My Combi has developed a fault which is gradually getting worse, to the point now that it actulally rarely heats either water or radiator.
The fault. Id turn on either the CH or tap, and the boiler would heat the water... then stop, and the water would go cold, then it would heat the water again. this would repeat, the time between hot and cols water would be inconsistance. As an inexperienced Boiler person, it seems like all the pumps etc are working fine, the power stays constent, and it would appear that the boiler simply decides temperature has been reached and the heating mechanism shuts down, only moments later lighting up and heating again.
Sadly for me, i think its finally given up this morning and now its freezing :).
Is this a fairly common fault where a simple sensor needs changing? any assistance or opinions would be greatly appreciated.
I had the exact same problem myself last week and today got it sorted. The boiler at first fired up and got the water slightly warm but after a few days it was not firing up at all and just gave cold water.
Let me say that I am in NO WAY A PLUMBER and I couldnt afford to get one in but with a bit of problem solving, here's the answer.
Get to your local plumbers counter and ask for a Sensor. I have a Ravenheat LS 100T boiler and have included the code for the sensor below (check your own by calling Ravenheat on 01132527007 and ask them)
The sensor it only slightly bigger than a 5p but sosts £20.89.
I have included pics below with my description to help
It looks tricky but its really not and will save you a few quid
1. TURN OFF THE POWER AT THE PLUG - VERY Important. You dont want to electrocute yourself!
2. Take off the Boiler cover - About 6 screws in the top & bottom (my cover needed a bit of encouragement as the plasterer plastered it into the wall!)
3. Find the sensor (as shown with arrow)
4. Pull off the clip at the end of sensor
5. Unscrew the Old sensor slowly (or water will squirt in your eye - like it did to me!) as some water will drip out (about 1 pint). I held a slim tray underneath to catch it as you dont want the water dripping onto the big round pump below. The pressure dial on the panel should drop right to Zero when empty
6. Screw in the new Sensor
7. Re-attach the wire clip at the end
8. Locate the bleed valve and turn on the water slowly until the pressure gets back upto about 2 bars
9. TEST - Turn the power / Plug back on. Turn your Hot tap on. You should now see in the little viewing window on the boiler flames firing up and you should now get hot water.
£7.09 later (eBay, including postage), we had a new sensor. I'd advise others that we had a LOT more than a pint of water - closer to 12 actually, most of which sprayed my girlfriend as we removed the old sensor.
However, the new sensor is working fine, giving us lovely hot water without turning on and off.
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