Raypak 336A low flow, pressure switch failure mode... (2024)

Raypak 336A. Has worked for 3 years at 1600rpm. Started it up today and 1600RPM yielded "Water Sw Open" error, which obviously means the water pressure switch is open (low flow). Had to raise it to 1800RPM to close the switch.

Two questions:
1) Is this a typical failure mode of the water pressures switch? (i.e. requiring a higher pressure year over year is indicative of future/eminent failure?)
2) Page 32 of the manual below talks about the water pressure switch adjustment. Factory is 1.75 PSI for Deck Level installation. Also indicates a lower pressure may be required for higher installation. Mine is about 2 feet above the deck. Step 3 of the adjustment procedure indicates:

• Turn the filter pump ON and confirm that the pressure switch is closed (use a multimeter to check). If the pressure switch fails to close, either the switch setting is too high or not enough pressure is being supplied by the filter pump

Obviously the switch is not closed with the pump on, so, if you don't know your actual flow, how do you determine if the switch setting is too high, you don't have enough flow, or the switch is going bad?

@ajw22 @JamesW @1poolman1 Thoughts? Thanks!

PoolStored said:

Raypak 336A. Has worked for 3 years at 1600rpm. Started it up today and 1600RPM yielded "Water Sw Open" error, which obviously means the water pressure switch is open (low flow). Had to raise it to 1800RPM to close the switch.

Two questions:
1) Is this a typical failure mode of the water pressures switch? (i.e. requiring a higher pressure year over year is indicative of future/eminent failure?)
2) Page 32 of the manual below talks about the water pressure switch adjustment. Factory is 1.75 PSI for Deck Level installation. Also indicates a lower pressure may be required for higher installation. Mine is about 2 feet above the deck. Step 3 of the adjustment procedure indicates:

• Turn the filter pump ON and confirm that the pressure switch is closed (use a multimeter to check). If the pressure switch fails to close, either the switch setting is too high or not enough pressure is being supplied by the filter pump

Obviously the switch is not closed with the pump on, so, if you don't know your actual flow, how do you determine if the switch setting is too high, you don't have enough flow, or the switch is going bad?

@ajw22 @JamesW @1poolman1 Thoughts? Thanks!

https://s3.amazonaws.com/AWSProd/sites/raypakcom/documents/241236.pdf

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See Also

Raypak Pool Heater Sensor Failures [Solved] - FireplaceHubsWhat is wrong with my Raypak Avia

Pressure switches are some of the simplest and most robust parts of any pool heater and seldom, if ever, need adjusting. Yours is just doing what it is supposed to do as a 3-year-old switch, unless water chemistry is bad, is barely broken in.

Pool heater 101, 90% of all service calls on heaters have nothing to do with the heater, the issues are caused by water flow problems. That was one of the first things that Laars (now Jandy), RayPak, and Hayward heater schools all taught. I have found it to be true. Your heater working at 1600 RPM may have been right at the bare minimum required and anything that could cause even a slight reduction in flow would not allow the heater to fire. Even a "clean" filter may not be "new clean." A specific RPM does not always mean the same amount of flow.

I typically set any pool that is heated first by finding the minimum flow required to get the switch to close (heater to fire) with a clean filter. The key is starting with a known clean filter. It also depends on whether the pump is a high-head, like an Intelliflo, or medium head like a SuperFlo.

With a high head pump I will add at least 15% more default RPM just to account for the filter getting dirty so it will still have enough flow and not have short cycling because of a flow issue. At the bare minimum RPM a pressure switch can "bounce" from slight variations in flow causing the heater to cycle on and off.

With a medium-head pump I add at least 20% more because they lose more flow with an increase in pressure (head). Sometimes that isn't enough. That's one reason I never use or recommend a medium-head pump for filtration except on the simplest pools and a customer with a very limited budget. So far, these settings have caused no issues (call-backs) and the customers are happy.

New pumps are amazing things, but the actual pumping technology is very old. The Intelliflow is still based on the 30 year-old Whisperflow design. The IntelliPro (Sta-Rite version) is still based on a 30 year old Max-E-Pro design. Sta-Rite "Pump University" used to have very good classes before Pentair bought them. Simplest definition is that a high-head pump's flow will not drop more than 10% with a 10 lb. rise in pressure, a medium-head pump will drop 20% or more with the same rise in pressure. Adjust accordingly.

1poolman1 said:

Yours is just doing what it is supposed to do as a 3-year-old switch, unless water chemistry is bad, is barely broken in.

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Switch is 13 years old, best I can tell (installation receipt). I've owned the pool 3 years.

1poolman1 said:

medium-head pump I add at least 20% more

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I have medium-head pump...SuperFlo VS, and Sta-rite system 3 sand filter.

So, I guess the best approach at this point is backwash the filter (sand with Zeolite). Find the lowest speed the pump will close the switch (let's say for grins it is 1600rpm), then I should add 20% (320RPM) and run the pump at 1920.

Or, replace the pump with an Intelliflo, find the minimum and add 10%. (not likely to happen until the superflo dies...the 50 extra watts for the 1920 doesn't warrant a pump change.

Thanks!

When was the filter sand last put through a deep clean process?

In all honesty, I agree with @JamesW on the point he’s made many, many times - pressure switches on heaters are just plain stupid. You could put a flow switch on your plumbing and then use that instead of the pressure switch. IIRC, heaters typically need around 40GPM to operate safely and efficiently.

Cheaper than a new pump at least …

I would always want a flow switch over a pressure switch.

Your heater requires about 35 to 40 GPM.

JoyfulNoise said:

When was the filter sand last put through a deep clean process?

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Never. It is pristine and "soft/pliable," with no channeling.

JoyfulNoise said:

In all honesty, I agree with @JamesW on the point he’s made many, many times - pressure switches on heaters are just plain stupid. You could put a flow switch on your plumbing and then use that instead of the pressure switch. IIRC, heaters typically need around 40GPM to operate safely and efficiently.

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So I figured it all out. I did a "soft" open, with hairnets and dolphin. I have changed hairnets religiously. Didn't think the filter could need a backwash and honestly didn't check pressure rise. I have put that on my spring list to check every week during soft open.

Followed the process I responded with to @1poolman1 . Filter was the dirtiest I've ever seen it. Apparently all the spring cleanup and storms and blowing wind put more in the filter than I thought. After backwash to clear and rinse, heater kicked on at 1320. 1320x1.2 = 1,584. Exactly where I had been running before, 1600.

All makes sense.

I hadn't seen @JamesW opine on pressure switches being stupid. Not sure I understand why they are stupid. I have two extra 1/2" "Ts" after the heater that are unused (were for future MA stenner and potential other uses). Are there adjustable, or 40GPM flow switches that would fit a 1/2" tee? Does the flow switch need to be before the heater? (pressure is likely higher and flow is likely lower before than after heater (?)).

Thanks for the insights...#alwayslearning.

PoolStored said:

I hadn't seen @JamesW opine on pressure switches being stupid. Not sure I understand why they are stupid.

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