looking at your photo again i think i was probably wrong about where the auto bypass goes. Is there a pipe that goes from the pump back to the boiler without going to either radiators or boiler? If there is i think it'll be the bypass circuit. I think there should be one as if the suprima 30 is like the 100 then the pump carries on for a bit after both the boiler and radiator mechanical valves are shut by your timer.
Potteron Suprima 30 Cutting Out When Hot Water On
- Thread starter ph0u203d
- Start date
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the suprima 30 manual says:
"Also, systems fitted with controls that close both hot water and central heating circuits while the boiler is still hot, must be fitted with a by-pass circuit to dissipate the residual heat from within the boiler".
It also says "If a three port valve is used as shown in Fig. 3 a by-pass is not necessary since one circuit is always open".
and:
"Where a pair of two port valves are used, a by-pass is necessary. The total length of the by-pass circuit taken from the boiler connections should be greater than 4 metres of 22mm pipe. It should be fitted with a lockshield valve and be adjusted to maintain a minimum flow through the boiler of 4.5litres/min (1 gal/min)."
i think ensuring this 4.5 l/min is best done with an auto bypass but what do the pros think?
"Also, systems fitted with controls that close both hot water and central heating circuits while the boiler is still hot, must be fitted with a by-pass circuit to dissipate the residual heat from within the boiler".
It also says "If a three port valve is used as shown in Fig. 3 a by-pass is not necessary since one circuit is always open".
and:
"Where a pair of two port valves are used, a by-pass is necessary. The total length of the by-pass circuit taken from the boiler connections should be greater than 4 metres of 22mm pipe. It should be fitted with a lockshield valve and be adjusted to maintain a minimum flow through the boiler of 4.5litres/min (1 gal/min)."
i think ensuring this 4.5 l/min is best done with an auto bypass but what do the pros think?
Looking at the photo a 3 port mid position valve can be seen and there is no by pass (between pump and 3 port valve).
Yes, I can confirm that there is a 3-port valve fitted (I know this because I had it replaced about a year ago as it was jammed, only allowing the hot water to come on & not the central heating).
I got a bit confused with all the technical stuff there, so what does the fact that I have a 3-port valve mean for the likely cause of the problem?
The hot water has not been on since Saturday now & the central heating was working fine until last night, when the boiler cut out just before the end of the programme. I reset it & when I woke up this morning the radiators were warm, but the boiler had cut out again, presumably mid-way through the programme. I tried to reset it but when attempting to fire up it cut out straight away. It did this 3 times, so I left it for 10 mins, then reset it again & the boiler fired up OK & stayed on until the end of the programme. I'll see what it's doing when I get home tonight, but it is very strange!
Do you think a PCB replacement may be the best cure?
I got a bit confused with all the technical stuff there, so what does the fact that I have a 3-port valve mean for the likely cause of the problem?
The hot water has not been on since Saturday now & the central heating was working fine until last night, when the boiler cut out just before the end of the programme. I reset it & when I woke up this morning the radiators were warm, but the boiler had cut out again, presumably mid-way through the programme. I tried to reset it but when attempting to fire up it cut out straight away. It did this 3 times, so I left it for 10 mins, then reset it again & the boiler fired up OK & stayed on until the end of the programme. I'll see what it's doing when I get home tonight, but it is very strange!
Do you think a PCB replacement may be the best cure?
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hi, i can't tell enough about how your circuit is set up from the photos.
if the 3-port valve is shut to the radiators and hot water tank is there another path for the water back to the boiler from the pump? (or is it always open at least in one direction?) if so and the return is low resistance then you can ignore what i said about an automatic bypass
i've only got experience of my suprima. I thought it wasn't the boiler because it appeared to be better when the heating was on. Initially i thought it was the lack of a bypass. Then i thought it might be the pump but that seemed ok. Then i thought maybe m motorised valves were at fault but even if i opened them manually i still got the problem.
As soon as i changed the PCB it was sorted straight away. I can't explain why a pcb problem was worse when one circuit was open rather than another but that does appear to be the case.
if you look around you can find one for less than a hundred quid. My thinking before i got one was that even if it wasn't the board 1) the old boards appear to have a problem and mine would give way eventually 2) there is an improved diagnostic utility on the new pcb so it might help locate the problem 3) if i got an gas man round then he'd probably want to put new circuit board in anyway. Still a bit of a gamble though.
if the 3-port valve is shut to the radiators and hot water tank is there another path for the water back to the boiler from the pump? (or is it always open at least in one direction?) if so and the return is low resistance then you can ignore what i said about an automatic bypass
i've only got experience of my suprima. I thought it wasn't the boiler because it appeared to be better when the heating was on. Initially i thought it was the lack of a bypass. Then i thought it might be the pump but that seemed ok. Then i thought maybe m motorised valves were at fault but even if i opened them manually i still got the problem.
As soon as i changed the PCB it was sorted straight away. I can't explain why a pcb problem was worse when one circuit was open rather than another but that does appear to be the case.
if you look around you can find one for less than a hundred quid. My thinking before i got one was that even if it wasn't the board 1) the old boards appear to have a problem and mine would give way eventually 2) there is an improved diagnostic utility on the new pcb so it might help locate the problem 3) if i got an gas man round then he'd probably want to put new circuit board in anyway. Still a bit of a gamble though.
Puzzlebobble indicated a by pass was not needed if a 3 port valve was fitted, ( and it isn't).
Also a 3 port valve means the pump has a role to play with HW side as well as the CH side, but the 3 port valve can't be part of the problem.
That aside, my opinion is the PCB is a monitoring device and when it goes to 'lock out' it indicates there's something wrong and it will not allow the boiler to be re-lit until the fault is corrected.
As you have found, it can be re-lit so at that moment in time there was no fault. Otherwise it wouldn't start.
But the problem keeps re occurring and eventually the culprit is found to be the monitoring device itself.ie the PCB.
This was a real problem 3 or 4 years ago as I mentioned and many PCBs when examined closely with magnifying glass revealed 'dry joints' and hair line cracks where the terminal posts were soldered.
I had to pay for a new version of the PCB and since then there's a 3rd version.
I understand the last version includes the connecting wires already attached to the PCB to prevent damage at the connecting points.
The symptons do equate with the PCB problem and it's not just the HW side as was first thought.
Best thing is to call potterton and see what's on offer.
Also a 3 port valve means the pump has a role to play with HW side as well as the CH side, but the 3 port valve can't be part of the problem.
That aside, my opinion is the PCB is a monitoring device and when it goes to 'lock out' it indicates there's something wrong and it will not allow the boiler to be re-lit until the fault is corrected.
As you have found, it can be re-lit so at that moment in time there was no fault. Otherwise it wouldn't start.
But the problem keeps re occurring and eventually the culprit is found to be the monitoring device itself.ie the PCB.
This was a real problem 3 or 4 years ago as I mentioned and many PCBs when examined closely with magnifying glass revealed 'dry joints' and hair line cracks where the terminal posts were soldered.
I had to pay for a new version of the PCB and since then there's a 3rd version.
I understand the last version includes the connecting wires already attached to the PCB to prevent damage at the connecting points.
The symptons do equate with the PCB problem and it's not just the HW side as was first thought.
Best thing is to call potterton and see what's on offer.
Just a quick update...
I asked my Dad (an electrician) to have a look at the existing PCB & he found (like many other people have) that there were many fractured solder joints on the board.
After repairing these joints around a month ago, the boiler has worked perfectly on hot water &/or central heating programs without a single lockout.
Glad I didn't fork out for a new PCB now!
Incidently, it may be worth asking an electrician to have a look at your existing board if your having similar lockout problems, as has been suggested by others.
Thanks for all your advice.
I asked my Dad (an electrician) to have a look at the existing PCB & he found (like many other people have) that there were many fractured solder joints on the board.
After repairing these joints around a month ago, the boiler has worked perfectly on hot water &/or central heating programs without a single lockout.
Glad I didn't fork out for a new PCB now!
Incidently, it may be worth asking an electrician to have a look at your existing board if your having similar lockout problems, as has been suggested by others.
Thanks for all your advice.
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