Feb 19th 2009
Temperatures have improved this week. 7 degrees C today.
Sun was shining. 9am and the bathroom seemed to be full of warm fresh air.
We have gas fired central heating. Gas is currently 7p per KWh of energy.
If the Solarventi solar panel produces 500w heat energy per hour, that's potentially 3.5p per hour saved.
But more than that, the lower humidity might reduce dust mite activity, mould in the bathroom and apparently water moisture is expensive to heat, so a less humid house is cheaper to heat. SolarVenti UK link
Thursday, 19 February 2009
Friday, 13 February 2009
Snow blanket
Photos, both taken Friday 13th Feb 2009. 9 am.
Peterborough had more snow fall last night. And temperatures dropped to -1 perhaps -2.
On the driveway, a car has a snow blanket, which has frozen, then started to thaw.
(The cotton blanket at the bottom of the windscreen just protects the wipers and spray jets overnight)
The same morning, 9am the solar panel is warming up.
Another dry (cold) sunny day in prospect. 
By this time of year, the sun is now high enough by 9am to ensure the shadow from the house next door does not cover the panel.
If you are contemplating solar panels on your house, even if the neighbouring houses are close, (approx. 8 metres apart in this case) the angle of the sun is enough to reach a well positioned panel.
In this case the panel is not vertically attached to the wall, but it's approx. 30 degrees from the vertical on a pair of aluminium stands. I understand these would normally be used if siting the panel on a tile roof, but here they serve well to maximise the exposure to the sun at this time of year.
Sunday, 8 February 2009
Winter sunshine - Feb 2009
Sunday 8th Feb 2009.
This week we have had 3 days of sunshine and glorious blue sky, and other days snow showers.
The media refer to this past week as the big freeze in the UK.
Southern counties have had more snow than usual that is true. But Tuesday, Wednesday and Saturday were beautiful days.
I made myself a nuisance on Tues, & Wed calling home to ask my wife to turn the fan speed up on the Solarventi controller. Saturday was such a lovely crisp bright day. I had a driveway to clear of snow, again.
Of course, such days are dry, and should be "tailor made" for the solarventi solar panel that is stuck on the side of the house. The dry air, and bright sunshine (the outside temperature rose to about 3 degrees C) caused the unit's fan to kick into action from 9am onwards, even though the sun was still low in the sky.
I monitored the humidity in the bathroom, it fell to 34%, (from a house norm of 55-60%) and the temperature in there held above 22 degrees C. (I should point out that the central heating is set at 20.) I guess that means the room was being dried effectively. Certainly all windows upstairs lost their usual inside surface moisture.
The solarventi panel and fan was working at full blast as far as I could tell. The controller was set to full fan speed. Whilst the sunshine was bright, so the unit worked, until 3pm, where the sun is too low this time of year.
The wall is South South-East facing, i.e. slightly east of due south, so it will do better in the morning, as the days get longer.
One point I should make is that the unit has produced an vague odour since installation (3 weeks ago now), but it's now diminishing. My wife describes it as smelly socks. I guess it is like a new car smell. It wears off eventually.
This week we have had 3 days of sunshine and glorious blue sky, and other days snow showers.
The media refer to this past week as the big freeze in the UK.
Southern counties have had more snow than usual that is true. But Tuesday, Wednesday and Saturday were beautiful days.
I made myself a nuisance on Tues, & Wed calling home to ask my wife to turn the fan speed up on the Solarventi controller. Saturday was such a lovely crisp bright day. I had a driveway to clear of snow, again.
Of course, such days are dry, and should be "tailor made" for the solarventi solar panel that is stuck on the side of the house. The dry air, and bright sunshine (the outside temperature rose to about 3 degrees C) caused the unit's fan to kick into action from 9am onwards, even though the sun was still low in the sky.
I monitored the humidity in the bathroom, it fell to 34%, (from a house norm of 55-60%) and the temperature in there held above 22 degrees C. (I should point out that the central heating is set at 20.) I guess that means the room was being dried effectively. Certainly all windows upstairs lost their usual inside surface moisture.
The solarventi panel and fan was working at full blast as far as I could tell. The controller was set to full fan speed. Whilst the sunshine was bright, so the unit worked, until 3pm, where the sun is too low this time of year.
The wall is South South-East facing, i.e. slightly east of due south, so it will do better in the morning, as the days get longer.
One point I should make is that the unit has produced an vague odour since installation (3 weeks ago now), but it's now diminishing. My wife describes it as smelly socks. I guess it is like a new car smell. It wears off eventually.
Sunday, 1 February 2009
Experimenting
Solarventi controls include fan on/off, variable fan speed, and maximum temp.
Max. Temp? That has bothered me slightly since I first read about it. (http://www.solarventi.co.uk/ has some details, UK prices etc., and http://www.solarventi.com/ has .pdf documents and further info.)
In fact, I asked the installer, from solarventi UK, to clarify was the temperature setting the minimum temperature, or the maximum that air should be vented into the property.
Answer: it is the maximum. The setting is intended for summer time, when you don’t want hot air pumped into the house. It cools itself, by blowing the air out (I think?).
It struck me that I would prefer to also have a minimum temperature setting, say 20 degrees.
That would prevent the fan starting until the air captured in the unit has been warmed to at least match the temperature in the house?
I have slightly re-evaluated my point of view. The week and a half since installation I have not been in, or there has been very little hazy sunshine at weekends. The fan makes a little effort in hazy sunshine, and cool air appeared to be pumped into the house. Virtually nothing happened it seemed to me.
Saturday, 31st January 09, with a bright clear morning, and a little time on my hands, I could see what was going on. It seemed at first that cooler air than room temperature was entering through the vent. What should I do? Think.
The outside temperature started that morning about 4 degrees C.
I thought about the controls. How can I get the air temperature I want, and the fresh air I have boasted to the wife about, at the same time, on a cold day like this? The fan was on full speed, as I had left it.
At regular intervals, I experimented with the fan speed, and checked the temperature and humidity in the bathroom, at the vent, and 50cm away from it for an idea of general room temperature.
This was the concept I developed. Number 1. You can't really estimate to what temperature the air will rise. The air actually needs to be drawn through, otherwise you won’t know if the air at the fan has risen enough, nor if it is dry air (low humidity will have the beneficial effect of drying the room).
Number 2. If that's the case, what fan speed? So I slowed the fan speed, and found the air temperature produced at the vent into the bathroom increased. I figured the air has more time to warm in the unit. I was pleased to see the hygrometer (humidity gauge and thermometer) climb to 23.1 degrees C next to the vent, (2 degrees more than room temp) humidity was 58 in the room and gradually over the morning, the vent produced air as low as 41% relative humidity.
So with the fan on full speed I was letting cooler air in, but was it dry? Not as dry as it was by lunch time, when the unit seemed to be delivering on my expectations. By this time I had moved the fan up to half speed, and sacrificed a degree in temp. for what I considered to be loads more volume of dry air pumped in.The upstairs in the house seemed fresher, but it also had a slight draft, as you would expect.
I am sorry to say lunchtime saw high cloud obscure the sun for the rest of the day.
But lesson learned, I think; when the system is struggling in early morning sun, in January, you will have to put-up with lower temperature air or turn the fan down low.
I have compromised for now and set the fan to just under half speed, for the next few days may be bright, but are forecast to be very cold.
But lesson learned, I think; when the system is struggling in early morning sun, in January, you will have to put-up with lower temperature air or turn the fan down low.
I have compromised for now and set the fan to just under half speed, for the next few days may be bright, but are forecast to be very cold.
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