Vokera 20/80, hot water going cold

[rob7475]

Hi,

I'm after a bit of advice please.

We have a vokera 20/80 rs flowmatic that was installed in 1992. At the moment we are having problems with the hot water. When we run h/w, it will go hot for about a minute before running cold for about a minute and continuing in this cycle.

Is this a common fault with this boiler, and if so, how easy is it to have it repaired or is it worth being repaired at 16 year old?

The boiler was last serviced last year but i'm not sure if the guy changed all the diaphragms or not - could this be the problem?

Thanks in advance.

Rob

 

[Agile]

There are all sorts of possibilities but the most obvious is that the secondary heat exchanger is sludged up.

If you are getting someone in then search for TJ on this forum and someone in Leeds was recommended recently.

Tony

 

[rob7475]

The boilser seems to have been OK for the past couple of days. I think it just needs a decent service.

Can anyone recommend anybody near Halifax, West Yorks. to do the job? If not, does anybody know if Vokera themselves are likely to do a good job of servicing the boiler?

Thanks,

Rob

 

[rob7475]

A bit of an update....

Things are starting to get worse with the hot water. After running OK for a couple of days, the boiler started playing up again the other day - the hot water started going cold again!

Today, I have had to drain down the system as I had added some system cleaner a few weeks ago. I drained down the system, then refilled using the filling loop whilst bleeding the radiators. C/H is working fine but I still have a problem with hot water.

Now, when i run hot water, the boiler clicks but the flame doesn't ignite for about 10 seconds. After running at full flame for a couple of minutes, it drops to a lower flame for about a minute before the flame returns to just the pilot light for about 2 minutes before restarting the process.

Also, when hot water is running, there is now a noise coming from the boiler that is different to before I drained it down today - it sounds like water running through the pipes (it's hard to explain but it is definitely different to before I drained the system down).

I have arranged for Vokera to come and service the boiler on Friday. But in the mean time I was wondering if anyone knows if I have missed something vital whilst refilling the system?

Thanks,

Rob

 

[Sloop]

Domestic Heat Exchanger needs bleeding white in color bleed nut on top 10mm spanner-probally venturis blocked causing flame to drop out.

 

[rob7475]

Thanks for the reply.

Do i just undo the nut on top of the h/w heat exchanger?

I had a look at it earlier and it looked like there is a screw in the top of the not so i wasn't sure whether to undo the nut or the screw?

thanks,

rob

 

[Sloop]

just slacken nut until water starts to come out then tighten back up.