Dehumidifier (for a conservatory)

[Bigric]

We have a 4m square conservatory on the back of our bungalow which we had put on 12 years ago . It is well made & we have had no real problems with it , other than over the years there has always been a certain amount of condensation in there on the roof sections/bars in particular , especially autumn/winter. The conservatory is on the back of the dining room , the doors to it from there are normally open all the time & there is a central heating radiator in there which is always on when the heating is on . Recently we have become concerned about the two internal corners furthest away from the bungalow as the wooden (mdf ?) window sills in these corners were showing appreciable damp penetration . Thinking it may be a leak that was the cause , we arranged for a M/C area conservatory leak/damage/repairs expert who had been recommended to us to come out to us & have a look . After 2 or 3 hours of thorough investigation , his conclusion was that there were no leaks at all & that the damp was purely down to large amounts of condensation (not helped by a number of plants in there !) .
              He recommended installing a dehumidifier which he said would make a significant difference to the problem very quickly . As the conservatory is quite large , he thought that we need a large-ish capacity dehumidifier & that we should consider continuous drainage to the outside or we would be forever emptying the water container . This is an area of technology which I know NOTHING about at all . I have looked at B & Q (all small machines) & on the John Lewis & Amazon websites , read lots & lots of reviews of different machines with different attributes , but I was wondering if ANYONE on the Forum had experience/expertise in this area & advice to offer !! Many thanks in advance , Ric

[Ditape]

I have only used one at work and that was a sizable unit and after having to empty the collection tank at least once a day we had a drain plumbed in.

[Jerry Howlett]

 :sleep:I can't help you with the big stuff but we have used the small plastic de-humidifiers in the portion of our house that is not used much during the winter.  They have to be emptied every 3 to 4 days, but are relatively cheap (even here in Italy) as well as effective.  I also have 2 in the train room which is unheated and full of card models.

Jerry

[mr bachmann]

treet your self to one , Argos for some information , around £200 or less mine is on most of the time - the water is great for the car washer bottle 
(not for the Hornby steamer though)


Alan

[johnk]

Our Conservatory is about 4 metres x 3.5 metres with a radiator on 1 wall of the Conservatory. We get  condensation on the outside wall which we successfully control with a small dehumidifier unit which is only necessary to use in winter months. In fact, we started up again in the last couple of days. Unit has been in use for about 10 years and is a small cheap plastic unit obtained from Homebase or similar.
Hope this of help. Cheers. John k

[Steve.T]

Don't forget though unless you keep the door to the conservatory shut you are dehumidifying the whole house, and then if windows are open at any time also trying to dehumidify all the fresh air entering.
If that were the case you would need a fairly large one like this.
http://www.appliancesdirect.co.uk/p/exd15dn3w/electrolux-exd15dn3w-dehumidifier?refsource=APadwords&crtag=AP&gclid=CPiC-PODisICFYHLtAodRDgAsA
They do work well but if removing a lot of moisture then they can be on the majority of the time and can use a fair bit of electricity. The above one is about £350 W, which I guess would cost about £450 to run, if it were to be on all year (Which I know it will not be).
But they do have a humidistat so do switch on and off as the room dries, hence would not be using 350W continuously anyway.

We have a shower in our bedroom and also dry a lot of laundry there so it does get damp in the colder months and we have one similar to the one above and it works really well, but when switched on I do tend to keep the bedroom door shut and it does seem to reduce the time it is switched on.

If you can I would plumb the pipe to a drain if not too difficult. Ours is just a length of clear hose, about 12mm diameter, so if you can pass it through a wall with a small hole then it can just run away to where ever.

Steve

[colpatben]

I am not sure that I can can put this simply but I will try.

The temperature at which moisture will be released from the air is called the dew point temperature.
Google Psychometric Chart but it will probably confuse and/or scare you!

Air in your home at 20°C and 50% Humidity will have a dew point of approx 14°C, so any surface at a lower temperature than 14°C will cause moisture to condense and therefore damp. Also higher humidities at the same temperature will have  higher dew points, such as during cooking, higher than average occupancy etc.

Warm air will carry more moisture (which will be produced by cooking, breathing, watering plants etc) than cold air. So in a warm room there will be no visible moisture but where this air touches a cold surfaces that is at a lower temperature than the dew point then the moisture will 'drop out' of the air and form water droplets (condensation). So it is more prominent in the winter when the outside temperature falls.

These cold surfaces will be the glazing bars particularly if metal and outside walls especially if they are uninsulated or single skin.

To remove this moisture and hence de humidify the air there are there several methods.

1) Mechanical or natural ventilation to remove the moist air before it can fall below its dew point. Leave windows open or use an extract fan. You will need to replace this air with preheated air.

2) Chemical or absorption by a hygroscopic medium, but this is a one way process so that once they have adsorbed their capacity of moisture then they need to be regenerated normally by heating and thus driving off the water and then can be reused (remember that this water when driven off so needs to be collected and disposed of outside of the affected area.

3) Reducing the temperature of the air by refrigeration within a refrigerated dryer below the dew point (say 13°C) which is how a mechanical dehumidifier works. Recirculating the air in the conservatory through its cooling unit and thereby extracting and capturing the moisture which will collect in a tray beneath the cooling unit, this has to be disposed of either by frequent emptying or piping the drain to outside the property. This cooled air will need to be reheated to maintain the normal room occupancy temperature. Links to these de humidifiers have been posted by others above.

All methods require quite a large amount of energy so there is a cost implication.

[Jon898]

You say "...there has always been a certain amount of condensation in there on the roof sections/bars in particular , especially autumn/winter".  It sounds like you already have a dehumidifier...it's the cold sections of the structure. 

A mechanical dehumidifier is essentially an air conditioning unit with the condenser (hot) and evaporator (cold) coils in the same room; moisture is condensed onto the cold coil and drips down into the bucket and the hot coil warms up the room again.  Whilst a dehumidifier will reduce the humidity in the space, if the "roof sections/bars" are below the dew point of the dried air, they will still condense water vapour.  Whether they still do that when you run a dehumidifier will depend on a number of factors (outside air temperature, insulation between the outside and the inside surfaces, whether there are any "thermal bridges" between the outside and inside that defeat the insulation, how good the air circulation is in the conservatory, etc.).  It's probably worth a try as the winter air is going to be lower humidity to begin with once it's heated up to room temperature, but I'd also try to limit the amount of water vapour you are adding in the house where you can (people, pets, plants, gas appliances, cooking, showers, etc. all add moisture).

[Malc]

Just as a matter of interest Ric, is you conservatory single glazed? We had one with a glass roof and suffered as you are doing. Eventually I replaced the single thickness glass and metal glazing bars with a triple walled polycarbonate roof and plastic glazing bars. It solved the problem for me.

[Bigric]

Many , many thanks to all who have been kind enough to reply to cry for help ! I now have lots more stuff to read & digest !!! I think the big decision now is which unit to buy , although I must admit that I hadn't looked at the Argos option . Malc - the roof is polycarbonate not glass , but not sure what sort of spec/thickness though . As I said in my ramblings at the beginning of this thread , the conservatory was built in 2002 . Thanks again to one & all , Ric

[Bealman]

Just as a matter of interest Ric, is you conservatory single glazed? We had one with a glass roof and suffered as you are doing. Eventually I replaced the single thickness glass and metal glazing bars with a triple walled polycarbonate roof and plastic glazing bars. It solved the problem for me.

Living where I do we don't really have the same prob... in fact it's the cost of running the air con that is my main worry! However, that sounds like a relatively simple and effective solution, Malc.

[FeelixTC]

We have a family property by the sea (I know; I'm the luckiest man alive  )
It's a ground floor flat in a large former hotel and there is a massive cellar below us.

As it has occasional use, we used to arrive and find the place smelling quite 'musty' and there were always damp/mould patches.

A few years ago, we invested in dehumidifier, which is always left on ('smart' setting) it's plumbed to the drain, so there are no issues with it filling up. The difference is unbelievable; always smells fresh and clean, no matter how long since we were last there and no more mould/damp patches. It's the best thing we ever did to the place.

Slightly different to your situation, but I can highly recommend them; you will see a benefit

[alypar11]

An alternative may be some sort of solar powered ventilation system. As you have a conservatory it may be in a good orientation for a solar panel. Some systems warm incoming air. Try this link to get an idea (no connection)
http://www.reuk.co.uk/SolarVenti.htm
Apart from the purchase and installation it shouldn't have running costs.

[Bigric]

Many thanks to all those people who took the time to put a post on here after my initial message ! There was a lot of agonising on my part about which route to follow on solving my problem here , especially when I discovered that there were 2 different types of dehumidifier that each worked in a completely different way than the other ! In the end  , I opted to go down the dessicant path & ordered an Eco Air DD122 Mk5 Classic , which seemed to get lots of good reviews from users . Awaiting delivery ! THANKS AGAIN !! Ric