Turn it down!

After setting off a MyJoulo logger just before Christmas, it’s already finished its week of temperature logging; this holiday is definitely going way too quickly!

The website seems a bit temperamental but after a few failed attempts to log on and several stalls loading and processing the data, it came up with a pretty unsurprising result:

Yep, the thermostat is definitely set on the warm side.

Still, it was interesting to get another vote on what the temperature actually is, having previously got conflicting readings from several other thermometers. (It seems I should recalibrate the thermostat back up a degree!) It was also interesting to see it showing the outside temperature, which must be based on the address details used to send the logger in the first place. Both indoor and outdoor readings seem to match what I was expecting:

Over all I definitely like the concept of re-usable data logging to give personalised advice, and MyJoulo is a pretty good beta. Aside from some confusion about what colour it flashes when it arrives, the logger seems to work well. At the end of the week you just plug the logger into a USB port to get a simple text file containing all the temperature data, and a device serial number.

The web site seems to have more teething problems but it did eventually work. I had assumed you need to log on to analyse the data but luckily they must link the serial number to your details since I wasn’t able to log on at all, even after resetting the password. I guess that I won’t get someone else’s details if I upload the file again after the logger has been reused but I have a copy of the data file just to see what happens in a few weeks!

The other slight disappointment was the actual analysis, which seems very basic. You can add your annual heating bill, but it might have been useful to get people to enter meter readings at the start and end of the week. It would also be nice to take account of temperatures in different rooms- maybe by sending a different number of loggers based on registration questions about where the thermostat is, or whether there are thermostatic radiator valves for example. Or you could just use a single logger in different locations over a few weeks instead. Maybe this is something that will develop over time.

The logger is now back in the return envelope ready to send off for its next mission.

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Early Christmas Joulo

After a tweet from @andysc I ordered a free Joulo logger– well free stuff is always hard to resist! Plus, since the Hursley CurrentCost craze (also Andy’s fault?!) it’s seemed like the first few days of monitoring are the most valuable and that, in most cases, you could just borrow a monitor. So there was a nice surprise in the post today- a logger and a freepost envelope to send it back after a week. Neat. Much better idea than a load of energy monitors gathering dust in peoples cupboards.

After a bit of confusion/user error about what colour the flashing button was, it’s now sat on top of the thermostat recording the temperature. (Apparently it’s supposed to arrive flashing orange, which is clearly not green like it is after pressing the button, doh!) It’ll be very interesting to see what it comes up with at the end of the week, especially after I had a collection of thermometers all showing different values while trying to figure out if the temperature on thermostat was right the other day!

To be continued!

Mad thermostat plan

Something I’ve really wanted to have a go at for a long time is hacking together a smarter heating system. The long process of moving house prevented any progress until now but I think a few things fell in to place today to get the project off the ground. And so a slightly mad thermostat plan was hatched…

The first part of the puzzle is a side effect of getting a solar water panel; to make the most of the solar panel we should only be using the boiler to top up the hot water at the end of the day. (Obviously that’s just theoretical at the moment because its pretty much been raining non stop since we got the solar panel!) Unfortunately the current central heating controller will only turn on the heating if the hot water is on at the same time, which is no help at all, so we really need a new controller to make the most of our zero carbon supply of hot water. There’s another, purely aesthetic reason to want a new heating controller; the kitchen upgrade got under way this week and the old controller has seen better days.

The current kitchen destruction has a bigger part to play though; now is an ideal opportunity to hide cables behind the new cupboards. For a while that didn’t actually seem like it was going to be all that much help, based on where the old thermostat was (hidden behind a door in the living room). I was looking at various programmable thermostats but the existing wiring from the thermostat restricted the options somewhat. The programmable thermostat we had in the old house seemed to work quite well with the existing wiring and controller… as long as the battery was fresh, otherwise it got confused about the temperature. Obviously not ideal for a thermostat, so I was hoping to avoid batteries this time!

Then, while being distracted by the wonky light switches yet again, inspiration struck…

The house hasn’t been constructed with the greatest care in the world, but those switches just could not have been original. The only thing that makes sense is if they were another botched DIY job, and it seemed highly unlikely that anyone would have dropped another cable run down the wall to do it. My hunch, based on the fact that there’s a water cylinder directly above those switches, is that there’s a horizontal cable run between the two. I checked, and… eureka! So now it’s a simple job to put both switches back on the same box, leaving an empty recessed box with a now bare kitchen wall behind it, making it perfect to run a new thermostat cable through the back of the box and round to the boiler! (Well I was pretty excited by this plan at the time.)

The thermostat to finish off this puzzle is a Heatmiser combined programmable thermostat and hot water timer. My theory is that I need the PRT/HW-N thermostat to go in the living room and a PRC powered relay card in place of the old central heating controller. I’m almost certain that the wiring will work with the existing system anyway, but if anyone has any experience/tips/gotchas, please let me know! That programmable thermostat should give me an RS485 interface to the thermostat which, if all goes well, won’t be too difficult to connect to my nanode– either with a bit of soldering, or one of these IO shields if I’m feeling lazy! The thing I like about this arrangement is that it should be possible to achieve plenty of automation if all goes well but, if there are any technical hitches, there’s a decent off the shelf controller to fall back on.

Update: a quick update since I’m doing some head scratching over whether the existing wiring from the central heating timer to the junction box in the airing cupboard will allow the heating to run independently from the hot water. If it does, the new thermostat is in place ready to go…

If it doesn’t, the new thermostat will just be a decorative feature while I figure out where I can sneak a new cable upstairs without disturbing the new kitchen! I don’t want to break the heating until I’m sure everything will work, so I’m working off a photo for now…

I’d love to hear from anyone who can decipher that lovely nest of wires! Here’s my theroy so far:

The black cable is the valve, and the other two cables that enter with it at the bottom are the pump and cylinder stat. It looks to me like the grey cable should be to turn the hot water off, which seems to be connected to the cylinder stat and a red wire from one of the cables above, which I’m hoping is from the timer. That just seems too easy for this house though, and I’m a bit puzzled by what the connections on the orange wire actually are. Lucky it’s all neatly connected and labelled so I can check the orange wire is connected to the cylinder stat and pump… bother. I guess I’m going to have to wait until Jo’s not looking so I can investigate more thoroughly!