Why is a pressure gauge so important?

[TreeFiter]

Recently, on another thread, I made some comments about pressure gauges, and I was met with opposition. Rather than hijack that thread, I thought I would bring up the topic here.

I'm of the opinion that they add very little value to the system. The main reasons I feel this way are:
-They don't last
-Since they don't last, there is no way of knowing if they are giving a reliable reading unless they are brand new
-The vast majority of situations where pressures are an issue involve pressure changes of roughly 10 psi, which can easily be seen through changes in the pressure at the return jets.

So why are they so critical? Why can't the average pool owner simply look at the return jets and see that there is very little pressure?

 

[RobbieH]

I notice no change at the return jets when the pressure at the filter changes.

Regarding not lasting, I don't know, mine's about 3 years old and still works fine. They don't have to necessarily be accurate as long as they are somewhat precise. We are really only looking for a change in pressure, and don't need to know the exact pressure.

 

[TreeFiter]

I notice no change at the return jets when the pressure at the filter changes.

Regarding not lasting, I don't know, mine's about 3 years old and still works fine. They don't have to necessarily be accurate as long as they are somewhat precise. We are really only looking for a change in pressure, and don't need to know the exact pressure.

When you say you notice no chance, in what way are you observing the return jets? Are you just looking at how they break the surface of the water, or are you putting your hand in front of them to feel the pressure?

Your pressure gauge being 3 years old almost amazes me, but I see you are located in TX. I suppose my experiences may be different, as I am in the Northeast. I often see pressure gauges fail in one season. Maybe in a dryer climate they last significantly longer.

 

[YippeeSkippy]

Mine is 3 years old, in a very VERY humid climate. I agree with RobbieH that the precise number isn't necessarily exactly accurate but you can monitor the trend and see when its rising.

 

[RobbieH]

My jets do not break the surface of the water. I feel no difference by putting my hand in front of the return no matter if the pressure reads 10 or 30 psi. And, I'm talking about when I had a one speed pump. Now that I have a VF pump, there will literally be no difference since the pump will maintain the same flow no matter what the pressure is.

 

[Isaac-1]

I suspect the short life you see on pressure gauges is from repeated freeze cycles. These problems could be solved by using a better quality gauge, as the industry standard ones are about as cheaply made as possible.

Ike

p.s. I typically see 5 years + from mine (industry standard type), but my equipment is indoors, but not in a climate controlled room

 

[TreeFiter]

Mine is 3 years old, in a very VERY humid climate. I agree with RobbieH that the precise number isn't necessarily exactly accurate but you can monitor the trend and see when its rising.

Maybe the humidity is only part of the equation, and the cold winters are contributing to the failures I see.

I'm on board with the idea that the number doesn't matter, but its the change that we care about. Many owners manuals simply say you need to backwash when the pressure has risen by 8-12 psi. I'm curious however if you have ever noticed the change at the returns without looking at the gauge.

Another question I'll ask is, you both have stated that your gauge is 3 years old, but how do you know that it is still functioning properly? A failing gauge might register and move, but it won't necessarily move the amount it is supposed to.

- - - Updated - - -

I suspect the short life you see on pressure gauges is from repeated freeze cycles. These problems could be solved by using a better quality gauge, as the industry standard ones are about as cheaply made as possible.

Ike

p.s. I typically see 5 years + from mine (industry standard type), but my equipment is indoors, but not in a climate controlled room

Great point about the freeze thaw cycle. Like you say, they are very cheaply made, but they still cost about $15 to replace. I would imagine a better gauge would cost significantly more.

 

[TreeFiter]

My jets do not break the surface of the water. I feel no difference by putting my hand in front of the return no matter if the pressure reads 10 or 30 psi. And, I'm talking about when I had a one speed pump. Now that I have a VF pump, there will literally be no difference since the pump will maintain the same flow no matter what the pressure is.

I find this hard to believe. The difference between 10 psi and 30 psi is very significant. I don't mean to suggest you are lieing, its just that the difference is very apparent to me.

As far as a variable speed pump, the faster the pump turns, the higher the pressure will go as long as the resistance caused by the filter remains the same. If you add resistance in the form of a dirty sand filter, the pressure on the gauge will go up, unless the pump slows down. In either case, the pressure at the return jets will drop.

 

[RobbieH]

My new pump tells me the pressure, and it matches what my gauge reads.

You don't have to believe me, but the difference at the return when the filter is clean and right before backwashing feels the same in my pool. And again, to ensure I'm clear, I'm talking about when I had my single speed pump, which is where a difference would have been noted.

Please note, I don't have a VS pump, I have a VF pump. Although both use variable speeds, my VF maintains flow. Yes, it will read higher pressure when the filter is dirty and it is working harder to maintain the same flow. BUT, the FLOW remains the same with a VF pump, this is where they differ from VS pumps. Because of this, knowing the pressure is even more important than with a non-VF pump.

 

[jblizzle]

I just put one of the better liquid filled gauges on my filter ($11 bigger display too). Nothing wrong with the old one and it was over 5 years old (that is when we bought the house). It is certainly the winters that shorten the life of them by you ... which is why in our pool closing procedures we say to remove the gauge and take it indoors.

The gauge consistently read the same pressures when filter was clean, so no reason to expect that it failed.

Also I think you realize that we recommend filter cleaning based on a 20-25% pressure rise over the clean pressure, the old +10psi recommendations is not a one size fits all thing and likely 10psi is waiting WAY too long and thus significantly reducing flow rate and filter efficiency.

I think the discussion about the VS pumps, really means a VF pump where the flow rate is set. The pump will raise the RPM and thus the pressure while maintaining the same flow rate and thus the jets would be the same.