Pump Efficiency and Head Loss... I’m at a Loss :(

[mas985]

Look at the part #

The quad de multiport is the same as the sand filter multiport.

It's different from the regular de multiport, which often causes confusion.

I suspect that it might be the wrong multiport. The model number will confirm.

There's a silver sticker on the vertical pipe coming out of the front bottom of the multiport. The part number should be 261050.

If the part number is 261142, it's the wrong multiport.

 

[JamesW]

They indicate that the part number is correct in their previous post.

I would recommend a filter cleaning by removing the cartridges and hosing them off.

Backwash really does not work.

I would also recommend that the in-line chlorinator not be used and the external bypass kept closed.

I would run the pump at 40 gpm when heating. Anything more won't make any difference.

There seems to be excessive restriction in the suction and return, but there's no obvious thing that stands out.

 

[Jimrahbe]

Brandon,

I see where you checked and said the MVP P/N was 261050.. If this were my system the very first thing I would do is to open the filter and manually clean it out and see what that did.

I always recommend cleaning the filter on a new pool after 30 days.. No telling what might be in there and even if nothing, it gives you a solid reading on what the "clean" filter pressure should be.

I am not much of a fan of backwashing...

Thanks,

Jim R.

 

[mas985]

Then I would open the filter and check the insides to make sure nothing is wrong with that. If that looks ok then perhaps the valve is defective.

 

[TxHr]

Thank you! I will open the filter this weekend, give everything a cleaning and report back. As for the possible restriction in suction and return, I was afraid it was due to the way the plumbing was ran in the pool itself. Based on the recent tests, it appears to mainly be isolated to the filter and/or MPV. Is there anything else I should look into at this point?


Thanks again,

Brandon

 

[TxHr]

Thank you again for your help. I completely disassembled and cleaned the pump. I did find a lot of clumped DE in the filter housing and on top of the cartridges. I cleaned the cartridges, filte housing, manifold and all piping, and air screen. When I was finished, everything looked brand new. I made a slurry (my PB just poured DE into the skimmer) and poured it into the skimmer closest to the equipment pad. The results are as follows:

RPM	GPM	Filter PSI	Pump PSI	Suction PSI
1000	16-17	0	3	3
1250	25	1	4	3
1500	32	2	7	5
1750	39	4	9	5
2000	46	6	12	6
2250	52	8	15	7
2500	56	9	19	10
2750	61	12	23	11
3000	66	15	27	12
3250	71	18	32	17
3450	75	20	36	16

For comparison purposes, here is the table I had previous provided, before cleaning the filter:

RPM	GPM	Filter PSI	Pump PSI	Suction PSI
1000	>15	0	3	3
1250	21	1	4	3
1500	28	3	7	4
1750	35	5	9	4
2000	42	7	12	5
2250	47	10	15	5
2500	52	12	19	7
2750	56	14	23	9
3000	61	18	27	9
3250	66	20	32	12
3450	69	23	36	13

I have also updated the GoogleDeive link with photos of the filter:
https://drive.google.com/drive/folders/1z0kdz7g0S7ZZZMu3efw743_rlFSgcd3M


Thanks again for any insight!


Brandon

 

[mas985]

It is definitely better but no where near where it should be for your plumbing setup. Also, your table shows suction PSI which I assume is just the Pump-Filter PSI but that is more than just the suction. It also includes the plumbing between the pump and the filter gauge which would be affected by the MPV. Any chance you could hook up a vacuum gauge to the suction side of the pump via the drain plug? That would isolate the issue between the suction plumbing and the MPV.

 

[JamesW]

It might be worthwhile opening the 3-way valve in front of the pump to see if there is anything stuck in it.

 

[TxHr]

It is definitely better but no where near where it should be for your plumbing setup. Also, your table shows suction PSI which I assume is just the Pump-Filter PSI but that is more than just the suction. It also includes the plumbing between the pump and the filter gauge which would be affected by the MPV. Any chance you could hook up a vacuum gauge to the suction side of the pump via the drain plug? That would isolate the issue between the suction plumbing and the MPV.

Hi Mark,

What gauge and parts will I need to connect into the suction side of the pump? My PB doesn’t have a gauge


Thanks,

Brandon

- - - Updated - - -

It might be worthwhile opening the 3-way valve in front of the pump to see if there is anything stuck in it.

Hi James,

How would I go about opening the 3-way valve? Do I need to simply disconnect the pump from the union and take a peek down the pipe or do I need to disassemble the valve?


Thanks,

Brandon

 

[JamesW]

I would probably open the valve.

Unscrew the top thumb screw to remove the handle and then remove the screws.

Mark the orientation of the top with a marker before removing so that you put it back on the same way.

When reinstalling the screws, rotate slowly in reverse to get the screw to drop into the original thread before tightening.

If you don't hit the original threads correctly, you can cross-thread and damage the threads.

For a vacuum gauge, just Google 1/4" npt vacuum gauge.

You can screw it into the front drain plug. Use a little bit of teflon tape and pipe sealant to make airtight but don't over tighten or you could crack the housing.

 

[mas985]

What gauge and parts will I need to connect into the suction side of the pump? My PB doesn’t have a gauge

Another option is to use a 1/4" pressure gauge, which is easier to find, and screw it into the return side drain plug. This will give you the pressure before the MPV. If that is much higher than the filter pressure, then the loss is in the filter. If the pressure is about the same as the filter pressure, then the problem would be in the suction side of the plumbing.

 

[jonpcar]

Hi Mark,

What gauge and parts will I need to connect into the suction side of the pump? My PB doesn’t have a gauge

Brandon

here is one I bought and still am using...a cheap model

https://www.amazon.com/gp/product/B0087UBCIE/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

or this one which is a liquid filled model (better)...amazon warehouse has a returned one for about $9...I haven’t had any problems with warehouse items...they take returns if there is any problem. EDIT...this one is actually a +30 to -30psi...could be used on both sides of pump but +30 would max out at higher rpms...maybe not so useful on the return side.

https://www.amazon.com/Winters-Stai...d=1547329864&sr=1-3&keywords=Vacuum+psi+gauge

These vacuum gauges would only be useful on the the suction (basket) side of the pump. see edit above...

 

[jonpcar]

Another option is to use a 1/4" pressure gauge, which is easier to find, and screw it into the return side drain plug. This will give you the pressure before the MPV. If that is much higher than the filter pressure, then the loss is in the filter. If the pressure is about the same as the filter pressure, then the problem would be in the suction side of the plumbing.

mark, I was under the impression that Brandon’s pump psi measurements (in the table) were built into his pump...will installing external gauges, either on the return side or suction side give him better measurements...I am probably misunderstanding where his pump psi tables were generated from.

I am hoping to learn few things...in a “normal, non-problem” pool equipment setup, ive always assumed the pump return side pressure should roughly match the filter pressure...I’ve never measured mine...is that assumption valid?

 

[mas985]

Only one of the measurements in the table is from the pump (Pump PSI). Filter PSI is from the filter itself. The "suction PSI" is just the difference of the two.

By measuring at the pump itself, one can determine the head loss between the pump and the filter gauge. This will determine where the excess head loss is coming from.

 

[JamesW]

The pump's pressure is the combined suction plus discharge pressure.

This gives you the total, but it doesn't tell you how much is suction vs pressure.

The filter gauge should tell you the pressure side. So, the pump minus the filter should give you the suction.

However, if there is an issue with the plumbing between the pump and the filter, that will throw off the numbers.

There might be an issue with the multiport. So, we need to rule it out.

 

[TxHr]

Thank you all. I’ve ordered the gauge and it will arrive on Tuesday. I’ll be back at the house from travels late Wednesday. I’ll install Thursday and and report the findings. I appreciate everyone’s patience and assistance in diagnosing the issue. Have a great weekend!

 

[TxHr]

While waiting on my gauge, I went out and opened-up and inspected the following valves: suction, return and heater bypass. Fortunately/unfortunately everything was clean as a whistle. I did discover that when the bypass has 1/2 going to heat and 1/2 going to bypass, there is little space for water to flow. Apparently it’s all or none, you can’t have both (kinda like being a little pregnant Anyway, the flow didn’t change from the above table when I sent everything 100% to the bypass. When I sent everything 100% to heater, there was a drastic drop in flow, as noted below. The heater has never had the power button pushed, it has simply been in standby the entire time. I wonder if the heater needs to be cycled on/off for the internals to initialize flow... just a thought.

Here are the flow rates going 100% heater:
1000 RPM = 10 GPM
1500 RPM = 23 GPM
2000 RPM = 33 GPM
3500 RPM = 43 GPM

Here are the flow rates going 100% to the heater bypass:
1000 RPM = 16-17 GPM
1500 RPM = 32 GPM
2000 RPM = 47 GPM
2500 RPM = 57 GPM

It appears I have two issues: first is the overall flow rate and second is the reduced flow rate when 100% of the water is sent through the heater. I am wondering if its an internal heater issue or if it’s the “Magic CR2 check valve” and/or the goofy rise coming off of it going into the return (check out photos for visual). Anyway, still scratching my head. Every time I feel we might be onto something another rabbit hole presents itself. Again, I appreciate everyone’s patience and assistance.


Thanks again,

Brandon


Link to plumbing pics:
https://drive.google.com/drive/folders/1z0kdz7g0S7ZZZMu3efw743_rlFSgcd3M

 

[JoyfulNoise]

Looking at the picture I would say that three way valve acting as a splitter is not setup correctly. The input to that valve should be the vertical leg of the “T” not one of the arms of the “T”. The width of the sliding door inside the valve is such that when you are setting it to what you think is a 50/50 split, it is 50/50 but the opening area to each pipe is greatly reduced.

Try this - turn the handle so the OFF tab is pointing up towards the sky then remeasure flow. With the OFF tab up and the handle down along to descending pipe, all orifices to that valve will be wide open. The flow will split based on the dynamic head loss of each leg.

In referring to picture - IMG_4376.JPG

- - - Updated - - -

And what is that T on the return line after puck chlorinated with the bonding wire attached to it??

 

[PoolguyinCT]

Looking at the picture I would say that three way valve acting as a splitter is not setup correctly. The input to that valve should be the vertical leg of the “T” not one of the arms of the “T”. The width of the sliding door inside the valve is such that when you are setting it to what you think is a 50/50 split, it is 50/50 but the opening area to each pipe is greatly reduced.

Try this - turn the handle so the OFF tab is pointing up towards the sky then remeasure flow. With the OFF tab up and the handle down along to descending pipe, all orifices to that valve will be wide open. The flow will split based on the dynamic head loss of each leg.

In referring to picture - IMG_4376.JPG

- - - Updated - - -

And what is that T on the return line after puck chlorinated with the bonding wire attached to it??

Joyful for the win..
The branch & run are reversed on the Tee / 3 way valve he spotted, at top of his posts.
Too Common a mistake with Tees.

 

[TxHr]

Looking at the picture I would say that three way valve acting as a splitter is not setup correctly. The input to that valve should be the vertical leg of the “T” not one of the arms of the “T”. The width of the sliding door inside the valve is such that when you are setting it to what you think is a 50/50 split, it is 50/50 but the opening area to each pipe is greatly reduced.

Try this - turn the handle so the OFF tab is pointing up towards the sky then remeasure flow. With the OFF tab up and the handle down along to descending pipe, all orifices to that valve will be wide open. The flow will split based on the dynamic head loss of each leg.

In referring to picture - IMG_4376.JPG

- - - Updated - - -

And what is that T on the return line after puck chlorinated with the bonding wire attached to it??

Hi Matt,

That’s the valve that I fixed earlier today. The PB had it to where it would shutoff the incoming flow and he had it half way between the heater and the bypass. You are correct, when it’s in the halfway position, the flow is greatly reduced to both legs. Unfortunately, even after moving it to all bypass (eliminating the heater), the flow didn’t change. As noted above, the flow going through the heater was greatly diminished, when the flow was sent 100% to heat. When I put the valve back together, I oriented the off position to either be all the way up, heater or bypass, removing the ability to shut-off incoming flow.

The T where the cholorinator should be is where the PB moved the bonding lug, I find it quite an odd location.


Thanks,

Brandon