Some questions about inflatable spas

[Superhero]

Hi there,

This is my first post so please be gentle ;-) I hope this isn't asked too often but I have struggled to find information online.

Basically, I am toying with the idea of bying a small inflatable tub. The tub I have in mind is the http://www.the-mspa.com/product/product13.htm.

I am struggling to understand the operation and cycles though, as I've never had a hot tub. I understand it is generally best to keep it running all the time, otherwise due to the lack of movement, bacteria can multiply (despite chemicals) and algae grow (the tub would be outside in the sun - if we get any here in the UK that is!) and if it looses too much temperature it will need to reheat more and this can be more expensive and time consuming.

So, if I leave the hot tub on, I guess it as something like a maintenance mode, in which is moves the water around just enough to filter it etc. and keep it moving. Yet, I was wondering if there are any "idle"cycles, how often the heater would come on, etc.

The reason I am asking this is that I am trying to figure out the running costs of the tub. I have found anything from 27p to 5 pounds (!) a day (as suggested by M-spa themselves!) - yet, when I take the pump sizes and stuff and calculate with my electricity costs (12p per 1kwh), I don't end up with 5 pounds. Unfortunately I end up with something around 1.60 a day (if I remember correctly), in which case I'd say a hot tub is not fur us right now.

Here are some stats about the tub:
 Control System
     220-240V 50Hz; 110-120V 60Hz (US)
Heater
     1500W/2.04HP; 1350W/1.8HP (US)
Massage Air Blower
     720W/1HP; 500W/0.7HP (US)
Filter Pump
     12V/60W; 24V/50W (US)
Heat Increasing Rate
     1.5 - 2°C/Hour; 2.5 - 3.5 °F/Hour (US)

Can anyone help me out?

Thanks!
Julia

[Superhero]

Would it make sense or no difference at all to have the spa on a timer so it goes off for a bit during the day? I read on the lay-z spa website to "run the filtration pump no more than 8 hrs after use" but am not sure whether that includes the normal cycle pump. Sorry I'm just so confused!

[Isaac-1]

Let me start this by saying that I am a person that thought about getting a soft sided tub, before investing in a conventional hard sided tub.  After doing a bit of research I found that hard sided hot tubs beat soft sided ones in every respect except portability by a great margin and would now only consider getting a soft sided tub if I was living in a situaiton where a hard sided one was simply not an option due to access, limited seaonal space, etc.

Having said that and with little knowledge of this brand, I can say that their numbers look "optimistic" at best, for example, I ended up buying a small 2/3 person 215 gallon hot tub which is fairly insulated with a tradtional foam top (inflatable tubs are not known for great insulation overall) , it is a convertible model with a 1,500 or 5,000 watt heater (1,500 if connected to a common 120V outlet, 5,000 if hard wired 240V), conencted in 120V 1,500 watt mode it manages just over 2 degrees F per hour heating fresh cold water when the outside temperature is in the 50's.   3.5 degree F might be possible in 115 degree Arizona summer, but I doubt it under normal conditions.  Therefore the practicality of letting it cool down between uses to save electrity would likely depend on how often you plan to use it (daily vs just on weekends, etc) I also notice there is no mention of a jet pump in those specs, only an air blower, so don't expect much of a "whirlpool" effect.  I suspect operating cost would be somewhere in their published ballpark, or maybe a bit outside, a lot depends on the climate it is located in, how well insulated the tub is (having the cover on when not in use is critical), etc.  The heater is on a thermostat so only runs when it needs to, how much it needs to depends on the amount of heat loss, operating with the cover off is much like trying to heat your house with the doors open, so amount of use the tub gets can also play a fairly big factor.  And of course operating cost will vary with the time of year.

[Superhero]

Thank you for your input. Due to our current situation and wallet size ;-) A hard shelled hot tub is not an option. We live in a rental accomodation with a small garden it would be too much hassle having to think about moving a big hot tub when we do move, let alone the cost of buying one (then I REALLY would have to use it every day to judge the expense) - maybe one day when my partner is back at work, but currently, unfortunately no.

So, inflatable it is or none, I'm afraid. The inlaw has got a "proper" tub, which he says would run on 50p a day - although I don't think he measure it and maybe took the figure from their website. he said this inflatable would would cost even less to run, as it is so much smaller - however, I do know that the insulation is a big issue.

So you think that 5 GBP a day running cost is reasonable? That sounds like an aweful lot?!

[Isaac-1]

I suspect it would be a good bit less than that, given your electrical rates perhaps more in the 1 GBP per day ballpark, maybe less, but that is a guess with a run time of around 25% on the heater

[Superhero]

I suspect it would be a good bit less than that, given your electrical rates perhaps more in the 1 GBP per day ballpark, maybe less, but that is a guess with a run time of around 25% on the heater

Thank you for your help! So did you take the run time of the heater from personal hut tub (hard shelled) experience?

Apparently on an average spring day (whatever that really means ;-) the water temperature drops 1 degree Celcius in 5 hours. So I guess... in 24 hours that would mean it would heat about 5 hrs. Does that make sense? In summer, with the sun shining on it, I don't expect the temperature to drop too much too quickly but then we don't always have long sunny spells and high air temperatures.

[Isaac-1]

It is a ballpark guestimate based on percent of run time I see on my tub, combined with you being in a cooler climate and a relative guess on insulation level, so it may be a big ballpark.

[aeajr]

I own a Spa2Go and used it for 3 years.
http://www.amazon.com/Spa2Go-STG-1-Round-Complete-Volt/dp/B000A0A3WK

Worked very well for what it is.   The goal was to see if it would help my wife's back and if she would actually use it.  It helped and she used it actively for 3 years.  After 3 years I retired it and bought a 4 person hard shell hot tub.

I live on Long Island, NY.  I would put it up in the spring.  Ran it off a 110 volt line.  I left the system turned on all the time.  Have no idea what it really cost to run it.   I would leave it up until Oct/Nov, then drain it and put it in the shed till the next spring.

I sat it on a bunch of these foam squares so it would not be subject to rocks, sticks or other things that might cut it.  Made the bottom very nice.  Worked great!
http://www.homedepot.com/p/Norsk-Stor-Multi-Purpose-24-in-x-24-in-Interlocking-Gray-Foam-Flooring-Recyclamat-4-Pieces-240247/204318886

Only problem I had was at the start of the third season the heater would not come on.  I called the help line in the manual and they were SUPER helpful. Turned out the heat sensor was corroded. Talked me through the diagnosis, sold me the parts, $50, and helped me over the phone when I installed them. 

She said this was not uncommon with tubs that were not left up all year round.  They tend to corrode in storage more than if they were wet all year.

I am sure it would have lasted for a 4th year but I decided to upgrade.   We purchased a Marquis Spirit and then enclosed it in a green house for all year round use.

Hope that helps.