Hottest since end of october today

[wookey]

Tank top 62C, 50l over 45C. 6hrs pump running (before 10 till almost-4). Last time we got up to 60C was 28th Oct. Feels like the dingy winter is starting to be behind us.

[Paulh_Boats]

Wookey,

What was the starting temperature? Temperature rise is the key statistic, also how big is your tank and panel?

cheers
-Paul

[dhaslam]

A full month since the shortest day makes quite a difference.   Two days ago panel was up to 51C and bottom of tank to 47C by 1.30.  Hard to calculate gain because top half  heated by immersion and centre from buffer tank at about 30C.  60 tubes 47mm and 250 litre tank.   Today was cloudy but still bottom of tank in mid 20s.   

[wookey]

Paul, true. It was sunny two days running, so start temp was much better than after a grey day. Temp rise was from 32-62 at tank-top. 34-57 at mid-tank (~50l)

See http://aleph1.co.uk/munin/wookware.org/control.wookware.org-heating.html (for next couple of days, until it scrolls off to the left :-)

40 tubes, 110l tank, side-arm PHE. (I was kind of assuming people knew this by now :-)

[Paulh_Boats]

wookey,

40 tubes! I hope you have a heat dump..... with 30 tubes and 120L we managed 92C top of tank, because I enabled the manifold protection to kick in the pump at 100C.

40 tubes is a great choice though, best excuse there is for a hot tub or swimming pool. 

-Paul

[kristen]

Wookey: just thinking about your stuck sensor at bottom-of-tank

I was thinking of having an alarm condition if the base of my tank hit 90 - if the boiler was on there would be nowhere for the heat to go.

A stuck sensor would make a bit of a horlicks of that ....

... so perhaps I need to consider all sensors in the store, and also have a special condition for any sensor repeatedly reporting 85

[CeeBee]

Wookey's "good sun day" (27th Jan 2009) worked well with my 2.1kWp PV as well (we live fairly close) 5.2kWh produced, best since 31st Oct 2008. I suppose my solar thermal must have done OK as well, but I don't monitor that - other than monthly (and possible dodgy) readouts from the Resol controller. Still intend more monitoring once round tuits become available.

[wookey]

re heat dump: No not yet(!) The provision of one will become increasingly urgent over next couple of months. It's (nearly) all software though. I just need to add a couple of relays/triacs (already bought) to control the system pump and s-plan valves, then turn them on if tank gets too hot. Planning to use some controllable rad-valves to select which rads get the dump-heat (bathroom first).

I do already have a 'turn off solar pump if tank is too hot' line in the software, so it'll just stagnate in a reversible way which should be OK.

[dhaslam]

One problem I came across is that the coil from the buffer tank only  reaches half way up the cylinder.     This means that the top half of the cylinder would  not be cooled.   I wonder if the lower coill can remove remove enough heat  or is it necessary to connect the upper coil as well.   I suppose most cylinders have a fairly similar problem when taking heat out instead of putting it in.

[StBarnabas]

11kWh solar today bottom of 230 Liter tank hp from 12 degrees to 44 degrees - though some water probably pulled off during that time. Need to put an energy meter back on my air source heat pump - it runs potentially from 2:00-4:00 pm on economy 7 and heats the tank from about midway to c 55-60.p.

Regards pulling heat out of a tank I was planning to get one with a shower coil  which I think might have been ideal. In summer however I use the excess hot water for my 4 year olds paddling pool. May resort to the dripping tap if we have a good summer and we are away on holiday.
StB