Dehumidifiers

[MdB]

I've done small areas of limecrete next to my old walls. My tip would be to get bags of different sized Leca to make it as this way you can adjust the ratio of sizes. I wouldn't just use the 10mm stuff that it used for chimneys as it would take a lot of lime mortar to fill the gaps in between.

 

[Zebra]

There was this post a while back, which I was basing my ideas on so far.
http://www.periodproperty.co.uk/forum/viewtopic.php?f=1&t=12010&p=158240#p158240
I haven't filled my trench in yet, only because I haven't got round to hiring a mixer to do it, but I thought I'd leave it open for a while anyway to help the house to dry out.
There's also another type of lightweight aggregate made out of foamed recycled glass that is used as an insulating layer. I don't know how well it compares with clay aggregate in terms of wicking, nor whether wicking is desirable.
I have got the impression, not necessarily correctly, that limecrete floors comply with Building Regulations because the aggregate resists wicking and therefore behaves in some ways like a damp barrier. I may very well be wrong about that.
But in this case we don't want to resist wicking.
MdB, how well does your breathing trench help with evaporation of damp so it doesn't go up the walls? How long has it been since you did it?

 

[MdB]

There's also another type of lightweight aggregate made out of foamed recycled glass that is used as an insulating layer

It wasn't easily available here so I went the Leca route.

I have got the impression, not necessarily correctly, that limecrete floors comply with Building Regulations because the aggregate resists wicking and therefore behaves in some ways like a damp barrier. I may very well be wrong about that.

Yep, you're wrong. Both Leca and especially lime are good at wicking moisture. That is the whole point. It allows it to reach the surface so it can evaporate off.

If you wan't a damp barrier then use a DPM + concrete.

MdB, how well does your breathing trench help with evaporation of damp so it doesn't go up the walls? How long has it been since you did it?

It has been about two years. It is a bit difficult to tell if it has helped or not though. The wall was damp and now it isn't but I have done an awful lot of other things to help the situation as well such as removal of render and lowering outside ground levels. To be honest, I think it is the lowering of the outside ground levels which has done the most in improving the situation. However, I think I'll do a similar thing when we build the extension on the other side of the wall.

 

[Zebra]

Both Leca and especially lime are good at wicking moisture. That is the whole point. It allows it to reach the surface so it can evaporate off.
If you wan't a damp barrier then use a DPM + concrete.

Yes I know that :wink: I'd just got it from somewhere that the aggregate resists wicking. Confused me at the time, must be why I made up that story about Building Control!
Thanks for the info - so you'd do the same again, well that's encouraging. What mix did you use on top of the leca? NHL5 mixed with ballast?

 

[MdB]

My mix was 1 part NHL 3.5, 1 part sand, 1 part 0-to-04mm, 1 part 4-to-10mm, 1 part 10-20mm if I remember correctly. I had far fewer voids than you see in the central section here and was more like the top:

I'm not sure if this was a good idea or not. Probably not.

I don't have a top layer as I'm going to place large tiles on it and it is strong enough as it is.

 

[Zebra]

So it was all one layer, with the mix you describe? May I ask MdB, since I'm picking your brain! - what kind of flooring are you using on top? What kind of tiles? I realise there are many options as long as they are breathable, I'd just like some inspiration!

 

[MdB]

I realise there are many options as long as they are breathable,

Then don't ask me... I'm fitting unbreathable slate.

I umm'd and err'd about this for a while but the damp problem is cured, most likely from the other fixes so I'm going to tempt fate and slate over the concrete floor and the small amount of limecrete. If the damp comes back, I'll remove the tiles at the edge and fit something else. The limecrete is also acting as an insulator so we will still have the benefit of that.

oh, and yes it was a single layer.

 

[Zebra]

Hopefully it will be fine. Thanks for all the food for thought.
And sorry tobydog for hijacking your thread!

 

[tobydog]

Zebra - no worries. It saved me from starting a new thread. I like the idea of mixing the Leca in with the limecrete although in some areas I will have to leave the void open lower down and just cap it off because the gap becomes too small and close to the wall.

I saw from the other thread that Andrew suggested removing a section approx. 300mm by 300mm. This won't be possible with me unless I start cutting through the existing tiles which I didn't plan to do. This will leave the void at a maximum of 75mm wide by 250 - 300mm deep. This would take forever to dry hence the idea of filling the lower part with Leca alone and capping it with limecrete. There is no dpc. Any thoughts on the effectiveness of this route would be appreciated.

 

[Lime]

I thought that a follow up report might be in order.

I've been running the 2 compressor dehumidifiers for about 5 months continuously at a setting that has maintained a 35-40% humidity throughout most of the house.

~ What has changed since my last report.

The amount of collected water has reduced considerably.
From about 4 - 6 litres a day to approx 3 litres every 4 - 5 days.
That figure of 3l/4-5days has remained constant since just after Christmas.
During the cold snap (it was -12°C here) there was only a small amount of condensation on windows but it was frozen in a strip about ¾" high at the bottom of most of the single glazed windows.

The efflorescence that used to appear regularly on some tiles in the parlour floor is disappearing noticeably.

So far no damage has occurred to furniture anywhere.
Most of my furniture is oak, some centuries old, and the humidity of 35-40% would seem to be satisfactory.
No mould has formed on any furniture which used to be a problem in the past.

My conclusion is that the use of dehumidifiers has been a success.
The windows remain dry and subsequent damage to paintwork by water and mould growth has been completely eliminated throughout the house.
The house feels better to live in. It feels warmer.
I no longer notice damp days when my bones used to tell me I was old.
My breathing is better, I sneeze less and feel more healthy.

The down side.
None really so far.
The electricity the dehumidifiers consume is small and has not made any noticeable difference to our bills compared to last year.
I did have to take one of the dehumidifiers back to B&Q because it began to make a motorboat noise but it was exchanged with no quibble.

 

[tobydog]

Those are some pretty impressive numbers. Unfortunately I have to run ours at 55-60 RH because the other lower option is way too noisy and expensive to run. It's not the most economical unit and runs at 380W even for 55-60. During the recent very cold weather I gave the machine a workout and got absolutely nothing!!. The windows were also dry at night even in the bedroom. Condensation is now beginning to return again.

On the point of cost, I did get myself a plug in meter so I could track this. Being rather mean I checked this along with the mains meter and something very odd has happended. I know it has to be purely coincidence but our mains meter is running very slow. BG gave us an estimate on Dec 12 because I didn't get round to giving them an actual. To be fair the estimate was pretty close to what I would have expected the actual to be, however, the actual was way behind, a long way behind. I thought I would monitor things and, given that we are now at Feb 28, the actual meter reading has still not caught up with the Dec 12 estimate :shock: . Seimens came round on Dec 29 to do a visible check of the meter for BG but I didn't hear anything further.

I know we are going to get asked for a reading very shortly so I'll just tell it the way it is. I think I could be getting a new meter very shortly.

 

[Lime]

IME energy suppliers nearly always over estimate consumption when they do not get actual readings.
It is made worse if you had a previous owner in your house who was profligate with electricity.
In the past I regularly received over estimates and now insist that the head of the accounts department responds to my monthly meter readings with a statement.
(In response to a letter from my MP about my credit being over £2000. :shock: :shock: :roll: )
However even monthly statements go wrong sometimes when they lose the last month's figures!

 

[MdB]

I know we are going to get asked for a reading very shortly so I'll just tell it the way it is. I think I could be getting a new meter very shortly.

Don't be surprised if you don't.

At my old work, the meter stopped working but it was something like 6 months before the meter got replaced after they had two readings with the same value. I guess we got free electricity for 9 months / a year.

 

[Lime]

During the recent very cold weather I gave the machine a workout and got absolutely nothing!!. The windows were also dry at night even in the bedroom. Condensation is now beginning to return again.

That may be because you didn't have anything to collect... as your windows were testament to the fact.

I read several revues before I bought my dehumidifiers and a couple stated that their dehumidifier appeared to stop working after a while, i.e. collect very little.
I could think that too if I didn't know what the humidity levels in my house were.
If you recall I said I have an hygrometer which I find invaluable for checking around the house and testing the effectiveness (or not) of the dehumidifiers.
(I think I gave a link to one in an earlier post)
I would not be without it, otherwise I might be convinced that my humidifiers had stopped working too.

 

[Flyfisher]

That sounds very impressive, Lime. Would you mind posting the make/model of your dehumidifier as I think I'd like to get one. Or PM me if you don't wish to advertise.

I have a couple of max/min hygrometers and over the past month they've recorded 80-95% RH in the unheated part of our house.

Also, unfortunately, we had an upstairs pipe burst a couple of weeks ago, which resulted in a lot of water soaking through our drawing room ceiling. Thankfully the ceiling itself is holding up well (literally!), although the paper is now peeling off. As long as the ceiling dries OK this will be no big deal as the room needs complete decoration anyway.

For those wondering how I could be so daft about not turning off the water into the unheated part of the house over winter - and especially during the recent very cold snap - all I can say is that I did. And I drained it. As I do every winter, because the temporary pushfit pipework in question freezes every winter and pushes open a joint where the water can't be drained, as you'd expect in an unheated room when the temperature falls to -2C inside.

No, the problem was nothing to do with not turning off/draining the water before the cold weather, but was everything to do with the water being turned back on without first checking if the cold weather had burst the pipework. :roll:

My only consolation is that the deed was not of my doing, but that makes precious little difference to the inevitable result.

So now would seem to be a good time to invest in a dehumidifier for some gentle assistance to the drying-out process.

 

[tobydog]

If my next post on the subject of meters comes from an address starting HMP you'll know BG didn't believe my story!!

On the issue of the estimate, I calculated what I thought it should have been and BG were very close so I'm still concerned. Looking forward to free electricity for a while though. Maybe it's divine intervention because I have thatched house and couldn't fit PV panels

On the issue of humidity, my concern was that the machine ran for two hours and delivered nothing. According to the manual it should have stopped when it reached the required level (55-60). I guessed the level was well below 55-60 because of the windows but just thought I'd try it out. Maybe the machine has an issue.

 

[Lime]

That sounds very impressive, Lime. Would you mind posting the make/model of your dehumidifier as I think I'd like to get one. Or PM me if you don't wish to advertise.

That present me with a problem because the dehumidifiers I purchased are not the same as the ones advertised online @ B&Q.
They appear to be old stock but my local B&Q still have dozens of them.
http://www.dooyoo.co.uk/small-kitchen-electrical/b-q-compact-dehumidifier-wdh-610ha/

On the issue of humidity, my concern was that the machine ran for two hours and delivered nothing. According to the manual it should have stopped when it reached the required level (55-60). I guessed the level was well below 55-60 because of the windows but just thought I'd try it out. Maybe the machine has an issue.

I would take no notice whatsoever of what the control suggests the humidity may be, almost certainly it will not correspond to reality.
Your windows were almost dry in cold conditions which must tell you the humidity at that time was low regardless of the machine's settings.
Once again without a hygrometer I wouldn't know where I was either.

 

[tobydog]

After being encouraged by Lime yesterday, I used the unit in the old kitchen last night on the lowest setting (I think it was 40-45 or 45-50 RH). This is where I have exposed the soleplate and brick plinth and the brick is still very damp. It sucked out about one litre an hour and a half. I had to close the door due to the noise but the plug in meter didn't register too much over this time. Hopefully the main meter was still going backwards in real terms . I'll do this each night during the early spring to try and dry out the wall quicker. It should also draw moisture from the rest of the house as well.