WC Cistern condensation

[Subby]

Hi all. am at a call out and the customer is complaining about water on the bathroom floor under the close coupled toilet. Nothing appears to be leaking but the Cistern is dripping with condensation. what can I do about this? The bathroom has bath,shower over bath and.is.quite small with no extractor.fan but has openable window.and is on first floor. There does not appear to be condensation elsewhere in the room. Cheers

 

[rpm]

You sure it is nothing to do with water splashing out under the lid and running down the back?

 

[Subby]

Hi.RPM. didn't check that, but can see the Cistern is covered in condensation from the bottom up to the water level and can seeing running.
I have quoted for 2 separate solutions, 1: fit extractor fan and 2: fit WC vanity. Cheers

 

[rpm]

Could be condensation, very hot room & cold water with no ventilation.

 

[CHRISX]

Hi all. am at a call out and the customer is complaining about water on the bathroom floor under the close coupled toilet. Nothing appears to be leaking but the Cistern is dripping with condensation. what can I do about this? The bathroom has bath,shower over bath and.is.quite small with no extractor.fan but has openable window.and is on first floor. There does not appear to be condensation elsewhere in the room. CheersView attachment 28366
View attachment 28367

Hello Subby,

As I am sure You know - this is caused by the temperature of the cold water in the Cistern in relation to the much higher Room temperature - the cold water is causing the external surface of the Cistern to be cold and then moisture in the Air is condensing upon the cold surface.

Apart from having seen this countless times I have a downstairs Toilet in my Home which is fed from the Mains water supply - in the late Autumn / Winter the Mains water coming in is only a few degrees above freezing - if we use the Toilet the water causes the Cistern surface to get cold and the natural moisture in the Air condenses onto it.

I have found that even a very powerful Extract fan will not solve this problem - in fact I have good Fans in the Main Bathroom - Kitchen and that W.C. - when we are `making moisture` - Showering - Cooking etc. the downstairs W.C. cistern drips water quite badly - even with all 3 Fans operating.

When I have encountered this problem on Cisterns that I have installed on `High Class Refurbishments` - usually Flats where the CWS is supplied from Tanks on a Roof [Flat roof] and where the CWS is almost as cold as the Mains water - the Builders have found someone to line the inside of the Cistern with waterproof sheet polystyrene [glued to the inner surface] to prevent the cold water from causing the Cistern external surface to become cold enough for moisture from the Air to condense upon it.

However I never did take the details of the people / Company [?] who did those `Fixes` with the sheet Polystyrene so I cannot let you know who / where they are located.


Sorry that I cannot be more helpful Subby - I don`t know of any other way that is within the Water Regulations in the UK.

Believe it or not - when they have exactly this problem in some States in the USA they install a `mixing valve` which mixes just enough Hot water with the Cold supply to the Cistern to prevent the Cistern walls getting cold enough for moisture from the Air to condense - the mixing valve is specifically made for that job.

Chris

 

[CHRISX]

Hello again Subby,

Here is a Youtube video of someone in the USA gluing some `Foam` onto the internal surface of a WC cistern - I did not watch it but it must be the same principle as what I described previously regarding the sheet waterproof polystyrene:

https://youtu.be/3RQ2Y5xWRko

I think that they call the problem of condensation on WC cisterns `Toilet Sweating` or something similar - If You / other Members are interested in seeing the `mixing valve` that I mentioned in my previous message - Google should find some webpages from the U.S. about that.

Chris

 

[Plumbstar Tom]

firstly i would change that toilet seat!

Then i think your two suggestions of a fan or vanity WC are good

A fan will help but it is dependant on a lot of external factors like how much steam is produced etc. so you could fit it and the customers complains it isn't making much of a difference, as long as you make them aware

A newer WC with a lower water volume will also help but you will get that anyway from the vanity WC

 

[Chalked]

That's the ball valve side. Looks like its continuously running. Was it dripping into the pan?

 

[mache]

Couple of options from You Tube.

Yoga Mat method.
https://www.youtube.com/watch?v=Y-CmiUw5N-U

Expanding Foam art
https://www.youtube.com/watch?v=nF0MtISF01k

 

[kay-jay]

Pipe the bleeding thing to the hot..
It will cure it and she will always have a sparkling clean crapper

 

[Subby]

Pipe the bleeding thing to the hot..
It will cure it and she will always have a sparkling clean crapper

Lmao I did think of that! I remember when I.was.an Apprentice the lads piped up a load of cisterns in an office to the hot by mistake and a couple of months later we were called back as the drop valves had warped and we're beginning to pass

 

[WaterTight]

You could also fit a lever valve iso and tell her to turn it on, wait it for it to fill, turn it off, flush.

Cistern only full when needed. Good god I'm a genius.

 

[WaterTight]

Clever thing about this solution is you've got to be sat on or infront of the thing at least as long as it takes to fill anyway -so you can wait. And if moving a lever is such a pain in the rear you may struggle flushing it.

 

[SteveWannadoGas]

its incoming cold mains water, in a warm(ish) bathroom, right? Try feeding the WC with warmer water from a cistern, not fresh cold water from outside.

 

[CHRISX]

its incoming cold mains water, in a warm(ish) bathroom, right? Try feeding the WC with warmer water from a cistern, not fresh cold water from outside.

Hello Steve,

As You know when CWS Tanks are installed correctly they are fitted with a tight fitting lid and insulation etc. and although there should not be any Loft insulation under the Tank base the Plywood base gets quite cold from the CWS Tank water temperature and the cold temperature of the Roof space.

Even with no Insulation under the Tank base this theoretically only helps to prevent the Tank water from Freezing - personally I don`t think that it would ever cause the volume of water to become much `warmer` in Winter / Cold weather.

I know that the theory is that heat from the Home / below does `warm` the water to prevent freezing - but I have never seen any evidence of this when I have taken the temperature of the CWS Tank water.

In a Household where water is being used throughout the day - or large volumes of water are used for Showers - Baths etc. the Tank water temperature would not be much higher than the incoming Mains water.

I have measured the `Winter temperature` of CWS Tank water - in correctly fitted Tanks - it was no more than 3 or 4 degrees higher than the Mains temperature and usually only about 2 degrees higher.

Chris

 

[SteveWannadoGas]

you don`t think that water would be significantly "less cold" than the cold main running into the house?

I am guessing yes, but Id have thought at least during the night, the water useage would be very low with the cwst just topping itself up whenever the wc is used.

How about running a dhw pipe through the tank, just to take the chill off the stored water? Or running the wc off the (less chilled) cistern and having everything else direct off the mains?

Maybe I need to get a life?

 

[Last Plumber]

Dehumidifier !

 

[CHRISX]

you don`t think that water would be significantly "less cold" than the cold main running into the house?

I am guessing yes, but Id have thought at least during the night, the water useage would be very low with the cwst just topping itself up whenever the wc is used.

How about running a dhw pipe through the tank, just to take the chill off the stored water? Or running the wc off the (less chilled) cistern and having everything else direct off the mains?

Maybe I need to get a life?

Hello again Steve,

As I mentioned in my previous message I have looked into the difference in temperature between an incoming Mains water supply and the water in a CWS Tank in late Autumn / Winter - with just `average` amount of water being drawn from the Tank there was never more than a couple of degrees difference.

It would take quite a lot of `ambient Heat` acting on the Tank / volume of stored water to raise the water from the Winter Mains water temperature of probably only 2, 3 or 4 degrees to a temperature such as You are envisaging which would be `warm` enough to supply a WC Cistern and ensure that condensation would not be forming on the Cistern exterior.

Also there are Water Regulations which stipulate that CWS Tank water should not exceed a certain temperature - and the Insulation around the Tank is not only to prevent the tank water freezing but also to prevent `Heat gain` in Summer / Hot weather.

So actually causing the CWS Tank water to `warm up` in late Autumn / Winter to the kind of temperature that would mean no condensation from a WC Cistern would not be easy or desirable.

Chris

 

[Subby]

That's the ball valve side. Looks like its continuously running. Was it dripping into the pan?

Good point, didn't realise this could cause condensation.