Hot Tub Buying Guide
How well the hot tub is insulated will effect its operating costs. Generally the better the insulation, the lower your operating costs. Just as in your home, with good insulation, you are going to hold the heat in your spa and not have it passed through to the air as quickly as without this important feature. Therefore your costs related to heating the water in your spa will be lessened. As you shop you may encounter three types of insulation in the tubs you look at.
In lower end hot tubs you are looking at a one application of polyurethane to the bottom of the shell. If you are looking at an indoor spa, it is also quite adequate. Keep in mind however there is no sound buffering here, and the spa might be a bit noisy for other occupants of your home. Bring the spa outdoors however, and you can see quickly that this is not enough insulation to keep the spa water warm without major costs.
Just as in your attic insulation, you will want to know the insulation's R value, or ability to block the transfer of warm air. With a blanket insulation approach, the insulation is layered between the exterior of the spa and the spa's surround. Look for a number of layers around the sides and at the base, that can be removed in case you need repairs to the spa's "innards". This makes for a lower service bill when it comes time for any repairs. And just like your attic, this blanket approach can offer soundproofing, keeping sounds from echoing around the home or making conversation difficult. Extra soundproofing should be located around the engine of the spa. Pads made of rubber placed under the pumps can muffle the humming noise they emit and make your hot tub a more pleasurable experience.
The most common method of insulating a hot tub is with foam. The whole space between the spa's shell and the cabinet is filled with foam, insulating and supporting the shell at the same time. Look for foam with multiple layers of closed cell polyurethane, densely packed. This type of foam will keep your spa heating bills down, and is impervious to water. If you find the insulation is open cell foam, pass this model up.
Most dealers will give you an estimate of the cost of operating your spa when you are shopping. Use this to help you determine which spa to purchase. With too much monthly power going to operate your spa, you are less likely to use it, so go with insulation that is highly efficient in keeping the heat where it belongs...in the tub.
Don't forget one of the most important parts of your insulation, hot tub covers keep that heat from escaping from the top.