Saunier Duval warm hot water, hot rads

[zanwan]

My Saunier Duval combi is playing up.

I get warm water from the hot taps, however this ONLY happens if i have the central heating on.

If the central heating is switched off, i will get lukewarm water at best.

I'm assuming its something to do with the divertor valve?

Is this a big job to sort or can a novice do this?

 

[Slugbabydotcom]

Saunier Duval made a lot of combi's !

Would you like to give us a clue?

 

[zanwan]

lol sorry my bad, its a F30e i think, of the top of my head.

 

[Slugbabydotcom]

So would that be the thema condens or the thema condens plus or the semia condens?

 

[zanwan]

therma F30e classic!

 

[Agile]

Thats the non condense boiler very similar to the plastic Glow Worms isn't it?

The ones that suddenly spring serious leaks from the plastic bits?

Tony

 

[zanwan]

Therma classic f30e (fanned flue combination boiler. I've had it about 6 years, and not had any leaks. Only issue is lukewarm water over the past few months.

So any ideas lads, or ladettes? Could it be the plate heat exchanger?

 

[mickyg]

hold on start again, the fault doesn't quite make sense for this boiler.

Turn off heating, open tap, what happens? does boiler fire? does it go off/on, do rads get hot? what temp at tap, does it get hotter of you reduce flow.

 

[Slugbabydotcom]

Its all on page 42 HERE
If that doesn't get you anywhere then post back with how you got on.

 

[zanwan]

hold on start again, the fault doesn't quite make sense for this boiler.

Turn off heating, open tap, what happens? does boiler fire? does it go off/on, do rads get hot? what temp at tap, does it get hotter of you reduce flow.

Hi Mickey

I turned off the heating, opened hot water tap and boiler fires up, and stays fired up. It does not go off (whilst the hot tap is running) The rads dont get hot.

If i reduce the flow on the tap, the water does get warmer. Sometimes it DOES actually get hot, but this is rare, it usually just gets slightly warmer if reduce the taps.

However the central heating seems to fire up ok.

 

[zanwan]

Its all on page 42 HERE
If that doesn't get you anywhere then post back with how you got on.

Hi Slugbaby

I'm going to open it and have a look and try the suggestion. However i'm unsure of these two steps

-Check the rate of flow.
-Check burner pressure is correct.

How exactly do i check this? This is all new to me so sorry if i sound a bit stupid!

 

[mickyg]

ok, much better info. I would be looking at the plate heat exchanger being blocked. If so will look like this one here

Untitled

• mickyg
• 26 Feb 2009
• 12

 

[zanwan]

ok, much better info. I would be looking at the plate heat exchanger being blocked. If so will look like this one here

Untitled

• mickyg
• 26 Feb 2009
• 12

ah brilliant! So would unblocking that simply be a case of removing it, and soaking it in a bucket with limescale remover? If so, would the normal descaling tabs you buy for kettles do the trick?

Many thanks for your help, appreciate it.

 

[mickyg]

It depends on whats causing the problem. The one in my photo is clearly blocked with "sludge" from the radiators(and incidentally is identical to the one in your boiler). This can be simply flushed through with mains water at high pressure whilst shaking it. If it is scaled then you can try various chemicals, different people use different techniques, various acids, cleaners etc all to reasonable effect. However I would suspect its sludge/metallic debris thats the problem. If so once fixed it may be worth your while searching the forum for info on magnaclean filters and DIY flushing techniques.

 

[zanwan]

Thanks once again. I have the day of work tomorrow so will have a go at tackling it. Will remove it, flush it through, and if i notice scale, will try some chemicals.

Hopefully this should do the trick. But as you say i'll probably need flush/drain the central heating. I searched the forum last week for this as i wanted to practice flushing systems out, so practised on my parents central heating! Worked a treat!

Will let you know how i got on!