DIY Doctor

Damp Issues in Older Property and Dehumidifer Servicing Advice

Postby tokenwelshman » Thu Mar 19, 2020 11:28 am

Hi

New forum member, so be gentle...

I live in an old cottage - mid 1800s. Thick stone walls and solid floor, apart from a relatively recent extension. Somebody involved in its renovation several decades ago said to me "it was always a damp little place, that". Sure enough we have problems with black mould, around windows and behind furniture. No obvious leaks. Double glazing although not exactly air tight in all cases.

I recently picked up a second hand commercial dehumidifier - a Koolbreeze Arizona. Seems a powerful unit, makes a noise like a plane taking off, extracts a fair bit of water. It also displays current humidity levels.

I have a few questions, any help very gratefully received.

1 - does anybody know where I could get this unit serviced and/or repaired, in the North Wales / Cheshire area? I contacted the manufacturer and they weren't able to help.

2 - before I switch the unit on, it is usually registering humidity levels of mid 60s / low 70s. I know this is too high. When I switch on, if in a room with the door closed the unit will quickly get the level down to high 40s. With all interior doors open, it's a slower process, but it gets the level down to around 50%. However, when I switch off, the humidity level very rapidly rises again, according to the Arizona's display, returning to the high 60s / low 70s within half an hour. Question - is this normal for domestic humidity levels - would you expect it to rise again so rapidly once the dehumidier is off? (Exterior doors and windows all shut.) Or is it possible the Arizona's sensor is too sensitive / faulty?

Thanks in advance,

Aaron
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Postby ericmark » Thu Mar 19, 2020 5:40 pm

Relative humidity is related to temperature, so figures mean nothing without the temperature as well.

Father-in-law triple glazing, gas cooking looking at 80% at 20°C same design of house only real change was electric cooking and 65% at 20°C, mother house with vents everywhere 55% at 20°C this house three floors bedroom 46% at 21°C living room 44% at 19.1°C.

I would say reason why this house is drier and utility room window left open with tumble drier pipe out the window, so air drawn in from outside, use an induction hob so no moisture burning gas, and has a chimney even if blocked with board still some ventilation.

To dry things you want cold air into the house, the colder the air the less moisture it can hold, but also removing damp air without circulating first, stand in the bath with glass panels to stop water escaping to have a shower and there is a massive hole below the panel where bath is and above, as panels don't touch the ceiling so during the shower the air circulates in at bottom out at top so whole room is damp.

However shower with a shower tray and at the bottom the glass doors are nearly sealed, so air does not circulate and water condenses onto shower tray. Even with mothers wet room air did not circulate as no curtain to create the chimney effect.

A cooker hood is really required with gas cooking, but with an induction hob with auto boil then simmer, far less moisture is produced.

In the summer our AC pipe is connected to the chimney so don't need windows open, so any condensate has to be collected and emptied, I would say around 4 litres a day is removed by the AC, this is in a reasonable dry house, so you can consider first 4 litres as normal, only after that are you really drying the place out.

So in general 65% is around normal for a house cooking with gas at 20°C and 4 people living there when using showers with curtains.

Replace shower curtain with a door which seals top or bottom and that really reduces the moisture in house, put an extractor above shower also helps, extractor above cooker helps, don't use gas to cook with, and ensure you draw in fresh air.

You could look at a heat recovery unit if house well sealed.

I did look for a refrigeration guy in North Wales, they had a minimum charge of £60 and the freezer only cost me £100 so felt not worth it.
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Postby tokenwelshman » Fri Mar 20, 2020 8:08 am

Hi

Thanks for such a comprehensive answer, really interesting.

Temperature is probably around 20 degrees, less during the daytime. During my current enforced period of working from home I've had the heating off and if not raining I've had windows open.

We have an electric cooker, and no tumble drier, clothes get dried outside. Extractor fan in the kitchen needs repairing so that's something to get on with.

Downstairs shower is in its own little room, open window lets all the steam out. Upstairs shower more of an issue, it's over the bath and just a normal shower curtain. That won't be helping, then.

I ran the dehumidifier yesterday morning and it extracted about a litre and a half of water. Sounds like you're saying that's fairly normal too.

Thanks

Aaron
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Postby ericmark » Fri Mar 20, 2020 11:24 pm

At moment my living room 19.1°C 41% humidity, bedroom 19.3°C 45% humidity, using a Lidi weather station. In summer when I use an air conditioning unit the humidity is a lot higher, I have found the meters can get damp inside and the remote which is in living room is designed to be outside in a Stevenson screen or similar, but I just put it on window sill.

It started reading 100% and I thought it was ruined, however it did dry out again and start giving reasonable readings, but only sure way is a wet/dry thermometer.

So the question is how much can you trust the meter on your de-humidifier? Once damp they take time to dry out, I had a old pop bottle in a bowl so if it did over flow would be caught in bowl, and empting once a day never did over flow, but got close, and this is on an AC not a de-humidifier so it would seem your not really that damp.
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