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 http://nbharnser.blogspot.com 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 http://nbharnser.blogspot.com 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 http://nbharnser.blogspot.com said...

thought you may fancy it

Brian and Diana on NB Harnser http://nbharnser.blogspot.com 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.