Marquis Pumps Vs Recirculating Pumps

[nereocystis]

I'm confused about buying an energy efficient model. I know, hot tubs

use lots of power, no matter what. I may add more solar panels to

offset the additional usage.

Does anyone have reliable information about energy efficiency of the

tubs? I'm comparing the Marquis's filtering at a few hours a day with

the lower power recirculating pumps which are on 24 hours/day. I want

real numbers, not a discussion of Marquis's employee buyout.

I include some of my calculations below, but my confidence isn't that

high.

The California Energy Commission established standards for hot tubs.

These standards were supposed to take effect January 1, 2006. The hot

tub industry complained that the standards were not quite correct.

The standards correct for volume and surface area of the tubs. This

is reasonable, but the standards don't include a minimum constant. A

tub needs a certain amount of energy, regardless of size. The energy

should increase in a way related to volume and surface area after

that. Volume for heating, surface area for cooling.

In short, the standard still are not in effect, and I want to buy a

tub.

Many manufacturers use an 85W circulating pump which runs 24

hours/day. This pump filters; much of the heat produced by the pump

is recovered and used to heat the water.

The Marquis tub, by contrast, uses a higher powered pump for

filtering, the same pump used by the jets. It uses 3.2A at 230V. The

official recommendation uses this pump for about 6.5 hours a day, for

filtering, testing the heat, heating the water.

Probably, I can cut this back to 3-4 hours a day or so. This is still

2.2-3kWh/day.

I can keep the heat off except for a short while before I use the tub.

With insulation, the temperature will be close to correct, and just

need a small amount of heating. I can cut the filtering down from 2

hours twice a day to 4 hours a day, plus one hour after use.

The 85W pump *might* be better, but I don't quite have enough details

to decide.

[D.P. Roberts]

Well, one of the main problems is that your mileage will vary. The filter's job is to clean the water. So, if you're asking "How often do I need to run the filter?", then first you have to ask yourself "How dirty will my water get?" High bather loads, lots of oils, shampoos, etc. will require you to use the filter more often, and thus use more energy.

[nereocystis]

Well, one of the main problems is that your mileage will vary. The filter's job is to clean the water. So, if you're asking "How often do I need to run the filter?", then first you have to ask yourself "How dirty will my water get?" High bather loads, lots of oils, shampoos, etc. will require you to use the filter more often, and thus use more energy.

Yes, the need varies, but the problem is getting numbers. If I run the filter for this many hours, how much energy do I consume. How does this compare with 24 hours of a recirculating pump.

Numbers are required, and almost impossible to find in the industry.

Also settings for reducing the energy usage are nice. The Marquis, for example, let's you set a mode where the heater is only working when the filter mode is on. Do I really need 102 degree water at 4AM. I don't. Then why keep it that hot? Tiger River has a setting which also turns off the heating for a few hours a day.

How much energy is used when the tub isn't doing anything? Televisions need to reduce this number to be energy efficient, but I haven't seen this number for hot tubs.

[New NW tub owner]

I'm confused about buying an energy efficient model. I know, hot tubs

use lots of power, no matter what. I may add more solar panels to

offset the additional usage.

Does anyone have reliable information about energy efficiency of the

tubs? I'm comparing the Marquis's filtering at a few hours a day with

the lower power recirculating pumps which are on 24 hours/day. I want

real numbers, not a discussion of Marquis's employee buyout.

I include some of my calculations below, but my confidence isn't that

high.

The California Energy Commission established standards for hot tubs.

These standards were supposed to take effect January 1, 2006. The hot

tub industry complained that the standards were not quite correct.

The standards correct for volume and surface area of the tubs. This

is reasonable, but the standards don't include a minimum constant. A

tub needs a certain amount of energy, regardless of size. The energy

should increase in a way related to volume and surface area after

that. Volume for heating, surface area for cooling.

In short, the standard still are not in effect, and I want to buy a

tub.

Many manufacturers use an 85W circulating pump which runs 24

hours/day. This pump filters; much of the heat produced by the pump

is recovered and used to heat the water.

The Marquis tub, by contrast, uses a higher powered pump for

filtering, the same pump used by the jets. It uses 3.2A at 230V. The

official recommendation uses this pump for about 6.5 hours a day, for

filtering, testing the heat, heating the water.

Probably, I can cut this back to 3-4 hours a day or so. This is still

2.2-3kWh/day.

I can keep the heat off except for a short while before I use the tub.

With insulation, the temperature will be close to correct, and just

need a small amount of heating. I can cut the filtering down from 2

hours twice a day to 4 hours a day, plus one hour after use.

The 85W pump *might* be better, but I don't quite have enough details

to decide.

My tub has a 1/15 hp (50 watt) circulation pump that runs 24/7. From looking at how it operates, I think that most of the electric power used to run the circ pump is transferred to the water as heat which makes the circ pump a very efficient way to filter. A jet pump is a much larger pump and pumps at a higher pressure so it uses a lot more electric power per hour of operation. If you shorten the jet pump operating time with a 'filter cycle', then you reduce the electric power used but then you are not filtering continuously but only during the period of time when the jet pump is on which I think would make the filters plug up sooner and also make the water filtration less effective. Bottom line is I think a continuous circ pump is the best way to go if you can, although it is a little more expensive because you need a second pump instead of just using one pump for both.

[Bond]

Wow this is a great question and you will get a lot of different answers.

Much to consider.Lots of people will give an opinion but thats all it is.As you say accurste details are hard to come by.

In my mind and I have pondered the same question but not really researched it yet but here is some things to consider.

I,m just giving thoughts not an estimate as I do not know and if I told you I did I would be giving you an opinion or B.S. which you will get enough of.

The circ pump running at 75 watts x 24 hrs will be 1800 watts or 1.8 kw. I do not know what your charge is per kw hour but just multiply.

The large pump has to still run each day to stir up the water I believe.I,m no expert here and I,m not sure if you can totally shut it off and just run the circ pump.If you can then your only cost per day is circ at 24 hrs and pump K.W x hrs of use each day fo total cost.

If you can not program the large pump off then how long does it have to run with the circ pump? ad the two for total daily cost.

Can your tub gain any of this heat generated by the pump or pumps?If so a 75 watt circ will give of a little heat which the spa can absorb if designed this way and a larger pump will give off a lot more heat which the spa can use.So even though the circ pump runs 24 the cost of running the larger pump will be offset by the heat gain and the reduced running of the 4k.w or 5.5 kw heater.I thought full foam spas were the way to go but pumps put off heat and if you use this heat obviously it will be cheaper to run as long as you have an insulated space to save and use this heat.

Just make sure that you can get rid of this heat when its 90 degrees out.

The other thing to consider is how long will a circ pump last?add that replacement cost into your factoring.

I would be interested if any of the spa service guys or gals on this site can say how long various circ pumps last and what is the most reliable circ pump out there?An honest answer not an opinion.

I too would love to know if anyone knows the answer and not just some Hype or phony lab tests to sell there Spa.

[D.P. Roberts]

Have you checked out the Marquis site? They do have energy costs listed for each model (not just one price for their smallest model). They're listed in the PDF specification file for each tub. It says "see dealer for details", so your local Marquis dealer may have more information about energy used and costs assumed.

[kengorman]

I know you asked for specific numbers and I can't answer your specific request, however, there have been several indepdent studies done that indicate that 24-hour circulation pumps for filtering are more efficient than having a pump which runs for a few hours a day on low-speed for the filtering cycle.

Reference 1:

Pacific Gas and Electric Company

Analysis of Standards Options For Portable Electric Spas

document link

Measure 2: Circulation/filtering pump Improvements.

In general this change would be understood as the addition of a low-wattage circulation

pump {snip}. This option could save roughly 15% of the energy consumption of the

average-efficiency spa and up to half of the pumping energy used for circulation and

filtering.

"some models include a separate, small pump for filtration and circulation duties, which can reduce energy requirements."

Reference 2:

Reference 2

Incorporating low-wattage circulation pumps might save as much as 15 percent in energy usage.

[thestallion]

I know you asked for specific numbers and I can't answer your specific request, however, there have been several indepdent studies done that indicate that 24-hour circulation pumps for filtering are more efficient than having a pump which runs for a few hours a day on low-speed for the filtering cycle.

Reference 1:

Pacific Gas and Electric Company

Analysis of Standards Options For Portable Electric Spas

document link

Measure 2: Circulation/filtering pump Improvements.

In general this change would be understood as the addition of a low-wattage circulation

pump {snip}. This option could save roughly 15% of the energy consumption of the

average-efficiency spa and up to half of the pumping energy used for circulation and

filtering.

"some models include a separate, small pump for filtration and circulation duties, which can reduce energy requirements."

Reference 2:

Reference 2

Incorporating low-wattage circulation pumps might save as much as 15 percent in energy usage.

is might save As much as...the same as just a little bit pregnant

[D.P. Roberts]

Did anyone notice that it MANDATES full foam insulation?

For anyone interested, the Davis report was brought up years ago, to a little debate (lots of people thought it would never come to anything). This was back when full foam vs. thermo pane was the big debate, back before the Costco threads. You can read it here

[D.P. Roberts]

The article mentions that 147 spas from 11 manufacturers have met the new standard, and that the list of spas is on the commission site. I haven't found it. Has anyone seen this list yet?

[nereocystis]

The article mentions that 147 spas from 11 manufacturers have met the new standard, and that the list of spas is on the commission site. I haven't found it. Has anyone seen this list yet?

Yes.

As I find out information, I have been adding it to the Wikipedia "Hot tub" article.

The URL is at http://en.wikipedia.org/wiki/Hot_tub.

The list of approved spas is at http://www.energy.ca.gov/appliances/applia...e_elec_spas.zip.

I talked to the Gary Fernstrom of PG&E today. He was responsible for the 2004 document. I'll try to summarize Wednesday. He had some interesting points.