New filter and some plumbing questions

[cchaynes]

Bought a new filter and multiport valve. The valve connections are backwards from what I have so I need to plumb the pump to the left side (see picture) of the valve. Thinking about using flex PVC to make it gentle, it would otherwise require 4 90s at least.

First, thoughts on this approach?

While I am at it, I also want to put a check valve before the pump so that the pump doesn't always drain back to the pool and stress the pump on priming.

Do I need a check valve like they have there at the inlet side to the multiport valve? Seems useless and I am going to redo right back to the pump and delete the cleaner line and associated Crud you see to the right.



I was thinking rigid pipe to a union to flex pvc from the pump. My return that runs through the heater would also be redone for better flow.

Overall this seems like the best approach to me.but wanted to ask here if I have missed something?

Questions.

1) thought on check valves, delete the one at the valve and add one before the pump?

2)flex PVC as opposed to some hard pipe gymnastics?

I think the flow may well be improved and thus make the new pump more efficient.

Proposed changes in sec


Thanks in advance.

 

[ajw22]

Welcome to TFP.

Don't get into flex PVC. Use four 90's if necessary. It will not make a difference in your flow.

Can you rotate the new filter 90 degrees counter-clockwise? Then it will only take two 90's to get into the MPV intake.

If your system is tight and does not leak air in it will not lose pressure and drain back into the pool. The CV in the suction line is a bandaid for the root cause. It will work but CV's eventually fail and become a problem.

 

[cchaynes]

Welcome to TFP.

Don't get into flex PVC. Use four 90's if necessary. It will not make a difference in your flow.

Can you rotate the new filter 90 degrees counter-clockwise? Then it will only take two 90's to get into the MPV intake.

If your system is tight and does not leak air in it will not lose pressure and drain back into the pool. The CV in the suction line is a bandaid for the root cause. It will work but CV's eventually fail and become a problem.

Thanks
Good call on the rotation of the filter!

Regarding the Check valve at the pump, I read that its simply a gravity issue, and that one is suggested there?

Another question, would you put a CV in the heater inlet line to prevent hot water backing up to the filter? and one between the pump and MPV?

 

[ajw22]

Regarding the Check valve at the pump, I read that its simply a gravity issue, and that one is suggested there?

When you keep your finger on a straw does gravity still suck the water out of it? If the pipe does not allow any air in the water will not flow out.

Another question, would you put a CV in the heater inlet line to prevent hot water backing up to the filter? and one between the pump and MPV?

No. Why? The only place you need a CV is between a tablet chlorinator and a heater to prevent acidic water from backflowing into the heater when the pump is off.

 

[cchaynes]

When you keep your finger on a straw does gravity still suck the water out of it? If the pipe does not allow any air in the water will not flow out.

Good point, not sure why it is losing its suction, could be the filter that I am replacing or some of the plumbing that I am dumping, so perhaps I will do that last!

No. Why? The only place you need a CV is between a tablet chlorinator and a heater to prevent acidic water from backflowing into the heater when the pump is off.

Pentair installation instruction suggest this, I suppose, no harm done and $40

Thanks!

 

[ajw22]

Which Pentair installation instruction suggest it?

 

[cchaynes]

Which Pentair installation instruction suggest it?

Sta-Rite - System 3 Modular D.E. 72 sq. ft Filter

"Valves: A check valve installed ahead of filter inlet will prevent contaminants from draining back into pool. A check valve installed between filter and heater will prevent hot water from backing up into filter and deforming internal components."

https://www.pentair.com/content/dam/extranet/product-related/product-manuals/pool-and-spa-equipment/filters/System3ModularDEOwnersManualEnglish.pdf

It's on Page 5

Seems that they may be overkill, but as long as there is no downside, then might as well throw them on was my thinking.

 

[Palpatine]

@cchaynes I put a check valve between my suction in and pump inlet so that when I empty out the pump basket it won't drain back into the pool and put more stress on the pump each time I fire it up after. Otherwise, it doesn't drain back.

Is this the reason you're putting a check valve in?

 

[cchaynes]

@cchaynes I put a check valve between my suction in and pump inlet so that when I empty out the pump basket it won't drain back into the pool and put more stress on the pump each time I fire it up after. Otherwise, it doesn't drain back.

Is this the reason you're putting a check valve in?

That and it does seem to drain back sometimes when the pump is off overnight and forces the pump to prime for a while.

The pool pump is likely a bit higher than the pool

 

[Palpatine]

it does seem to drain back sometimes when the pump is off overnight

Not sure that should happen. It's like @ajw22 said:

When you keep your finger on a straw does gravity still suck the water out of it? If the pipe does not allow any air in the water will not flow out.