Can I install a circulation pump on an old Spa hottub? (circ pump was optional, but not done)

[SantiagoPG]

Hello,
I bought a house recently and with it I inherited a hot tub from the previous owner. I have enjoyed it a lot this summer but I want to 'upgrade' it since energy usage is imporant for me. I want to install a heat pump on it, but from what I read I cannot do it without a circ pump since they need a slower flow than what the jet pump provides. so that is my first step.

I've tried to find information on this but I could not. Reading on the spa pack (balboa GS501z), it is supposed to support circ pumps as an option, but I guess the previous owner didn't chose it.
What would I need to install one? can I do it with my current pack or would I also need an upgrade? can you recommend a model or spec?

Information on my spa:
-Canadian Spa Company, model toronto, built in 2012
-It has a GS501z pack and a single 2 speed 3hp pump
-currently no air blower or circ pump
-The top panel has 3 buttons (lights, temp and jets). From what I read it is a VL404 (3 buttton variant).

ps- I asked my local spa tech which replied: buy a new spa! which Im not doing, but Im happy to get my hands dirty.

 

[Mdragger88]

No clue but I’m sure @RDspaguy will know when he comes around.

 

[RDspaguy]

want to install a heat pump

Why? Is it a portable spa or inground?

, but from what I read I cannot do it without a circ pump

Like any heater, it has a minimum flow rate and a max pressure. Have to size the heater to the pump or the pump to the heater.

it is supposed to support circ pumps as an option

Minimum flow rates for balboa heaters are typically not met by low-flow circulation pumps such as laing and grundfos. The gs501 is not designed to run a peripheral heater and you will likely have issues.
This control pack is generic and used in hundreds of tubs, some of which are designed and plumbed to use a circ pump. If yours is not you do not want to add one.

What would I need to install one?

Depends on what you want it to do and if the spa is plumbed for it.

I get the feeling you're under the impression that this will in some way improve your spa or reduce operating costs. It will not. Leave it as designed.

 

[SantiagoPG]

hi @RDspaguy

I get the feeling you're under the impression that this will in some way improve your spa or reduce operating costs. It will not. Leave it as designed.

Yes. reducing operating costs (electricity) is my motivation. My idea was to disconnect it's 3kw heater and heat it using a small 5~7kw air source heat pump with hopefully a large enough COP rating (and I have mild winters here).

Are you suggesting a heat pump wont reduce my energy costs, that the savings are just not the trouble, or that I will end up having issues and will probably regret it?

Why? Is it a portable spa or inground?

If by portable you mean inflatable, no. it's an acrylic outdoor. it sits rather permanently in my backyard. looks like this one ( but mine is older):

Canadian-Spa-Co-6-Person-44-Jet-Toronto-Spa-with-Waterfall-CSCHTTOR.jpg

• SantiagoPG
• Aug 9, 2023

photo of a canadian spa company toronto hottub

 

[RDspaguy]

that I will end up having issues and will probably regret it?

The entire control system operates based on the readings of 2 sensors at each end of the heater. This is how it determines water flow as well as temp, and by moving the heat source you will change that.

heat pump wont reduce my energy costs,

You will not find a heat pump as efficient as a directly submerged heating element, so more energy will be wasted. Plus the cost of the heat pump and necessary plumbing.

an acrylic outdoor.

Those are called portable spas.

 

[SantiagoPG]

ok, I see.

The entire control system operates based on the readings of 2 sensors at each end of the heater. This is how it determines water flow as well as temp, and by moving the heat source you will change that.

thanks for the clarification @RDspaguy, that is a very good point which I was not considering.

 

[thermodynamics]

You will not find a heat pump as efficient as a directly submerged heating element, so more energy will be wasted. Plus the cost of the heat pump and necessary plumbing.

I registered and necrothreaded this because I am sick of seeing this kind of garbage information provided by people in the pool / spa industry. I am not sure if it's due to not understanding how heat pumps work or just trying to make sales with lower upfront prices.

At most a heating element can be 100% efficient - you put say 1kw of electricity in and get 1kw worth of heat energy out.

A heat pump depending on the model and climate can be 500% or more efficient - 1kw of electrical energy can get you 5kw or more of heat energy out due to the increased efficiency of moving heat vs creating it via a resistive element. Yes there are some small losses compared to the integrated heater due to longer pipework and pumping etc but it's not anywhere close to to 400%!

I had a salesperson tell me with a straight face that the spa I purchased would be much cheaper to run with the integrated 3kw heater rather than a 5kw heat pump because 3kw is less electricity than 5kw so the running costs would be 60% higher with the heat pump which is so very wrong it's not funny.

Compared runnings costs are chalk and cheese - the heat pump costs around 3x less to run and heats the spa 60% faster than the integrated heater. Payoff time for ours was just under 3 years before it was saving money on electricity having recouped the initial cost of the unit and install.

 

[RDspaguy]

500% efficient? You've discovered a new free energy source that will transform the world! You'd think someone with your user name would know a little physics.

 

[Nickypoo]

500% efficient? You've discovered a new free energy source that will transform the world! You'd think someone with your user name would know a little physics.

Heat pumps are typically 300+ efficient because they’re not creating heat, they’re just moving it. Instead of using 1 unit of energy to create 1 equivalent unit of heat, they use 1 unit of energy to move 3-5 units of heat from one place to another (yes, this even works when it’s colder outside the hot tub than inside).

A few years ago we pulled the gas furnace out of our house and replaced with a heat pump. We now have a heat pump water heater and clothes dryer. All 3 heat pumps use vastly less energy than the appliances they replaced. Welcome to the future of heating!

 

[JamesW]

Heat pumps have a COP (Coefficient of Performance), which is the amount of heat transferred divided by the amount of energy used.

5.3 Kw is 18,100 BTU per hour.

110,000/18,100 = 6.1.

So, you are using 5.3 KW (18,100 BTU per hour) and getting 32.24 KW (110,000 BTU per hour) of heat.

For a resistance element, you use 5.3 KW and you get 5.3 KW of heat.

So, a heat pump in this case is 610% efficient for energy used vs. heat energy gained.

The term used for the efficiency is coefficient of performance.

However, the heat does not magically appear out of nowhere, it literally comes out of thin air.

The heat pump transfers heat from the air to the water.

This is why the air from the top fan is cold when the heat pump is operating.

You can also use a heat pump to move heat from anywhere that contains heat, like the ground.

 

[JamesW]

Note that the weather conditions and water temperature affect the performance of the heat pump, so you have to look up the heat pump performance at the conditions you will use.

For gas or electric, the amount of heat produced is the same regardless of the conditions.

A 5 KW electric heater always produces 5 KW of heat.

A 400,000 btu/hr gas heater at 84% efficiency always produces 336,000 btu/hr. (64,000 btu/hr is lost in the hot exhaust gas).

A heat pump is only good under the conditions specified by the manufacturer.

If the conditions are favorable, then a heat pump is the most efficient.

Under certain conditions, a heat pump will not work because there is not enough heat available to move or pump.

A ground source heat pump uses tubes that go into the ground to get heat from the ground.

However, there is a large upfront cost to installing the tubing systems into the ground.

Electricity and natural gas have have different costs, so you have to consider the cost of the energy when comparing the costs of operating different types of heaters.

In the below chart, you can see the performance at three sets of conditions.

The lowest air temperature given is 50°F and you would need to check with the manufacturer to see if the unit can be used in colder temperatures.

The C.O.P at 50°F air temperature, 80% Relative Humidity and 80°F (27°C) Water Inlet Temp is 4.0.

* 80A-80RH-80W: 80°F (27°C) Air Temp, 80% RH, 80°F (27°C) Water Inlet Temp.
** 80A-63RH-80W: 80°F (27°C) Air Temp, 63% RH, 80°F (27°C) Water Inlet Temp.
*** 50A-63RH-80W: 50°F (10°C) Air Temp, 63% RH, 80°F (27°C) Water Inlet Temp.



COP = Coefficient of Performance.

A heat pump is like solar, where you are not producing heat; you are taking it from the environment.

A solar heater takes heat from the sunlight and transfers it to the water.

So, the “Efficiency” of the solar heating system depends on the cost of pumping the water through the solar system.

If you use 1,000 watts of power to move the water and you get 30,000 watts of heat, then that is 3,000% efficiency.

However, “efficiency” is a technically incorrect word for the ratio of power used compared to the heat gained.

For solar, you can also use the term Coefficient of Performance instead of efficiency.

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/heaters/ultratemp/manuals/ultratemp-heat-pump-installation-and-users-guide-en-fr-sp.pdf

 

[RDspaguy]

Well, you learn something new everyday.