Check Valve / Pressure Problem

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R

rkaessner

Active member
Dec 2, 2021
35
Phoenix
Pool Size
15000
Surface
Plaster
Chlorine
Salt Water Generator
I recently added a SWG to my pool. It’s a Jacuzzi cell and love it. But it requires a check valve before the unit and now when my solar heater turns on at 1500 recommended RPM by solar touch for maximum heating. But the check valve swing head pressure is too high for it to physically open and pass back through SWG and into the pool. I can turn up the RPM and water will pass though but then heat the pool very slow or not at all.

I tried removing the spring which worked but then I run the possibility of the valve not closing.

Does anyone know if they sell springs related at a very low pressure to operate.

I had picked up a SCH40 in line check valve at a irrigation store which opens with minimal effort but it’s not the clear type to
Visualize which I like.

Please help
 
The water heats the pool the same rate regardless of flow rate. The heater puts out a fixed amount of BTU heat. All the BTUs in the water will go into the pool.

Heater exit temperature will vary with flow. Higher flow will have lower exit temperature but BTUs of heat to the pool will be the same over time.

If your check valve is not dead heading the pump, which I doubt it is, then water is flowing past it to the pool.

And you don’t really need that CV with the SWG even though some manufacturers may specify it in the Installation Manual.
 
SWGs do not, contrary to popular belief, require a check valve. Check valves are needed with chlorine puck feeders since they always contain a high percent of chlorine (and are very acidic) which can back up into your heater core even when the pump is off. The SWG is not producing chlorine when the pump is off so you simply don't have this scenario. I suggest you open up the check valve and remove the insides (if that's possible).
 
Ajw22- Its a solar heater, there for the lower the speed / flow the more time it has to pass through the solar panels to become hotter.

Pool Gate - Yeah I didn’t quite understand why either because but was just following manufacturer directions. At most I will get a little backflow when the pump turns off but very minimally . Yesterday I took the spring off and runs perfect at 1500 during heating and scorching hot water is flowing in. Gained 5 degrees in 6 hours yesterday in AZ.
 
rkaessner said:
Ajw22- Its a solar heater, there for the lower the speed / flow the more time it has to pass through the solar panels to become hotter.
Click to expand...

Optimum flow rate for solar depends on the size and number of panels. Slower is not better and faster then optimum has little penalty. The solar BTUs still get in the pool.

Here is a typical efficiency curve:

Solar_Panel_Efficiency_Curve.png


Solar Pool Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com
 
rkaessner said:
Manufacturers Recommendation
Click to expand...
As discussed above, it is not necessary. The SWCG does not create a corrosive environment. The recommendation is a carryover from the trichlor chlorinators that seeped an acidic stew when the pump was off.
 

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Pool_Medic said:
Manufacturers recommend check valves, so one installed is correct,

Change out the spring to a half lb one, your current spring is too strong.
Click to expand...
I’m having trouble finding the spring itself with that rating online. Which is specifically states the lb rating. I thought I saw one the other day but now I can’t find that same site. Most sites don’t specify. Do you know of a good resource.
 
ajw22 said:
Optimum flow rate for solar depends on the size and number of panels. Slower is not better and faster then optimum has little penalty. The solar BTUs still get in the pool.

Here is a typical efficiency curve:

Solar_Panel_Efficiency_Curve.png


Solar Pool Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com
Click to expand...
Yeah I totally get it. Thanks for the chart. Pretty cool. But as I mess with the RPM while heating it’s SIGNIFICANTLY hotter when running slower. 1500 RPM — HOT HOT WATER , 1800 RPM —- same temp as pool
Water.
 
Heat Flow = mass flow X heat capacity X delta T

Lower flow and delta T (the difference between heated water temperature and pool temperature) goes up. Raise flow and delta T goes down.

Heat flow is the same in both cases. It's actually slightly higher in the high flow condition, as shown in the chart above.
 
MITBeta said:
Heat Flow = mass flow X heat capacity X delta T

Lower flow and delta T (the difference between heated water temperature and pool temperature) goes up. Raise flow and delta T goes down.

Heat flow is the same in both cases. It's actually slightly higher in the high flow condition, as shown in the chart above.
Click to expand...
So Sunday I ran the pump at 1500 RPM and gained 10 degrees in
MITBeta said:
Heat Flow = mass flow X heat capacity X delta T

Lower flow and delta T (the difference between heated water temperature and pool temperature) goes up. Raise flow and delta T goes down.

Heat flow is the same in both cases. It's actually slightly higher in the high flow condition, as shown in the chart above.
Click to expand...
On Sunday I ran the pump at 1500 RPM during solar heating and gained 10 degrees in 8 hours. (Not enough flow to engage SWG). Yesterday I ran it at 1800 RPM and gained 5 degrees in 8 hours. Exact same weather conditions in Arizona both days….
 
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