Is My Pressure Tank Too Big

Users who are viewing this thread

Collin E

New Member
Messages
17
Reaction score
0
Points
1
Location
Illinois
Hello,

I have a 22 gpm Grundfos SQE with a CU 301 controller. The manual says that it should be paired with a 2 gallon tank, however we have a 22 gallon tank. We had our original well replaced last year because we needed to put an irrigation system in our new construction home and the well the builder put in was not powerful enough.

Is it possible that the person who installed this newer pump gave us a bigger tank because it helps with the water hammering when the irrigation system turns on outside? It is just bothersome because when we are running a faucet or shower, it doesn't use enough water to keep the pump on constantly since the tank is so oversized, so it short cycles by turning on for 20 seconds to bring the pressure back up and turning off for a minute or so.
 

Valveman

Cary Austin
Staff member
Messages
14,599
Reaction score
1,296
Points
113
Location
Lubbock, Texas
Website
cyclestopvalves.com
A 22 gallon size tank only holds 5 gallons of water. It should not be too big. Your problem is most likely in the CU301 box as is usually the case. Those things are made to help pump guys make a lot of money, which causes you to purchase a new one fairly often. Sounds like your CU301 box has lost connection with the electronics in the motor. When that happens, which is does regularly, the system just works like a regular pressure switch system turning the pump on and off with 15 PSI differential. In this case the larger tank is actually helping a lot.

Since you are already researching problems with the SQE and CU310, you should look at a permanent fix, which is to replace the CU301 box with a regular 40/60 pressure switch and use a Cycle Stop Valve to deliver constant pressure and keep the pump from cycling. The SQ pump itself is fairly dependable if you don't use the CU301 and try to vary the speed. The CSV is just a simple valve that will do a better job than the complicated and computerized CU301. Simple is what makes a pump system dependable. The CSV is what makes pumps system last many times longer than normal, which is exactly why pump manufacturers don't want you to know about it.

We do this so often I even have a CU301 or VFD repair kit that uses a CSV. You can see it here.
https://cyclestopvalves.com/pages/vfd-repair-kit
 

Collin E

New Member
Messages
17
Reaction score
0
Points
1
Location
Illinois
A 22 gallon size tank only holds 5 gallons of water. It should not be too big. Your problem is most likely in the CU301 box as is usually the case. Those things are made to help pump guys make a lot of money, which causes you to purchase a new one fairly often. Sounds like your CU301 box has lost connection with the electronics in the motor. When that happens, which is does regularly, the system just works like a regular pressure switch system turning the pump on and off with 15 PSI differential. In this case the larger tank is actually helping a lot.

Since you are already researching problems with the SQE and CU310, you should look at a permanent fix, which is to replace the CU301 box with a regular 40/60 pressure switch and use a Cycle Stop Valve to deliver constant pressure and keep the pump from cycling. The SQ pump itself is fairly dependable if you don't use the CU301 and try to vary the speed. The CSV is just a simple valve that will do a better job than the complicated and computerized CU301. Simple is what makes a pump system dependable. The CSV is what makes pumps system last many times longer than normal, which is exactly why pump manufacturers don't want you to know about it.

We do this so often I even have a CU301 or VFD repair kit that uses a CSV. You can see it here.
https://cyclestopvalves.com/pages/vfd-repair-kit
Thank you for your response. I should have included this information. If I am using a little amount of water (showering, running a faucet, flushing a toilet, etc) it acts as a regular pressure switch, however if we run the bathtub, pot filler over stove, or multiple showers/faucets, it keeps everything at a constant 70 psi. I just don't like that it doesn't do that when one shower is running because a 10 minute shower can cause the pump to run 15-20 times.
 

Reach4

Well-Known Member
Messages
38,798
Reaction score
4,412
Points
113
Location
IL
Last edited:

Collin E

New Member
Messages
17
Reaction score
0
Points
1
Location
Illinois
With SQE/CU301 the precharge is different -- 70% of the pressure setting, but the table gives 49 psi precharge for 70 psi system (less than 70%).

http://kesko-onninen-pim-resources-...est-1.amazonaws.com/pimdocuments/13464829.pdf section 1.6 page 8.
I have mine pressurized to 49 psi. Originally it was at around 10 psi. Not sure what the installer was thinking, so the pump would turn on more often, but with it properly pressurized, it doesn't maintain constant pressure unless there are multiple faucets running. Any ideas other than a CSV?
 

Collin E

New Member
Messages
17
Reaction score
0
Points
1
Location
Illinois
Yeah it is already malfunctioning. It should hold the same 70 PSI even with one faucet on.
Is there a way to "fix" the malfunction other than changing everything out with a CSV? I have already considered it, but not sure I want to make the switch because I am happy with how it operates now when running my irrigation system.
 

Collin E

New Member
Messages
17
Reaction score
0
Points
1
Location
Illinois
Should be under warranty? Most people don't switch to a CSV until the warranty is out and it starts costing them.
I will contact the company. I drained the tank back to the 10 psi it was set at when installed, and it will run constantly for everything except a faucet. When pressurized to the correct 49 psi, it won't run constantly even for running the bath tub or outdoor faucets. It will just run constantly for the irrigation system.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks