General > Beating a dead horse

full foam vs thermopannels

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spa_newb:

--- Quote ---The war is about to start again.  You can look at some of the older pages and fine whole threads on this.  In a nutshell the dealers that sell thermopane will say they are better and the dealers that sell full foam will say that they are better.  As I am not a dealer or a energy expert (nor do I want to spark the war again) I will refrain from adding my opinion to this question.

Dave
--- End quote ---


Is it any indication as to what the better solution is when I have not visited a single dealer that sells anything other than Full Foam?

Tom:

--- Quote --- The pumps would have to bring the cabinet air temperature up to a level "above" the temperature of the thin foam, plumbing, vessel shell, and water for the heat to travel through the air by convection, transfer to the thin foam and plumbing  and on through the shell and into the water by conduction. I would venture to guess that, especially in colder climates, the pump or pumps heat energy input would be hard pressed to reach and/or maintain a temperature high enough for this theory to work.
--- End quote ---
I point out again that an Arctic has NO foam on the shell.  A temperature gradient of only one degree is sufficient to transfer energy from the cabinet air into the water through the uninsulated shell. Some heat is transferred by radiation, I expect. Provided the cabinet is sufficiently insulated to prevent heat loss, energy will transfer into the water, reducing (but not eliminating) the time the heater is required to run.

Engineer wants hot tub:
Anybody out there?  Is this thread still alive?

Anyways, I am struggling with the question of FF vs TP question.  The consensus of the thread seems to be FF offers more advantages at higher cost.  Does a third method of insulation exist where TP is used with fully sealed air cavity between shell and skirt?

I would like to have a hot tub with the highest R-value.  I have not seen any published R-value information.  Has any research institute or public agency attempted to assemble this data?

I am particularly interested in the R-value of the sides between the shell and the skirt.  I have already settled in my mind that the top is where approximately 70% of heat would be lost (with no insulation whatsoever).  Any cover that forms a full contact seal with the rim and provides several inches of foam insulation over the top will prevent most heat loss from this source.  The heat loss from the bottom is solved by resting on a thermopane panel.

This leaves the sides for which I have not resolved the question of the "ideal" insulation method.

I accept that FF may result in higher repair cost if a leak occurs (which is less likely to occur since additional pipe support is provided by FF and longer time to freeze pipes during periods of no power).

It seems to me that a third option may exist where the air cavity between the shell and the skirt is fully sealed.  The air serves as the insulation with some TP under the skirt.

Does anyone know if it is reasonable to expect a fully sealed air cavity between the shell and the skirt?  If this method was relied upon for a superior R-value then no leaks in the air cavity could be tolerated since any cold air intrusion would significantly reduce the effectiveness. 

If I am allowed to wish, then I would like to see comparisons of infrared thermography scans using various techniques of insulation (to go along with my wish of tabulated R-values for each model).

I may just give up and design-build my own hot tub.

Tman122:
The dilemma would be cooling of the pump motors. I purchased a partially foamed tub (Great Lakes) and actually removed some foam from beneath the entry step (the pump motor was located right under it.) Then fully sealed the cabinet walls with reflextics 2 inch insulation. Shiny silver side facing the vessel. My thoughts here were it would reflect any warmth back to the vessel. Then I designed and installed a thermostatically controlled 110V actuated 2 damper and fan system for incoming vent air and out going waste air. The dampers were ducted so the incoming air went across the pump motor down low and the outgoing air was drawn from the top on the opposite side. The fan was on the outgoing duct/damper to create a positive flow in and across the motor. It was set for 115 degrees which was slightly lower than the motor manufactures maximum safe operating range. I live in Northern Minnesota so the system seemed to save on some dimes. The funny thing is all the components and labor added up to about a 10 year ROI with the minimal cost to operate savings that was realized. Instead of a 50 dollar bill to operate on a particular cold month it was a 40 dollar bill. I have all the KWH data to prove the savings as the spa was metered. I believe the pumps running at max temp may cause premature failure. Never kept the tub long enough to know. The new owners lived far enough away that they never called me for service. I do know it is or was still running about a year ago which would make the tub about 9 years old. Not sure if a new pump was ever put in it but their life expectancy on that value brand was likely only 5-6 years anyway.

Any way just some thoughts for you.

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