Tuesday 25 September 2012

How I plan to make a cheap timer for a Webasto

When Jubilee was built the Webasto heater unit had, apparently, a time switch fitted. By the time we bought the boat the timer had failed, and the previous owner had substituted a simple on/off switch. This works fine and is ultra-reliable, but Ally and Ben would like to be able to wake up in a pre-warmed boat these cooler mornings.

I know, I thought, I'll use a mains time switch to supply a small power supply to operate a relay, the contacts of which will be connected across the Webasto switch. I had a small power supply, so all I needed was the relay. I looked in a Maplin catalogue and found something even better: a mains actuated relay. I didn't know these existed! The relay coil takes 230V AC mains.

Here it is. I've tested it by connecting the coil to the mains and, yes, it switches. It buzzes a bit too, but I can hide it away somewhere so that shouldn't be too much of a problem.

And this is the time switch which I'll plug in next to the existing timer for the immersion heater (or in place of it - the Webasto will heat the domestic water as well as the radiators).

All I'll need then is a 13A plug and a bit of cable. And I'll obviously have to insulate the mains connection to the relay.

Cost of components: Relay £4.49; Time switch about £5.00. Total: about a tenner.

Compare this with £85 for a genuine Webasto timer! Of course, my method needs mains to work - fine for Ally and Ben in the marina on shoreline power, not so handy on the move.

I'll let you know how I get on installing it next time I'm on the boat.

6 comments:

Brian and Diana on NB Harnser said...

I have see somewhere instructions for converting a 230 volt programmer to 12 volt DC. It was on the net but cant remember where. I think it was an easy job

Brian and Diana on NB Harnser said...

I have found it
http://www.reuk.co.uk/Convert-Digital-Mains-Timer-To-Low-Voltage.htm

Halfie said...

Brilliant! Thanks Brian. I've been to this useful website in the past but, at the time, I wasn't looking for a timer. I fancy having a go at this mains-free project, maybe in six months' time.

Brian and Diana on NB Harnser said...

thought you may fancy it

Brian and Diana on NB Harnser said...

Some has just suggested this timer for turning deck lights on. It may do what you wanted as well
http://www.ebay.co.uk/itm/New-LCD-Digital-Power-Programmable-Timer-AC-12V-16A-Time-Relay-Switch-UK-SELLER-/221160314866?

Halfie said...

Thanks Brian, yes, just had a look. This one has the advantage of being totally mains-free - but I've already made and installed my home-made device.