Help! Boiler keeps locking out

Discussion in 'Plumbing and Central Heating' started by SJCam3r0n, 21 Jan 2017.

  1. SJCam3r0n

    SJCam3r0n

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    I have a ravenheat CSI 85 (T) 780 series combi boiler. Its the bane of my existence!

    Came home yesterday to find boiler locked out. Normally, resetting our boiler is pretty simple - switch everything off, ensure pressure is between 1 - 1.5bar (usually requires a top up of pressure or a drain from 1rst rad in sys down from boiler to ensure its not an airlock) winter button in, hot water & CH turned down low and bingo, pilot light comes back on, fan kicks in and so does pump. After 5 mins or so its back to normal. This sequence normally takes one or two goes as once its locked out it seems to need a few minutes between switching the power off and trying a reset otherwise it simply trips again and pilot light doesnt illuminate. Thats our normal issue.

    However, yesterday came home to find boiler locked out and the pressure had dropped to less than 0.5 which in itself is unusual. Followed the normal procedure to reset boiler (inc bleeding all 4 rads slightly to take any air out of sys and topped up to correct pressure) and it worked for maybe 5 - 10 mins? and locked out again. The pressure had rapidly climbed in that time to over 2.5 bar, so I assumed I must have overpressured it so bleed 1rst rad in sys again to bring it back down to 1br. Tried again. Locked out. Tried several times with no success. Ended up leaving the thing switched off overnight with HW & CH turned down to low. Got up this morning to find pressure in boiler at zero.So started from the beginning following fault finder. pressured boiler to 1bar, turned CH up to full with winter button in. Boiler comes on works for 5-10mins, rads heat up. But pressure rises to over 2.5 bar and locks out. Inspecting the condensation drain outside, it appears its loosing water. No visible leaks anywhere inside. Upon removing the bottom plate and front panel of boiler theres water markings (but no water) on the bottom plate. No water is being lost from pipes or rads (inc bleed valves) that I can see. Only other thing worth noting is I can get the boiler to fire up and run only if HW is turned down low - if I turn up the HW, it goes to lock out within less than a minute.

    Any suggestions?
     
    Last edited: 21 Jan 2017
  2. SJCam3r0n

    SJCam3r0n

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    Only further info - have tried numerous times today to get boiler to work.

    Trying HW only causes lockout as the pilot light does not come on.

    Trying CH only (full) runs for 5-10mins, heat in rads but pressure climbs to over 2.5 bar, locks out. Adjusting the temp at all during this causes immediate lockout.

    Trying CH + HW (low) brings boiler on for a short period, no heat, but eventually locks out.

    Trying CH + HW (med/high) causes lockout.

    boiler currently off just now, pressure has dropped in last half hour from 1.5 to less than 0.5 bar. No water appears to be being lost from anywhere in house, drain outside has some markings but is not visibly damp

    Cant get anyone to come look at this, about ready to tear my hair out.
     
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  4. Madrab

    Madrab

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    By the sounds of it, the first to be checking would be the Expansion vessel but I'd get a registered engineer in tomorrow to diagnose.
     
  5. SJCam3r0n

    SJCam3r0n

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    Update: Boiler has been off now since Friday - yesterday, I checked the pressure and it was back at zero.

    But did find after pressuring it to 1bar there is a small water leak (no more than a few drops - 5mil) of water coming from the boiler itself when I switched it on. It appears to drip down the pressure relief valve.

    I reckon at this point the most obvious cause is the expansion tank..? can anyone talk me through what I should be looking for to recharge it?

    To clarify Ive removed the white outer casing only - I have no intention of going anywhere near the gas supply.

    I have been trying since friday - I cant get an engineer out and im worried that in this cold im going to burst pipes etc


    Ive got an oil heater keeping a room at a time warm in the meantime. Can anyone help?
     
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