Alpha CB28X - Not firing up problem

[julesg007]

Dave,

The control know is working fine.

I have removed the PSS and from looking at it doesn't look serviceable - is that the case - if that is the case such is life I'll have to get a new one, again quite an inexpensive bit to buy.

Thanks again

Jules

 

[gas4you]

Again, not wanting to sound negative, but it is impossible to say from afar.

I am hopefully offering suggestions to which you will have to make your own decisions from.

What happens if you disconnect the PPS? Does the boiler keep firing?

 

[julesg007]

Hi Dave,

No, as soon as I disconect the PPS a fault is shown. The A & B lights immediately start flashing on & off alternatively, which according to the instruction manual I have means that the system pressure is too low and need re-pressuring. Although of course the pressure is fine, it is only showing the fault due to dissconnection of the PPS.

I have now removed the PPS and was wondering if you know if it serviceable? just in case all it it needs is cleaning.

If not, I can pick a PPS up for around £25 inc p&p so again it won't break the bank to try a new one and let you know what happens.

If at the end of the day it is PCB it'll be a kick in the pants but such is the way of things. I'll get my HE to give it service at the same time as it is probably a tad overdue anyhow.

Thanks again
Jules

 

[gas4you]

At present I would move on from the PPS. In fact I have led you astray here I, for some stupid reason, was thinking this was a primary flow switch

This is just to read the system pressure.

 

[julesg007]

Evening Dave,

Ah well such is life no probs about the PPS. I think I am going to change it anyway (about £25 to change so the bank isn't going to break) as I was messing around with it as I thought it could be dismantled and I am now not sure exactly what position it was set at - bugger!!!

You mentioned a primary flow switch - I am unable to see this from the information I have to hand - are you able to direct me to where it could be found and I will see if this is the problem.

I would presume at this stage it is call my heating engineer if by some chance the new PPS solves the problem.

Hope you had a good weekend and the weather was fine where you are.

Thanks again for the help.

Jules

 

[julesg007]

Hi All,

I wanted to give you all an update.

After a visit of my guy he suspected that the heat exchanger was blocked and therefore using spirit of salts gave it a clean. Although he said it wasn't that bad.

He also felt that the 3 port valve (part of the diverter valve assembly) might be sticking, so I have stripped it all down, cleaned it and replaced all of the rubber seals. I noticed that the pin was slightly bent so I straightened it up. I also replaced the diaphragm as that was already showing signs of wear and was looking like it was going to split.

I am pleased to report that I have had a partial success following this - the boiler is now firing up when HW is demanded and doesn't appear to be cutting out. It also doesn't seem to be having any mental fits trying to fire up when it shouldn't be. Off course this may change but I am hopeful that the problem has been sorted.

However, the boiler now doesn't want to fire up when in CH mode. The boiler is set to HW & CH and been switched over to constant but doesn't want to do anything and it's cold enough today. The system doesn't rely on a room stat but purely on TRV's on each rad - I also have the CH temp guage on boiler set to max.

Any thoughts or comments as to what may be causing this? although I will be speaking to my guy about the problem.

Thanks for the help

Jules

 

[petit_pablo]

If no room stat fitted then check at the PCB for a link fitted where the room stat would be connected. I cant remember off the top of my head where it is on your boiler.

With a multimeter, check you have 240 on both connections and that the link hasnt been dislodged with all the other work done.

 

[julesg007]

Hello,

Thank you for the help.

I have had a check on the PCB and all connections are fine, I have double checked and they are all in place.

On my model the way the room stat is connected is via a plastic connector block which forms part of the strip that the incoming mains is connected to. There are 2 sets of L&N wires from the incoming feed. One set is connected to the PCB via a connector and the other is connected directly to the segment timer clock.

2 red wires leave the clock, one attaches directly back to the PCB and the other attaches to one side of the connector block where the room stat would be connected. As no room stat is fitted it just loops back to the other side of the connector block and then attaches to the PCB. Both of the red wires share the same connector as the mains wires where they attached to the PCB.


If I can upload a picture of the PCB I will do so to make things a bit clearer.

I will double check voltages a bit later when I dig my mutli meter out (buried somewhere in my basement!), but what I can presently say is this. There is power to the PCB as the B lights flashes and the boiler does fire up and the clock is at least ticking away so there is a supply to it.

If you can think of anything else which may help I would be very grateful.

Regards

Jules

 

[julesg007]

Hi,

I have checked the voltages and they are as follows:

At mains/incoming, segment timer/internal clock and PCB (where mains connects) are all 235V

At outcoming from segment timer (red wires) and where it connects to PCB is 198V.

Checking back to the fault finding section of my instructions there is a section where it asks if 240v at clock across terminals 1 (N) & 2 (L) is there continuity across terminals 3 & 4. Not being an expert from the voltages I have given, do I have continuity?

If not I think I have to replace the clock, which may sort out my problem.

I have uploaded a picture of the PCB which I hope you can see the wires I refer to. If you need any clarification please just ask and I will be more than happy to assist.

Thanks again for the help

Jules

Untitled

• julesg007
• 13 May 2009
• 1

 

[petit_pablo]

Checking back to the fault finding section of my instructions there is a section where it asks if 240v at clock across terminals 1 (N) & 2 (L) is there continuity across terminals 3 & 4. Not being an expert from the voltages I have given, do I have continuity?

Turn off power to boiler, disconnect wires from 3 & 4 and set our multimeter to ohms. Test across 3 & 4, continuity will be less than 1 ohm but may read a touch more due to resistance of meter leads.

Alternatively, link the wires to 3 & 4 with a piece of wire and see if it fires up.

 

[julesg007]

Hi,

Thanks for the advice - was away for the day so checked things this morning.

I am getting a reading of about 1ohm and when connecting 3 & 4 together the boiler fires straightaway.

It therefore seems that the clock/timer is u/s - a new on is being sorted.

 

[julesg007]

Good evening all,

I am sorry to have to report that the boiler has decided to be a real pain.

Although I thought the problem on the HW side was sorted it doesn't seem to be as the boiler has again decided to fire up only when it wants to and I can't even get the CH side to fire the boiler by connecting wires 3 & 4.

Also the boiler is again trying to fire up when no demand is being made either HW or CH.

Seems that basically I am back a square one.

If anyone has any thoughts or suggestions I'd be grateful but I am aware of the "distance diagnosis" problem. Although I must say I am getting the feeling that I may be needing a new PCB

Thanks again for the help.
Jules