Glow-Worm 24cxi no hot water and leak help

[Reeves2k2]

After getting up this morning to no hot water I've been poking around having a look to see if I can see or diagnose a problem.

Whilst looking i seem to have found a small leak as well and I'm not sure if it's related or not.

Symptoms :
- No hot water
- Very Luke warm for first few seconds
- Light comes on and switches to show pressure.
- CH flow pipe remains cold.
-If left running for a while once tap switched off if I turn it back on the light doesnt light and pressure not displayed.

I had the P2P heat exchanger cleaned last year as that was blocked. Although that caused a fault code to show.

I'll attach a picture of where I found the slight leak. It's from the nipple ar the top of the part behind the main pump in the picture.

Any help would be appreciated.

 

[ianmcd]

That is the Automatic air valve or AAV it is there to release air that gets into the system, most only leave them open when filling the system then close them by screwing down the small plastic part, they are terrible for leaking, not just that brand but all of them, you can just screw it down to stop it leaking, up to you if you want to replace it, but as long as you have sufficient pressure in your system the no DHW is not connected

 

[Reeves2k2]

That is the Automatic air valve or AAV it is there to release air that gets into the system, most only leave them open when filling the system then close them by screwing down the small plastic part, they are terrible for leaking, not just that brand but all of them, you can just screw it down to stop it leaking, up to you if you want to replace it, but as long as you have sufficient pressure in your system the no DHW is not connected

Thank you for the quick reply.

I'll screw that down to stop that then.

Good to know it's not related.

Any ideas what could be causing the DHW issue.

I think from looking around the internet the most likely culprits are:

Diverter valve
Flow sensor
Flow switch?
P2P heat exchanger sludged up again.

I've verified that the light comes on and pressure shows on LCD when DHW called. So does that rule out the diverter?

 

[ianmcd]

I think you are getting confused, when you run the HW the display will show a HW tap symbol to shaw the demand for HW has registered and it should show temperature not pressure, if you can record it with your mobile and post it so we can see what is happening

 

[Reeves2k2]

I think you are getting confused, when you run the HW the display will show a HW tap symbol to shaw the demand for HW has registered and it should show temperature not pressure, if you can record it with your mobile and post it so we can see what is happening

This particular model of boiler doesnt show a tap symbol.

It has a led that lights when demand is called for and it shows the pressure of the system.

If the CH is on it shows temperature and when DHW is called for when the heating is on it switches and shows the pressure again.

Of there is no CH on the led just lights and display stays showing the system pressure

 

[ianmcd]

well if it is showing the pressure during HW demand it is not sensing a demand for HW, it should show temperature not pressure.

 

[Reeves2k2]

well if it is showing the pressure during HW demand it is not sensing a demand for HW, it should show temperature not pressure.

It has always showed the system pressure on HW and temp on CH
Unless you are mistaking it for a slightly different model.

The 24cxi I have has been like this for the last 15 years lol

 

[Reeves2k2]

well if it is showing the pressure during HW demand it is not sensing a demand for HW, it should show temperature not pressure.

I promise you you have it the wrong way around.

I'm not trying to come across as a know it all far from it but I can honestly say this particular boiler model shows temp when CH demand is on and pressure when DHW is demanded.

 

[Reeves2k2]

After doing some more observing I've noted.

The boiler fires for both CH and DHW when as it should. But if the CH is on Then I open a tap to demand DHW nothing happens and the CH continues as if there is no demand for DHW.

If the boiler is in a state with CH off and I demand DHW then the boiler fires but I still get no DHW

I've also noticed a slight damp patch around the switch area

Does all this point to a faulty flow switch and or sensor?

I can't find any information in the manual regarding the flow switch only the flow sensor

 

[ollski]

If the boiler fires for hw do the radiators get warm while the taps running?

 

[Reeves2k2]

If the boiler fires for hw do the radiators get warm while the taps running?

No I checked this first yesterday. So I'm a bit stumped

 

[ollski]

Then it’s not fired up, heat has to go one way or another

 

[Reeves2k2]

Then it’s not fired up, heat has to go one way or another

If it's not switching when the CH is on then it's still going to be going into the CH.

Which is leading me to believe it's got to be either the flow switch and or sensor or the divertor.

But I obviously don't want to be changing all of them if it doesn't need it.

 

[ollski]

It’s the flow sensor usually, if it’s got the rubbish grey one then I’d say virtually definitely

 

[Reeves2k2]

It’s the flow sensor usually, if it’s got the rubbish grey one then I’d say virtually definitely

Yup it's got the grey one in!

I've noticed the part directly behind it id a bit damp
Is that a seperate part that will need changing or will it come as 1 unit?