Glow-worm Cxi 30

[Jules101]

Hi

I've recently had a Glow-work Cxi 30 installed and have had a couple of problems that the installer doesn't seem to be able to rectify.

Firstly, when you turn off the cold tap, the boiler starts up. It doesn't actually fire up, just primes itself. I was told it could be due to a 'dead leg'. The installer fitted a PRV, which didn't help.

Secondly, the boiler will randomly start up. When it does, it displays the temperature which increases until around 70, when it eventually stops. The installer claims the boiler has some sort of internal storage and that the boiler is maintaining the temperature of the water.

The installer has also said that he is going to try fitting some sort of value which will divert the pressure through a membrane so the boiler doesn't sense the pressure drop, which is apparently why it starts up when you turn off the tap.

Also, I thought that the whole point of this type of boiler was so it provided on demand hot water without the need for storage?!

Any help would be really appreciated.

Many thanks

Jules

 

[Agile]

The boiler has a facility which keeps the inside warm to enable hot water quicker.

The best attempt to stop dead legs is to fit a non return valve after the boiler DHW output connection.

Tony

 

[Jules101]

Thanks for the reply Tony.

Would you know why it needs to heat the water to around 70-75 before it shuts off? The water is set to economy (50).

Also, excuse my igonorance here but, how would fitting a non return valve on the hot water output fix a problem with the cold water? Or am I missing the point?

I'm assuming the dead leg is the reason for my first problem - or is there a possible other cause?

Thansk again

Jules

 

[Agile]

I charge for fixing boilers.

I give some free advice on boiler faults on forums.

But I dont give long explanations to anyone who does not want to take my advice or does not believe it!

Probably someone else here will explain it for you.

The boiler reads the circulating water temperature and it heats it to 70 because its designed that way. It will stay hot longer and increase the cycle time.

I dont agree with that design concept though as it encourages lime scaling. You may be able to disable the preheat.

Tony

 

[ChrisR]

The installer fitted a PRV, which didn't help.

Sure that wasn't an NRV? Non return valve?

That is a normal fix.

I give some free advice on boiler faults on forums.

But I dont give long explanations to anyone who does not want to take my advice or does not believe it!

Probably someone else here will explain it for you.

The non return valve stops the water bouncing back and forth when you turn a tap on, which triggers the HW flow switch.
Didn't take as many words....

 

[Jules101]

Thanks for the reply Tony although I don't recall saying I didn't believe you, I was just a bit confused, as I stated. Thanks for the advice though.

ChrisR - thanks for the comments. Yes, it was definitely a PRV. Apparently, Glow-Worm advised him to fit it. It did help but made the flow for filling the bath and shower incredibly low.

 

[gas4you]

Get the installer to remove the dead leg, or at least fit an air bleed on the end of it so the air can be removed . This will solve the problem.

Look in the boiler instructions and turn off the pre-heat for DHW.

You need to go into d74 and select '0'. This will turn the pre-heat off.

 

[The Baker]

Whilst a dead leg may be the problem its also possible there is a pocket of trapped air in the pipes that are between the boiler and the taps on the hot side of in the pipe work on the cold side.

It may not be possible to bleed this air out.

If you could be hang on a week or two you may find the problem goes away as the pocket of air slowly gets drawn out via the taps.

For now please try turning the hot and cold taps off "slowly" (a, no charge for this advice, emoticon)

Tim

PS this has worked for me.

 

[Jules101]

Thanks for all the advice. I will pass on the info to the installer.

Cheers all.

Jules