Biasi 24s boiler issue.

Hi all,Im new to the forums and am after a spot of help or info.

My girlfreinds boiler a Biasi 24s!!!! has actually been fine since she had it installed in 2002,with just the odd spot of maintenance every now and again.

Just before xmas I noticed water dripping from the Prv outlet outside and she told me that she had to refill the system everytime she put the heating on.

So I spoke to my friend who works as a plumber and central heating installer for the local council and he said looks like the prv is faulty and to take it off and give it a check over.

I removed the Prv and yes it was black and gunged up inside,I tried to clean it out as a temp measure but it didnt work.
Ive now fitted a new Prv to the boiler and all is well,no dripping outside and it also holds its pressure too.

Today after fitting the valve i had the heating switched onto constant just to test it out but after about 10 minutes the boiler cut out.The trip switch stays in and the lock out lamp stays off.if i leave the boiler for say 2 minutes it will come back on,but then after afew mins of running it will cut out again!!! DHW is fine though,the boiler ingnites and hot water will flow from the tap.
It is just the central heatin that seems to be the problem.All the radiators have been bled and the pressure is at 1.3 bar. This is only happening since i replaced the PRV, and ive now drawn a blank!!!.One thing is for sure though,if i can get it sorted by the time the Gf comes home then she may not hit the roof!!!!!

can anyone help please

Lee

Without flow pipe temperatures being quoted, all I can say is that its probably just following its normal operation with a three minute anti cycling delay.

Tony

Hiya,Thanks for replying,

I will check the heating temp later as im not at the house now,I presume that this is something its supposed to do then?.From cold it heats up to a certain operating temp then flame cuts out but boiler sounds like its still running,which is probs the pump/fan,then once temp drops it re-ignites. Is this correct?. Its never done this before,just stayed on constantly on timer setting,but this is when it was leaking bad from the Prv outlet.

If its meant to do this then I can explain to the girlfriend that its how the boiler operates.

Lee

The boiler should burn until it reaches the set flow tempoerature and modulate down to its minumum power setting. If thats still too great it turns off the fan and burner for three minutes during which the pump continues to run.

Tony

Hiya,

I see, So is this normal then,or would it seem that its trying to run at a higher temp setting than its supposed to?,and also why would replacing the leaky prv suddenly cause this to happen?.

Sorry for all the questions,but i just want to make sure the boiler is ok to use,as it always worries me if the gas/flame goes out but the boiler keeps running.

If this is ok and the boiler will kick in and out on its own then i shall explain this to the gf who should hopefully finger crossed stay calm!!! but we all no how women like to panic!! lol

Thanks again for your help, and i will check the temp of the boiler when it shuts off and post on here later.

Lee

Check the temperature controls do turn down the flame size.

Yoiu may have knocked off an NTC connection. They are the two green ones either side at the bottom.

Tony

Thanks Tony,


I will be back at the house later and will try it again and check all connections and then post my report back on here,

Oh i do know the Ch control knob did turn the flame down but she has it sent on max.

Lee

The pump remains running but the fan only runs when the boiler is ready to ignite.

Tony

I've checked the boiler from cold to when it turns off,

The ch knob is now set at halfway according to the manual for temps outside between -5 and + 5. The gauge is reading bang on 50c and pressure is set at about 1.2 bar.

It's been running for a while now and has only turned off twice where the temp gauge dropped slightly and pump continued to run, after 3 mins it fired back up and temp Rose to 50c again.

Seems to be fine and rads are all hot, and no dripping water from prv anymore


I was just worried as to why it started to turn off after replacing prv but it looks like this is the correct procedure.

The gf said the boiler was running constantly on timer so no wonder the gas bill was pricey

Lee