Lower Pressure at Filter & Suction Side Vacuum

[Stigy]

Recently I noticed that my Pentair Rebel suction side vacuum was moving a lot slower & was not climbing the walls as easy as it had in the past. Unfortunately there are two things that I suspect to be culprits and wasn't paying too much attention to the issue until this week so not sure which one might be the actual root cause.

Last week I had an electric heater installed to my existing pool setup (Hydro Royal HR125) and I noticed that after the install the flow gauge above my cartridge filter was reading lower than normal. Since the heater is after the pump I didn't think this would cause an issue with the vacuum not moving as it used to. Is it okay if the pressure guage on my filter dropped by 1-2 bar after the heater install?

I also noticed last week that my skimmer basket had broken on the bottom so I wonder if something got through it and made its way into the line between the skimmer & the pump. I don't see anything in the pump side basket so not sure if that's something that can happen, but just thinking out loud.

Any thoughts, or insight or where else to look would be greatly appreciated.

 

[Jimrahbe]

S,

Anything that you put in the water flow path will cause the backpressure to increase and reduces flow at any given RPM. I suspect the problem will go away if you crank up your pump speed.

Thanks,

Jim R.

 

[Stigy]

Hey Jim - thanks for the prompt reply. So even though the heater is after my pump it would still cause the issues described? I am currently running my variable speed pump at 2,900 and that seems pretty high compared to what I've read about while browsing around this incredibly informative site.

So based on your reply, after installing the heater -

• Normal to see slightly lower pressure at the cartridge filter gauge?
• Normal to see slower vacuum speeds, less suction at the same RPM.
• Increasing the RPM at the pump should fix these issues?

 

[Jimrahbe]

S,

I would think the filter pressure would go up. While the amount of flow would go down.

I do think the 2900 is a pretty high RPM for an IntelliFlo pump. That said, you are sucking water from the vac port, most of your main drain as well as your skimmer.. The more water you suck from the main drain and skimmer the less water will flow through the vacuum.

I don't see the heater in your pic, but assume it is in series with the pool return flow.

Do you have standard side-wall pool returns or do you have an In-floor cleaning system?

Is your pump running RPM or GPM mode?

Thanks,

Jim R.

 

[Stigy]

Hey Jim - that was my confusion as well, I thought my pressure would go up, but its gone slightly down which had my confused.

I have attached a picture of the heater, but the outlet of the filter goes into the inlet of the heater and then the outlet of the heater goes to the returns.

My pump is currently running in RPM mode - wasn't even aware that you could switch it over to GPM mode.

I have two circular main drains (the picture in the first post) and 3 in-wall returns. Normally I find I get better performance if I shut off the main drain valve and let it just suck water from the skimmer & from the vacuum port.

 

[Jimrahbe]

S,

Is that an electric heater or heat pump???

Heat pumps are known to add restrictions to the water flow path.

I don't recommend the GPM mode, just wanted to make sure what you are using.

There is really no reason to even have the main drain on. Mine is open about 5% just to keep some fresh water in the pipes.

Thanks,

Jim R.

 

[Stigy]

Jim -

It's an electric heater / heat exchanger (linked here so make sure the terminology is correct - Hydroroyal.com).

I left my main drain open slightly just to keep fresh water in the pipes as you recommended and will play around with the RPMs to see if that makes a difference with vacuum speed or climbing ability and the ability to cycle water through the system. I assume there is some minimum RPM that I need to have enough flow to trigger the flow sensor in the heater to make it run.

The pool (and probably the vacuum as well) are only 7 years old and I just did the refurb kit last year so didn't think it was anything wrong with the vacuum.

Thanks for all the insight!

 

[Jimrahbe]

S,

We call that unit a heat pump. It does not use electrical heating eliminates like most electric heater do. It has a compressor and works like an air conditioner in reverse. Takes heat out of the air and uses that heat to heat the pool water.

Heaters of any kind will add resistance to the flow of water back to the pool.

Thanks,

Jim R.