Condensation issue in airing cupbd

[lurch]

Hi. Havent been on forum for some time.

Ive been in the industry for some years, and came across a scenario that I had not seen before. Got a call from landlord saying immersion heater not working. On inspection the thermal overload had tripped on the thermostat. Reset the trip and bingo all ok. I'm a little concerned that trip popped as this may indicate the stat is not working correctly and may swap out if it happens again.

However when I opened the cap to the immersion heater element I noticed condensation, and some water pooling. The airing cupboard has a very draughty single glazed window, and the second you open the door you can feel the temperature difference. Landlord advised that previously the cupboard never got this cold before as the lagging to the tank was nearly non-existent, and kept everything warm. 3-4 months ago a new tank was fitted with hi performace lagging.

Has anyone come across this before, and did theu do anything to resolve?

Lurch

 

[telectrix]

nail some shuttering ply over the window with expandy foam round the edges

 

[Wilko]

A different thought - condensation forms on the coldest surface in the area, and I'm thinking anything attached to the hot water tank is not going to be the coldest thing in the room (?). Any possibility of a leak?

 

[lurch]

A different thought - condensation forms on the coldest surface in the area, and I'm thinking anything attached to the hot water tank is not going to be the coldest thing in the room (?). Any possibility of a leak?

I know where your coming from, but did check and could not see a leak. I'm thinking outside of cap is exposed to cold air and inside the cap is warm air from element.

Also thinking that under normal circumstances any condensation would be burnt of by hot element in cap. Because the power was down for a couple of days this has highlighted the "issue". like I say haven't seen this before.

 

[Midwest]

I think the opposite. As the thermal overload had tripped, the immersion would of become very cold, once the tank had filled with cold water and the user realised there was no hot water.

Therefore any moist air settling on said immersion, would form condensation.

 

[lurch]

I think the opposite. As the thermal overload had tripped, the immersion would of become very cold, once the tank had filled with cold water and the user realised there was no hot water.

Therefore any moist air settling on said immersion, would form condensation.

ah! good point. always good to hear other view points!! Thanks

 

[ferg]

I believe that sometimes the pocket for the stat can become perforated and leak slightly.
Unusual though.

 

[PEG]

Airing cupboard,with a window?

I don't feel so shameful,now,for fitting a Velux on my coal-hole...

 

[I2C]

If the immersion's thermal-overload is below the set temperature using the boiler for hot-water, the client may have turned the immersion on and tripped the thermal-overload. It might be worth checking the set temperature of the hot-water-cylinder from the boiler and adjusting either as needed.

condensation forms on the coldest surface in the area

I agree with Wilko on this point. Condensation will form on a cooler surface than the ambient temperature, and the difference in that temperature between them will vary in the amount of condensation formed.

My question:- If the immersion was turned on, the conductors will warm-up (even when properly sized) and shouldn't cause condensation to build up on them?

Also distilled-water (effectively condensation) despite many opinions, isn't actually a great conductor due to the lack of impurities. Even if it was, the current passing through the condensation would cause it to heat and evaporate quickly.

However, condensation could provide an earth-fault of >30mA which could trip an RCD, but again, if the immersion is in use then it seems unlikely due to previous points.

Conclusion:
I'm not entirely sure of the cause, just providing food for thought. I think it's likely that the trip happened the moment that the immersion was turned on (rather than a while after it was on).
I would also check the set-temperatures of both the immersion and boiler-hot-water as this might be a cause.
Also, check for leaks, resulting in moisture to form.