HOT TUB
- Thread starter evej1
- Start date
Sponsored Links
Impossible.
I think that calculation may be a little pessimistic. IHNI either about the likely heat losses from the tub, but what I do know is that a 'fixed figure' (be it 300W or whatever) is not really appropriate during the heating-up phase. Particularly with a cover, there will presumably be no significant heat loss until the water temperature rises above the ambient temperature (which could be well into the 20s (°C) in a reasonable summer), and even once the water temp is above ambient, the heat loss will be roughly proportional to the water-ambient difference, hence pretty low until the water gets quite warm.
Of course, once the desired water temperature has (eventually!) been achieved, the power required to maintain that temperature will be just that which corresponds to the heat loss at the particular water and ambient temps concerned.
Kind Regards, John
With no losses at any time it's 0.6°/hr, so just under 2 days....
Sponsored Links
True (well, about 1¾ days). Of course, as you (I think) have observed, what we don't know is what final temp ricicle's s-i-l regards as 'fine' - by your calcs, it could get up to about 30°C in about 'a day'.
Kind Regards, John
I
ImayKnow
Hot tubs: a breeding ground for some very nasty bacteria.
I would never have one.
I would never have one.
A friend of mine in Wiltshire has one. I had not seen him for 2 years and i turned up for a weekend birthday party on the friday. There was no rcd protection has he had a bs3036 fuses and the tub did not contain its on rcd protection. I would not get in on the friday night and was accused of being a scare mongerer. I just sat and drank wine observing the potential dead. On the saturday morning, i went to a local retailer and bought an rcd plug in outlet so that i might feel a little more involved on the saturday night. When energised the rcd was disconnecting immediatley. no test equipment so tested by plugging in other devices, no problem. I discussed the potential dangers and told them in no uncertain terms that it should not be used under any circumstances. beers and beers later, they removed the rcd and were partying in there. I again sat nearby, drank wine and watched the potential dead. Amazing.
I installed an IP66, RCD protected socket for it on Friday night 
... and, indeed, how much better we may have survived with them! [/more sarcasm]
Kind Regards, John
I have a 3kw version, heat to 35 degrees [body temp] 40 is far too hot unless we use it in the snow, insulation keeps it at 35 running for an hours or two each day during summer which also filters and treats water with Bromine. In cold weather needs a boost for an extra 2-4 hours to get it back to temp.
If it takes 8 hours to achieve temp at 3 kW and it leaks 0.3 kw and you use it infrequently (<each 80 hours) it might pay to leave it off.
You can use an analog 230v electric clock wired across the heating element to measure heat loss. If the 3 kw heater is on 5 minutes out of every 50 minutes when unused, it's 300w lost.
To measure this loss overnight with my elec. water heater I had to reduce the 240v across the heating element to 120v using dropping resistors, 4 ea., 2W, for my 120v elec. clock.
The 4500w element was on 5 minutes each ~7 hours.
You can use an analog 230v electric clock wired across the heating element to measure heat loss. If the 3 kw heater is on 5 minutes out of every 50 minutes when unused, it's 300w lost.
To measure this loss overnight with my elec. water heater I had to reduce the 240v across the heating element to 120v using dropping resistors, 4 ea., 2W, for my 120v elec. clock.
The 4500w element was on 5 minutes each ~7 hours.
DIYnot Local
Staff member
If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.
Select the supplier or trade you require, enter your location to begin your search.
Are you a trade or supplier? You can create your listing free at DIYnot Local
Sponsored Links
