Fix Problems with Continental UH3 UFH Wiring Centre

[coofercat]

We have a Continental UH3 under floor heating wiring centre (which may be the same as the Heatmiser UH3, although I'm not 100% sure about that). It's got a 'sticky relay', which means that sometimes the heating doesn't work (although some 'percussive maintenance' clicks it into gear again). I checked with the supplier, and it's out of warranty (after just a year), and they want £120 to send me a new one. A bit of sleuthing shows up that the relays are Omron G2R-2 230VAC. You can get those from RS for about £4-5 each (http://uk.rs-online.com/web/p/products/0369337/). So long as you're happy to do a bit of fiddling about with a soldering iron, you can save yourself a hundred quid.

If you're wondering, the wiring centre is an almost entirely 230V (AC) device - there's no low voltage anywhere. The two relays turn on the boiler and manifold pump, or operate the valve. The relays are activated whenever any of the zones turns on. Electrically each zone has a diode and a resistor all sort of connected together to energise the coils. If you do decide to do any fixing, make sure it's all turned off first, and be careful!