Lightwave Heating announced

Well, at long last, the much fabled heating controls seem to be imminent.

I received an email yesterday with a link to a pre-order store where home thermostats, boiler switches and radiator valves were available. Apparently ready to ship in March 2014.


There is very little information about the products. At the very least I think people would need to check the installation instructions, to see if the devices are going to work with their existing heating infrastructure.

They do seem to be putting more emphasis on using professional installers these days. Perhaps they feel that fewer people are going to be confident tinkering with their heating wiring than are willing to attempt to replace a light switch.

There’s no mention of room thermostats as yet. Although the radiator valves have thermostats in them. But a room thermostat would give you more information about the current temperature and means you wouldn’t need to scrabble around behind the sofa looking for the little LEDs on the radiator valve.

The only time I’ve seen any kind of official mention of the room thermostats was on the site of a company called Megaman UK. They have since removed the page, but I managed to grab a PDF of Google’s cache (PDF) before it got updated. You can see some small images of the devices there.

Bizarrely, there is a handheld remote on the site. I’m not sure how useful that would be, due to the absence of any kind of screen on there to let you keep track of set temperatures etc. I suppose you could use it to switch your heating on or off from in bed? From the picture (singular) I can’t see if there’s even an LED to let you know whether the system is on or off.

The site says:

Please note: In order for Lightwave heating to operate each household will require a Wifi Link, Boiler Control Switch and a Home Thermostat plus any additional items required.

Considering the boiler switch and Home Thermostat retail for £74.99 (so that’s £150 for both) and one radiator valve going for £49.98, retrofitting an entire house could get a bit costly.

I’ve got 11 radiators I’d want to (eventually) convert, so the whole system would set me back £700!



Water, Water Everywhere

So, just in time for the heatwave that’s forecast to hit the UK, I’ve installed an irrigation system.

Now, we don’t have a particularly big garden, so the idea of installing an automatic irrigation system might seem like extreme overkill. But of course, it’s a great big gadget that needs tinkering with, so I was interested.

The idea is that there is an electronic valve, called a solenoid, attached to a pipe connected to the outside tap. This controls the flow of water, which is then connected to a loop of pipe that runs around the perimeter of the garden. At four main points around the garden (pretty much the corners) there are short lengths of pipe that split off from the main feed that run to four pop-up sprinklers.

There are several different types of sprinkler, each using slightly different methods to distribute the water over the ground. In my case I was limited by the available flow-rate, the amount of water that passes out of the tap per minute . I used a standard petrol can to measure the flow-rate available to me. It took about 18 seconds to fill the 5 litre can, so I worked that out to be about 18 litres per minute. Many of the more simple fan design type sprinklers have quite a high flow rate, in the region of 4-6 litres per minute, so if I had four of those, I’d be hitting my limit pretty quickly.

Then I chanced upon some ‘rotator’ nozzles instead. The Hunter HP 2000 nozzles produce several thin streams of water, at varying trajectories. The picture at the top of this post shows one of the heads while it’s running. They use the water pressure to rotate the head to provide even coverage over an adjustable arc of up to about 6 meters. Crucially, the rotators were specified to need only 1-3 litres of water per minute, so they were ideal. Plus they look cool when they’re running.

I think pop-ups are generally intended to be used in lawns where the ability to drop down out of sight is desirable, in fact you can even run the mower over them. But I liked the idea of them disappearing out of sight when not in use even though they’re in the borders of our garden.

I ignored most of the advice I’d read and also included some simple ‘micro misters‘ like those you’ll probably find in your local DIY store. They sit on spikes and just hammer out some water over an arc. These were to fill in some edges and gaps around the patio that couldn’t be covered by a pop-up.

The next stage now is to hook an Arduino (or possibly even a Raspberry Pi) up to a relay controlling the power to the solenoid. This will mean that the whole thing can then be switched on or off automatically. The ultimate plan is to get a rain meter hooked up to it too, so it can postpone the watering program if it’s rained in the past 24 hours or so.

I’ve also ordered a water flow sensor, which I’m hoping I can hook up to the Arduino too, in order to measure the amount of water that’s dispatched during each watering session.


Lightwave Heating Control & App Update

I had a brief exchange with one of the people over at JSJS Designs. He told me the new heating controls are still being worked on by the development team. They’ve experienced some ‘technical issues’ so they are having to work through those. Apparently they’ve had to make some component changes, which to me sounds pretty serious, and could add quite a delay.

Clearly they’ve missed the first quarter 2013 launch, which won’t surprise many people…

He also told me they are still developing the new apps. Seems very disingenuous to put images on your website of apps that aren’t anywhere near release. It appears they’re re-writing the apps from the ground up, I guess to incorporate the new capabilities of the heating controls.

So unfortunately, it looks like they are some months away from releasing anything new.


WiFly Sensor Pins

I’ve just got around to fine tuning the WiFly sensor prototype. I’ve made another perfboard prototype, this time with my own 3.3V voltage regulator and a mini USB connector to provide power. It’s taken me a while, but I keep getting distracted by everything else I’m tryinig to do!

The main issue was working out what the hell the sensor pins on the RN-XV were doing. I managed to get a reasonably accurate set-up with some suck-it-and-see numbers. But they only worked accurately for a very very narrow range of temperatures.

I finally made some headway when I stumbled across this forum thread: WiFly sensor pin readings on the Sparkfun site. The crux of the issue is that the sensor pins already have a voltage divider across them. The excellent work the guys have done on the forum meant I could start getting some sensible readings from the WiFly.

Essentially, the RN-XV manual is very misleading. It makes reference to the max Voltage for the analogue pins, but fails to mention anywhere the voltage divider built into the RN-XV itself. It is possible to remove the resistors from the board yourself, as Bjorn has done here. But for my purposes this is unnecessary, and having them in place means that the pins remain 3.3V tolerant.

You also have to shift the HEX value reported for each sensor to the right before converting it to decimal.

This is a little section of my PHP script that processes the GET requests from the RN-XV

//pin19 = TMP36
// Grab the GET data.
 $wiflyData = stripslashes($_GET['data']);
// Split the data stream into each sensor value, every 4 digits.
 $myArray = str_split($wiflyData, 4);
// Add an extra byte to the HEX values
 $pin19HEX = str_pad($myArray[4], 5, "0", STR_PAD_RIGHT);
// Convert the padded HEX value to Decimal.
 $pin19Dec = base_convert($pin19HEX,16,10);
// Perform the weird RN-XV multiplier
 $microV = ($pin19Dec*5.064);
// Convert microVolts to milliVolts
 $milliV = ($microV/1000);
//Convert millivolts into temperature for the TMP36
 $degC = (($milliV - 500) / 10);

Then it gets inserted into a mySQL database for graphing etc

It took a while to get this all sorted, but now I can leave the two prototypes running 24/7 for a few days and see how they hold up.

Messing around with sensors and little computers.