Hotspot FPH pool heater install

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newpoolj

Well-known member
Oct 15, 2020
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Sacramento, Ca
I have a pool build under way and am currently planning a Hotspot FPH pool heater install. I received the unit a few days ago and wanted to share a few noteworthy changes/improvements over prior versions:

- There's a new version of the FPH controller (v2) that has a better display and user interface (see attached picture) and is more straightfoward to wire, requiring only a few simple connections.
- The controller no longer requires a separate 120v input. Instead it takes power from a 24VAC transformer connected to your AC condenser's contactor which is easier to install.
- The new controller and instructions allow for an optional flow switch to be easily installed, to disable the FPH if there's no water flow detected

I'm planning to connect the FPH to a Jandy Aqualink by treating it as a solar thermostat using resistors as described by @JamesW here. In the meantime, I'm currently ordering a few misc small parts for the install, which will probably be in a month or so.
 

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newpoolj said:
I have a pool build under way and am currently planning a Hotspot FPH pool heater install. I received the unit a few days ago and wanted to share a few noteworthy changes/improvements over prior versions:

- There's a new version of the FPH controller (v2) that has a better display and user interface (see attached picture) and is more straightfoward to wire, requiring only a few simple connections.
- The controller no longer requires a separate 120v input. Instead it takes power from a 24VAC transformer connected to your AC condenser's contactor which is easier to install.
- The new controller and instructions allow for an optional flow switch to be easily installed, to disable the FPH if there's no water flow detected

I'm planning to connect the FPH to a Jandy Aqualink by treating it as a solar thermostat using resistors as described by @JamesW here. In the meantime, I'm currently ordering a few misc small parts for the install, which will probably be in a month or so.

One thing I'm unsure about is which exact relay to purchase for the condenser fan cutoff. Any recommendations on that?
Click to expand...
Most relays are specified by the voltage/current of the trigger side and the voltage/current for the line/load side. If you know this you should be able to find at Digikey or hopefully James can help further.

Chris
 
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newpoolj said:
I have a pool build under way and am currently planning a Hotspot FPH pool heater install. I received the unit a few days ago and wanted to share a few noteworthy changes/improvements over prior versions:

- There's a new version of the FPH controller (v2) that has a better display and user interface (see attached picture) and is more straightfoward to wire, requiring only a few simple connections.
- The controller no longer requires a separate 120v input. Instead it takes power from a 24VAC transformer connected to your AC condenser's contactor which is easier to install.
- The new controller and instructions allow for an optional flow switch to be easily installed, to disable the FPH if there's no water flow detected

I'm planning to connect the FPH to a Jandy Aqualink by treating it as a solar thermostat using resistors as described by @JamesW here. In the meantime, I'm currently ordering a few misc small parts for the install, which will probably be in a month or so.
Click to expand...
How is your install coming along? Anymore pics of the new Controller?
 
I also have one hopefully going in soon. I've had the FPH for a few months but couldn't find anyone to install it. I've had 4 different HVAC guys lined up to do the installation and they all backed out. Eventually I just started calling every HVAC contractor in the phone book and I changed my "pitch" a bit, on how I described the work I was asking them to do. Last week for the first time, someone actually gave me a written estimate, and I put down the deposit this morning. So hopefully I'll get it installed in the next couple of weeks, just in time to close up for the season! At least this means it will be all ready to go in the spring though. Fingers crossed.

I'm also planning on using the resistor approach and I have that part wired up already, just waiting for the FPH connection. I can share my shopping list if anyone is interested.
 
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My HVAC install finally starts tomorrow. Here are a pair of diagrams I created for the HVAC portion that show what it's like to have the 3 way valve inside the AC unit vs outside. These diagrams show a more realistic layout of the AC unit and hotspot, relative to each other. We'll decide tomorrow which of these to go with, but having it inside, which is what @riny did, has some benefits. I'll post pics of the install and also some wiring pics later.

Two recent wrinkles that came up for the install:

- The FPH requires a minimum GPM which won't exist when my cleaner is running (it's pressure side using the main pump). Because of this, I'm planning to add an additional 24v relay that disables the FPH when the cleaner is turned on. An alternative idea was to use the pressure sensor to detect when the cleaner is on, but I realized that sensor is vulnerable to large pressure changes as the water temp changes.
- The Tecmark pressure switch cover is not in stock anywhere at all, so I'll have to rig up something, perhaps using a PVC cap
 

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Here are some pictures from my install. The HVAC connections, including the 3 way valve, and one of the T connections that contains the additional solenoid and restrictor, are all located inside the HVAC unit itself, following the 2nd diagram in the post above. This install only has 1 new copper line going out of the unit, to the FPH and receiver, which then Ts into the liquid line before going back into the house. I also followed @riny's approach for wiring the FPH controller using a terminal strip mounted in the box to jumper all the wires, which kept things well organized, and added an external shutoff switch at the top of the controller.
 

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So the system is running and generating heat, but the HVAC install didn't go as expected, given the instructions, and might not be working safely yet. The install appears correct, but refrigerant seems to get trapped on the water cooled side of the install, and talking to Hotspot support hasn't given us a clear answer why yet.

I've asked several times how refrigerant is meant to get back from the water cooled side to the air cooled side, and haven't received an answer. It almost makes me think this is a flaw in the system's design which is why they're not responding.
 
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@drglanton So the instructions are to charge up the system to where it should be when it's on, or where it previously was if it's an existing AC system, and then that's it. When the FPH turns on the refrigerant should all move to the water side, and when it turns off the refrigerant should all move back to the air side. From what we could tell refrigerant didn't move back from the water to the air side since the pressure on the HVAC line on the air side would stay low, too low to safely run, and the pressure on the water side where we installed a service port would stay high. It changed a little but not much, even after 30 minutes.

My HVAC guy and I separately talked to Hotspot this week. The person I talked to said something was wrong, and we shouldn't need to add more than the original refrigerant. The person my HVAC guy talked to said that since we have a receiver on the water side, not all the refrigerant would move back, and he'd need to add more refrigerant until things looked correct in both air and water cooled modes. I think essentially this means that all the refrigerant doesn't move back and forth, and that both sides of the system always contain refrigerant. Whether this is good or bad or correct, we're not even sure since we got mixed messages, but that's how it's setup right now.

@drglanton Did you have a water side receiver too? Do you recall how the system was charged?
 
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I've been troubleshooting my system on and off for a few months and it's still having problems with refrigerant. I'm getting close to just removing the system and calling it a loss.

The problem is refrigerant needs to move back and forth between the air and water cooled sides of the system. And while it moves to the water cooled side fine it seems to get stuck there and doesn't move back. So in air cooled mode the system won't have enough refrigerant and my AC doesn't cool. I've talked to Hotspot about potential causes for this and I haven't identified the problem yet since the 3 way valve seems to be working ok.
 
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I might be talking nonsense here since this is not my area of expertise, but did you try charging it up to the correct pressure with the valve open? Then when the valve closes, any refrigerant in the water loop will be "excess" and trapping it is the right thing to do. When the valve opens, then you get the additional refrigerant to match the increased volume.
 
riny said:
I might be talking nonsense here since this is not my area of expertise, but did you try charging it up to the correct pressure with the valve open? Then when the valve closes, any refrigerant in the water loop will be "excess" and trapping it is the right thing to do. When the valve opens, then you get the additional refrigerant to match the increased volume.
Click to expand...
Yea, that's how we initially setup the system - add refrigerant in both air and water modes till the charge looked good in both modes. It worked fine like that for a while till the August heat kicked in. Then it became apparent that the system was way overcharged. Pressure got really high on the water side and eventually my compressor would shutoff.

Talking to Hotspot about this they said we should not need to add any extra refrigerant at all, just the normal charge the system would have if the FPH wasn't installed. In theory, all of the refrigerant is supposed to move back and forth. Having extra refrigerant in there risks the charge being too high in some cases, which is what happened to me. The problem in my case is that refrigerant doesn't all move back to the air side, for some reason.
 

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