Hey all. My wife and I just bought a year and a half old hot tub last week. I'm wondering about adding some extra insulation to the cabinet before we put it in it's final resting place and actually get her running. It's by no means a "high end" tub, but it's also not a cheapie IMO. It's a Four Winds "Honolulu" tub, about 450 gallons. I've taken the side panels off and it appears that it's just heavily spray foamed (appears to be "open cell" foam) for insulation and I think that the skirting/side panels are also made out of some type of dense (but lightweight) foam which is then formed and pained to look like wood paneling.
My question is, would it be worth it to add more foam (IE "Right Stuff") even though it seems pretty thick already? Would another type of insulation be better (IE stuff existing voids with batting)? Also, the foam is lacking a bit on the motor/plumbing side of the tub; obviously to keep those parts accessible. Can anything else be done in this area? I'd be interested in utilizing the heat from the motors, but I'm not sure this can be accomplished with the existing spray foam in place.
Any suggestions would be appreciated. I'll see if I can snap some pictures tomorrow and post 'em up.

What you have on top matters more (probably a lot more) than what's in the sides. A nice hefty cover supported by the rim is a must. Bonus points for adding bubble wrap or closed-cell foam floating directly on the water.
--paulr

The cover that came with the tub is beyond adequate, so I'm not worried there. I think you're grossly underestimating the importance of insulation in the cabinet though.
I'm just wondering if adding more to what I've got is worth it or not. Also wondering about spraying foam UNDER the tub, between the runners and concrete pad, once it's in it's final resting place too... To keep the cold winter ground from radiating cold into the cabinet and so on. Might be a little overkill though. Mainly I'm interested in the inside of the cabinet and maybe trying to make it possible to utilize the motor's heat too.

I think the issue is Paulr is in California and Wes is in Ontario, could those places be more different. I say go for it Wes and let us know how you get on. Would that foam be dense enough to support that weight + persons. If your motor kicks out enough heat for you to want to utilise it I would get a more efficient motor, pumping is what you want not heat. On the subject of heating how much power does your heater consume?

I added fiberglass insulation to the inside of the cabinet and tucked some under the tub. Result: Approx $30.00 savings in electric costs over the past year.

Teapot - I can't comment on the heater's hydro consumption as the tub isn't hooked up yet and the manual doesn't specify as far as I can see.
As for utilizing the motor's heat, again I can't say how hot it runs but in reading around on the topic of insulation, lots of people seem to recommend an attempt to use your motors heat as even the most efficient motors still radiate a significant amount of heat. Especially if you trap that heat into a small space, IE the cabinet of the tub.
My pool's pump is pretty new, brand name, and runs about 6 hours a day. When it's running, it heats up the ~10x10 pool house significantly. That's just a 1 horse pump in a big space like that. I'd have to imagine that 2 5 horse pumps could put out more than enough heat to make it worth trying to use to assist in tub/water temperature. How this would be attained, I'm not entirely sure.

Meatloaf - fiberglass batting? Did you just stuff it into any voids? Is your tub otherwise insulated?

Yes, I used fiberglass batting. I just filled the voids. I've had it insulated like this for over a year and no problems. The hot tub had the factory spray on insulation.

Fair play Wes, I will be putting one of those electrical consumption meters in soon just to check. I expect around 550 watts so you are probably 700-800 watts which isn't all going into circulating the water. I want to buy the lates ECO pump from Europe end of this season or ready for next. I watched it circulating (not filtering) at 10m3/hour and that was 27 watts! manufacturer reckons with 5m head (filtering) it should be around 350 watts. So yes, use that heat if you can.

Can you get sealed cell foam with the aluminium facing at that may reflect more heat back at the tub.

I wonder about finding some type of thin (-ish) insulation that I can staple onto the backs of the skirting panels which might help keep the heat in the cabinet ... either that, or do what 'meatloaf' did and just stuff the voids around the spray-foam with fiberglass batting, or spray more canned spray-foam on top of the original stuff. I don't want to throw away money if it's going to be useless though. What do you all think of those 3 options? Insulation backing on skirting boards, stuff with batting, or additional spray foam? Or, save my money and leave well enough alone? lol

Stuffing with batting is what I would do. Cheap, easy, and removable.

How about multifoil insulation? Obviously that's a UK site maybe you have something similar.

Yes, didn't notice the location, sorry.
--paulr

I filled the voids of my tub with slabs and pieces of styrofoam packing material over a year ago. There was already spray on foam on the tub underside and aluminized bubble wrap inside the side panels.

I kept the motor areas fairly clear and now wonder if I should add some ventilation holes to avoid overheating the motors in the summer (I'm in NC).

I'm confident the added insulation is saving some heat, but have no estimate of how much.


Curmudgeon

350 gal Infinity using BBB

be careful filling around motors/heaters- they sometimes need the space not only for maintenance access but also to allow equipment to "breath" and not overheat. The pump is water cooled, but the motor is air cooled!

I think for the sake of the few bucks it'll cost, I'm going to stuff all the voids around the foam with batting insulation; just for my own piece of mind. I'll leave the motor area pretty clear; maybe even leave that whole side of the tub as-is. Maybe it'll make a difference, maybe it wont. I don't think it'll cost much for the batting, so I think I'll give it a shot. ****, I'm not even sure how "good" (or bad) the original spray foam is, so just in case it's on the lower end of the R scale, I think this will help.