Heater Plumbed In Reverse

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gigi747

0
May 2, 2012
19
Southern CA
So, umm yeah, title says it all.

I should have caught this sooner. After many hiccups, I finally got pebble and water in my pool about a week ago. Now that I have familiarized myself with my Intellicenter and my new pool/plumbing, I noticed my pool returns were kinda weak, or at least felt so to me.

I have a Sta-Rite IntelliFlo VSF 3hp pump, Sta-Rite Mod 3 500 filter, and Master Temp 400 heater.

After pulling a few pieces of shotcrete out of my main drain line to my skimmer, I figured perhaps there were more that would work themselves loose and perhaps causing my low flow.

Not content, I charted my pump RPMs vs. GPMs:
Screen Shot 2021-06-02 at 11.26.19 PM.png

Next I stumbled upon mihzyd777's thread about return eyeball sizes. Looking at some of the posted pump speeds in the thread vs GPM measurements lead me to realize something was wrong with my setup. Realizing I did not have a bypass plumbed across my heater I pulled up the manual for my Master Temp 400. After looking at the schematics was when I realized my PB plumbed my heater backwards.

I'm guessing this is the cause of my low flow, along with whatever left over shotcrete is working its way around in my plumbing?

Are my pump speeds vs flow readings pretty far off from a similar setup?

While running water backwards through your heater is not ideal, I'm wondering what actually could be harmed by doing so? Looking at the 'Water System' portion of the heater schematic, it looks like the only things that could really be affected would be the bypass valve, and perhaps the manifold plates and insert depending on what they are made of.

Screen Shot 2021-06-03 at 12.16.38 AM.png
 
gigi747 said:
While running water backwards through your heater is not ideal, I'm wondering what actually could be harmed by doing so? Looking at the 'Water System' portion of the heater schematic, it looks like the only things that could really be affected would be the bypass valve, and perhaps the manifold plates and insert depending on what they are made of.

View attachment 340702
Click to expand...

Lots of things are not going to work right because the sensors are positioned on the input or output pipes.

The thermistor temperature sensor will show output water temperature, not input water temperature.

The thermal regulator and high limit sensor should be working off of output water temperature and will not work properly.

If you are asking if you can leave your heater connected backwards the answer is no. You need to have it fixed.


Pentair_MasterTemp_Water_Manifold.jpg
 
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The internal bypass is a check valve and water can only go one way.

The thermal regulator is closed when the heater is off.

So, water really should not be going through the heater at all.

You need to get this fixed correctly as soon as possible.
 
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Below is a graph of the pump performance curves at different speeds with 3 system curves.

Curve B is a typical curve and shows a system that is poorly designed.

Curve C is a well designed system curve.

Most curves hit somewhere between the arrows.

Your curve (A) indicates a serious problem that needs to be addressed right away.

I would shut the system off and tell the builder that it needs to be fixed immediately.

gigi747 Intelliflo and system.jpg

IntelliPro Performance Curve with system curves_LI.jpg
Do you have a Sta Rite IntelliPro (Black) or a Pentair IntelliFlo (Tan)?
 
Pentair_MasterTemp_400_operating_pic.png


If you try to push water into the outlet, the water can't go through the thermal regulator or the internal bypass.

So, I don't see how you are getting any flow at all through the heater?

Do you have pictures of everything?
 
Thank you all for the replies!

Sorry, it was late when I was typing up the first post; I have the black Sta-Rite IntelliPro VSF 3hp pump.

PB is going to fix it tomorrow to include a bypass valve. Reading up on this a bit more, I think it would be a good idea to add the recommended, but not included pressure relief valve. My filter pressure with the pump on high was ~<30 psi, while a relief valve wouldn't have helped me out in this situation, looking at the internals of the manifold, I can see how things could go bad quickly without one.

Since I turned my system off until it is fixed, I decided to disassemble the manifold and see if anything was broken and just how water could flow through the heater backwards. Note the hole drilled into manifold baffle plate (#7) and the hole drilled into the mounting plate of the bypass valve assembly. Although the hole in the baffle plate is pretty tiny, apparently it was enough to allow water to flow. The bypass assembly looked fine and the thermostat assembly, or rather the 'thermal regulator' looked fine, I even checked it in a pan of hot water. I ran water through each port on the tube coil assembly and nothing appeared to be lodged inside of it.

Since pictures are better than me rambling, here they are:

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IMG_7458.jpg

IMG_7460.jpg
IMG_7461.jpg
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@gigi747 just came across your post
It appears my installer might have done the same thing - plumbed the heater in reverse
By plumbing it correctly as per the inlets and outlets, did that solve your problem?

I've had it like this for a week now and interesting enough the heater was able to warm the pool from 61F to 75F in a matter of 12hrs (14,200 gal pool)
My installer is coming tomorrow to correct it
 
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