No hot water but heating works fine

[brianj42]

Got a Vaillant vcw-gb 242 eh combi boiler. Now 18 years old but serviced annually and worked like a dream, until now.

Central heating works no problem.

Turn on the kitchen hot water tap whilst the CH is on and the boiler switches off and the pressure rapidly drops off to zero.

Without the CH on the bathroom taps run hot and kicks the boiler into play no problem, but the kitchen hot tap does not start the boiler and runs cold.

The secondary HE has a slight leak, common problem with this boiler. But should that cause these issues ?

I have read it could be the expansion tank, another says it could be the HE and another it could be the diverter......

Corgi fitter has been here for 5 hours and he cannot make head nor tail of it.

Help

 

[fiona1581]

i have a baxi combi 80Eco boiler and recently the hot water has turned cold, it was working when the heating was on but now it is just freezing cold all the time.

any ideas?

 

[buck51]

I hope your not paying him by the hour if he is just stud there scratching his head!!!
Fiona Start your own thread!!!

 

[petertheplumber12]

most combi don't like the pressure below .3-.5 bar so below that they won't fire. make sure your not loosing pressure out the 15mm safety pipe. In the manual there is a very comprehensive fault finding chart, if you have one look on pages 66 and 69 they will point you and the gas safe (not corgi) man in the right direction. but check pressure first.

 

[picasso]

Corgi ? will the that dog never die ?

 

[petertheplumber12]

Yes fiona your own thread please

 

[petertheplumber12]

Yes I get fed up with too, pity it happened really, they should have owned their own emblem then they would have lasted, or was it the name? still doesn't matter whats done is done.

 

[brianj42]

Sorry, did I say Corgi, I meant to say Gas Safe. Have been out of the Uk construction industry for a while now.

New events

To add to my quandary the system is now losing pressure without any use of the hot water taps. I put the pressure up to 1.5 and within 20 minutes its down to about 0.5.....

If the central heating is running fine and I turn on a tap, no problem. Turn off the tap and the boiler goes orf.....

Does this ring any bells ? Please....

 

[kevplumb]

check the prv first

 

[Agile]

Pressure going down means water leaking out!

Why did your Corgi man not find that instead of just scratching his head?

I think you need a new Gas Safe man.

It amazes me that consumers dont realise that there is no standard assessment or qualification for diagnosing heating faults and every engineer has a different level of capability.

Tony

 

[brianj42]

Ok. Upped the regulated water pressure to the house to 3bar and the System is now running normal, can get hot water from all taps, CH running normal.

Only issue now seems the drops in pressure which signifies a leak.

Will the fact that the secondary heat exchanger (DHW) is leaking (Drip every 20 seconds) cause such a significant drop in the pressure ?

If this is the case then I may be looking at just swapping out the HE ????

Thanks to all who have replied thus far, including odd comments.....