Hottub running hot. What to do?

[mrwkuk]

Hi all, I am new here, and a DIYer, so please be gentle.

I recently bought an Intex portable hottub. One of the inflatable ones like the Lay-Z-Spa units. The unit claims it is only pulling 2400w and comes with a pre-fitted 13a socket with an inline RCD, and I confirmed this with an inline power meter.

I had previously installed a IP rated external power socket in the garden for external devices, and as it has 2x13a sockets this seemd like it would be fine. After an hour or so of the hottub in heating mode the socket was very hot, so i unplugged it and let it cool down. I then replugged it in a few hours later, and after maybe an hour it was hot enough to be making a smell. I unplugged it and investigated, it had melted the inside of the socket.

In this instance it may have been poor installation on my part, looking at the area around the melting it looks like it may have been arcing so thats likely what caused the melting. It seems like the screws were loose. Lesson learned, crisis averted.

But yeh, not ideal.

Anyway. In an effort to eliminate my potential poor workmanship from the equation I relocated the tub to power off of a professionally installed regular socket inside the house. However after doing this, this socket started to get hot too. After running the hot tub for about an hour the cable, plug, and socket, are all hot to the touch. Although not melting this time, but certainly so hot as to cause concern.

So, my question is, should these units get this hot under normal conditions?

My understanding is that hot cables = problems, but I dont see how I can do anything that would resolve this as a normal consumer. The device comes with a 13a plug suggesting that it should be fine to just plug into a regular 13a socket.

The only solution I can think of is removing the factory fitted plug/cable, and hard wiring in a higher rated 16a+ feed (either using a 16a commando plug or just a dedicated feed direct from the consumer unit) which would ideally be done by a qualified electrican. But theres no indication that this is a requirement on the box. I could understand this being a requirement of a bespoke fixed hottub installation as they are usually bigger, and more powerful anyway, but these units should essentially work like a regular consumer device.

Sorry for the wall of text, and again, be gentle

 

[telectrix]

should be fine on a 13A plug. the usual cause of overheating is poor contact between the plug pins and the socket. generally due to cheap sockets. the tub pulls 10A when heating, which is well within the capabilities of a BS1363 socket. having said that, there is guidance in the regs. that loads of that size would be preferable on a dedicated circuit. your suggestion of such with a commando socket and plug is good,but first, I'd fit (or get fitted) a good quality outside socket ...BG are what I fit... and ensure that the plug pins are clean.

 

[Midwest]

Did you replace the plug(top) after your first socket melted?

 

[mattg4321]

Could've been a loose connection inside the plug top or just a cheap and nasty plug top

 

[telectrix]

Could've been a loose connection inside the plug top or just a cheap and nasty plug top

shouldn'tbe.factory fitted plugs are usually good quality. but could be a manufacturing fault. hot tub cable is qiute thick. it's 1.5mm but with the thicker sheath, looks more like 2.5mm. had same problem, but was own fault. plugged it into a cheapo extension lead as a temp. "see if it works OK" prior to fitting a IP rated socket close to tub.

 

[mattg4321]

I agree, they are usually good. But not always. As Midwest says though, it shouldve been replaced after the first time it overheated.

Think the flex was 1.5 3C H07 when I've seen them so that shouldn't be an issue at all.

 

[UNG]

Moulded 13A plug top by any chance, that would be the first thing to get rid of and replace it with a 13A plug or a 16A commando plug and socket.
Over the years since they were introduced I have seen very few fitted to high load appliances that have not caused damage to sockets and / or the plug top

 

[UNG]

shouldn'tbe.factory fitted plugs are usually good quality. but could be a manufacturing fault.

By fitted do you mean the moulded type plug top
I've always been suspicious of the moulded plugs since the 80's when a HTM came out recommending they were replaced in all NHS premises as some were found to have strands of wire visible in the moulding, although I can't remember if there were any reports of shocks

 

[FatAlan]

Out of interest, what is a good solid make of BS1363 plug? Some of the ones I’ve purchased recently have looked a bit naff (cheap and nasty)

 

[telectrix]

these are pretty well bomb proof.

13A Fused Heavy Duty Plug Black - Screwfix

Order online at Screwfix.com. Durable and hardwearing. FREE next day delivery available, free collection in 1 minute.

www.screwfix.com

 

[Deleted member 26818]

Out of interest, what is a good solid make of BS1363 plug? Some of the ones I’ve purchased recently have looked a bit naff (cheap and nasty)

MK, Duraplug or any from Woolworths.

 

[telectrix]

woolworths??? who's zat?

 

[ackbarthestar]

A hot tub getting hot ? .... umm, interesting.
As others have stated, a good quality moulded plug would suggest loose terminal connections in the socket or/and a weak plug-socket fitting.

 

[mrwkuk]

Thanks all for the replies. The plug, which is molded to the cable, looks in perfect external condition so i dont think its a fault there, i think its likely just high constant load. It just surprised me that it would get that warm. I will look at upgrading the cable / getting a dedicated feed put in at some point to reduce load on the main ring, but for now i will just make sure not to leave it running unattended.

 

[Midwest]

Thanks all for the replies. The plug, which is molded to the cable, looks in perfect external condition so i dont think its a fault there, i think its likely just high constant load. It just surprised me that it would get that warm. I will look at upgrading the cable / getting a dedicated feed put in at some point to reduce load on the main ring, but for now i will just make sure not to leave it running unattended.

When thermal decomposition occurs, such as with loose terminal connections, all the associated terminals, connectors & pins will be effected, Are you sure your manufacturers plug (top) is not 'dirty'?

 

[mrwkuk]

The plug is brand new so, as you might expect, its clean as a whistle. Internally i have no idea, as its molded, but all the pins seem solid, and the cable isnt loose, so i would have to assume its all good. The only other option is to cut it off and replace it, which probably voids the warranty so not something i want to do until i have at least used the tub a few times.

Currently everything has been running an hour or so, and its warmer than ambient, but not hot. But then theres a decent breeze blowing over everything so thats probably helping. I will keep an eye on it for now and, as noted, upgrade later when i can.

 

[davesparks]

MK, Duraplug or any from Woolworths.

Out if those three MK are the only one left, duraplug went bust last year.

 

[UNG]

A hot tub getting hot ? .... umm, interesting.
As others have stated, a good quality moulded plug would suggest loose terminal connections in the socket or/and a weak plug-socket fitting.

A bit of an oxymoron if ever there was, can't ever remember seeing a good quality moulded plug if I can't see or check the connections then you can't exclude it from being the problem

The plug is brand new so, as you might expect, its clean as a whistle. Internally i have no idea, as its molded, but all the pins seem solid, and the cable isnt loose, so i would have to assume its all good.

The only other option is to cut it off and replace it, which probably voids the warranty so not something i want to do until i have at least used the tub a few times.

Currently everything has been running an hour or so, and its warmer than ambient, but not hot. But then theres a decent breeze blowing over everything so thats probably helping. I will keep an eye on it for now and, as noted, upgrade later when i can.

How will cutting the plug off void the warranty

 

[mrwkuk]

I am guessing, it might not, but I would think that direct permanent physical alteration to the product potentially affecting its operation would be considered a warranty issue.

If it wasn't a factory molded plug, I would have gotten shot of that in a heartbeat. I might check out the other end and see if there are screw terminals to replace the whole cable at the pump end.

 

[GeorgeCooke]

The only other option is to cut it off and replace it, which probably voids the warranty so not something i want to do until i have at least used the tub a few times.

It doesn't (void the warrenty).

 

[telectrix]

I am guessing, it might not, but I would think that direct permanent physical alteration to the product potentially affecting its operation would be considered a warranty issue.

If it wasn't a factory molded plug, I would have gotten shot of that in a heartbeat. I might check out the other end and see if there are screw terminals to replace the whole cable at the pump end.

far better to replace the plug. don't forget there's an in-line 10mA RCD in that lead.

 

[Midwest]

It doesn't (void the warrenty).

It depends on the manufacturers.

Some time ago, I did some research on this subject and posted here with my results, as I was of the opinion cutting off such plugs would void the warranty; sorry I meant plugtops .

I emailed several of the top manufacturers of kitchen appliances, and other devices. The replies that came back were mostly that it wouldn’t void warranties. However, there were a couple of exceptions. Unfortunately I never kept a link to the thread, so I can’t remember who they were. It was mostly to do with using their own leads, but on was just specifically cutting off the plug. Don’t know where they would stand over a warranty claim, if one took them to a civil court.

I would suggest reading MI’s, or ringing them to enquire.

 

[GeorgeCooke]

I was of the opinion cutting off such plugs would void the warranty; sorry I meant plugtops .

No you didn't. You were right the first time.

 

[DPG]

I'd go with replacing the plug with a good quality one as mentioned above. It won't affect your warranty or rights. Think about what would happen if the plug got damaged by being stood on for example - you wouldn't throw the whole hot tub away, you'd just fit a new plug.

George, do you have to keep banging on about this on every thread? Some people say plug, some say plug too. Makes no difference to the discussion.

 

[GeorgeCooke]

George, do you have to keep banging on about this on every thread? Some people say plug, some say plug too.

Plug too!

It seems some people don't learn from their mistakes. The OP is a new member. Let's not teach him incorrect terms.

 

[DPG]

Plug too!

It seems some people don't learn from their mistakes. The OP is a new member. Let's not teach him incorrect terms.

It doesn't help matters, it just means the thread gets derailed and the OP gives up.

 

[Midwest]

No you didn't. You were right the first time.

Yes you did. You were wrong for the second time.

 

[mrwkuk]

Think about what would happen if the plug got damaged by being stood on

But in doing so you have damaged the product outside of what could be considered normal wear and tear which, imho, would constitute voiding the warranty. Like if you tripped with scissors and cut a gash in the side of the hot tub, or dropped tea directly into the electrics. Thats human error, your fault. Not something the manuf should have to accept.

you wouldn't throw the whole hot tub away, you'd just fit a new plug.

Indeed because at that point theres no warranty issue to worry about.

Ultimately I am less concerned about the warranty after the tub has been used a few times. As long as the core functionality is ok, i would probably never claim on the warranty anyway. But until its been confirmed not-DOA I will always leave devices fully intact, and keep all the packaging.

 

[Pete999]

But in doing so you have damaged the product outside of what could be considered normal wear and tear which, imho, would constitute voiding the warranty. Like if you tripped with scissors and cut a gash in the side of the hot tub, or dropped tea directly into the electrics. Thats human error, your fault. Not something the manuf should have to accept.



Indeed because at that point theres no warranty issue to worry about.

Ultimately I am less concerned about the warranty after the tub has been used a few times. As long as the core functionality is ok, i would probably never claim on the warranty anyway. But until its been confirmed not-DOA I will always leave devices fully intact, and keep all the packaging.

Is your hot tub thermostatically controlled, if yes have you tried turning the thermostat down a tad

 

[mrwkuk]

It is, but this was during the initial heat up phase from cold, so the heater was running full time to get the water from 18°c (current tap water temp) to 38°c Takes a little over 30minutes to get a 1°c increase in temp so it has to run for around 12-15hrs flat out from cold. Once its at temp it will just idle between the hysteresis points.

 

[telectrix]

It is, but this was during the initial heat up phase from cold, so the heater was running full time to get the water from 18°c (current tap water temp) to 38°c Takes a little over 30minutes to get a 1°c increase in temp so it has to run for around 12-15hrs flat out from cold. Once its at temp it will just idle between the hysteresis points.

even so, the plug/socket should not overheat.that is caused by bad connection/s, either between the plug and socket, or the terminations into the socket, mainly caused by either poor quality items or wear through excessive use.

 

[mrwkuk]

We're kind of going round in circles now guys. Thanks for the input.

 

[Pete999]

Is the plug factory fitted, can you get at the connections, have you checked the connections at the socket? loose connections at these locations caN cause a high resistance hence a higher temperature, WORTH CHECKING

 

[DPG]

We're kind of going round in circles now guys. Thanks for the input.

Ah but only because you refuse to try changing the plug for a good quality item. Surely worth a try? It is a suspect item.

 

[mrwkuk]

I never said I wouldnt change it. In fact i said in the first post that seems like the only sensible option. (although i suggested going for a 16a connector instead but a better socket is also worth a try)

But I wont make irreversible changes to a brand new purchase until its proven working as-shipped. If its not, it goes back under warranty / not fit for purpose.

My point was the last few posts have basically repeated what people have already said a number of times in the thread, suggesting that people have stopped reading the thread and are just responding to the first post so theres no point going round in circles over and over again. You have all given me some useful advice and I will be taking action based on that advice. Thank you.

 

[DPG]

I never said I wouldnt change it. In fact i said in the first post that seems like the only sensible option. (although i suggested going for a 16a connector instead but a better socket is also worth a try)

But I wont make irreversible changes to a brand new purchase until its proven working as-shipped. If its not, it goes back under warranty / not fit for purpose.

My point was the last few posts have basically repeated what people have already said a number of times in the thread, suggesting that people have stopped reading the thread and are just responding to the first post so theres no point going round in circles over and over again. You have all given me some useful advice and I will be taking action based on that advice. Thank you.

It's not that people have stopped reading the thread - the reason the advice is being repeated is that it is good advice.

Hope you get it sorted though.

 

[Bobster]

Without repeating what others have mentioned.

How far away from the house is this hot tub situated.

Is the circuit compliant to have <5% volt drop?

 

[Simon47]

Just a thought ...
Was it plugged into one of those enclosed "waterproof" sockets, with the cover closed ?
That would restrict airflow and hence cooling of the plug. Our 13A plugs all have a little "heater" in them otherwise referred to as a fuse. Under continuous loading this will heat up the plug - relying on varoius routes for heat disipation : air cooling, conduction down the cable and air cooling from that, conduction through the socket body and air cooling of that, conduction through the socket wiring, and conduction through wiring and case to the mounting surface (eg bricks). I suspect aa good metalclad socket wired with thicker cable will run còoler (all other things being equal) than a plastic one with thin wiring.

As to warranty ...
Cutting the plug off would void your ability to return it because you've changed your mind. It could also remove any manufacturer or retailer provided warranty which could quite reasonably exclude modified devices. However, it could not be used to remove your legal rights should any other part of the unit become faulty. The law is clear that any contract clause that removes your legal rights as a consumer is automatically void and unenforceable.

 

[mrwkuk]

How far away from the house is this hot tub situated.

Its literally right at the back of the house within reach of the house itself. So less than 5m (the length of the cable that came with it). Allowing about 0.5m for the cable to go in the window and down to the indoor socket.

Like I suggested earlier in the thread, the problem of the socket "overheating" is largely solved running the cable to the professionally installed socket inside the house. The cable does, however, still run warm, and that was my main question. Should it.

Most of my research seems to suggest that warm is fine, and hot is not, especially rapidly-heating hot. In its current configuration it seems to be just getting warm. (about 32°c based on FLIR camera)

@Simon47 Thats actually a fairly good point that i had not considered. But i am pretty sure the key cause was inadequate cable and poor socket installation.

Ultimately I think a new external socket, with better quality, and better fitting cable, should solve the overheating issue, but wont stop it running warm due to the nature of the load.

Also @Simon47, the point about the warranty... that was exactly my point. I am happy to alter the unit once its clear it works and i am not going to return it within a week/month/whatever.

 

[Midwest]

Deleted