Heating a 500 gallon in ground spa

[Jesusfreak]

I’m a new homeowner and have an in ground spa without a heater. The pad is there, along with the electrical box with breakers available. I just received a quote of $10,000 for a 138,000 btu heat pump install. Is there more affordable options available? I just want to heat the spa, not the pool and spa. Thank you

 

[mknauss]

Much better to use natural gas to heat a spa. Do you have natural gas to your home? Maybe even the equipment pad?

 

[Jesusfreak]

No natural gas in the area. Electric or propane only.

 

[RDspaguy]

Electric or propane only.

Either would be fine. Electric would be a cheaper unit and likely install too depending on electric/propane availability at the pad.
For electric you'll want at least 5.5kw but an 11kw would be better, especially if you plan to use it in the winter.
250 btu propane will be more than sufficient, less if closing it in the winter.
What are you controlling it with?

 

[phonedave]

No natural gas in the area. Electric or propane only.

Propane works too.

For a 500 gal spa, I would say natural gas or propane. For something large like the pool, and if you planned on getting it warm and keeping it warm, then the heat pump is more efficient and will pay for itself (maybe) over time.

I don't know how large your property is, but before you go pulling the trigger on propane, talk to your local propane company. Some will not drive their delivery trucks onto your property (even the driveway). So your tanks have to be within reach of their hose. If your pool is way in the back of a big backyard, you may have to budget of a long run of gas pipe between your tanks and the heater.

 

[Jesusfreak]

Either would be fine. Electric would be a cheaper unit and likely install too depending on electric/propane availability at the pad.
For electric you'll want at least 5.5kw but an 11kw would be better, especially if you plan to use it in the winter.
250 btu propane will be more than sufficient, less if closing it in the winter.
What are you controlling it with?

Electric is what was used in the past. The breaker is already in place beside the pad for the heater. I just purchased the house and the existing heater had been removed.

I was thinking electric and the plumbing is straight forward, as the spa has its own pump. I just don’t know the correct size for a 500 gallon spa. I believe you just answered that for me.

 

[RDspaguy]

Electric Heater, Coates, 11.0kW, 240V, Single Phase

Coates Heater Co. - Electric Heater, Coates, 11.0kW, 240V, Single Phase - 12411STReplaces: 85092 , 9285-001 , CHC-15-505Heater ApplicationPool, SpaVoltage230vWattage11.0kWHeater TypeStand AloneManufacturerCoatesModel12411STHeater Inlet Size1-1/2"Heater Inlet TypeSlip (s)Heater Outlet...

pool-spa-supplies.com

 

[Jesusfreak]

Electric Heater, Coates, 11.0kW, 240V, Single Phase

Coates Heater Co. - Electric Heater, Coates, 11.0kW, 240V, Single Phase - 12411STReplaces: 85092 , 9285-001 , CHC-15-505Heater ApplicationPool, SpaVoltage230vWattage11.0kWHeater TypeStand AloneManufacturerCoatesModel12411STHeater Inlet Size1-1/2"Heater Inlet TypeSlip (s)Heater Outlet...

pool-spa-supplies.com

So this will do the trick for winter spa only?

 

[RDspaguy]

Hydro-Quip - Heater, HeatMax RHS 230v, 11kW, Weather Tight - RHS-11, HEATMAX 11.0

Hydro-Quip - Heater, Hydro-Quip, HeatMax RHS 230v, 11kW, Weather Tight - RHS-11 Replaces: 609961 , 9287A , HQP-85-8532 , HQRHS110 , RHS-11.0 , RHS110Hydro-Quip RHS Weather-tight HeaterDimensions: 21"L x 15"H x 8"WUnions measure 7" center-to-centerFeatures:230v operation2" unions on inlet and...

pool-spa-supplies.com

A cheaper option with dial thermostat instead of digital. This one uses spa heating elements, which are a bit more expensive and labor intensive to replace than the standard water heater element used in the coates, which is available at most hardware stores.

 

[RDspaguy]

If you won't be using it in the winter you can probably get by with the 5.5kw, available from both manufacturers.
Coates is 1.5" plumbing, hydroquip is 2".

 

[Jesusfreak]

Picking up the 11kw Coates today. Thank you!

 

[phonedave]

There is a difference (a big difference) between an electric heater and an electric heat pump.

@Jesusfreak initially said they were looking at a heat pump, and was trying to decide between a heat pump and a gas heater, there was no mention of an electric heater.

@Jesusfreak

Heat Pump - it is like an air conditioner in reverse. A heat pump will extract heat from the ambient air, and transfer it to the water. It does not *make* heat, it *moves* heat. A typical heat pump has Coefficient of Efficiency of 3 to 4. Meaning you use 100Kw of electric and get 300 to 400 Kw equivalent of heat energy added to your water. The drawbacks are they are expensive (as you found out) and typically generate less heat over a given time than other options. The positive is they are a *lot* cheaper to run. You can also run some heat pumps in reverse, making them a water chiller (read the bottom of the original ad you posted) if you want to make a cold plunge spa or maybe a giant cooler for beers.

Electric Heater - It takes energy in the from of electricity and converts it to heat. At an almost 1:1 efficiency. Put in 100kW of electric get out basically 100kW of heat. They also are cheaper than a heat pump and can heat your water up quicker because they can be sized accordingly. The downside, they use 3 - 4 times the electricity of a heat pump to do the same amount of heating. They also require a larger electric circuit than a heat pump, and if you do not have one in place, that could be a factor.

Gas Heater - Pretty straightforward, uses gas. Either natural gas if you have natural gas service or propane to fire a burner that heats the water. They can heat water quite quickly if they are sized accordingly. They all have different efficiencies - how many BTUs of gas you put in and how many BTUs you get our. They require minimal electric - just to run the electronics in them. The cost to run depends on what sort of gas you can get in your area, and how much that gas costs.