Greenstar 42CDi Combi Boiler - CH Not Working

[coldguyfromwales]

Hi everyone!

Since coming back to the house from a weekend away, I've found that the CH for my Greenstar 42CDi Combi Boiler is not working. Here's a picture of the boiler panel:

http://i43.tinypic.com/sy9xqt.jpg

And here's a picture of the digital thermostat:

http://i44.tinypic.com/2sb3ds3.jpg

I've tried restarting the boiler via the reset button, but the same thing seems to happen:

- The number dial on the top right in the first pic drops from 60+ to around 50.
- The flame light comes on for a short while and it appears that everything may be okay.
- The number quickly rises from 50 to 60+ again and the flame light goes out.
- Back to where I started.

Here are some more notes about the problem:

- The water temperature is fine, it's just the CH that's the problem.
- The pressure gauge is displaying flat out 0, as can be seen in the first picture. It hasn't changed since the problem started.
- The flame light is usually out.
- I can hear gurgling noises in some of the radiators around the house.
- I've tried changing the thermostat batteries but it hasn't fixed the problem.

And yes, it's probably cold here as it is with you. Any ideas? Is this likely to be a simple fix or something a professional needs to look at?[/url]

 

[Crusader52]

Have you tried re-pressurising the boiler?

 

[coldguyfromwales]

I definitely haven't tried that. I haven't tried much apart from resetting and changing batteries.

Is this a straightforward procedure?

 

[Crusader52]

Its straightforward enough, I am having to do it regularly at the moment as I have a loss of pressure that I can't trace! The pressure should be between 1 and 1.5 bar, in the green part of the scale.

If you have the User Manual it's in there. If not, you can find one on the Worcester website

It involves removing the plastic tray from underneath the boiler. You should find a plastic key shaped like a T. Remove this and locate the refill nut underneath the boiler (white plastic on mine). By the side of this is a hole. Insert the key in the hole and push it upwards. Be sure the arrowheads on the key and the hole line up, or you won't be able to push the key fully up. Then turn the key to the right till it stops. Now undo the plastic nut slowly and you should hear water entering the boiler.

At this point you could get water escaping if you haven't pushed the key home fully. So take it easy as you undo the nut, Watch the gauge rise to the required pressure (1 to 1.5 bar) than tighten the nut again and remove the key. Expect a few drops of water to come out, this is normal.

Good luck

 

[coldguyfromwales]

IT WORKED!

Excellent, thank you so much. You described the process wonderfully. You even nailed the "Expect a few drops of water to come out, this is normal" bit. I've just re-pressurised the boiler to 1.5 and everything is looking good so far. You're a champ.

HERES WHAT I DID:

For anyone that stumbles on this thread with the same problem as me, here's a picture of the nuts and keys Crusader52 was describing:

http://i42.tinypic.com/28qk5c.jpg

These nuts and keys were underneath the boiler and on the right hand side.

I turned the big key in the middle to the right (only turned 90 degrees at most for me) and the white nut on the left to the left for a rotation or two (it was a bit stiff at first). For the first 10 - 20 seconds the pressure gauge did not change, but then it slowly rose to the 1.5 mark after about 2 - 3 minutes.

I then returned the nuts and keys back to their starting position and everything is looking good.

Thanks again Crusader52. Huge help and saved me a lot of hassle.[/b]

 

[coldguyfromwales]

By the way, any ideas why this happened? Cold weather? Or just one of those things that happens with boilers like this from time to time?

 

[Crusader52]

I'm no expert, but as I said before I have to so this regularly. I believe you can get a pressure loss over time without having any problems - your pressure may have been dropping gradually for a while without you noticing it. Sudden loss of pressure is indicative of problems somewhere in the system - leaking radiator, pipework etc.

I suggest you keep your eye on the pressure gauge just in case it drops again. If this is sooner rather than later you probably do have a problem somewhere. You will probably get advice from this forum as to how you can isolate it.

I wish I could get to the bottom of mine! I know it isn't the pressure relief valve in the boiler, so most likely a leaking pipe - unfortunate for me as downstairs pipes are underneath concrete floors

 

[Murf520970]

If its not leaking from the prv &if you want to fnd out if the leaks internal to the boiler or on the system pipe work etc you can try repressurising the boiler to 1 bar boiler cold. Close the isolation valves under the boiler on the flow & return ch pipes & leave for 24 hrs . Take a look after that & if dropped its internal to boiler. If when you open the isolation valves it then drops its on the pipework somewhere. Some Isolation valves can leak if messed with so beware & check what theyre like on here first.Check visually all pipework, rad valves first.

 

[coldguyfromwales]

Okay, I'm still having a few problems with the CH despite the pressure looking fine and steady at 1.5. The boiler is basically repeating the same routine:

1) The flame lights, but the temperature display rises rapidly (around 1 degree per second) until it hits around 60 degrees or more.
2) The flame then goes out, and the display drops to below 50 before the flame lights again and repeats the cycle.

The hot water is still fine, but I'm still having this problem with the CH.

Any ideas of what may be wrong?

 

[coldguyfromwales]

It's also now showing this error:

"The display shows alternatively the CH flow temperature and this code. The gradient limitation is active. The primary temperature is rising too fast and the burner has switched off for 2 minutes."

According to the installation manual, these are the suggested checks and solutions:

- Sealed system (pressure between 1 and 2 bar
- Open vented system (enough water in the feed and expansion tank)
- Pump seized or sticking
- Harness disconnected or broken between flue safety stat or overheat stat
- Harness connections from both safety stats to the PCB
- PCB board defective

Anything I can do about these? I have no idea about any of it.

 

[Crusader52]

Sorry, its beyond my experience level.

Suggest you start a new thread with this latest problem, experienced engineers would probably pick up on it better

 

[RichThompson]

Hi,

On your first photo I notice that the CH knob is pointing at 4, if you turn it round to max does the temperature go above 60 and the burner stay lit? I've turned mine to max these past few weeks and temperature displayed reaches just over 80. Worth a try. Your's might be set too low for the ambient temperature required.

My boiler has been a pain these past few months but has been ok so far since the pump was replaced. It was intermitently failing both for CH and HW, with the temperature displaying U9 (>100) apparently due to the pump not working.

Good luck!

Rich

 

[gasanstuff]

Okay, I'm still having a few problems with the CH despite the pressure looking fine and steady at 1.5. The boiler is basically repeating the same routine:

1) The flame lights, but the temperature display rises rapidly (around 1 degree per second) until it hits around 60 degrees or more.
2) The flame then goes out, and the display drops to below 50 before the flame lights again and repeats the cycle.

The hot water is still fine, but I'm still having this problem with the CH.

Any ideas of what may be wrong?

Are your rads heating up?

 

[misterdubya]

I take it the condense pipe is clear? Thats the white pipe that can freeze up. I suspect not, as you should have seen the eroor code 'EA'.

Mr. W.

 

[swbjackson]

Sounds like two things to me.

1. The pump is goosed through running with no pressure in the system or

2. Air in the boiler.

I would think that number 2 is more likely. There is a way of forcing the boiler to repeat the initial start up routine to clear air but I'm not sure if it's in the instruction manual supplied or if it's in the guide supplied to engineers.