Worcester 24i combi boiler problems

Hi all.

We have a Worcester 24i combi boiler which is about 8 years old. It has been problematic in the past, with it not lighting or slow to produc hot water however it is only today after noticing this forum that I paid much attention.

After running the shower it was producing no hot water, so after reading some threads on here I thought I`d try the bathroom tap at the same time to see if it was the thermostat in the power shower but no hot water came. On examining the boiler it was not firing up and was not even lit so I tried the reset button on top which would not depress. I then turned the boiler off and on ten seconds later, the boiler fired up, how water could be drawn from the taps and shower (no water using appliances were on during any of this, or any other taps).

So is there anything that I can do myself to the boiler or will I have to call out a plumber.

Thanks

Vertical

Also what pressure should these run at?

These can cycle between firing so it depends how long you left it to relight.
If its a fault then it could be the DHW flow switch, ive had a few that stick when hot.
the system pressure should be around 1.3 - 1.5 bar when cold. Expect this to rise to around 2 bar when hot.

hi,
these 24i boilers need to dump excess heat after having provided hot water. they do this by running the pump for a few seconds to cool themselves down dumping the heat into the radiator circuit. if all the trvs on the rads are off/low/stuck, or there is no other bypass circuit in the pipework, they will be unable to do this and will overheat and trip out. try it with at least one radiator valve full up and see if it helps. also could be a pump over-run fault which will need a corgi engineer to change the pcb maybe

theaky said:

hi,
these 24i boilers need to dump excess heat after having provided hot water. they do this by running the pump for a few seconds to cool themselves down dumping the heat into the radiator circuit. if all the trvs on the rads are off/low/stuck, or there is no other bypass circuit in the pipework, they will be unable to do this and will overheat and trip out. try it with at least one radiator valve full up and see if it helps. also could be a pump over-run fault which will need a corgi engineer to change the pcb maybe

Click to expand...

the 24i's got a built in bypass ! had problems before with Trv's truned down and boiler kettling as bypass is not very good for c/h but never on DHW demand only.

mmalone said:

the 24i's got a built in bypass

Click to expand...

yeah it has but it's a silly little tube which blocks up sometimes and when the dhw has just run a bath, it's not enough to get rid of the heat on pump over-run.

or so i have found at least...

worth a try is all i mean.

Thanks for your replies.

Ending up calling worcester out, they came the next day. He couldn`t find the fault, so he replace the PCB, fan and its controller, PRV, tubing for pressure sensor and the knob that I broke the last time I took it apart and stood on it.

Due to the amount of sludge on the PRV he recommended a power flush or at least a chemical flush (or inhibitor I think) to remove the sludge. We did have an inhibitor put in around a year or more ago but due to adding water to the system to increase the pressure and the PRV leaking it is probably that diluted it is of negligible concentration.

So, I thought I read on here about hiring a machine to do a power flush ( is this one word or two), if roughly how much are these and where from? How difficult is this procedure? Would your advice be to have a go or get someone in too do it ?

We have a worcester 24i combi boiler and 13 radiators, system is 8 years old.

Thanks