heating wont turn off. red hot rads

[Amy92]

Hi all,
hope you can help me.
Ive got a biasi riva compact M96 24 sm c2
hot water is fine.
when I put the heating on, it stays on constantly, the rads get
too hot to touch. the boiler goes off and I have to re-set it.
I had an engineer out. He replaced the heating sensor. He said he also
set the boilers minimum and maximum gas pressure. (whatever
that is)
I messed a bit, and when the hot water is on I turned the hot water
knob up and down, and the flame moved up and down. This also happened when the heating is on. Is this right ?
Even when i turn the heating knob to the lowest setting, the flame
is constant, untill it gets too hot and turns itself off.
I called another engineer who said it could be a pcb or safety stat.
All means nothing to me, just would like to be armed with some info
so I dont get ripped off again.
Thanks in advance for any advice.

 

[temps]

Anyone with some advice please ?

 

[jackthom]

Take a look at section 1.5 of this manual and see if you get a meaningful sequence of operation lights when the heating is running. This should help identify any problem areas.

http://www.biasi.co.uk/images/manuals/RIVA_COMPACT_HE/USER_INSTALLATION/0907 EDITION.pdf

 

[Amy92]

Yes, that would be helpfull temps

 

[Amy92]

Thanks Jackthom,
Iv'e had a look at the manual. When the boiler's running
it gives the correct sequence of lights for heating, aswell as when the
hot water is on. When heating is on, and on, and on, and then goes
off, according to the manual the lights indicate a safety thermostat
lock out. By this times the rads are scorching aswell as the two
biggest pipes under the boiler.
Appreciate your help Jackthom

 

[Agile]

You need to check that someone has not swapped over the wires to each sensor.

The manual does have this, but may be difficult for you to find as you need to look on the interconnection diagram.

From memory the blue is CH and the red is DHW although I dont trust my memory for diagnostic work. If thats right then its not intuitive as I would assign blue to DHW and red to CH but perhaps in Italy they do things differently.

Or take a picture and post it here showing left hand side of the works just above the control panel box.

Tony

 

[Amy92]

Hi Tony,
I reluctantly called the engineer to ask if he
could of by mistake switched the wires.
He said he couldn't have as he only replaced
the heating sensor, and didnt touch the hot water sensor.
Nobody else has worked on the boiler, and it was working
prior to the engineers visit, so it cant be that.

Any other ideas, as I've called 4 engineers now and explained
the problem. All have said too busy.

 

[Agile]

Hi Tony,
I reluctantly called the engineer to ask if he
could of by mistake switched the wires.
He said he couldn't have as he only replaced
the heating sensor, and didnt touch the hot water sensor.
Nobody else has worked on the boiler, and it was working
prior to the engineers visit, so it cant be that.
Any other ideas, as I've called 4 engineers now and explained
the problem. All have said too busy.

I dont see how you can come to that conclusion.

Even if he had he might not admit it. Or even remember what he did!

I went to one with that fault which was only about 16 months old.

Two others had tried to repair it without success. It took me less than 10 min to identify the problem. The tenants had not noticed the over hot rads but had complained about the hot water regulation.

It might have come from the factory like that or the installer may have swapped them for some reason.

When repairing boilers you have to keep an open mind and not assume anything!

You could check that yourself if you would take off the front panel. If it was wrong you could change them over yourself. Or you could just change them over and see what effect that has.

Tony

 

[Amy92]

Thanks Tony,
I'll give that a go and let you know.

 

[Amy92]

Thanks Tony.
Spot on. Heating sensor & hot water sensor leads
where switched over. I can only presume that someone
working on it at some point have taken both leads off at
the same time to check them & put them back wrongly.
Thanks Tony. Youre a star.