I'm having a pool built at the moment with a Hotspot FPH heater that is about 120 feet away from the pump. I'm curious what's common or better in this situation, to have the heated water returned directly to the pool, which is about 75 feet away from the heater, or go all the way back to the pump to then be distributed? My builder mentioned having the heater go straight back to the pool into some floor returns, but that going back to the pump to be sent evenly to all the returns was another option. The downside of going all the way back is more distance to travel and lose heat, harder on pump, etc. Any thoughts?
Pool heater return locations
- Thread starter newpoolj
- Start date
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I don't know how to answer that, but others here will. For clarification for them:
- Is there just one pump involved?
- And by "back to the pump" do you mean back to the pad?
If there is one pump, which is feeding the heater, the flow from the heater can't go back to that same pump. Nor can two pool pumps feed each other like that. So I'm trying to understand the schematic.
It sounds like the choice is: when sending water to the heater, it can either go to the pool to a set of dedicated returns, or it can go back to the pad to join into the plumbing there that feeds the regular set of returns.
And since someone will ask (and cause I'm curious), why can't you put the heater on the equipment pad and simplify everything? OK, scratch that. It has to be by your AC unit, right?
How deep is your pool? Deep water returns can help with minimizing hot spots. So that might be a factor in the answer.
@JamesW, thoughts?
- Is there just one pump involved?
- And by "back to the pump" do you mean back to the pad?
If there is one pump, which is feeding the heater, the flow from the heater can't go back to that same pump. Nor can two pool pumps feed each other like that. So I'm trying to understand the schematic.
It sounds like the choice is: when sending water to the heater, it can either go to the pool to a set of dedicated returns, or it can go back to the pad to join into the plumbing there that feeds the regular set of returns.
How deep is your pool? Deep water returns can help with minimizing hot spots. So that might be a factor in the answer.
@JamesW, thoughts?
Yep, it's a 2.7HP VSP Jandy.
Yep, I attached a picture that shows the overall arrangement of things. The pump sends water 120' to the heater, going past the pool in the process. It could go 75' back to the pool or continue 120' all the way back to the equipment pad. If it goes back to the pool it would use a pair of floor returns. Otherwise if it goes back to the pad, all 5 returns would receive the heated water. One potential benefit of going back to the pad is SWG can be done after heating, though I'm not sure that matters much.
Right, the Hotspot will be next to my AC.
It's 3.5' at the shallow end, 6' at the deep end.
Attachments
- May 3, 2014
- 62,705
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
If you decide to have dedicated returns for the heated water, I would suggest wall returns. Not floor. You can place them a foot or two deeper than normal returns, if you like.
In the future, for whatever reason, those return lines get compromised, having them in the floor will make repair quite costly.
In the future, for whatever reason, those return lines get compromised, having them in the floor will make repair quite costly.
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Hmm, the SWG might be an issue, and the deciding factor. If you go heater-to-pool, unless that pump can handle pushing water through the heater returns and the filter returns at the same time, then you'd only be able to chlorinate the pool when the heater is off. Since both functions will probably require a good amount of runtime, you might be doubling pump runtime when you need the heat. In terms of energy consumption, doubling your runtime might be worse than the heat loss from running all the way back to the pad. I have no idea how to do that math, but someone here might.
So you're thinking the equipment should maybe be setup to either make salt or generate heat but not both at the same time? That could be arranged. If I understand you, that seems separate from whether the heater should return straight to the pool or go back to a trunk line before branching out to all of the returns. I'm really not sure with that.
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
You can't feed the heater with SWG water. In order for the SWG to be chlorinating your pool and your heater to be heating, at the same time, one of two things must be true:
- either the pump has to be strong enough to drive water through all the returns at the same time, or
- the water flowing through the heater has to come back to the pad to then go through the SWG.
If neither of those things can happen, then you'll have to run the water through the SWG for many hours a day, and then switch the valves to run the water through the heater for many hours.
So the first thing to determine, before you decide about how to run the plumbing, is if the pump can handle the GPM (gallons per minute) necessary to drive the filter circuit (the flow required by the SWG and x-number of "regular" returns) and the heater circuit and its returns, at the same time. If the pump can do all that, then you should run the heater directly to the pool.
If the pump can't do that, then maybe a bigger pump could. Or you'll need to run the heater back to the pad so that you can chlorinate and heat at the same time.
I don't think sharing the pump, being able to only chlorinate or only heat, but not both at the same time, is an option.
- either the pump has to be strong enough to drive water through all the returns at the same time, or
- the water flowing through the heater has to come back to the pad to then go through the SWG.
If neither of those things can happen, then you'll have to run the water through the SWG for many hours a day, and then switch the valves to run the water through the heater for many hours.
So the first thing to determine, before you decide about how to run the plumbing, is if the pump can handle the GPM (gallons per minute) necessary to drive the filter circuit (the flow required by the SWG and x-number of "regular" returns) and the heater circuit and its returns, at the same time. If the pump can do all that, then you should run the heater directly to the pool.
If the pump can't do that, then maybe a bigger pump could. Or you'll need to run the heater back to the pad so that you can chlorinate and heat at the same time.
I don't think sharing the pump, being able to only chlorinate or only heat, but not both at the same time, is an option.
Why is that?
Wouldn't any combination of chlorinating and heating at the same time require the same pump power?
Last edited:
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
The SWG will have a minimum flow rate for it to chlorinate, below that flow rate, it will shut down. The heater will also have a minimum flow rate or it will shut down. And it might also have an optimum flow rate, higher than the minimum, that will be the most efficient in terms of fuel-to-heat ratio. Owner manuals for each component should state those rates.
Now when you combine all those returns with all the pipe runs (lengths and elbows) you'll get resistance to the flow your pump can deliver. Running just the filter circuit will require X amount of flow. Heater circuit will require Y. Because you're thinking of having two separate circuits, to run them at the same time, you'll need X + Y flow. If they were all on the same circuit, and you had less returns, that would require less flow (probably). You may or may not be able to run all the returns and still achieve the flow that both the SWG and heater require. This can all be calculated (or at least estimated) beforehand, but I just don't know how. Your PB should know how. Anywho, if it turns out your pump cannot deliver the required flow for running the two separate circuits at the same time, you'll either need to run them at different times, or combine them into one circuit (by running the heater back to the pad) or by using a bigger pump.
When the SWG is right next to the heater, and you're running the pump at the flow rate the heater requires, the SWG impacts the flow rate next to nothing. That's not the problem. It's all the pipe lengths and diameters, and returns and elbows, that determine what the pump can do. Plumbing is in part engineering. Simple pools don't need much engineering. Yours probably does. Some PBs wing it. Others know how to do the math. I've already pinged one of our experts that knows this stuff, he just hasn't responded yet (@JamesW).
He'll no doubt get around to here at some point. He's good like that.
Now when you combine all those returns with all the pipe runs (lengths and elbows) you'll get resistance to the flow your pump can deliver. Running just the filter circuit will require X amount of flow. Heater circuit will require Y. Because you're thinking of having two separate circuits, to run them at the same time, you'll need X + Y flow. If they were all on the same circuit, and you had less returns, that would require less flow (probably). You may or may not be able to run all the returns and still achieve the flow that both the SWG and heater require. This can all be calculated (or at least estimated) beforehand, but I just don't know how. Your PB should know how. Anywho, if it turns out your pump cannot deliver the required flow for running the two separate circuits at the same time, you'll either need to run them at different times, or combine them into one circuit (by running the heater back to the pad) or by using a bigger pump.
When the SWG is right next to the heater, and you're running the pump at the flow rate the heater requires, the SWG impacts the flow rate next to nothing. That's not the problem. It's all the pipe lengths and diameters, and returns and elbows, that determine what the pump can do. Plumbing is in part engineering. Simple pools don't need much engineering. Yours probably does. Some PBs wing it. Others know how to do the math. I've already pinged one of our experts that knows this stuff, he just hasn't responded yet (@JamesW).
He'll no doubt get around to here at some point. He's good like that.
Last edited:
I would go from the heater back to the pad so that the water can go through the SWG after the heater.
You can use an automated bypass to send water to the heater on call for heat or bypass the heater when no call for heat.
Here is the general sizing for plumbing.
For suction, you want to keep the water velocity below 6 ft/sec. For returns, you want to keep the water velocity below 8 ft/sec.
Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138.............184 gpm
4”...........234.............313 gpm
Since the distance is so far, I would use the 6 feet per second chart for the plumbing to the heater and back.
How much flow will the heater require?
You can use an automated bypass to send water to the heater on call for heat or bypass the heater when no call for heat.
Here is the general sizing for plumbing.
For suction, you want to keep the water velocity below 6 ft/sec. For returns, you want to keep the water velocity below 8 ft/sec.
Size.......6 ft/sec......8 ft/sec.
1.5"...........38...............51 gpm
2"..............63...............84 gpm
2.5............90.............119 gpm
3.0".........138.............184 gpm
4”...........234.............313 gpm
Since the distance is so far, I would use the 6 feet per second chart for the plumbing to the heater and back.
How much flow will the heater require?
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
Thanks James! Is the heat loss from all that pipe a consideration? Or will that be minimal? Does pool plumbing ever get insulated underground?
I like the idea of less returns (penetrations) in the pool. And the automated bypass. And being able to heat and chlorinate at the same time, that's a biggie, IMO.
I like the idea of less returns (penetrations) in the pool. And the automated bypass. And being able to heat and chlorinate at the same time, that's a biggie, IMO.
I'm not sure how much heat is lost. I don't think that pipes generally get insulated, but I suppose that it wouldn't hurt.
- May 3, 2014
- 62,705
- Pool Size
- 6000
- Surface
- Fiberglass
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I would suspect in the OP's climate, the ground temperature will not be all that cold during the time frame the FPH heater would be in use.
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
I don't know how to do the math, or if heat dissipation works this way, but if we can use 6'/sec, the heated water wouldn't be in the pipe for more than about 15 seconds longer by going back to the pad (depending on how far away the pool is from the pad). You're going to lose some heat, but the first 15 secs would be the worst. The lost heat would heat the pipe and surrounding ground, right? So I think the heat loss would diminish some over time. Along with Marty's thought about climate, I can't imagine the loss would be that great, overall.
Here's a read that might contradict that though! (Oh, I'm so helpful!
)
www.insulfoam.com
Here's a read that might contradict that though! (Oh, I'm so helpful!
)The Dirt on Below-Grade Insulation – Insulfoam
There are many facts on why you should insulate foundation walls and below floor slabs. And once you’ve decided to insulate below grade, the next question is which insulation to use. For building teams that prefer the ease of working with rigid foam insulations, when choosing a product to...
www.insulfoam.com
Any thoughts on whether the pump would be good to push water to the heater and back to the pad, then go through a SWG before going out to the various returns?
- Jun 7, 2017
- 9,979
- Pool Size
- 29000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
Why is this being set up this way? This is a fairly non-standard way to set equipment up. Is it just to save money on running electric/gas to the heater? In any case my first suggestion is to put the heater on the equipment pad where it belongs. If for whatever reason that isn't happening, then I would suggest you go from the heater to the pool in the shortest path possible. Floor or wall returns, it doesn't really matter.
- Nov 12, 2017
- 12,654
- Pool Size
- 12300
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-40
The heater is some sort of exchanger that works with the existing HVAC unit, so it needs to be located by the AC compressor. You might have glazed over some posts that explain this conversation...
- Jun 7, 2017
- 9,979
- Pool Size
- 29000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Jandy Aquapure 1400
Ah ok. Without knowing the setup I am wondering if the pool equipment could all have been put over where the heater is located.