[Greenbuilding] Hot tubs and recirculating pumps (Kevin Dalley)

[Kevin Dalley]

Great information.  Why didn't I post here earlier?  I tried other
places without results.

I just found out about a study created by PG&E and the Davis Energy Group.

http://www.energy.ca.gov/appliances/2003rulemaking/documents/case_studies/CASE_Portable_Spa.pdf



Here's a quote:

        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."


I haven't read the study carefully yet.  

Here's a quote from an industry publication:

http://www.poolspanews.com/2007/091/091title20.html

Of course, PG&E's Energy Line didn't tell me about this study when I
started to hot tub investigation 2-3 months ago.  I complained to them
about that problem this morning.  Someone from their pool division may
get back to me soon.

Here is the thread which mentions this study.

http://www.poolspaforum.com/forum/index.php?showtopic=9331&pid=37522&mode=threaded&start=#entry37522

Marquis claims that their studies show equal energy consumption.  I
will call them today and have them explain the inconsistencies.
Unfortunately, Marquis works better on my wife's back than the
competing brands we have tried.  We may go with a less efficient model
which provides relief, rather than the more efficient model which
doesn't work as well.

Paul Eldridge <paul.eldridge at ns.sympatico.ca> writes:

> Hi Kevin,
>
> Just to expand on your last point.... Hot Spring Spas use a 
> min-circulation pump called the "Slientflo 5000" to clean and filter the 
> water 24 hours a day.  It uses 68-watts and approximately 80 per cent of 
> the waste heat from its operation is transferred directly to the water 
> that passes through it, offsetting at least a portion of the spa's 
> heating demand (~ 1.3 kWh/day).  These spas have a "Summer" mode which, 
> as you mention, allows the pump to be turned off for eight hours a day 
> -- a great feature if you're a time-of-use customer [do NOT use "Summer" 
> mode in very cold weather, as this may increase the risk of freeze-up].
>
> In addition, Hot Spring spas have their own, unique GFI panel, which 
> consists of a two-breaker system -- one breaker for the heater and 
> another for everything (i.e., pumps, lights, ozonator, etc.); a 
> five-wire cable connects the GFI panel to the spa.  Since the heater 
> operates on its own circuit, an electrician can easily add a mechanical 
> or electronic timer circuit to restrict its operation to specific times 
> of the day (e.g., off-peak periods); everything else will continue to 
> function as normal.
>
> If you plan to use your spa each day, I wouldn't bother to turn the 
> temperature up and down  -- these things are so well insulated (at least 
> in the case of the better ones), any reduction in power consumption is 
> likely to be fairly modest.  But for Hot Spring spa owners with TOU 
> meters, adding a timer control to the heater circuit makes good sense.
>
> Cheers,
> Paul
>
>>------------------------------
>>
>>Message: 6
>>Date: Sun, 09 Sep 2007 15:30:28 -0700
>>From: Kevin Dalley <kevin at kelphead.org>
>>Subject: Re: [Greenbuilding] Hot tubs and recirculating pumps
>>To: geoedb at idiom.com
>>Cc: Greenbuilding at listserv.repp.org
>>Message-ID: <87myvveakb.fsf at kelphead.org>
>>Content-Type: text/plain; charset=us-ascii
>>
>>Thanks for the analysis, George.  And healthy is fun, perhaps.
>>
>>Some of the 75-85W 24 hour/day pumps can be shut off for 8 hours
>>during the day, to remove usage during the hours of the day when
>>energy costs are highest, and temperatures are highest..  Of course,
>>these tubs still heat at 4AM, when outside temperatures are low and I
>>won't be using the tub.
>>
>>Why is it so difficult to get good data on energy usage for so many
>>items?  Do the manufacturers mislead on purpose?  Or do they not care?
>>  
>>
>
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