combi boiler - radiators and water boiling, plus losing pressure

[notnoweric]

Hi all
we have a biasi combi boiler. 10 months ago, it was given a new lease of life with a new diverter valve. It's been reasonably ok since except it went through a period of faults and errors. We realised that if we absolutely left it alone it would work fine, for who knows how long.
Anyway present problem is this radiators get boiling hot , so is running water. I have a basic knowledge, and promise it is not consumer type things like thermostat on too high or trv valves on rads. Even dials on boiler. Nothing will lower the actual temp of water. Also an occasional error message (via the three lights seems to be "safety thermostat lockout". The temp solution to this is using the reset button on control panel.
Today I have noticed the following..
The pressure had dropped to 0.5 so I thought maybe this is the issue. I refilled using loop and bled all radiators, then topped up again. Pressure was at an ideal 1.5
I then tested the system. Have now noticed pressure is back down to below 1. I understand that pressure can change with temp. I assume I've gone from a cold 1.5 to a cold < 1, however time will tell.
I initally suspect a leak, which will be fun to find and I am capable of repairing. I assured my partner that it would not be like a mains pressure leak. Not ideal but we could keep refilling, and eventually we may spot the problem in the ceiling (no pipes are along ground floor).
I now wonder if the drop in pressure and likely loss of water is because of the high temperature and it is being allowed to escape somewhere (exapnsion valve? or the copper pipe that runs through the wall and out for emergencies [I have no understanding of this feature]
So with the info above I am hoping that it may be failry obvious to someone what the issue is (I'm grateful that this site confirmed the diverter problem 10months ago).
Bolier is about 13 yrs old. I know they die at some point but given cost of living and evertything else, I am keen to get more life out of it.
Also it would be good for my partner and kids to know that as long as we dont touch the boiling radiators, there is no explaosion imminent (we have no plastic pipes in the central heating system, but bathroom water is fed by plastic (which could be suffering somewhat
Thanks in advance.

 

[terryplumb]

Does pressure rise to around 3 bar when heating is on ?
The copper pipe externally is the pressure relief pipework ,see if water has been coming out of it.
What model is the Biasi ?
Does turning down the central heating temperature dial on the boiler result in lower temperature at radiators ?
Does turning the tap water temperature dial lower on the boiler result in lower temperature water at the taps ?

 

[notnoweric]

Thanks for the reply.
Biasi M96 28SM/C2
It could well have gone above 3 but I didn't think to look. Since then I reduced the default pressure from 1.5 to 1 by bleeding, so I expect this may be better. At present heating is well and truly on and it's just above 2 bar.
The running water is still boiling hot, despite both dials turned down. They seem to have no effect on boiling radiators. Also even with TRV off the radiators seem impossible to cool (although that may well be because the whole system is hot?)
An extra bit of info..
The radiators have never been properly balanced, so at present I have them almost totally open on the pliers side. I was going to gradually adjust them down according to which rads are hottest, but they are all hot!
My partner was compmaing about them being all too hot before I did this step, and I can't imagine it being the problem, but apologies if it is.
It's wet and dark at present but I have wedged a plastic bottle between wall and external pipe to see if anything collects, obviously ignoring a small amount if drizzle...
Oh we've now gone just past 3 bar, so maybe it will lock out soon? It's now at a constant 3 with no sign of going higher.
Is it possible for it to right itself?
I've taken cover off before but I didn't fancy trying to put air back into expansion vessel (have read a few threads).
Can EV if not broken, reset itself somehow?
I still can't explain the over hot water in system...
Oh and the boiler has a very slight rattle but it's a noise I haven't noticed before..
Sorry for running commentary...
Extrnal thermostat is still demanding heat, but boiler just stopped heating (still on and rattling, but no lockout pressure now reducing to 2.5
I wonder what it will do next.
Ah its just relit again, so it seems to be able to regulate itself in some way

 

[notnoweric]

Aha!
Just went to bottle outside. The external pipe has emitted about 2cm in washing up bottle of light brown water. So I am definitely losing water through this pipe. Does this mean EV needs repressurising or replacing.
I was competent enough yrs ago to take cover off and fit a honeywell external thermostat. I've done all the plumbing in kitchen and bathroom (not boasting). I would never touch gas obviously but can a householder repressurise the EV?

 

[notnoweric]

Aha!
Just went to bottle outside. The external pipe has emitted about 2cm in washing up bottle of light brown water. So I am definitely losing water through this pipe. Does this mean EV needs repressurising or replacing.
I was competent enough yrs ago to take cover off and fit a honeywell external thermostat. I've done all the plumbing in kitchen and bathroom (not boasting). I would never touch gas obviously but can a householder repressurise the EV

 

[terryplumb]

Your EV ( expansion vessel) isn't functioning ,and will not re set itself. If pressure rises to 3 bar ,the PRV Will lift and water will come out the external pipe,to lower pressure.
If the external Stat is still demanding heat the boiler will continue to run ,so it's either duff or your room temperature has not reached its target temperature.
If the potentiometers have no effect on rad / tap temperatures ,then you have an internal issue in the boiler ,and need an engineer. Sounds like a PCB issue ,but could be other things.
What temperature is displayed on the boilers temperature gauge ?

 

[notnoweric]

Thank you. Yes, I think that I will have to find someone. Boiler is reading 65 at present. I hadn't thought to look at this dial before! I'll keep an eye on it, what is the ideal temp for this gauge.

 

[omph]

Thank you. Yes, I think that I will have to find someone. Boiler is reading 65 at present. I hadn't thought to look at this dial before! I'll keep an eye on it, what is the ideal temp for this gauge.

As low as possible, until you start to feel the cold, then increment till you feel comfortable.

 

[terryplumb]

That's not a high temperature at all ,but if you watch it for 5 mins it may increase as boiler cycles on/ off. 65c wouldnt give excessive radiator temperatures ,and definitely not " boiling" as you indicated !

 

[notnoweric]

Thanks. It is arguable what is meant by a hot radiator but I've just tested the tap and I genuinely can't keep my hand under, yet boiler is showing 65.
Also to be clear when you said as low as possible is ideal etc, we haven't had the heating on much at a recently, and only out room temp demand to 16. This is for all the right reasons, but your comment implies I can somehow control that 65. As mentioned before the dials on boiler seem to do nothing (although zero does literally turn heating off). Apart from that I have no control (I realise that portable thermostat literally cycles boiler on/off as required, and is not the same as on controlling boiler settings)

 

[omph]

Thanks. It is arguable what is meant by a hot radiator but I've just tested the tap and I genuinely can't keep my hand under, yet boiler is showing 65.
Also to be clear when you said as low as possible is ideal etc, we haven't had the heating on much at a recently, and only out room temp demand to 16. This is for all the right reasons, but your comment implies I can somehow control that 65. As mentioned before the dials on boiler seem to do nothing (although zero does literally turn heating off). Apart from that I have no control (I realise that portable thermostat literally cycles boiler on/off as required, and is not the same as on controlling boiler settings)

Might be useful getting your hands on an infra red temp reader. 65c rads are very hot to touch, and I'm pretty sure 65c water can cause scalding. It may be the case the rads need balancing. Is your boiler thermostat working ?

 

[notnoweric]

I don't know what you mean by boiler thermostat. The only thermostat I see is the external portable one, and yes that works fine

 

[notnoweric]

Just noticed now while removing the loop hose...
The system seems to be leaking - dripping from the non return valve.
I've had to keep the hose in place for now.
Usually after any maintenance I remove it so that my pipes can be.nicely concealed with a wooden cover. When the hose is attached, my cover does not fit.
Main point is that the valve which allows water INTO system, is letting water OUT
I do not know if this is related to all the other issues.

 

[terryplumb]

The pressure is going to drop . Show us a pic of where it's leaking ,you may be able to fit a cap.

 

[notnoweric]

The pressure is going to drop . Show us a pic of where it's leaking ,you may be able to fit a cap.