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Hot tub waste water - where can it go?


readiescards

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Busy getting on with our new holiday cottage, trying to work out best sewage treatment solution, lady from holiday cottage booking company just been, she says normally holiday cottage owners are refreshing the hot tub water every week! Woa thats a lot of waste water.

 

Where can I discharge that too?  Does it have to go through the sewage treatment plant or can it go into local dyke?

 

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A hot tub will usually have either a chlorine dosing system, an ozone dosing system or, perhaps, a UV exposure system, built in to the circulating pipework, so where it goes depends on which system your tub uses.  If it uses a chlorine-based treatment system, then don't put it in the treatment plant, if it uses an ozone or UV system then it's fine to do down the treatment plant.

 

The same really goes for draining it directly to the local dyke - if it uses a chlorine based system then I'd be inclined to drain it over a wide area of ground that has nothing growing on it to allow the chlorine to evaporate out as it drains away.

 

If the hot tub has no treatment at all, then personally I'd be very wary of using it at all.  Apart from the abundance of faecal coliforms that will inevitably colonise it, there's also a fairly significant risk of legionnaires.  Adding ozone treatment via a venturi and ozone generator into the pump pipework isn't hard to do, and is probably one of the simplest and lowest maintenance ways of keeping the water safe.

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1 hour ago, SteamyTea said:

The worse job I ever did was cleaning out the spa bath filter at the Sheffield YMCA, I have do idea what those young men got up to in it.

 

Real adult content and 1970's language.  But this is the cleaner version.

 

 

I've got that on vinyl somewhere! 

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4 hours ago, readiescards said:

So legally it does NOT have to go through the sewage treatment plant?

Which would be great news

 

 

As above, it depends entirely on the treatment system that's fitted to the tub.  If it is a chlorine based one (as a lot are, especially older, or dare I say it cheaper, ones are) then you cannot put the waste into a treatment plant, as there is a chance that the chlorine will kill off the aerobic bacteria in it for a while.  If the water in the tub hasn't been chlorinated recently (as I suspect it may not have been over the winter) then you could probably put it through the treatment plant OK, but it would tend to dilute the contents a fair bit and may slow it down due to lack of nutrients.  On the other hand, often (as @SteamyTea has mentioned) these things do tend to accumulate a lot of pretty nasty anaerobic bugs in their pipe work, so it may well be better to empty it via the treatment plant to that the effluent that is finally discharged has a lower biological oxygen demand.

 

I did some work on a tub that had no treatment system at all (not sure how they are allowed to sell them like that, really) that belongs to an acquaintance who had read my exploits with water treatment.  I fitted a Mazzei injector and ozone generator in a bypass arm fitted to the main circulation pump and it's worked very well indeed.  The water and pipe work stays nice and clean now.  I have to say that our first go at cleaning out the mucky pipes before fitting the ozone system was a dreadful job - you really do not want to look at what grows inside those things, it's bloody dire, to say the least. We ended up fitting new pipes throughout, as neither of us could face the idea of cleaning all the pipes, they were that bad.

 

 

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We had a hot tub on a cruise ship and the water had to be replaced every two or three days as it started to go cloudy. The heater was also broken and it had to be constantly filled up with hot water. The ship/hot tub was only 3 months old. I don't think they do well with heavy use.

 

Admittedly it was not helped by a relative letting their 2 year old go in it.

 

Would people not expect you to change the water every time there are new guests? That will cause a lot of work.

 

I looked into one for our new house and decided they were too much hassle. Even relative to a swimming pool, the constant warm temperature of the water makes it very easy for bacteria to grow in them.

Edited by AliG
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@AndyT was telling me of Sunamps being specifically used to store heat from hot tubs between guests at I think big "Centreparc" type establishments if I recall. 

 

Having stayed at CP etc myself a good few times you have to be out by say 10am with new guests coming in at say 3pm or whatever. Arriving you expect the hot tub to be ready for you from the off. In those 5 unoccupied hours you don't really want to waste that heat so they pump it through a Sunamp to grab the heat. I presume the process is reversed and clean water run back through to heat up just before the new guests arrive.

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2 hours ago, Onoff said:

@AndyT was telling me of Sunamps being specifically used to store heat from hot tubs between guests at I think big "Centreparc" type establishments if I recall. 

 

Having stayed at CP etc myself a good few times you have to be out by say 10am with new guests coming in at say 3pm or whatever. Arriving you expect the hot tub to be ready for you from the off. In those 5 unoccupied hours you don't really want to waste that heat so they pump it through a Sunamp to grab the heat. I presume the process is reversed and clean water run back through to heat up just before the new guests arrive.

Yup. Spoke to andy about that too. They're a good product for recovering heat that would otherwise be lost, and the refill flow rate for those types of cells are better than any combi or inline electric heater could ever dream of being. 

The limit with the SA units seems to be imagination.

 

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9 hours ago, Nickfromwales said:

I can't see it being cost effective in that scenario but I'll be happy to be corrected. 

 

 

I wonder if, with careful positioning of the Sunamp unit in relation to combined, insulated waste water pipework they could include a "waste water loop"?

 

 

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It would probably have to be a pumped circuit with the waste water heat being gleaned to a heat exchanger. You couldn't have the cells wide open to free flowing water as they're then lose whatever heat they collected as quick as they gained it. You'd effectively be adding a chimney to it, hence why WWHR units only allow you to immediately consume what they produce. 

Waste heat from combustion would be a winner, reclaiming flue gas heat etc. 

Boiler Plus ( +? ) is coming to England iirc where some sort of energy efficiency must feature in every install. Flue gas heat recovery being one, Internet / wifi smart controls being another. Haven't read up too much on it yet though. 

 

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Installer magazine has a half-decent summary. To summarise the summary of the summary:

 

It will require a new minimum performance standard of 92% ErP, and will require people fitting new boilers to include one of the following in the system:

  • Flue gas heat recovery systems
  • Weather Compensation
  • Load Compensation
  • Smart controls featuring automation and optimisation functions

Plus another £3.6 billion of investment in Energy Company Obligation (ECO).

Edited by richi
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20 minutes ago, SteamyTea said:

Is the concept behind condensing boilers really just flue heat recovery?

Even with condensing some heat still gets through. 

How fitting a smart controller to your boiler will make you house retain more heat is beyond me. 

Modern controls which have been good enough up until now are accurate enough. I don't ever need to turn mine on or off or monitor its performance whilst jet-skiing in the Sahara.  

And anyone here ever try getting an OEM Weather Comp to ACTUALLY bloody work ? I gave up on Vaillant, after they talked me through it on the phone and told me where to locate the external unit. Then the customer had Vaillant come out and he said "what idiot told you to put the external unit there, it'll never work?!?" to which he replied "you idiots, that's who!"    

 

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