energy efficiency questions

[sledjunkie]

Energy efficiency questions

Sorry for the silly questions, but do you guys ever have moisture/condensation marks on top of your cover where the seam is where it flips over.
It was down in the low to mid 50's the other night and when I looked outside at the tub in the morning I noticed it. I would imagine this winter when it's in the single digits it must loose heat through that seam.
It seems like a real nice cover. I think it's a cal cover which came with my Artesian. It's got to be like 5" in the middle, tapered down to 4" on edges.
Normal?

Also on the energy efficient topic, wouldn’t a tub on a slab vs. a deck tend to hold the heat better. I would think since it’s on a solid surface it would stay warmer. Similar to a road on a packed base vs. over a bridge. Lots of cold air going underneath.

[Brewman]

I don't have that happening on my cover, not that I've noticed, anyway.  I suspect that there is some heat loss on that seam, but I don't see any condensation on top of it.  

I suppose there may be some difference between a spa on concrete vs a deck for heat loss, I'm guessing that the difference is relatively minor.

But.....


What about a spa on a concrete pad vs a spa on an Ezpad or similar?  I'd suspect that the Ezpads would act as better insulators from the ground than concrete.
But is it enough to even make a practical difference?

Or does the insulation style of the spa matter in regard to heat loss thru the bottom?  Full foam keeps the heat in the shell, and thermopane keeps the heat in the cabinet.  Some warmed air must be in contact with the ground and if the ground is cooler than the air in the cabinet, heat will transfer.

[DPS]

There is heat loss through the bottom of most spas.  If the bottom of the spa is open it seems true that air would tend to circulate more under the spa on a deck than one on concrete.  
When Marquis tested their models for energy efficiency a couple years ago, the only 2 places with any heat loss were the center (hinge) of the cover and beneath the footwell.  They corrected both areas with relatively simple solutions.

[Dr. Spa™ Ret.]

When Marquis tested their models for energy efficiency a couple years ago, the only 2 places with any heat loss were the center (hinge) of the cover and beneath the footwell.  They corrected both areas with relatively simple solutions.

Are you saying that now, Marquis requires no heat what so ever to stay hot? WOW! Now that's even better than the DAIT

[DPS]

With electronic thermometers all over the outside of the spa, there were only 2 spots registering higher temperatures than the ambient air (30 degrees) with the water in the tub at 102 degrees.  One was beneath the spa and the other was the hinge area of the cover.

[Vinny]

The Island spa Cal cover is a 4" to 2" config. I asked about upgrading the cover and it was going to cost too much money so I didn't. I'll wait and get one of Doc's extreme covers when the time comes.

How's this for being silly ... my tub is right outside the kitchen window at sill height and whenever it snowed I would look to see where the snow was melting. It did melt at the seam until enough snow fell and then the seam starts to get covered.

As far as concrete vs deck - 2 things - 1) a concrete slab 8'x8' is going to get awfully cold pretty much over it's entire surface (a house built on a slab) so I can't see it being too efficient and 2) wood does have an R value - even though it's very low so wherever there's a 2x there's some insulation. Of course you have the spaces and the bridge effect as mentioned ... so there probably is no difference!

[Bonibelle]

I have to comment on Marquis insulation because I must be the only one during this heat wave who didn't have to  prop my cover to maintain my water temperature. My tub was set at 97 and it didn't go above that. My tub gets the direct sun and my solar panels on my roof were reading 146 in full sun...(no kiddin')...

[Tman122]

Energy efficiency questions

Sorry for the silly questions, but do you guys ever have moisture/condensation marks on top of your cover where the seam is where it flips over.
It was down in the low to mid 50's the other night and when I looked outside at the tub in the morning I noticed it. I would imagine this winter when it's in the single digits it must loose heat through that seam.
It seems like a real nice cover. I think it's a cal cover which came with my Artesian. It's got to be like 5" in the middle, tapered down to 4" on edges.
Normal?

Also on the energy efficient topic, wouldn’t a tub on a slab vs. a deck tend to hold the heat better. I would think since it’s on a solid surface it would stay warmer. Similar to a road on a packed base vs. over a bridge. Lots of cold air going underneath.

Very simple answer, yes you will loose heat at the seam of any cover. Some less than others and unless you get a really really crappy one the difference will be negligable IMO a few cents. And yes there may be a difference between wood or concrete bases but, again a low heat loss area (heat rises) negligable. I would worry more about the cover and get myself a thermal blanket or a cover upgrade and go for docs he puts a really neat seam on his, check it out.

Forgot to mention I insulated the wood base I made for my tub, after all this is Northern Minnesota and the frost permiates 4-5 feet!!! Easy to do when theres no tub on the base. Tipped it up and filled the voids with foam board. But again ask me how much my tub cost to operate and it is about the same as any other. And well worth the buck a day!

[sledjunkie]

Vinny -
Are you sure your cover measures 4" tapered down to 2"?
I just measured mine and it's a Cal cover and it clearly measures 5" tapered down to 3".

[Bonibelle]

Tman-I also have one of Doc's spa blankets on my tub, so that is also helping keep my tub temp where it belongs

[Vinny]

Vinny -
Are you sure your cover measures 4" tapered down to 2"?
I just measured mine and it's a Cal cover and it clearly measures 5" tapered down to 3".

Yes, the Island has an inferior cover compared to the Platinum and Gold. I inquired about that when I was buying the tub and the cost was too much for the upgrade, about $400. I have been on Doc's site for a long time (lurking quite a while before participating) and from what I can tell the Cal cover isn't quite like Doc's based on his website.

I guess that's something else that the higher end spas get that the Island doesn't!

[Dr. Spa™ Ret.]

Very simple answer, yes you will loose heat at the seam of any cover.

OH! I'm so disappointed. Haven't I been spamming enough?

The typical spa cover;

Notice that BIG gap in the middle?

My cover;

NO GAP! Completely filled with an insulating flap that's as WIDE and LONG as the cover......

And here's the spam (feel free to edit here Bill   ):
http://www.rhtubs.com/store/insulate1.htm

[MarKee]

The Marquis DuraCover has this "flap" down the center of the spa.  We call it the linear heat seal.  In combination with a 2lb. foam it creates a really nice cover.  Very few other manufacturers have these, I don't know why.  Marquis and I think Arctic are the only ones that I know of using any sort of seal for the center seam of a cover.  Are there others?

[sledjunkie]

See now that design makes sense to me. I'll see you in hopefully 5 years if my current one lasts that long. Thanks Doc.

Curious who manufacturers that cover for you?

[Dr. Spa™ Ret.]

Curious who manufacturers that cover for you?

A little over 100 employees   We're on track to make about 35,000 this year.