September 17th, 2009

marcus 2013

Plumbed

A plumber who has done some jobs for my sister over the years took a look at my heating system tonight. The verdict; nothing wrong with the pipes, no silt in the radiators, just some fairly crappy radiator valves. Two hours and a lot of bashing with a hammer later, six out of seven radiators are red hot, the seventh (fortunately the one I least need) is slowly getting warm, and will probably be OK eventually. Total cost forty quid, as compared to the £500+ I was being quoted for power flushing or the hundred plus for chemical treatment. Apparently most power flushing is a con - it's only really needed if you go over to a condenser boiler and have to get the pipes cleared completely to avoid corroding its innards.

As you can probably imagine, this is a BIG relief!

Only problem now is that I need to leave the radiators running for a couple of days to let the valve rubbers soften, and it's actually quite warm...
Planets of Peril

Rotation period for fictional ganymede

According to Stanley Weinbaum (or rather Helen Weinbaum, who wrote most of Tidal Moon after he died) Ganymede has high tides caused by Jupiter's gravity, with peak tides every three months. To me this suggests that Ganymede is rotating just a little faster than it orbits Jupiter, and slowing towards a tidal lock.

My maths is crap, but given that Ganymede's orbital period is 7.16 days, and you would get two high tides per rotation, I'm working this out as a day of about 6.5 earth days. Anyone feel able to work this out properly?