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Hot Tub Heaters: Gas vs. Electric

July 7th, 2016 by

spa-heaters-gas-vs-electric
In the old days, all hot tub heaters were gas-fired heaters; small pool heaters specifically. And most hot tubs were not hot all the time, and not covered with a thick insulated spa top; they were heated up on demand.

When portable spas came on the market in the late 70’s, manufacturers were looking for a way to market a plug and play appliance that could be easily installed without too much hassle. The Spa Pack was born, an integrated electric heater and controller system.

Nowadays, most spas and hot tubs are heated with an electric heating element, tucked into a stainless steel tube. Gas heat is always an option however… which is better? Today they fight it out, to the finish – Gas Spa Heaters Vs. Electric Spa Heaters!

 

hayward-gas-spa-heaterGAS SPA HEATERS

Gas spa heaters such as the Hayward H-100 or the Raypak 106A, powered by either propane or natural gas are used on inground spas, free standing wooden hot tubs, or even for portable spas, installed outside of the heater cabinet. A gas line is connected to the heater by a gas contractor to provide a constant supply of fuel, which is ignited by spark ignition.

 

PROS: Gas spa heaters do have some benefits, including:

  1. Low Operation Cost: Natural gas has become less expensive in recent years. Propane gas is more costly, but produces slightly more BTU’s than NG.
  2. Fast Heating: Gas heaters are the clear winner in the speed of heating competition. A gas spa heater can add 1-2° per minute, but an electric heater can take an hour to add a few degrees. This lets you keep the spa at a lower resting temp, and heat it up quickly.
  3. Overcomes Obstacles: For large spas over 700 gallons, or for poorly insulated spas or wooden hot tubs that are used year around in freezing climates, electric spa heaters can cost a small fortune to operate as compared to gas heat.

CONS: Gas spa heaters have a downside, like most everything, including:

  1. Higher Initial Cost: A gas spa heater costs about $1000, plus it needs to have a gas line connected to the natural gas meter (or the propane tank). Costs for a buried gas line vary on the distance of the meter to the heater, and can exceed the price of the heater itself.
  2. They’re Gas: For those of you concerned about the safety of gas appliances, with possible gas leaks and carbon monoxide exhaust, accidents with gas spa heaters rarely happen, but they do happen.
  3. External Installation: Not that they are ugly, but you can’t tuck a gas heater underneath a portable spa, it needs to sit outside in the open air with access to fresh air and clear sky above for the exhaust.

 

spa-heater-manifoldsELECTRIC SPA HEATERS

Electric spa heaters are sometimes called Flow-Thru heaters, and are basically a long electric heating element inside of a stainless steel tube. Union connectors on the end make it easy to access the element, inside of the slim and compact tube. Attached to the tube are temperature sensors, high limit and pressure switches to monitor temp and water flow.

 

PROS: Electric spa heaters have their own benefits, including:

  1. Low Operation Cost: If your spa is located in a mild climate, and is well insulated and has a good spa cover, using electric spa heaters is  usually less expensive to operate than gas heaters. Unless you live in a very expensive electricity area, that is.
  2. Low Initial Cost: Electric spa heaters cost much less than gas heaters, in the $100-$300 range, and there’s no gas line to run. Most spa heaters, or Spa Packs, are powered with 240 volts, from a 60 amp GFCI circuit breaker.
  3. Low Repair Costs: Electric spa heaters are simple devices, and repairs are usually under $100. Gas heaters are by design much more complicated, and repair costs are much more costly.

CONS: Electric spa heaters also aren’t perfect. Here’s some common complaints:

  1. Slow to Heat: The best you can hope for is 2-3 degrees per hour on a small, well insulated spa with a 5.5 or 11 kw element(s). Cold outside temperatures and high winds can reduce heat gain to just 1° per hour on spas with smaller 4 or 5.5 kw elements, and smaller 1.5 kw heaters may not keep up.
  2. They’re Electric: We all know that water and electricity don’t mix, but spa heaters are protected by a GFCI and several safety components to prevent overheating and electric shock. However, accidents can still happen with 240 volts.
  3. Higher Operational Costs: Possibly. If your electrical costs are greater than 25¢ per kw, you’ll reach a tipping point where it costs more to heat with electric spa heaters than with a gas spa heater. Especially for spas/hot tubs with poor insulation located in cold northern climates; you will find it more expensive to maintain hot water, during winter.

 



BOTTOM LINE: 
For most people, myself included, an electric spa heater is simpler and cheaper in the short run and the long run. For those who live in much colder regions than southern California 🙂 however, a small gas heater may be a better choice, especially for low use spas, which can be maintained at 85°, and cranked up to 104° in just a half hour.

COST COMPARISON: If you want to figure out the cost comparison between gas and electric, it takes 8.34 BTUs to raise one gallon of water one degree Fahrenheit. Assume that heat loss is constant in both cases (although it does increase during colder months), and know that gas heaters are only 80% efficient, but electric heaters are close to 100% efficient. Then you can compare your cost of gas (in therms) and electricity (in Kilowatts) to produce your own analysis. bromine-wins

I’m not sure who wins this battle royale between two heavy weight spa heaters. Gas heaters are costly to install (and replace), but can be cheaper to operate (in many cases) than an equally sized electric spa heater.

Let me know in the comments ~ whatcha think?!?

 

XOXO;

Gina Galvin
Hot Tub Works

 

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