SQ pumps on mod sine wave [RE-wrenches]

[Jeffrey Wolfe, Global Resources]

Kirk,

Just a guess. Check the check valve in the pump line to teh pressure tank. 
Does it share a check valve with the spring pump system, or does it have 
it's own? It could be hanging, causing the pressure drop off. The slow 
start should not do this. Sounds like you're getting water flow the wrong 
way sometimes.

Jef

On Monday, April 22, 2002 11:08 AM, Kirk Herander [SMTP:kirk at vtsolar.com] 
wrote:
> Group,
> I have a customer running a 1/2 HP Grundfos SQ series (soft start) pump 
on
> an old Trace U 2024 mod sine inverter. Occasionally, like once every two
> weeks, the pump won't fill the pressure tank when cut-in pressure(30 psi) 
is
> reached. The pump turns on, but the pressure hovers around 10-15 psi. 
There
> is also a dc pump plumbed to the tank from a spring. Once we switch over 
and
> allow the DC pump to pressurize the tank, then switch back to the 
Grundfos,
> it will work fine for a couple of weeks until this happens again. Any 
ideas?
> Battery voltage is not low when this occurs.
>
> Also when cut-in is reached, the pressure will drop from 30 to 0 psi for 
a
> second, then rise normally as the pump pressurizes the tank. Is this 
sudden
> pressure drop to be expected from a soft-start pump?
>
> thanks
> Kirk
>
> Vermont Solar Engineering - a Xantrex / Trace Certified Dealer
> Kirk Herander
> PO Box 697
> Burlington, VT. 05402
> www.vermontsolar.com
> www.backeastsolar.com
> 800.286.1252 - 802.863.1202
> fax 802.863.7908
>
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