Should I Finally buy a Spa Blanket?

[Gomboman]

I've had my HS Envoy for two years now. I've never considered using a spa blanket until now. Seems like most people on this forum are believers so I would like to give it a try. Since I live in Southern California I was never really concerned about losing heat. I figured my HS cover was built well enough to hold in the heat. I'm willing to give it a try to see if I can cut down on my $.30 KwH bill. Saving the cover won't hurt either.

Anyway, what type of Spa Blanket should I go with? Do I have to cut it out to match my shell shape or can I buy one that fits correctly? Any suggestions would be appreciated.  

[Vinny]

I have not tried the bubble pool blanket type based on what I've read. I have bought Doc's foam blanket and it held up for 2 years. I did cut it to fit the shape of the tub ... although I did screw up in a couple of places and it didn't fit the tub 100%. I did use the spa leash and IMO it worked very well. I now have a foam spa blanket from the Spa Depot and it is thinner than Doc's. I just got it 3 weeks ago and I am imagining that it will not hold up the same way as Doc's did but I guess time will telll. I have not cut it to the tub's shape and I don't think it would stay put if I did and since it's not as robust as Doc's I don't think it will handle the cover leash.

The way insulation works is to help with the heat retention ... the closer you are to the temp on both sides the less the insulation matters. At 40º air temp it may be a difference but at 80º air temp you might not see any difference in savings. It may help with the chlorine and ozone off gassing eating up the cover, my tub is 2 1/2 YO and the cover seems like it is OK. I do see wear on the center seam but the insulating foam seems like it is as good as new.

I would also say you have to weigh the cost vs benefit. For me I might be saving some money in electric as the heater doesn't seem to be kicking on as often as it seems the water retains the heat better(I know you've read my other post). The additional benefit may be a prolonged cover life ... but to what extent. If I paid $50 for a blanket and needed one a year is it worth it - If I saved $40/yr in electric and the cover lasts 6 years vs 3 without one then YES it's worth it. But if I only saved $10 in electric and the cover lasted 4 years vs 3 then I would say it isn't worth it.

Here in NJ we get at least 4 months of winter, Nov to early March and if I save $0.20 a day ($0.15 KWH) it would be a savings of $24 in electricity - not a lot and I am not saying I am even saving that ... I am thinking I do or maybe more based on my observation.

[Bonibelle]

I had a spa blanket on my tub also. It didn't last 2 years, more like 16 months, but I think it made a difference.

Vinny, you didn't calculate the savings from evaporation. I know that I am filling my tub much more often now without the blanket and that additional water has to be heated, so I think the spa blanket is definately a good thing. ...I just keep hoping Doc will have a Christmas Spa Blanket Sale   .. or maybe a blanket replacement coupon for return customers

Now I have a question..Vinny, you say the closer that you are to the temp on both sides, the less insulation matters. Then would it be more beneficial floating the blanket on the water where the temp is say 101 and the air layer directly above it is maybe 80 under the spa cover..or would it be better served to sit on the top of the spa, adding to the layer of insulation that the cover offers and filling any gaps between the cover and the shell? My cover forms a vacuum. I left my blanket large enough to cover the top of the spa, so it didn't sit on the water. There was still a vacuum when I lifted my cover and my entire cover remained dry.

 Maybe that is why my blanket deteriorated so much faster than Vinny's. Maybe the exposure to the off gassing in steam and air is more detramental to the blanket than the chemicals in the water??? :-/

In any case, I will replace my blanket soon...

[Shaamus]

If you're only getting 2 years out of the foam covers, I would switch to the bubble type.  We sell the bubble type for just this reason.  The foam covers cost at least twice as much and don't last longer.

Bonibelle - your cover is not forming a vacuum per se.  The skirt is wet and sticks to the acrylic forming a water bond.  The resistance you feel when opening the cover is this water bond breaking, not vacuum.  Many people mistake this phenomenon.

[Vinny]

Boni,

The answer to your question IMO is that it is more beneficial that the blanket touches the water as it stops the convection currents and any stray cold air from physically touching the water. The main insulator is the cover with a R 14 to R 21 but it may not be perfect in closing all the gaps. I know that my center seam is leaking heat all the time. I do not get that suction effect on my spa and I do know there are gaps in the center, I used to push the 2 halves together but after 10 minutes they are apart again.

Also, the temp difference is probably not as dramatic as you said it is, it is probably warmer than 80º between the cover and the blanket. Remember that a blanket is only 1/8" to 1/4" in depth so it has a very small R value but by sealing off the top of the water to the cover with the blanket you've eliminated most of the moisture that sucks the heat away too.

I once read a book on superinsulating houses and it was interesting as they showed the difference between R14 fiberglass insulation and R14 foam and it has to do with air infiltration and humidity ... foam has 0 air infiltration and doesn't absorb humidity. I think that's why the blanket works well - even though the convection current (or air infiltration) is happening between the cover and blanket, the blanket is not letting it touch the water so the water slowly gives up its heat. If the blanket wasn't there then the water would cool down quicker.

If you could put an insulated room around the tub and it was some what air tight then the room would eventually become warmer than the outside air temp because the tub is giving off heat even with the cover closed and the tub would become that much more efficient (think of a heated pool at the Y or high school)

You are right about the evaporation ... fortunately I pay very little for the water but if you do pay a lot or may be taxing a well then it is beneficial there as well.

I know it's long winded but I hope it helps!

Vinny

[Vinny]

If you're only getting 2 years out of the foam covers, I would switch to the bubble type.  We sell the bubble type for just this reason.  The foam covers cost at least twice as much and don't last longer.

Bonibelle - your cover is not forming a vacuum per se.  The skirt is wet and sticks to the acrylic forming a water bond.  The resistance you feel when opening the cover is this water bond breaking, not vacuum.  Many people mistake this phenomenon.

I've read that when they go they leave all the plastic from the bubbles in the water ... is this true?

For about $17 one can get a 7'x7' bubble blanket.

[Tonyf]

With our previous spa, we got more than 5 years out of each bubble blanket. Being in upstate NY, it really pays for itself in a short time due to our cold winters. May times when  it is below 15 degrees outside, we just fold over and area of the blanket where will will be sitting and it does help to retain the heat.
Tony

[hottub.pool_boy]

Nah, too much to fuss with! Been away from here for awhile, you made it through the fires o.k. I see.

[kokanee001]

Speaking of the cover leash for the blanket, the instructions for installing the leash require you to make a couple of holes on the underside of your cover in order to attach it. Somehow the idea of making holes there doesn't sit too well with me as it makes openings for heat and moisture to enter the cover. Can anyone who has tried a cover leash for a spa blanket alleviate my fears on this? Thanx

[kokanee001]

BTW, the temp here in SE BC is usually around -20C in winter (brrrr) so I've been considering a spa blanket, but am unsure which type would be best. Can anyone w/experience list the pros & cons of both the foam and the bubble type? Thx

[Dr. Spa™ Ret.]

Your cover should already have some holes in the bottom for condensation to escape from. If it doesn't it'll fill  up with water :-)

[Gomboman]

I guess I have one last question. If a spa blanket is indeed beneficial, why don't the Spa Manufacturers include one with the purchase? Are there any dealers out there besides hottub.pool_boy who think they are bunk? Just curious.....

[kervis]

I've read that when they go they leave all the plastic from the bubbles in the water ... is this true?

For about $17 one can get a 7'x7' bubble blanket.

Yes, little blue plastic circles!  Thank goodness they don't all go at the same time!

I do not have a cover leash.  I open the cover halfway, grab the blanket and flip it over onto the opened cover, open the rest of the cover and off it goes.  When I get in the water, I straighten it out--no big deal.  When it's windy, it blows off and crumples on the ground.  The simple things I have tried to keep it in place have not worked, so thankfully it does not happen often.  The only time it's a bother is when it blows off in miserable weather, otherwise it's no big deal at all.  I like mine.  

[Shaamus]

I guess I have one last question. If a spa blanket is indeed beneficial, why don't the Spa Manufacturers include one with the purchase? Are there any dealers out there besides hottub.pool_boy who think they are bunk? Just curious.....

Probably the same reason most of them spec crap covers and not the good 2# foam ones.   $$$$$$$$

The downside to a floating cover is the hassle of using it.  It is something you have to take out of the spa before you get in and return after you get out.

[IlliniFan]

I have the closed cell one.  I have no idea about energy effeciency and savings, but the cover does stay dryer.  I can tell you that if I am in the tub and pull it down on the water, the water is noticeably warmer.  I have also used it as a kind of tent in an icy rain.