November 2008 Temperatures

[Gixer]

It's early November and I'm surprised how well the panels are doing. I'm getting around 35 deg on a 550Ltr tank with an E/W system.
Looking at how low the sun is with the fact it's hardly striking my E/W panels I'm amaised at the results.
You guys with true South faciing systems must be doing well with all this sun, even if it is low powered.

Hopefully when my 300Ltr tank is finally installed my temps will go up accordingly.

Darren

[dhaslam]

Does the large tank not even things out by storing some heat from the previous day?      I am hoping to install my two panels 60 tubes as you have in the week after next.     I the sun direction  sun at midday, or at least 1 minute past twelve when I remembered.     It is very close to south.   

[Gixer]

Hi, my tank cools between water use and standing overnight to around 16deg by the morning.

I made a 500+Ltr tank on the general advice of 5lts per tube. I have 100 tubes so 500Ltr tank.
However, this advice is generally given for South facing tubes which after watching my temps over the last few months is a bit ambitious for an E/W system. It is said that E/W looses about 80%  over a full South facing system.

80% of 500 is 400Lts. So I need a 400Ltr tanks then. I could just reduce the amount of water in my current tank. But there are other problems so I just bought a 300Ltr Unvented tank Instead.
Excess summer heat will be directed into our wet room underfloor heating.
I'm hoping this will be a good all round solution for us, have to wait and see !!

Darren

[countryboy37]

With regards October temperatures.I am reading with interest and  admiration of the favourable results. I am new to this activity, as I have only set up and started my system on 1 September.Unfortunately I do not seem to obtain such favourable results to date. My setup is : 206 litres Navitron tank, TDC2 controller and 2x20 47mm. tubes.
I have recorded the daily heat input and according the TDC2, during October the system contributed 265 KWh energy.The best day, on 8 October the input was 14 KWh, the average daily input was about 7 KWh and the worst input was on 23 October  just 2 KWh.
I am located in the West Midlands, the 40 degree tied roof is facing almost due South. The 10 mm flow and return pipes are well insulated and both are 8 metres long.
The controller set as follows: Tmin: 20 degrees, Tmax: 74 degrees, T R1: 11 degrees.
At 19.46 this evening the S1 reading is 10 degrees, S2 reading is 16 degrees. S3 reading is 68 degrees. As it has been another miserable drizzly day, the heat input is 0.
Any suggestion to improve my situation would be most welcome. Mike.

[Ivan]

Hope you don't mind, I've shifted your message to a new 'November' topic, given that we are now in November. You'll notice first of all the absence of posts for November - mainly due to the fact that temperatures are nothing to shout about.

For the record, on good sunny days in November, I've managed 35-40C at bottom of cylinder, but I've probably also had the woodstove on, which means the top 2/3 will have been heated the evening before. On bad days - which seems to be most of them so far - I've managed around 24C on most days, as I normally get a little solar input at some time during the day. A couple of days have been so dark I haven't had any solar gain, in which case BofC temp is merely 13C.

To answer your question. First, you have an immersion or boiler on so you're heating the top of your cylinder to 68C (a bit on the high side), so you can't easily see what your solar input has been - that's pretty typical at this time of year, as you can't rely on solar in November. Second point, is that the bottom temperature will drop to attic header tank temperature as soon as you have enough cold water enter the tank. Third point - Your panel will cool down in the evening. At 7.45pm, the sun has been down for a few hours (assuming it was ever up!), and so the panel has had plenty of time to cool - so don't expect a high temperature at this time.

Paul is heating c.75litres at the top of his cylinder with 30 tubes (2.5litres/tube), mine was recently upgraded to 70 tubes heating 260litres (3.7litres/tube)

I wouldn't worry - your system is probably performing fine - 14kWh/day in early October is very respectable. The only way I can see you could significantly improve on this is to move south - say Cornwall!!

[langstroth2]

For comparison, these are my figures for 19/11/08, when we finally saw that yellow ball in the sky for once:

Ave cylinder temp 8am: 23.6 (Panel at 7.9C, air temp 7.2C)
Ave cylinder temp 2pm: 32.0 (Panel at 36.3C, air temp 12.6C)
Gain: 8.4C

Bit crude this calc I know, but roughly:
Total of ~3 hr pump operation therefor input approx 0.52 Kw/hr ave.

System: 20 tubes, 160L, 8M pipe runs in 10mm, faces due South, some shading of panel around 2-3pm this time of year.
Going on recommendation from this forum my system could probably do with 10 more tubes, but still, today will mean a little less heat input from boiler, so it all helps.

[StBarnabas]

Hi

last sunday the bottom of my 230 litre tank was at 54 degrees (s2) at about 4:00pm. Mid way up the tank is normally  heated by an air source heat pump (Trianco) but that was temporally out of action so using an immersion heater on economy 7.  I have a 40 tube system on a 50 degree roof pitch pointing 10 degrees west of south. (Installed April) I am in Northumberland. It does work when the sun shines! Air source pump now back in action and as my ground source heat pump was commissioned on Monday I will watch my electricity bill with interest over the winter.

StB
P.S. Can anyone suggest a reasonably priced data logger? I have an Efergy power metre but would like something like my Omega temperature/Humidity Data logger which records every 1/2 hour for the best part of a year (about the size of a memory stick) connects to the USB and has a circular buffer.....

[Ivan]

Today was cloudless (but very cold first thing) until about 2pm.

We haven't heated the hot water tank for several days, and was definitely only just warm enough for a shower last night. By mid afternoon, the bottom of tank had reached 40C. Typically, over the last week or so, I've seen 34-36 if we get some sunshine, and 25 if it's overcast.

The SFG air heater panel was belting out hot air, with it's new super-duper high power fan, and did so from around 10am CONTINUOUSLY until around 2.30pm, when I turned it off (it's in the house shadow after 2pm). It raised the room temperture from 19C to 22C - and it's a large room.

[Billy]

Ivan,


"The SFG air heater panel was belting out hot air, with it's new super-duper high power fan,"

Can't find any reference to this, what is it, sound nice!

Billy the Barge

 

[Ivan]

It's designed as a direct air heating evacuated tube solar panel - it produces copious amounts of warm air when the sun is shining, regardless of outside air temperature - ideal for frosty mornings, but will also produce some heat even in overcast weather. I've been testing one for a month or so now, and I'm pretty impressed. Obviously you couldn't use it as a sole source of heat, but it's great for reducing fuel usage.

There's a picture of the installation in this thread: http://www.navitron.org.uk/forum/index.php/topic,4961.0.html

We'll be installing a double-SFG Air heater on the Navitron showroom this week.

[Billy]

Thanks, Ivan

v interesting

[Paulh_Boats]

Ivan,

I fancy an SFG heater - now many pesos (less VAT  )?

They look like a standard panel but with 50mm connections instead of 22mm, a clever modification that could work very well. Our house faces south east so we would get early morning heat, just when its needed.

But what happens in summer when the tubes get up to 200C?

-Paul

[Ivan]

Can't remember offhand. Approximately £400 incl the vat (of course vat's come down a bit). We've got 20 panels arriving in the next 4 weeks or so, assuming we've got space in the container.

Mine has been performing well on these frosty, sunny mornings.

I'll let you know what happens when summer comes. I don't think that far ahead! I suspect I can just turn off the fan, and let it stagnate. It doesn't seem to convect.

It's very different from an SFB. It has two compartments inside the manifold, and two ports for each tube - one which seals on the outer edge of the glass, and another that seals on a silicone fitting on the end of a stainless steel tube which is inserted into the glass tube. It's quite a complex design. It's not as well insulated as the SFB due to the size of both compartments. We couldn't do this without making the header too big.