Selecting the right pump (1/2 or 3/4 HP) 2 wire or 3 wire

[Texas Wellman]

How does the bleed-off work? Automatically on temperature? Where does the bleed water go?

I think you have exited the KISS method philosophy and I think you are headed for trouble.

I'm in New England so water heating up is not a problem. I have not changed the avatar yet. I just singed up and was looking for help to resolve my pump situation.

My bleed scenario is more likely in the winter than the summer.

I really appreciate all the feedback. This have been really great. I'm talking to my pump installer and will report on progress.

What is the easiest quickest way to measure pump consumption? Something that i can install to monitor progress.

 

[Digital Geek]

i was looking for infor on the 16S05-5 Grundfos pump and found to be very limited. However, i found this 15SQE05-70 with 2.9AMP. Thoughts?

 

[Sponsor]

 

[Reach4]

What is the easiest quickest way to measure pump consumption?

AC current consumption at a given time? A clamp around ammeter around one of the pump power supply legs.

Power consumption per day/month? I think you would need to wire in a watthour meter.

 

[Digital Geek]

I have a clamp meter and used to measure AMPs. But would like something that I can fix and get more accurate measurement in real time.

 

[Digital Geek]

How does the bleed-off work? Automatically on temperature? Where does the bleed water go?

I think you have exited the KISS method philosophy and I think you are headed for trouble.

When temp reaches 40F, it bleeds 1 gpm. water goes under the basement slab, that is how the pump installer suggested.

 

[Valveman]

Stay with the 16S05-5. It will be a much better pump than the SQ. Here is all I can find on it.

 

[Digital Geek]

Stay with the 16S05-5. It will be a much better pump than the SQ. Here is all I can find on it.

Excuse my ignorance again on this subject. Looking at Grandfos pumps seriously and comparing models. You recommended the 16S05-5 and not the 15SQE05-70. Looking at power consumption data, I'm seeing that the 15SQE05-70 only needs 2.9amp at full load which is around 15gpm (that is awesome). 70% of the time i will need around 8gpm which is even less. The 16S05-5 requires double the power. I understand that the SQE is the newer models and have not been out for long. What is important for me is energy consumption and longevity. Its my first experience with pumps so i'm not even sure how long these things should last. Thoughts?

 

[Valveman]

Your not comparing apples to apples. The 15SQ05-70 is basically a 1/3HP pump. It will only do 16 GPM from 70' of head. The 16S05-5 will do 16 GPM from 100' of head. You would need to use the 15SQ05-110 to have the same size pump. The SQ110 uses .81HP at 16 GPM and only drops to .72HP at 8 GPM. The 16S05-5 only uses .7oHP at 16 GPM and drops to .52HP at 8 GPM. Here are the curves.

 

[Digital Geek]

Thanks again valveman, i wish you were in MA, i would hired you for the job. DO you know where i can find the same HP curve for my Gould 18GS07 pump?

 

[Reach4]

Remember that pressure counts as head too. 30PSI takes 70 ft of head and 60 PSI takes 140 ft of head.

See http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/B5-25GS-R4.pdf

 

[Texas Wellman]

The sq series pumps are 3" and use permanent magnet motors and are more electrically efficient. They also rotate at 10,600 rpms vs 3450 for a std. motor. They have a soft start and take about 3 seconds to get up to full speed, which reduces the surge amps. The sqe is vfd version of the sq.

 

[Digital Geek]

The sq series pumps are 3" and use permanent magnet motors and are more electrically efficient. They also rotate at 10,600 rpms vs 3450 for a std. motor. They have a soft start and take about 3 seconds to get up to full speed, which reduces the surge amps. The sqe is vfd version of the sq.

From the graphs above, looks like the 16S05-5 uses less energy to run than the 15SQ05-110 when i'm need my pump 80% of the time.

 

[Digital Geek]

Remember that pressure counts as head too. 30PSI takes 70 ft of head and 60 PSI takes 140 ft of head.

See http://documentlibrary.xylemappliedwater.com/wp-content/blogs.dir/22/files/2012/07/B5-25GS-R4.pdf

If i add a CSV1 set at 20 PSI, will that increase the head on my current pump? Does increasing head increases power consumption?

 

[Texas Wellman]

Increasing the head lowers the output (GPM) and this actually decreases the power consumption.

 

[Reach4]

If i add a CSV1 set at 20 PSI, will that increase the head on my current pump? Does increasing head increases power consumption?

Increasing the head will decrease the amps and watts, but will increase the KWH per gallon. For household use the power cost is small, but for the heating/cooling the power is more significant. As you have figured out, you don't want too much pump. But then you don't want too little. Your study is worthwhile.

The main purpose of the Cycle Stop Valve is to reduce cycling. However the reason that I brought up head is that the pump that you select should be able to support the flow and the pressure at the point of use after being raised through the well system. I don't know if 10 PSI is enough pressure into your heat pump heat exchanger or if something more would be needed. Maybe you know.

I can't estimate a number, but your shroud system is going to take some available head also. The pressure loss will be like the loss through a long large diameter pipe. At the flow rates you have, that loss is going to be pretty small, but not zero.

 

[Digital Geek]

Update. I had a new well/pump contractor come in. He adjusted the pressure so that the system will not cycle when pressure is increased and we restrict the flow using the valve. We closed the valve on the returned water to the well to allow about 5 or 6gpm at pressure of 68psi. However, the amps ONLY dropped from 7.2 to 6.6amps. I was expecting a couple of amp drop.

We discussed replacing the pump, he is going to look into the Grundfos. Considering that my water table is at 29', we used 50' head as a conservative number. We looked at the chart for the 15SQ05-70, he indicated that it could work. Before making any changes, we are going to verify the well 3gpm recovery rate. Looking a the 16S05-5 it also works, but at 6 amps vs the SQ at 2.9 amps!!!

 

[Reach4]

Considering that my water table is at 29', we used 50' head as a conservative number.

50 ft-29 ft=21 ft if your point of use is at ground level. If it is higher, subtract the appropriate number of feet. You have some restriction for flow, so that takes a little head. I don't know what that number would be, but lets say it is 2 ft of head to pull a non-conservative number out of... the air. If we presume your water use is at ground level, we don't have to subtract for that. And if we presume that your water level does not drop, then you don't have to subtract for that either... but that is a pretty daring presumption.

So now you have 19 ft of head to turn to water pressure. That would be 8.2 PSI. So is that enough? I think you could measure the pressure before and after the heat exchanger to find out.

This presumes that you don't use that water for household use, because 8.2 PSI is not enough for household use.

And if the pump numbers are average instead of worst case, that could be important.

 

[Digital Geek]

50 ft-29 ft=21 ft if your point of use is at ground level. If it is higher, subtract the appropriate number of feet. You have some restriction for flow, so that takes a little head. I don't know what that number would be, but lets say it is 2 ft of head to pull a non-conservative number out of... the air. If we presume your water use is at ground level, we don't have to subtract for that. And if we presume that your water level does not drop, then you don't have to subtract for that either... but that is a pretty daring presumption.

So now you have 19 ft of head to turn to water pressure. That would be 8.2 PSI. So is that enough? I think you could measure the pressure before and after the heat exchanger to find out.

This presumes that you don't use that water for household use, because 8.2 PSI is not enough for household use.

And if the pump numbers are average instead of worst case, that could be important.

This well is for the heat pump and water is return to the well, so i dont expect the static well level to change unless it bleeds. Bleed is set to 2 gpm, the well recovers at 3 gpm. so we should be fine. The water enters the house below the well opening about 5'. Pressure is not important for me as all what I care for is the flow rate for the heat exchange.

 

[Valveman]

We closed the valve on the returned water to the well to allow about 5 or 6gpm at pressure of 68psi.

Those are good numbers to know. With that I can figure your pumping level so you no longer have to guess. A 18GS07 pumping 5 GPM at 68 PSI means you are pumping from a level of 23’.

You need to figure about 20 PSI (46’) for the heat pump. Add that to the 23’ of lift and you get a total head of 69’ of head.

According to the curves above, the 15SQ05-70 will only do 16 GPM at 70’. That might work, but leaves no margin for error, any wear, or reduced pumping level when bleeding 2 GPM.

The 15SQ05-110 and the 16S05-5 will both do it easily, with some margin for safety. Notice that the 15SQ uses .8HP at 17 GPM while the 16S05 only use .72HP. Also notice that when restricted to 6 GPM the 15 SQ still uses .68HP while the 16S05 only uses .45HP.
So if the 16S05 uses 6 amps when pumping 17 GPM at .72HP, then it will only draw 3.4 amps at 6 GPM and .45HP.

With a heat pump you need as small a well pump as possible to save energy. But you want to err to the high side, because it is better to have a little too much pump than not enough to make it work properly.

I also heard the thing about the “permanent magnet motor” being more efficient. And it maybe more efficient than other 3” diameter pumps/motors, but it is not as efficient as a 4” diameter motor/pump. The larger the diameter of the pump and motor the more efficient it can be. That is why the normal 4” pumps do good to get up to 60% efficient, while an 8” diameter pump can be as high as 82% efficient.

It looks like the 3” pump at best can get up to about 55% efficient. Not to mention that it spins 10,700 RPM as compared to 3450 RPM of the 4” pumps. A quote from an old Grundfos engineering manual says, “doubling the RPM of a pump will quadruple the wear rate”.

PS: That is about as good an amp drop as you will get with the Goulds as they have a different impeller stack design than Grundfos. Goulds will drop maybe 30% while a Grundfos will drop by about 50%.

 

[Digital Geek]

thanks again valveman . The measurement was done using a bucket, so i would expect the water level had dropped as we were doing over a period of 15 minutes while the water was running. i plan to install a flow meter (pulse) to accurately measure the flow vs pressure, and measure the recovery rate over time before I change the pump.

I'm curious though, why did the amps on the Goulds pump did not drop by much? from 7.2 to 6.8 to maybe 6.5?