Flow Sensor or Pump?

[doubleohwhatever]

Hi All,

I seem to either be having an odd issue with my return pump or my FMM/flow sensor. Please see the attached chart.

flow-chart.jpg

Basically, the flow rate is slowing dropping but it seems to be doing so in odd 24 hour high/low intervals. I have no clue what's causing this. The pump is pulling the exact same current it always has and I've noticed no reduction in the water moving through the sump.

Any ideas what could be going on?

[iamchadster]

Try cleaning the flow sensor first.

[doubleohwhatever]

I'll try that tomorrow morning and see what happens.

That said, I just noticed something that might play into this. My sump is located in my (mostly) unheated garage. The sump is insulated and there's an electric heater in the garage that kicks on if the temp drops below 50F. Now the tank water has been staying quite constant due to the heaters in the sump and the sump itself being insulated. However, the flow sensor itself is on the pipe exposed to the garage air.

The reason I think this may be relevant is because the weather here has turned cooler over the past week and the garage has been much warmer during the day than it has at night. Basically the highs and lows in the flow chart seem to line up with the temperature in the garage.

Are these flow sensors or the FMM sensitive to ambient temperature changes?

[doubleohwhatever]

I wrapped some foam insulation around the flow sensor just to see what happens and the flow rate is going up. Odd. I'm just going to set the flow rate alarm lower and not worry about it unless there's a noticeable change in flow through the sump.

[iamchadster]

Yeah that is odd. The heat from the water going through the sensor itself would be a factor keeping it warm. I can't see temperature being an issue at all with the sensor but then again it always rains when I wash my car. . Keep us posted, but I would still take the time and remove the sensor and give it an inspection and cleaning and see if that helps.

[TerraReef]

Planning to install some flow sensors in a similar unheated room. Please update when you can. I am curious if this resolved the issue.(and even more curious as to how this could have been an issue)

[doubleohwhatever]

This did resolve my issue. You would think the water flowing through the sensor would keep it sufficiently warm. However, wrapping the sensor in insulating material solved the problem. Kinda. The "problem" now is that the sensor is reading a higher flow than it ever has before. So I've come to the conclusion that my sensor is greatly impacted by temperature. I have no clue if mine is defective or if this is a problem with these sensors in general. Unfortunately, this means that I can't trust the flow rate my sensor reads. The good news is that it's still effective as low flow rate monitor to trigger a warning.

[TerraReef]

Maybe removing all the cables from the FMM, removing it from your modules, then reinstalling it will help.

Does the manufacturer of your pump claim it can push 1200gph and it is reading 2000gph? Or could it be that the higher reading you are getting then you got before is actually accurate.

[doubleohwhatever]

Maybe removing all the cables from the FMM, removing it from your modules, then reinstalling it will help.

Already did that when it first started giving me problems.

Does the manufacturer of your pump claim it can push 1200gph and it is reading 2000gph?

Nah, nothing like that. It's well within what the pump should be pushing based on the plumbing. It's just odd that it now reads a little over 100gph higher than it ever has before. Nothing else in the system has changed.

Or could it be that the higher reading you are getting then you got before is actually accurate.

Dunno. That's possible. Maybe now that the sensor is insulated it's reading accurately. I really have no way to know.

Anyway, I can see that the flow through the sump is sufficient. So I'm not going to worry about the sensor being dead accurate. Mine seems to have an accuracy swing of plus or minus 100gph and that's good enough for a low flow warning. Just gonna leave it as is. I have other things that need tending to.

[TerraReef]

I have other things that need tending to.

:-) I hear you. The list of things to do is never short when you love to learn and you care for the animals. Add a busy life and even the seemingly important things are on the over due list.

Thanks for sharing your experience. I have several of these I haven't used yet and I'm considering adding a lot to the different projects we are working on.