Outdoor Winter Hot Tub Question

We live in NW Montana, where it’s currently snowing lightly and the temperature is 7 degrees F, with the expected high today of 16 degrees F. We have a 6 person hot tub that sits outside on our deck and we keep it running at 104 degrees F throughout the year. It has a hefty, tightly fitting insulated cover on it.

Since we haven’t used it in the past few days the snow has piled up on the cover. There’s about 8 inches of light powdery snow sitting on it right now. My wife asked me last night if I should brush off the snow, but I said no since it was providing additional free insulation. (I know a pile of snow is mostly air, so I figured it would actually help keep the hot tub from losing heat to the cold night air).

This morning I woke up and realized that since the snow was cold it might actually conduct the heat away faster than not having the snow there. :smack: Or will it?

So which is it? Does a thick layer of powdery snow help insulate the hot tub, reduce the insulating capacity of the cover, or make little or no real difference? And yes, I need a hobby…

When winter hiking it is common to bury water bottles in the snow to help keep them from freezing over night. The air temps are usually much colder. I think the snow is helping keep the heat in your hot tub.

Just make sure the snow doesn’t get too heavy, as it could collapse the cover…

Igloos work the same way Telemark describes - snow/ice tends to keep the temperature warmer than the outside air.

Plus, the fact that the snow hasn’t melted on top of the spa cover shows you that the cover is pretty much doing its job. If the snow was cooling it down appreciably, it would be melting pretty quickly.

I have been told that covering the spa using a gazebo, awning, etc. is even better for keeping it warm during the winter. It keeps both snow and cold down-drafts off of it. However, I don’t have any formal cite on that one.

Thanks everyone. That makes sense. I guess I should always trust my first instinct.

I suppose the snow on my roof also provides some added insulation, although I’m not sure how much heat I actually lose through my roof, compared to my windows. (I just have to make sure the weight of the snow doesn’t exceed the carrying capacity of my roof… not that I know of any easy way to do that.)

Actually, te snow on your roof is a fairly good indicator of how good your insulation is. If you get a big pile on there and it stays for a long time, you have good insulation. If not, you need more. The snow is not really adding any benefit for your house, since you want the insulation to be at your ceiling, not your roof, and outside air circulates (or should) pretty freely above the celiling via the soffit vents on your house.

That’s a good way to tell how well insulated your house is-- on a house with good roof insulation the snow on the roof shouldn’t melt. Until the rest of the snow does, that is.

Wow, where have I heard that before? :wink:

Am I the only one that thought that maybe the best solution is to get some take the cover off, grab the wine and the wife and make use of the tub?