Replacing pump, will dual speed be ok?

[Canuck107]

Pump is leaking and terribly noisy. Read the threads on replacing motors and seals, but I am pretty sure a new pump is best option considering the terrible DIY Disaster this new-to-us house/pool has been. Would like to go dual speed - electric rates are $0.16 peak and 0.08 off peak hours, pool open 4-5 months a year. Typically run the pump at night (off peak), but sometimes want to vacuum or heat during day/peak hours.

Pool store warns that dual speed pump may be too weak for heater to fire. Looking for advice on replacement pump...

current pump... STA-RITE Dyna-Glas 1 HP, 115/230v, 60 Hz, .75kW. Pressure gauge on filter normally reads 12 or 13 PSI. Equipment in pool shed about 23' from shallow end skimmer at deck height. Two skimmers and three returns. No drain. Lines are 2 inch all around (I think). No cleaner currently, but could be a future addition.

 

[jblizzle]

Welcome to TFP!!!

A 2-speed pump running on high is the equivalent of a single speed pump. So worst case would be the need to run on high speed when you want to run the heater. And run on low speed (half the flow rate for 1/4 the electrical cost) when you do not need the heater.

A bit more pricey would be to add some automation that could automatically kick the pump up to high when the heater was needed and low when it is not. That is how I run my solar.

 

[Canuck107]

Thanks. I understand that, and willing to deal with it (manually). I am wondering if any of the dual speed pumps can be expected to fire the heater at low speed?

i tried to calculate head loss... 42 ft ???
i tried to calculate flow rate for three turnovers a day... 64 GPM ???
i checked the super pump and whisperflo charts, but not sure how to read them exactly...

 

[jblizzle]

Calculating head loss is far from trivial ... I do not usually try because there is just not usually a need to know.
What you may be missing is that the head loss is variable and changes with the flow rate ... so I would not worry about it. There are ways to estimate the head loss given a lot of details about your pool.

Also realize there is no need for 3 turn overs a day ... or any turn overs for that matter. Just run the pump long enough to keep it clean. See the Determine Pump Run Time.

It is possible that the low speed might have enough flow to run the heater.

 

[Agent99]

It looks like your MasterTemp 250 requires a minimum of 25 GPM flow rate. I have no clue if in your system with the pump on low speed if you can maintain that kind of flow. I'm guessing that you're likely to be fine but I'm not at your place, right? If for some reason it doesn't, just flip the pump to max speed when running the heater and call it good.

If possible, hook up a pipe/hose to one of your returns and do a bucket test. See how fast one of your returns fills up a bucket. I'm betting you'll be fine.

 

[Canuck107]

Ok. Thanks everyone. Will go for it and hope for heat on low speed, but if not, I will still be better off than I am now on high speed every night!

only a few weeks left before closing up here