ok.. skint student here looking for advice,

the landlord has told us itl be cheaper if we kept the heating on all the time on a low temperature rather than putting it on a higher temperature for a 2 hour blast each evening?

im not entirely sure what to believe… so any advice?

a few of the other guys in the house are having issues with mould growing on the walls…

If you’ve got mould growing, having the heating on all the time should help to dry the house out (and therefore inhibit the mould). Depending on how hard the heating has to work to warm the house up, I’m not convinced that leaving the heating on all the time will be cheaper though.

Definately wont be cheaper leaving it on all the time. It will however sort out the mould problem, combined with gentle ventilation.

The mould also needs to be scrubbed with anti fungal mould solution, get some from b&q or wilkinsons, poss supermarket too

you are getting mould because your walls are damp.

your walls are damp because the warm(ish) humid air is condensing on the cold walls.

the walls in your house are almost certainly not insulated, and have been plastered with cement based plaster.
originally lime-based plaster would have been used – this ‘breathes’ – allowing air/moisture to slowly move through it.

the warmer you try to get your house, the more condensation will form on the walls.

remember, the walls are not insulated, you cannot warm them up because they are connected to a very deep heatsink – the outside world.

just turning the heating up will not dry the house, because the walls will always be at a temperature somewhere between the inside and outside.

unless you get them insulated.

or re-plastered with a breathable plaster

There is a school of thought that suggests it being cheaper to run low heat all day as it maintains warmth in the fabric of the building and you are not starting from scratch every day. Our house is also badly insulated so you get some mould in the rooms upstairs. As suggested above, the best way to stay on top of that is heating and ventilation.

Having the heatiing on sot he temperature doesnt drop below say 15deg all day wont cost more than a few pennies, combine that with a window left on the latch (only realy needs to eb one inthe whole house to be effective, pick one where you can leave a door to that room ajar so that air can circulate throught he house and out the window, e.g. a spare room.

Basicly you need to have the heating on more than you do, and some ventilation. Otherwise the landlord would eb well within his rights to withold a deposit to put right issues caused by condensation (e.g. mould).

Yes heating is expensive, about £400 a year to do a 2 bed house, and most of that will be over the winter, but break it down further and its probably only a tiny fraction of what your paying in rent, spit 3 ways its what 20-30p a day to live as you are, 30-40p not to have mould on your walls and be nice and warm into the bargain? And you’d be supprised what uses more, you probably spend more on hot water for your shower than you do heating your hosue, especialy if theres more of you in the house than average.

ahwiles is partialy correct,
if you increace temeprature the relative humidity (% water in the air relative tot he max it can contain, warm air can hold more water for example at 100deg C at sea level it can be 100% water otherwise known as steam) drops, but the absolute humitidy (grams per m3 of air) remains the same obviously.

Now if you have some ventilation to your house (e.g. the window mentioned earlier) your drawing cold air in, reducing its relative humidity as it warms up, so it wont condense on the walls after all it wasn’t condensing outside which will been colde).

What causes the moisture in the house is infact you. burning gas is ch4 + 2o2 -> 2h20 + co2, drying your clothes, having a shower, and just breathing all produce lots of water vapour, which brings up the relative humidity to the point where at the walls where it cools down it condenses and produces condensation.

the warmer you try to get your house, the more condensation will form on the walls.

It depends… My folks have got an old cottage. 2′ thick stone walls and no insulation. To avoid condensation they heat the place. Keep it warm all the time and the walls will stay warm. No condensation.

If they heated the place in short sharp blasts then the walls would cool down and condensation would form.

Another top tip… to avoid your expensive cotswold stone roof slates from freezing and disintegrating don’t insulate your attic. You keep the tiles nice and warm and they don’t freeze.

None of the above is a cheap solution.

and i’m betting that the walls in your parent’s house are plastered with lime-based plaster which breathes.

warm house + cold walls + cement based plaster = condensation + mould

And when repainting the mouldy walls, use exterior grade emulsion. It’s got anti mould stuff in it and…. no more mould.

Get rid of the mould as it could provoke health problems. I believe my asthma was caused by a mouldy environment.

My housemate Chris knows all about this stuff and he reckons that keeping it low all the time is just a teeny bit more expensive than having it come on in shorts bursts in the morning and afternoon. Which is fine by me it’s toasty. 🙂 we live in old three bed semi if that makes a difference.

thisisnotaspoon – Member

Having the heatiing on sot he temperature doesnt drop below say 15deg all day wont cost more than a few pennies …

… would cost me a fortune.

i live in an old house, with cold walls and cement based plaster all over the place.

if if leave the heating on all day, i can just about get it up to 14degrees.

totally house dependent, but it might be worth trying it for a couple of weeks or a month… the mould wont go away without extra help as suggested above with cleaners, but just see how the house feels. Do you usual couple of hours a day heating, and check consumption on the meter, then put heating on low all day and check after a few days (i.e. once house walls etc… are up to temp) do the same consumption check over a few days.

probably worth it in a new house with high thermal value and excellent insulation
Given mold you probably live in a draughty old house.
How long does it stay hot for after you switch the heating off – the shorter this is the worse your insulation.
It will cost loads based on what is said here.

Having the heatiing on sot he temperature doesnt drop below say 15deg all day wont cost more than a few pennies, combine that with a window left on the latch (only realy needs to eb one inthe whole house to be effective

A boiler that is running will consume considerable amounts of energy. So leaving the heating on all day will use considerably more gas than running it for a 2 hour period each night!

I would install a programmable 3 event/day 7 day timer. Knock the chill off in the morning for half an hour and them have a couple of phases in the evening.

Condensation is not the same as damp. If there is a damp problem (ingress of moisture from outside the property), your landlord needs to sort it out as no amount of ventilation will get rid of this. Living in a damp property is not good for your health.

In winter humid air condenses on cold walls. If you have condensation issues, have a think about what is causing this. Bedrooms need ventillating for a period after being slept in. Bathroom – do certain individuals leave sodden wet towels out to dry? Try flannelling off and then using the towel. That way most of the moisture goes down the plug hole and not into the towel, onlyto later evaporate into the property. When you cook, ventilate the room. Washing, air/dry clothes in a room shut off from the rest of the house and leave a window open.

Leaving your heating on will cost a fortune. If you don’t believe me, take a gas meter reading for both scenarios and then do the maths. It’s a no brainer – heating off uses much less energy.

As a student, I don’t know why you are worrying about this. Use the library if you want to study and keep warm.

Having the heatiing on sot he temperature doesnt drop below say 15deg all day wont cost more than a few pennies,

Wouldn’t cost me anything, over the last few days our house hasn’t dropped below 16 degrees during the 12 hour stints between “on” times for our heating, and it’s been -5 outside. And it’s an old-ish house.

Ultimately the heat loss from the house (and so power required) is proportional to the temperature difference across the walls (conduction and convection are proportional on a temp difference among other variables, radiation is related to absolute temp so also higher=more loss). The higher the temp inside, the more heat you lose. There’s a slight lag factor introduced by the fabric of the house warming up, meaning it still feels a bit cold when the air temp is fine, but once up to temp that heat is stored and given back when you turn the heating off/down again – so you can turn it off earlier without the house dropping to freezing instantly.

Another one here with some mould problems (spent the afternoon cleaning it off walls behind our wardrobes).

Would using a dehumidifier help sort the problem out?

Mould behind wardrobes is a key symptom of condensation.

Dehumidifier yes, if normal ventilation doesn’t cure the problem.

if normal ventilation doesn’t cure the problem.

Tried opening windows, but of course that really doesn’t work in this weather. Always try to keep doors shut when using the shower (with bathroom window open) then open all doors after showers (once steam has gone) to try to get a good ventilation going.

There was water droplets/wet to touch yesterday on some walls in our house – not helped by being in an exposed location so the end wall gets very cold.

Constantly heating and cooling anything is never good, I’d also just leave the heating on plus vent the house.

I also use a dehumid aong with exterior emulsion. We don’t get any condensation/mould problems now. The house in question is empty most of the time and we used to get water running down the walls and the ceramic floor tiles were slippery (and dangerous) when we first arrived.

Dehumid=no condensation. Exterior emulsion=no mould.

oooh there’s lots of writing on this thread.

LANDLORDS POINT of VIEW (I’m a landlord)

If any of the following are ture then you have some culpability in the mould problem.
Do you :
1) Not open windows/vent?
2) Not use the extractor fan when cooking
3) Dry your clothes on radiotors?

All these contribute to condensation.

Now tenants point of view

1) No trickle vents – if its a victorian house with double glazing this can cause mega problems so get landlord to install trrickle vents.
2) Over population – which whilst legal causes condensation so you can push more responsibility to landlord, see if you can persuade landlord to fit a positive pressure fan or a heat recovery extractor, both which will reduce or remove condesation.
3) We havent got a tumble dryer – again make landlord provide a nice condensing one or a vented one with a vent to outside.

The heating on/condesation thing is a bit of a myth I think, I have got three victorian terrace student houses all have had condesation at one time or another and it is often tenant dependant .

Now I don’t have condensation probs any more becasue I have:
1) Trickle vents
2) Positive pressure fan in one house and humidstat controlled heat recovery fans in the other two.
3) Condensing tumble dryers.
4) Cooker hoods vented to outside
5) No tolerance for those who close trickle vents or dry clothes on rads, I always photograph this when I see it.

A boiler that is running will consume considerable amounts of energy.

Heating on does not mean the boilers on, the boiler will kick in when the temp drops below 15degC, and turn off when it goes back above etc etc.

No tolerance for those who close trickle vents or dry clothes on rads, I always photograph this when I see it.

Stop taking pictures of my underwear you pervert!

Our kitchen’s in a rubbish uninsulated extension. Running a dehumidifier made a much bigger difference than trying to heat it. It was only £30 off ebay and pulls about 800w, so not outrageous to leave it on in the evenings (cooking/eating/washing up etc). The warm exhaust dries clothes a treat too.