Tender plant jottings

I take a different view which is that condensation tells you that the air near the glass became 100% humid. That doesn't translate into what the rest of the air mass is ... but your humidity meter is obviously saying its saturated.

I wonder whether dehumidifying it is actually going to achieve the effect you want, or whether its pretty much impossible in a garden room full of plants (no idea, just thinking out loud).

I think my Recording Logger is duff (electronics not as waterproof as the manufacturer promised :( ) otherwise I would put it in my conservatory for a week and report back, but here are two recordings from my Greenhouse (clearly cold, and wet!) from last winter and spring. I don't appear to have any recordings from my conservatory for comparison, which is a pity (I have a remote temperature sensor in there and I guess I never put the Logger in there as I wasn't interested, at the time, about Humidity :( )

Jan 2013


Apr 2013

 

That's a fair point Kristen - and needed verifying. So today I taped the temperature element of one of my sensors to the inside of the roof, at a time when it was little more than freezing outside. After an hour it was recording a temperature only about 0.5C less than in the middle of the room. That pleased me because if it had been a lot lower then the condensation, which is mainly on the roof, could well have been as a result of the local conditions as you said. And if it had recorded 5C rather than the 10C in the middle of the room - then a dehumidifier would have no effect, as the roof would have been virtually as cold as the dehumidifier element.

Speaking of dehumidifiers, the one I ordered arrived today. I was most impressed at a next day delivery and within the hour window that was specified in the e-mail. They even got the driver's name right too. As a scientist, I like to check these facts .

I set it up and after one and a half hours I measured the water collected as 0.17 litres. That translates into 2.7 litres an day, which is very close to the 3 litres they said. This morning I measured the condensation of the last 24 hours, which was 1.5 litres. 0.8 litres collected in a container, and then I wiped the ceiling and windows down with a couple of towels that I weighed before and after - another 0.7 kg (= litres). So, so far the dehumidifier seems to be a success and hopefully can cope. They had an interesting fact in their literature and that is - that condensation occurs at 100% humidity, but mould occurs around 68% humidity. So you can have mould without any condensation.

I was really interested in your remote logger and your graphs. I am seriously tempted
to get one and will do a bit more research. Research pays - I found graphs that said the larger dehumidifier worked no better than the smaller one at 10C. And I had that confirmed today, when I rang them. The larger one has a different compressor which is not as efficient at low temperatures.

 

Makes sense, because although I have some condensation in the conservatory it isn't "all the time" ... and without the Fan moving the air I definitely used to get moulds growing ...

The ones I have are these:
http://gardenerscorner.co.uk/forum/threads/discounted-usb-weather-station.48138/#post-619419

The Arexx ones are a remote sensor and transmitter. They don't transmit far (there is a model that transmits further ... I have that and yes it transmits further, but not as far as advertised. It has one pane of glass in the greenhouse to get through, and my double glazing, and less than 50M ... and is hit & miss. It works OK for conservatory though (its, comparatively, very close to the base station)

The other is a USB one. Plug in, download, reset and carry back to greenhouse - and remember to press the START button. So you have a bit at the start and end that is the temperature of your hand / pocket ... not a problem, but it means that you have to tidy up/sort out the data rather than just "consume" it.

In fairness I bought the cheapest I could, and there must be more sure-fire tools out there.

Herewith a graph from the Arexx gear by way of comparison [to the graph from the USB loggers above]. On reboot it usually loses the names of the sensors, and sometimes the names of the Graph elements ... I have no idea what all the other sensors are it seems to have found !



the two "spare" sensors are sat on my desk ...

You can change the Zoom on the graph from 2 hours to one year (in logarithmic-ish steps)

You can export data to delimited file, choosing a time interval (from 10 mins to 1 day) and for any date period (from first logging date, it seems, but maybe there is a way to clear down and start over periodically). It outputs a separate file for each sensors.

Logging is not possible when PC is off (well, if there is power to the USB device it will log & hold, and then "maybe" upload to PC on boot, but DOCs say there is risk of data loss on Boot uf USB is sent some sort of RESET signal - which "some" PCs do, apparently.

 

Great success this morning. I looked in my garden room to find no condensation at all - the first time ever. So I am very pleased with the dehumidifier, even though it had stopped after filling the 2 litre reservoir. However, the minimum RH has not fallen below 99% yet. That doesn't surprise me, as there were still a few remnants of moisture in the difficult to reach places that had never been dried manually. The dehumidifier has already removed 2L of moisture - faster than the 1.5L rate per day that was being created, so I have no doubt that in a day or two the RH will come down - especially if I can remember to empty the reservoir twice a day!

Kristen - I have had a very useful time Googling remote loggers. Thanks for all that infomation. There are quite a few available ranging from expensive to very expensive. I then got on to 'tipping bucket' rain gauges, which I never knew existed, and then to snow gauges. All very informative.

But at the moment I am not going to do anything. If the dehumidifier works as I hope, the combination of a constant RH controlled by the hygrostat and a constant temperature controlled by the thermostat would make for a very boring graph.

If the RH will come down to 60%, then the next step would be to have a fan circulating the air to remove local areas of very high humidity.

 

Hopefully its fixed ... however (sorry!) ... temperature here climbed overnight by several degrees, if it did that up your way that might have reduced the chance of condensation for you too?

Although given you pulled 2L out of the air that sounds promising. Particularly given your earlier concern (which I shared) about how effective dehumidifier would be at lower temperatures.

That was my experience too. No idea why, the 1-wire sensor components (for example) are cheap as chips. In fact they ARE chips!

I have a weather station with one of them. Spiders nest in it and then it doesn't tip :( If you are interested the Fine Offset brand (rebadged as a variety of things, usually a Watson) come up for about £60 when On Offer (currently on offer at Maplins). Its a full weather station with remote logger and download to PC (when it is on). Cheap and Cheerful, so some caveats apply, but I like mine. Coupled with freebie Cumulus software (much better than the bundled one) it uploads to Wunderground, and I tend to find that I now check that, rather than the local display!

Some details in this thread:
http://gardenerscorner.co.uk/forum/threads/jwks-tropical-border.36017/page-3#post-459026

Maplins offer:
http://www.maplin.co.uk/p/black-usb-wireless-touchscreen-weather-forecaster-n96gy

Sorry if you stumbled over that already when "researching" earlier.

I reckon the money you have spent on Dehumidifier was better spent than spending money on gadgets to diagnose the problem. Me - I like gadgets though!