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Thread: Heaters: NG v. electric

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    Prav's Avatar
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    Heaters: NG v. electric

    Have an ancient heat pump (plate with model specs is barely legible, pretty beat up, probably quite inefficient) and considering replacement. Saw some discussion in another thread about rationale for NG/electric - quick heat of spa vs. maintain temp with a cover, cost of therms v. kWh. If I recall correctly, NG is good choice for quick heating of spa (likely what Iwould do most of the time: in Miami so never really cold, and that's my 20-month old's private 1K gallon little pool), but previous owner apparently did "heat" entire 15k gallon pool (not to broth temperature, but something comfortable) at least once or twice per winter.

    Also, don't recall which thread I saw the formula to compare therm/KwH. For me: 10.56¢/kWH and $1.15/therm.

    Supposedly, cost of similar capacity gas/electric unit are similar. Additional cost of switching to NG would be running the gas line.

    Thoughts/advise/links appreciated.

    Thanks.
    14'x30' (est. 14K gal) w/spillover spa (est. 500 gal) - 1995 // Diamond Brite Blue Quartz - 2006
    Hayward SwimPure Plus T-15 - 2013 // Zodiac MX-8 - 2013
    Plain ol' Intermatic mechanical timer // Pump: 1 HP Pentair SuperFlo - 2012
    Filter: Hayward C17502(S) Cartridge Filter - 2011 // Heat Pump: Sunrunner/Aquapro 1300 (127K BTU) - 2011

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    Re: Heaters: NG v. electric

    I live in S. FL too, but I don't have access to NG in my neighborhood.

    I just recently purchased an electric heater and got an INCREDIBLE deal completely installed. If you're interested, shoot me a PM and I'll send you his information. He did an incredible job for less than anyone else in town.

    But I will say this... If I had the opportunity to go NG, I would have definitely considered that option as I hear that NG heats up a lot faster. Not that it's a big deal here in South Florida, but it's a nice benefit to have nonetheless. With my electric heater, my <1000 gallon spa heated up 50 degrees (from 55 to 105 back when it was really cold a couple weeks ago) in about an hour and a half. I'd imagine it would be much quicker in the warmer months when the normal pool water temp is in the mid-upper 70s - maybe 45 minutes.

    Quite honestly though, if the heating times were the same, I'd go with an electric heat pump no question about it. It's cheaper and very convenient with no hazard risks associated with gas leaks or anything like that. Plus, you also have to consider the cost of running a gas line to your unit which might also raise the price of installation substantially.
    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    Re: Heaters: NG v. electric

    Quote Originally Posted by Prav
    Also, don't recall which thread I saw the formula to compare therm/KwH. For me: 10.56¢/kWH and $1.15/therm.
    Just so everyone is on the same page. There is a big difference between an electric heater and a heat pump. You can not directly compare kW to therms of NG or gallons of propane. A heat pump puts out more heat than the kW that are put in since it draws heat from the ambient air and puts it into the pool. The comparison for a heat pump vs gas should be cost per BTU of heat put into the pool.

    For a typical heat pump, the electrical draw is around 6000 watts, give or take. BTU outputs vary by model, and ambient conditions, but figure 100,000 BTU per hour for comparison purposes. At 15 cents a kW/hr (I increased it to 15 cents becasue you have to include transmission fees and taxes in there too. if you already did that, you can recalculate) your cost for 100,000 BTU is around 90 cents. A therm of NG is around 100,000 BTU, so the cost comoparison is;

    $0.90 per 100,000 for the HP
    $1.15 per 100,000 for the NG heater

    About 25 cents difference. I think thats a pretty typical comparison (Californina residents excluded)! For me, if NG was available, it would be NG hands down just for the speed alone. Plus, NG rates for me are 70 cents a therm, so it's a no brainer. The builder of my addition got cheap and didnt run the gas lines so im stuck with heating oil and propane.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Heaters: NG v. electric

    Quote Originally Posted by bk406
    if you already did that, you can recalculate) your cost for 100,000 BTU is around 90 cents. A therm of NG is around 100,000 BTU, so the cost comoparison is;

    $0.90 per 100,000 for the HP
    $1.15 per 100,000 for the NG heater

    About 25 cents difference.
    I don't know how accurate this is but I found some different calculations. In full disclosure, this data is from the manufacturer of a Heat Pump, but that doesn't mean that it's biased. This graph shows the cost to generate 1 Million btu of heat. My understanding from people down here in South Florida that have natural gas is that it isn't cheap for heating their pool (for cooking, it isn't so bad).

    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    Re: Heaters: NG v. electric

    I've seen those numbers before. A lot of it depends on how much you pay for energy. For instance, the heat pump numbers are pretty close if you pay only 8 cents per kW/hr. Very few pay that. My rate IS 8 cents...for generation charge only! Once you figure everything else, its around 14-15 cents. The numbers you see quoted most of the time only account for generation charges. I'll still stick to my 90 cents per 100,000, or 9 bucks per million for a HP. The NG prices they show are for $1.60 per therm. Average price last this week for NG is around a $1 per therm. The chart uses a high number there. In terms of propane, yes, propane is the most expensive, around $2.50 a therm. So..it can vary, depending on energy prices in a given area. By and large, with electric rates (total price) between 15-20 cents per kW/Hr, and NG at $1 per therm, give or take 20 cents or so, NG pool heat is as economical as a heat pump without all the drawbacks (with the caveats of energy price differentials in a given area).

    And no, I dont sell gas pool heaters,
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Heaters: NG v. electric

    OK, so far, so good.... Some follow-up questions:

    (1) How do I know if I currently have an electric heater vs. heat pump? To me, it looks like an A/C unit, so that's why I think I'm correct in calling it a heat pump.

    (2) Heat pump >>> electric heater because of the "assist" of drawing ambient heat, right?

    (3) While a EH may be cheaper than an equal capacity HP, in the long-run HP wins because of operating costs.

    Hopefully, so far, so good.... now:

    My understanding from people down here in South Florida that have natural gas is that it isn't cheap for heating their pool (for cooking, it isn't so bad).
    Isn't it all the same price per therm? It's still the cost per 100K BTU that BK compared NG vs. kWH.

    By and large, with electric rates (total price) between 15-20 cents per kW/Hr, and NG at $1 per therm, give or take 20 cents or so, NG pool heat is as economical as a heat pump without all the drawbacks (with the caveats of energy price differentials in a given area).
    Are the drawbacks the speed to heat up? Maintenance? Other? I know for me the NG drawback is having to run the gas line (and the 25¢ per 100K BTU additional cost).

    Niceguymr: did you get electric heater? Or heat pump... You reference both in your post ("I just recently purchased an electric heater" and later "Quite honestly though, if the heating times were the same, I'd go with an electric heat pump no question about it.").

    Thanks for the feedback so far!
    14'x30' (est. 14K gal) w/spillover spa (est. 500 gal) - 1995 // Diamond Brite Blue Quartz - 2006
    Hayward SwimPure Plus T-15 - 2013 // Zodiac MX-8 - 2013
    Plain ol' Intermatic mechanical timer // Pump: 1 HP Pentair SuperFlo - 2012
    Filter: Hayward C17502(S) Cartridge Filter - 2011 // Heat Pump: Sunrunner/Aquapro 1300 (127K BTU) - 2011

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    Re: Heaters: NG v. electric

    Quote Originally Posted by Prav
    (1) How do I know if I currently have an electric heater vs. heat pump? To me, it looks like an A/C unit, so that's why I think I'm correct in calling it a heat pump.:
    Yep, thats a heat pump



    Quote Originally Posted by Prav
    (2) Heat pump >>> electric heater because of the "assist" of drawing ambient heat, right?

    (3) While a EH may be cheaper than an equal capacity HP, in the long-run HP wins because of operating costs.
    Yes to both

    Quote Originally Posted by Prav
    My understanding from people down here in South Florida that have natural gas is that it isn't cheap for heating their pool (for cooking, it isn't so bad).

    Isn't it all the same price per therm? It's still the cost per 100K BTU that BK compared NG vs. kWH.
    I dont understand this either


    Quote Originally Posted by Prav
    Are the drawbacks the speed to heat up? Maintenance? Other? I know for me the NG drawback is having to run the gas line (and the 25¢ per 100K BTU additional cost).
    For you, mostly speed. Further north, the heat pump usefulness goes down quite a bit depending on the time of year you are trying to use one. The BTU rating for a heat pump is really misleading too. They are rated using 80 degree ambient air temp and 80% humidity; not realistic, IMO. If its raining and 65 degrees, they wont put out much at all. The 25 cents extra is an estimate on my part. Again, you need to figure out prices for your own situation and location. For me, i'd gladly pay the extra 25 cents for the faster heat up.

    Quote Originally Posted by Prav
    Niceguymr: did you get electric heater? Or heat pump... You reference both in your post ("I just recently purchased an electric heater" and later "Quite honestly though, if the heating times were the same, I'd go with an electric heat pump no question about it.").

    :
    He has a heat pump. When he said electric the meant the fuel type, I believe.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Heaters: NG v. electric

    Quote Originally Posted by Prav
    OK, so far, so good.... Some follow-up questions:

    (1) How do I know if I currently have an electric heater vs. heat pump? To me, it looks like an A/C unit, so that's why I think I'm correct in calling it a heat pump.

    (2) Heat pump >>> electric heater because of the "assist" of drawing ambient heat, right?

    (3) While a EH may be cheaper than an equal capacity HP, in the long-run HP wins because of operating costs.

    Hopefully, so far, so good.... now:

    My understanding from people down here in South Florida that have natural gas is that it isn't cheap for heating their pool (for cooking, it isn't so bad).
    Isn't it all the same price per therm? It's still the cost per 100K BTU that BK compared NG vs. kWH.

    [quote:443uk4f3]By and large, with electric rates (total price) between 15-20 cents per kW/Hr, and NG at $1 per therm, give or take 20 cents or so, NG pool heat is as economical as a heat pump without all the drawbacks (with the caveats of energy price differentials in a given area).
    Are the drawbacks the speed to heat up? Maintenance? Other? I know for me the NG drawback is having to run the gas line (and the 25¢ per 100K BTU additional cost).

    Niceguymr: did you get electric heater? Or heat pump... You reference both in your post ("I just recently purchased an electric heater" and later "Quite honestly though, if the heating times were the same, I'd go with an electric heat pump no question about it.").

    Thanks for the feedback so far! [/quote:443uk4f3]

    Here are some answers to your above questions:

    (1) When I say electric heater, I'm referring to a heat pump. So the answers to 2 and 3 not relevant. Electric heater = heat pump.

    As for the cooking comment, the amount of gas used to cook is relatively low. Therefore, you may spend $25/month in NG for cooking and maybe $100/month to heat your pool. (I just made up those numbers completely, but it was to make my previous point about cooking cost clear). I know from people who have an NG pool heater that they don't use it often b/c of the cost, but they love it for the kitchen and personal water heater (a lot smaller than a pool).

    I just looked at my FPL bill and I pay about .09/kwh (.11/kwh total if you include everything else - keeping in mind that NG also has taxes & surcharges too). Just look at your last FPL bill to confirm what I'm saying. I have no idea what natural gas costs in South Florida but you should check the rates for yourself. Don't go by what someone on the interweb tells you.

    And yes, I went with an electric heat pump. Why? Well, first - I didn't have a choice between electric and NG - that was easy. 2nd, Propane is even much more expensive than NG down here. Someone I know recently spent $500 to fill their tank. So an electric heat pump was the best choice for me, and I'm very happy with my purchase.

    As for maintenance cost, I don't know the answer to that. My unit (Rheem) comes with a 5 year manufacturers warranty. I know that Rheem has been in the heat pump business for a very long time. My home has 2 A/C units. Both units are Rheem. I'm very happy with the service of my units.

    Look, I don't know much about heaters, particularly NG ones. For me, the only drawback to the electric system was the amount of time it would take to heat up the pool/spa. If you can handle waiting an hour or so to heat up your spa and a 1/2 day to heat up your pool, then that issue is moot.

    Down here, heat pumps are the most commonly used for pools. I used mine last week when it was relatively cold outside (remember?). On a night that was about 65 degrees outside, I brought my spa from 55 degrees to 105 degrees in about 90 minutes. Consider that the average year round temps in South Florida are 75 degrees and our Summers last 6 months. My heat pump is 117k btu. I could have gone with a 130k btu unit for only $200 more but I really didn't see the need for it. It worked excellently I promise you.
    TFP SUPPORTER through TFTestKits.com - My Pool: South Florida, 11K gallons, In ground, concrete / Diamond Brite, Free Form with attached spa (no heater- go figure) Built around 1998, original surface, Jacuzzi Magnum Force 1.5HP pump, Jacuzzi Cartridge Filter, Rainbow 320 Tablet Feeder, Hayward Navigator Pro, Taylor K-2006 w/ TFTestKits replacemeng Reagents.

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    Re: Heaters: NG v. electric

    > Down here, heat pumps are the most commonly used for pools.

    Just to emphasize your point, in my house I do not have conventional A/C units, all my heating and cooling units are heat pumps, full inverter models, 240vdc (Direct Current not Alternating Current), variable speed compressors and blowers, totally silent (you can stand outside by the compressor and see grass blades move but can not hear any sounds..) and I run my house year-round at 22 C (72 F).

    FPL paid for half of the unit costs and federal energy credits plus manufacturer rebates paid 80 percent of the other half.

    I can't understand why anyone would purchase a conventional A/C unit these days

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    Re: Heaters: NG v. electric

    Quote Originally Posted by susa
    I can't understand why anyone would purchase a conventional A/C unit these days
    Because they dont work in much of the country
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Heaters: NG v. electric

    > Because they dont work in much of the country

    Not so certain about that as the new inverter systems from Fujitsu, Daikin, Mitsubishi are in use by the US Military, Air Force, Marines and GE Systems have some amazing applications globally in temperature conditions that are far exceeding the climate conditions in most of the country.

    Canada, Europe and most advanced countries in Asia are also running inverter based heat pumps for climate control.

    SEER ratings on these new systems are 26 and higher.

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    Re: Heaters: NG v. electric

    Governments can afford the added costs those systems command. The average homeowner can justify that expense.

    Scott
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    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Heaters: NG v. electric

    > The average homeowner can justify that expense.

    I quite agree. My monthly FPL bill dropped from close to $300/m at peak temperatures to $120/m and I paid very little due to the generous FPL rebate,Federal Energy Credit and manufacturer rebate. All in all, the systems recouped initial cost in about 1 year.

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    Re: Heaters: NG v. electric

    I believe Scott meant CAN'T justify the expense.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Heaters: NG v. electric

    Thanks for all the input. Have yet another related question:

    All else being equal, are the only deciding factors between same BTU heat pumps (or NG heaters for that matter) price and mfg reputation/warranty? Or, like A/Cs there could be different Energy Star/efficiencies which may lead to lower kWh consumption?

    Ultimately, I'm curious to identify what I have - - it looks old/beat up, but for all I know it just looks ugly and it would be pretty hard to justify expense of a new one for minimal energy savings... I don't have much to go on (the "model number" seems to be quite short - something like 85-18 and I can't even tell the manufacturer). At worst, it's likely mid-90s as that is when it appears the pool was put in.
    14'x30' (est. 14K gal) w/spillover spa (est. 500 gal) - 1995 // Diamond Brite Blue Quartz - 2006
    Hayward SwimPure Plus T-15 - 2013 // Zodiac MX-8 - 2013
    Plain ol' Intermatic mechanical timer // Pump: 1 HP Pentair SuperFlo - 2012
    Filter: Hayward C17502(S) Cartridge Filter - 2011 // Heat Pump: Sunrunner/Aquapro 1300 (127K BTU) - 2011

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    Re: Heaters: NG v. electric

    Just to be clear, electric resistance heating is usually much more expensive compared to natural gas, except for places of the country where electricity is very cheap and natural gas very expensive. One Therm is 100,000 BTU (about 100 cubic feet of natural gas) and is equivalent in energy to 29.3 kWh assuming equivalent efficiency. Even with only 80% efficiency of a (poor) gas heater, this means that 1 Therm would have to cost more than 23.4 times more than 1 kWh in order for NG to be more expensive that electric resistance heating. The lowest electricity rate in the U.S. is around 8.0 cents per kWh (in Idaho; see this link) while the highest natural gas prices are around $2.20 per Therm (in Florida; see this link where I'm ignoring Hawaii which has insane NG prices) so in those places only a very efficient NG heater would be comparable to electric resistance heating. However, usually people with pools aren't at the lowest electricity rate tier and if you look at each state individually, the gas/electricity ratio spread isn't as high.

    As for heat pumps, the chart which came from this link implies a coefficient of performance (COP) for the heat pump of $26.38 / $4.40 = 6. A COP of 6 is pretty generous (i.e. best case). The pool heat pumps listed at AHRI mostly have a COP of 6 at high temperature (80.6ºF air temp) and a COP of 4 at low temperature (50.0ºF air temp) where the water is at 80ºF and relative humidity is at 63%. So you can certainly compare efficiencies for AHRI certified heat pumps at the link I just gave.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Heaters: NG v. electric

    I dont think anybody is really talkig about electrical res. heating on this thread. When anyone has refered to electric, they have meant heat pumps. As far as COP ratings for heat pumps, IMO they are misleading at best and downright false advertising at the worst.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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    Re: Heaters: NG v. electric

    Quote Originally Posted by bk406
    I believe Scott meant CAN'T justify the expense.
    Quite correct. Thank you.

    Scott
    Owner of - PoolGuyNJ LLC
    Expert Pool and Spa Repairs, Renovations, and Augmentation. Helping people decide what is the right gear for meeting their needs. Expectations Set, Expectations Met, No Surprises.

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    Re: Heaters: NG v. electric

    Here is a link to the FPL website which compares the cost of using a Heat Pump to a Natural Gas heater in a 14x28 pool from November through April in different regions of Florida.
    The comparison is calculated using a Heatpump with an average COP=5.0 and electricity at 12 cents/kw. The Natural gas heater in the example is rated at 80% with a cost of fuel at $1 / therm.

    http://www.fpl.com/residential/energy_s ... _spa.shtml

    The pool pump operating cost calculator is based on electricity cost at 12 cents/kw
    poolschoolgrad

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    Re: Heaters: NG v. electric

    A COP of 5 out of a heat pump MIGHT be possible in Florida. Anywhere else, you're lucky to get 3 or 4 unless its in July or August.
    14,000 gallon IG, Vinyl. Hayward 3/4 hp superpump, Penatair IC40 SWCG, Pentair automation, Hayward sand filter, Aqua Comfort heat pump, Hayward 400k Lo-Nox LP heater.

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