Balboa vs520sz spa packby Admin
Oct 2013

Message: Hello, I currently own a Master Spa LS 850 (circa ~1999) using a Balboa ST-MAS300-DCAH (X300700) Spa Controller.  I am currently looking at either the Balboa VS520sz or the Balboa EL2000 as a replacement control.  From what I have seen, the VS520sz should fit the bill nicely.  Previously, my unit had a defective Tiny Might pump rated at 10-15 GPH that I replaced with an Iron Might which is rated at 40 GPH.  It appears that the main line feeding the pump is 1” flex PVC that expands to a 1.5” union at the pump inlet.  The outlet union of the pump is also 1.5” that goes to the heater manifold (believe at 2”).  The line on the other side of the heater manifold also drops down to 1” flex PVC through a shutoff and various plumbing adaptors.  The main question I have concerns the pumps flow rate.  Balboa had specified a minimum of 23 GPH for their M7 system.  Although the current circulation pump can produce up to 40GPH, I fear it may not be capable of delivering this within the confines of a 1” line.  Since increasing the diameter of the lines is really not a viable option, I was considering the possibility of lowering the heater element wattage to compensate, if I must.  My current configuration includes two, 2-speed, 240VAC pumps (Pump 1 & 2) and a 120VAC circulation pump (Iron Might).  Although I still have to verify the voltage requirements, the Spa also has a blower, ozonator and light which I believe are all at 120VAC.  The current heater element is rated at 5.5kW and the GFCI service to the tub is at 240VAC, 50A.  Any input or suggestions would be appreciated before moving forward with a replacement.  The current rectangular top-side control looks similar to the one for the VS520 and may not need to be replaced as well.  I still need to remove and absolutely verify the dimensions, but from the specs I have seen, all appears workable.  Thank you for your reply. Regards, Richard L. Diercks Emai

Dated on : 09-11-2012




Richard, Your option is the VS520SZ or the EL2001.  Given, what you have all described, there is indeed some risk that you will not obtain the 23 GPM (US) that the Balboa M7 spa packs require with a 5.5 kW heater.  You are also right that simply upgrading to a higher volume pump doesn't necessarily give you much more flow, if the piping is restrictive. You are correct reducing the heater power will drop the flow requirements proportionally.  It would be reasonable to use a 4 kW heater instead.  That we can supply instead of the 5.5 kW standard unit.  No difference in cost but you do need to bring it to our attention in the order.  We sell the spa pack only, which assumes it is a direct replacement and comes as Balboa packages it.  We also sell a retrofit version which comes with top side control panel, cables and a comprehensive manual (our own) as well as technical support, by myself.  Warranty is 2 years. While we list the EL2000 and not the EL2001, we can supply it.  It has the additional small board which is used for the blower when the two jet pumps are both 2 speed.  Comparison between EL2000/2001 and VS520SZ can be found in the attachment. Dieter Jung Technical Support

Click to see attachment
Post By : Dieter Jung Dated On : 09-11-2012

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