Confused about variable speed pumps

[Iguanod]

Hello.

I want to change my pump (0.75 single speed hp, 2'' pipes) to a VSP, because I'm gonna add a SWG, but also because I'm so very done with how noisy my current pump is.

So I've seen most people around here recommending a 3hp VSP pump. The thing is my pool is both simpler (one skimmer, one vacuum plug, three returns, no features) and much smaller (around 7500 gallons) than what is usually seen in this forum.

I know you can just run the pump slower, so I'm worried I would be overspending by buying a much more expensive pump than makes sense for my pool, and that I would have to run it at so low RPM that the SWG wouldn't run.

On the other hand I'm also worried that if I go with let's say a 1.5hp VSP the noise difference with my current pump won't be much.

And there's something that makes me very confused. I have seen in local stores three VSP models that offer both a 1.5hp and a 2hp version, and in all three cases the 1.5hp was rated for 2'' pipes while the 2hp was rated for 1.5'' pipes. How is this possible? I know smaller pipes have more friction, but how can that offset the fact that you have to move much more water (and so I assume more hp or more RPM) through the bigger pipes to achieve the same flow rate?

 

[PoolStored]

The biggest $$ benefit is going SS to VSP. That will save you the most $$. A bigger VSP will move the same amount at a lower RPM, than as a smaller VSP. Which you will save a bit more money. The bigger VSP will be quieter, and may last longer.

The pipe rating, doesn't matter. Whatever VSP you get will work (remember we are operating the VSP at low RPM).

What are the VSP models the local store offers? Post up the models and we can give you an opinion...

 

[Iguanod]

I know a bigger pump saves money in electricity but we are talking roughly about 400€ for 1.5hp vs 1400€ for 3hp... It would take ages to offset the difference, that's why I'm mostly concerned about the noise level, so I'm having a bit of a crysis as I feel helpless since I have no way of knowing how much less noise would the 1.5hp at low rpm make than my current pump

I'll try to gather info about the options, what would be useful info besides hp and flow capacity? I don't know how much more I can find since the pumps' documentation around here is pretty lackluster, most don't even have the pump curves.

 

[Jimrahbe]

I,

The size of the pool your pool, and the size of your pipes does not matter... Because the whole idea of a VS pump is to run it as slow as you can, and still get the job done.

The slower you run the pump, the less it costs for electricity. The slower you run the pump, the quieter it will be.

The large the pump, the slower you can run it and still turn on your SWCG.

If you forget cost, it is always better to get the 3 HP VS pump, rather than a smaller VS pump.

I always recommend the large VS pump, but then it is not my money..

But, I do put my money where my mouth is... Until recently I owned three pools.. I installed 3 HP IntelliFlo pumps in all of them.. This started about 15 years ago and all three pumps have been running 24/7/365, mostly at 1200 rpm, as my pools are also very simple. The pumps work today, just like they did when installed. They are so quiet, that you almost have to touch them just to make sure they are still running..

The world will not end, no matter which VS pump you buy. I buy what works best for me.. You need to buy what works best for you.

Thanks,

Jim R.

 

[Iguanod]

Well you just said something that made me realize I'm a bit of a moron hahaha.

I was under the impression the pump needs to run at a minimum rpm for the SGW to work, but what that actually means is that a particular pump needs to run at a minimum rpm, not that whatever the pump is it needs to run at X rpm?

So what the SWG needs is a minimum water gpm, regardless of the rpm needed in the pump to produce said gpm?

 

[Iguanod]

So these are two of the 3hp pumps I was looking at and the info I have found (not sure if useful cause I don't even know what's half of what I'm looking at). They are spanish brands (my wife isn't a fan of buying expensive equipement online), so you probably won't have heard of them.

ESPA Silen Plus 3CV: 1400€


QP 500VS22: 700€ (suspiciously cheap?):

 

[Bperry]

So these are two of the 3hp pumps I was looking at and the info I have found (not sure if useful cause I don't even know what's half of what I'm looking at). They are spanish brands (my wife isn't a fan of buying expensive equipement online), so you probably won't have heard of them.

ESPA Silen Plus 3CV: 1400€
View attachment 644606
View attachment 644607
QP 500VS22: 700€ (suspiciously cheap?):
View attachment 644608

The noise difference between a 1.5hp single speed pump and a 1.5hp variable speed is substantial when the VSP is running lower RPM. I use a 1.6hp variable speed pump that replaced a single speed and it’s a night and day difference. If you don’t have any water features or equipment that requires extra flow then probably not super useful to get the bigger pump. But if you have the cash, it doesn’t hurt anything except maybe saving a bit more electricity.