DIY Doctor

boiler help

Postby ajr41 » Sun Aug 30, 2009 12:56 pm

i have a 19yr old boiler, (i know its time to change it but i do not have the money to do so) also, i really dont think there is that much wrong with it and parts for my acctual boiler are still available. i have had it checked and there are no leaks or anything dangerously wrong with it, he just wouldnt try fixing it coz its too old and wanted 3k for a new 1 to be fitted.
recently the pressure was dropping and required topping up every few hours, i have replaced the outlet velve that was corroded inside and seams to have resolved that problem.
however, when i turn the heating and water on together, the ignitor sparks then after a few seconds of trying to light the safty button and red light pop out.
you can tell if its goin to light as it makes a different click sound before the ignitor starts. if i put the hot water on by itself it works all day long no problem, so the only way i can get my heating on is by draining the hot water tank, turn hot water on, once the boiler has lit, then turn heating on it works perfectly then untill it reaches temp, the only way it will come back on is if i repeat the process.
now and then it works normally by itself, on, off and back on, but not that often, thats what makes me think its not such a big fault. as i said if i had the money i would just change it but i dont.
i would be very gratefull for any help/suggestions
many thanks
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Simply Build It

Postby Steve the gas » Sun Sep 06, 2009 8:14 am

Need to know more about boiler make/model and system design.
But - do you have any 2 or 3 port valves- if so I would start there.
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Postby ajr41 » Sun Oct 18, 2009 9:42 am

after a few weeks of trying this and that i have discovered that, its the pressure or lack of it.
if i put water in it works perfectly for hours, either with water or heating or both.
its just when its turned off even for 30mins, the pressure is zero, even tho 30mins ago, when it was on it was almost at 3bar.
i have fitted a new release valve and theres no water coming out of the overflow, so its not losing pressure from there.
the last rad is quite slow heating up, do u think maybe it could be the pump.
as when i turn the heating or water on, if i havent put water in, you can hear lost of air and makes a groaning sound untill i put water it and then it works perfecly
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Postby htg engineer » Sun Oct 18, 2009 1:10 pm

IF the pressure rises to 3 bar when the heating is on, the PRV will open - the water will be disharged outside and then when the boiler cools the pressure will be at 0 or just above and wont come on.

Re-pressurise or renew expansion vessel.

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