understanding how a booster pump effects the system

[smallpool]

I have a few questions about how booster pumps work in a system:

- After they are "primed", do you shut the circulation pump shut down?

- If you have a variable speed circulation pump, would it be more efficient just to increase it's speed? For example, if I was running my VS pump at 20 gpm, but wanted 60 gpm for a solar array, would it make sense just to increase the circulation pump to 60?


- Does a T before the booster pump effect its output, or does it just work "harder" to produce that output?

? gpm
|
? gpm <--- booster pump at 60 gpm <-- + <--- filter <--- circulation pump

 

[mas985]

- After they are "primed", do you shut the circulation pump shut down?

A booster pump is plumbed in series with the main pump so the main pump should never be shut off. However, most boosters used for cleaners don't require a lot of flow rate, they are used to create higher pressure. What is the booster for?

- If you have a variable speed circulation pump, would it be more efficient just to increase it's speed? For example, if I was running my VS pump at 20 gpm, but wanted 60 gpm for a solar array, would it make sense just to increase the circulation pump to 60?

If the booster is for solar, the scrap it. You do not need a booster pump for nearly any solar installation. What is the height of the panels relative to the pump?

 

[smallpool]

- After they are "primed", do you shut the circulation pump shut down?

A booster pump is plumbed in series with the main pump so the main pump should never be shut off. However, most boosters used for cleaners don't require a lot of flow rate, they are used to create higher pressure. What is the booster for?


[quote:1w38frlc]- If you have a variable speed circulation pump, would it be more efficient just to increase it's speed? For example, if I was running my VS pump at 20 gpm, but wanted 60 gpm for a solar array, would it make sense just to increase the circulation pump to 60?

If the booster is for solar, the scrap it. You do not need a booster pump for nearly any solar installation. What is the height of the panels relative to the pump?[/quote:1w38frlc]

I have 2 sets of 3 inlets -- 3 at the bottom of the wall for heating/rolling the water up and 3 at the top of the walls for circulation. I would like only bottom set (of 3) used for heating; however, I believe that I would have to use more energy to push enough water to feed both the heater (min gpm is 33) set and circulation set.

What I've been told (and this could be completely wrong) is that:

lower set upper set
| |
+ heater ----------+ --- filter -- circulation pump
in the above diagram, running the circulation pump at 36 gpm (200 W for an Intelliflow VS @10 head), would send 18 gpm to each set (i.e, halves the gpm). That would be too low of flow for my heater (needs 33gpm min flow).

I thought that if I did the following:
lower set upper set
| |
+ heater -- pond pump----+ --- filter -- circulation pump

Run my Intelliflo @ 20 gpm (100W @<4 head), add in an efficient pond pump (maxes out at 147W, will push 42 gpm at 12 head) I would be ahead of the game (pushing way over the gpm the heater needs at a total W of 247W). When running the heater, I'd be only adding 147W, much less than what the Intelliflow would cost (having to go to min of 66 gpm). I only mentioned solar, as I thought the extra gpm the pond "booster' pump would add would help, if we added solar later (not important now).

 

[mas985]

What I've been told (and this could be completely wrong) is that:

lower set upper set
| |
+ heater ----------+ --- filter -- circulation pump
in the above diagram, running the circulation pump at 36 gpm (200 W for an Intelliflow VS @10 head), would send 18 gpm to each set (i.e, halves the gpm). That would be too low of flow for my heater (needs 33gpm min flow).

The diagram is a little confusing. The spaces are removed by the forum software. After quoting, it looks better but can you post a picture of your pad equipment?

If you move all the returns plumbed after the heater, flow rate should not be an issue.

 

[smallpool]

What I've been told (and this could be completely wrong) is that:

lower set upper set
| |
+ heater ----------+ --- filter -- circulation pump
in the above diagram, running the circulation pump at 36 gpm (200 W for an Intelliflow VS @10 head), would send 18 gpm to each set (i.e, halves the gpm). That would be too low of flow for my heater (needs 33gpm min flow).

The diagram is a little confusing. The spaces are removed by the forum software. After quoting, it looks better but can you post a picture of your pad equipment?

If you move all the returns plumbed after the heater, flow rate should not be an issue.

I don't have a current setup -- this is all theory. My issue is that I only want my "lower set" to go through the heater (i.e, just have the heat come up through the bottom set and not the top). My understanding is that if I split off the circulation set before the heater, I would be splitting the gpm (i.e 18 gpm after the heater and 18 gpm at the split before the heater). If that were true, I was wondering could add an efficient booster pump before the heater to compensate. I could add a 147W booster pump, but continue to run my Intelliflo at 20gpm (100W), thus only pulling 247W when the heater is on. However, that could be increasing the head to the Intelliflo, thus increasing it's power usage, too.

 

[mas985]

You are correct in that the flow rate will split but the split is dependent on the head loss in each path. So in reality, with the heater and probably longer return paths for the lower returns, the head loss in the heater path is likely to be higher and thus flow rate in the heater path will be less than 50%.

But I don't understand why you want to split the returns. Heating will be much more effective to have all the flow going through the heater than trying to split flow. You will be able to run on lower speeds so the efficiency will end up higher than if you split the flow.

The worst think you can do is add a second pump which would be the least efficient option and not likely to work very well especially with a pond pump.

 

[smallpool]

tI don't understand why you want to split the returns. Heating will be much more effective to have all the flow going through the heater than trying to split flow. You will be able to run on lower speeds so the efficiency will end up higher than if you split the flow.

I would think that heating only from the bottom of the pool would be better than heating 1/2 at the top and 1/2 from the bottom. Why is heating the top of the pool important? I was thinking that I'd have bypass values such that when the heater wasn't in use, the water flow would bypass it, but connect into the bottom inlet set, so that all inlets would be powered by the circulation pump (this would allow for some of the daytime warmer top water being diverted to the bottom of the pool).

The worst think you can do is add a second pump which would be the least efficient option and not likely to work very well especially with a pond pump.

The pond pump that I've selected runs 42 gpm at 12 head @ 147W (it tops out at 147W; it'll be less if I dial down the gpm). Why wouldn't this kind of pump work well?

 

[mas985]

It isn't that heating at the top is that important, but neither is heating the bottom. In reality, the water does not stay separated so it really doesn't matter much where you return water, after 30 min, it is pretty much all mixed up anyway.

But what does matter is the amount of water that goes through the heater and to run the VS at the slowest speed possible and save the most amount of energy possible, you want ALL of the water to go through the heater. If you want a bypass for when the heater isn't running, put in a bypass pipe with 2-way valve between the input and output ports of the heater. That will allow for bypassing when not using the heater but it also allow you to close the bypass and force all of the water through the heater and so allow you to run the VS at the lowest speed possible.

BTW, I don't think you are looking at the pond pump specs correctly. Most pond pump specs are for maximum head and maximum flow rate but those do not occur at the same location on the head curve. Maximum head is achieved at 0 GPM while maximum flow rate is achieved at very low head loss. So if you put that pump in series with the VS, you will probably find that the combined energy use of both pumps is higher the VS alone without any improvement in performance. In fact, it is likely to degrade performance.

My recommendation is to plumb the heater right after the filter and send all the water through the heater. Plumb in a bypass if want the capability to do that. This will give you the best heater performance, pump performance at the lowest energy costs without question.