know the flow in order to derive the pressure and vice versa. The Intelliflo manual recommends that the pump be installed with a straight length of pipe on the suction side of the pump, with a minimum length of 5 times the pipe diameter. This recommendation could be to simply minimise turbulence and cavitation within the pump. I am in the water industry here in Sydney and that same recommendation applies to flowmeters installed within the water network.

Regarding 5) - do most people use the filter mode or a manually set speed?

Thanks again guys, I do have a few more pool questions that I'll post elsewhere. I'll promise to keep them brief

 

[JasonLion]

We know the pump measures current, and that, plus water temperature (which they ask for as a configuration setting), is sufficient to derive GPM. Also, the granularity in the current measurement seems to match up with the lack of GPM precision at lower speeds.

Pentair really pushes constant flow as being the best mode, but I see only very minor advantages to that and some small risks. I generally recommend using fixed RPM rather than fixed GPM for pool circulation. Fixed GPM is better for waterfalls, or other situations where lower flow rates cause obvious problems. In the real world people do both, and it doesn't seem to make much difference.

The straight pipe before the pump rule is common for all kinds pumps from just about any manufacturer, and is often ignored.

 

[mas985]

You don't need pressure to determine flow rate. For a variable speed pump, also any pump, the only thing required is RPM and Watts. Those two values are unique for every flow rate. Or I should say there is a unique flow rate for every combination of RPM and watts.