Bartimaeus

Rob was true to his word and came to find us at the visitor moorings on Tuesday.  He was with us most of the day running wires that will allow the control system to send electrical signals to the heat pump.  The original plan to control it by sending digital signals is not currently tenable because the heat pump doesn't seem to be able to communicate.  We hope that an upgrade to the firmware will allow that to work in the future.

To make the relevant connections, Rob needed to add an additional module to the PLC (programmable logic controller) which looks after a lot of the boat functions.  There was just enough room in the electrical cupboard for the extra (black) module if he moved the adjacent (blue) controller along a bit.

An added bonus of adding the new controller is that there are some further additional control outputs.  Before the upgrade we had been able to run the bilge pumps manually, but there weren't enough control lines to provide this rarely needed option.  That functionality has now been restored.

Rob also addressed another minor issue.  We have two DC-DC converters that provide 12v supplies from the 48v battery.  Previously they were wired in parallel for resilience, but this had caused problems.  When we flush the toilet, the macerator motor pulls a very high current which causes the voltage to drop momentarily.  That voltage drop can cause various controllers to restart - we used to lose control of the electric motor on the previous set up until Rob found a fix.

After the upgrades, Rob has used one of the supplies as a "domestic" supply (water pump, toilet, lights...) and the other as a "critical" supply (controllers, bilge pumps).  This has worked well for the controllers, but has made the problem more acute for some of my items using the domestic supply.  The Raspberry Pi computer and speakers were most affected.  While he was in the cupboard Rob moved my "critical" items to the other supply.

Rob spent a lot of time carefully labelling and photographing the changes he was making.  This means the job takes longer, but future changes and remote support are vastly easier.  While putting the wires in to the heat pump, he found another well labelled connector.

While trying to communicate with the heat pump, Rob had been puzzled by the fact that it started running the compressor whenever mains power was applied.  It turns out that it was shipped with this temporary link wire.  The wire was connected to the location normally connected to a timer and thermostat.  Presumably the manufacturer finds this removes a source of confusion during commissioning.  It confused us until its discovery.

So we now have the capacity to apply power to the heat pump without it starting the compressor.  From the control panel I can then put the heat pump in to central heating or hot water mode, and I can also choose to send the heated water it produces around the radiators, the hot water tank or both.  After some more experimenting, we'll try to work out which options the control system should offer.  A timer to start the central heating in the morning will certainly be on the list.

Heating the cabin is not a priority this week however.  Another heatwave was forecast, but we'd let the batteries run down a bit, including using some of the power to put the heat pump through its paces.  We stayed on the 1 day mooring for Rob's convenience, but once he'd left we reversed round the corner to the unrestricted area. Usually this would be a 14 day mooring - in the current drought conditions we are allowed to stay here until at least the end of August.

On Wednesday morning, we got the tandem out while the day was still cool.  I had noticed that we were running low on coffee supplies, so I made that an excuse for a ride back to Kidderminster.  We began by climbing out of Kinver through the shade of the trees and then along the pretty road on the far side of Kinver Edge.  On the way back we stopped for ice cream again at Wolverley before following the towpath back to Bartimaeus.  The afternoon was very hot as forecast, so we mostly tried to keep cool.

The eclipse that we had intended to see in totality from Spain was going to be partial here, and just above the hedge.  I'd spotted a few suitable gaps in the vegetation and tested the eclipse glasses that had been bought months ago in preparation.  In the early phases, the stern deck made a good viewpoint.

As the eclipse progressed and the sun dipped we thought the view was being blocked by vegetation, but soon realised that in fact cloud was forming.  Our view was blocked for 10 minutes either side of the maximum extent of the eclipse.  That was always the worry - we might have travelled a thousand miles each way and only watched a cloud, just as we did in 1999.

It was pleasantly cool as the light gradually returned to normal evening levels.  The sky cleared before dark, so we lay on the back deck seats hoping to see some Perseids.  We saw a large number of passing satellites, but no meteors.  Perhaps yesterday was not my day for observing the sky.  I took all the canal side windows out again, so the cabin temperature had returned to comfortable levels well before midnight.

I might look out for shooting stars tonight, but we are again hiding from the heat. Despite missing the eclipse, I am also remembering that our original plans meant we'd be in places where it is 10°C warmer than this for many days.