How to prevent condensation on toilet cistern

[Anj]

Bit of an odd one...
1930s house has a toilet in an extension room at the back. It’s a room effectively cut out of a utility room.
Toilet room has no radiator or vent and is generally quite cold. But the water in the cistern is much colder and the cistern is covered in condensation. It virtually drips of the cistern so much so I though there must be a leak somewhere but there isn’t.

the owner doesn’t want to rip up the tiled floor to install under floor heating or a rad which would reduce the humidity in the room but would still need a vent added to let the humidity escape. So I’m going to suggest having a vent added to the room but I’m not sure that’s going to be enough.

I saw some folks recommend lining the cistern with insulation material (yoga mat or some foam material).

Any thoughts?

 

[Stigster]

You can buy toilet cistern lining kits to supposedly cure this common problem. However I have no experience with these myself. I have also heard of DIY solutions like lining the inside of the cistern with some insulating material like neoprene. If I was going to try that I'd try something like a thin roll-up camping mattress, cut it to size/shape and use a sealant like CT1 to bond it to the cistern walls. I have had a bit of a look around for solutions to this problem and there doesn't seem to be much out there other than lining the tank, using a drip tray under the cistern to protect the floor or an "anti-sweat valve" that seems to be used in the US but again I've not seen one here. The valve is plumbed into a hot supply pipe and mixes in some warm water as it fills. Hopefully someone will have either used one or has another method they've had success with.

 

[SimonG]

Ventilation.

Its physics.

 

[Anj]

Ventilation.

Its physics.

Thanks both for the replies.

I can stick in a vent but tbh there isn’t much point wiring to a light fitting - not the toilet gets used that much and light won’t be used in the day (room has a window).

Anyone recommend the humidistat fans? Any particular brand reliable? I can see the thing running quite a while in the winter

I’ve noticed they are drying their clothes in the utility room!! So that has to stop pronto (they even have a space for a dryer).

 

[Chuck]

As SimonG says, ventilation. Also, try to figure out the root cause of the high humidity and fix it at source. Maybe a kitchen or bathroom needs a fan fitting, maybe there is a leak or poor damp proofing.

Also, if you just stop the condensation forming on the tank with insulation without fixing the humidity, it will likely appear elsewhere and cause mould/rot.

 

[Stigster]

Ventilation.

Its physics.

Yeah, that would be the first place to look! Lining tanks and all that malarkey should be a last resort

 

[SimonG]

Yeah, that would be the first place to look! Lining tanks and all that malarkey should be a last resort

I think in the last 15 years I've only seen one WC that came with a plastic liner inside the cistern. It was like a concealed cistern within a cistern.

 

[centralheatking]

Look its obvious if the ambient air temperature one side of a surface is higher than the other side then condensation occurs on the warmer side. Internal condensation .. Its normal only exacerbated by 2x glazing and inhabitants that do not ventilate their smelly fugged up dwellings. Flush the wc with warm water if they are really in a tizz or bang in a dehumidifier ....try living in Cornwall chking
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Bit of an odd one...
1930s house has a toilet in an extension room at the back. It’s a room effectively cut out of a utility room.
Toilet room has no radiator or vent and is generally quite cold. But the water in the cistern is much colder and the cistern is covered in condensation. It virtually drips of the cistern so much so I though there must be a leak somewhere but there isn’t.

the owner doesn’t want to rip up the tiled floor to install under floor heating or a rad which would reduce the humidity in the room but would still need a vent added to let the humidity escape. So I’m going to suggest having a vent added to the room but I’m not sure that’s going to be enough.

I saw some folks recommend lining the cistern with insulation material (yoga mat or some foam material).

Any thoughts?

two passive vents ...one low level and the other high level they will not like it as it will make the room cold...centralheatking

 

[Murdoch]

Anyone recommend the humidistat fans? Any particular brand reliable? I can see the thing running quite a while in the winter

Adding a fan without any heating would be pointless. ...

 

[Anj]

Thanks all for the advice.
Looked around the place and thought there was a little gap where the outside wall meets the ground paving outside
Seems the wall was not sound behind the toilet (groundfloor toilet).
Bit of rendering on the outside wall seems to have stopped the damp coming in the toilet and now no more condensation.

No vents or fans needed.