Saunier Duval Thelia 623 - No hot water but CH ok!

[upacs]

Hi all

We have a Saunier Duval Thelia 623 that has just started giving us trouble. In short, we have no hot water, although the central heating works fine.

When the hot water tap is open, I can hear the boiler becoming active. The fan goes off, but it won't fire. The pilot is lit, but it just won't fire. It will fire just fine for the central heating however. If the boiler is fired up for the heating, and you turn on the tap, it will turn itself off until the tap is closed

I can see that the pin from the valve-diaphragm is being pushed. I replaced the diaphragm earlier this year as it broke, so this is not the cause. The microswitch also appears to work fine. Going through the fault finding chart in the manual leads me to a circuit board replacement, but this is an expensive part, and I rather rule out other possibilities.

In the meantime, I have disconnected the wires from plug "3" in the micro switch assembly. This means the boiler cannot detect when the tap is open. With this measure, as long as the central heating is on and the boiler fired up, we can also get hot water. Not ideal, but works as a temporary measure.

Any ideas as to what may be causing the problem?

Cheers

 

[Agile]

With that make and model you are lucky to get anything out of it.

Is yours the only one in the country that is not leaking ?

Have you measured the resistance of the temperature sensors?

Tony

 

[upacs]

No, this bugger leaks all over the place. Unfortunately it came with the property when we bought it. Installed sometime in the 90s, and for the past four years has been working fine, but has started giving trouble.

Had it been my choice, there's not enough French wine in this world that would make me buy a Saunier Duval. Alas, we are stuck with it for now

I have replaced the hot water thermistor, thinking that was the cause, to no avail.

We will be replacing this rubbish in late 2012, as we will be doing some work in the property and need to move the boiler anyway. We'll take the chance then to replace it, but until then, we'd like to keep this one limping along

 

[Agile]

I try to avoid going to those because they always leak and the customer will blame me for every leak during the following year.

Since all that I can guarantee is that they WILL leak, its easier for me to just not to go to them!

If the DHW sensor is OK ( I would measure the resistance first before replacing ) then it might well be the PCB IF the demand switch is really OK. Just clicking is NOT any indication that they are working, only a resistance measurement confirms that.

Better to replace it now!

Tony

 

[DP]

OP, there are worst boilers than yours so do not be dispair. Call Saunier Duval and ask for a fixed price repair.

 

[Agile]

I thought that Sonya Duval had ceased operating in the UK about 3-4 years ago?

Do you have any number for them?

A British Gas fixed price repair might be the only option but I expect they will use every excuse to not repair one, particularly if its already leaking.

Tony

 

[upacs]

Hi

Thanks for your replies. I'm trying to fix this boiler myself, rather than having it professionally repaired. We have already decided to get rid of this boiler, so just want to keep it working until we replace it next year. As such, I would rather avoid the expense of getting someone to sort it out, when the money will be better put towards a new boiler

 

[Agile]

Oh good!

I can have a nice quiet Christmas then!

I will be thinking of you with your cold showers!

 

[Andygasman2010]

Take a close look at the micro switches, just above the lever. You may have had a leak onto one of these.

 

[bell824]

OP, there are worst boilers than yours so do not be dispair. Call Saunier Duval and ask for a fixed price repair.

Under the chain of companies that own them these are not repaired any more no point in asking!!

look at more than likely problems with reversing valve and or changeover valve

 

[upacs]

Oh good!

I can have a nice quiet Christmas then!

I will be thinking of you with your cold showers!

Hi Tony. Don't worry, we still have hot water, we just have to switch on the heating first

 

[upacs]

Take a close look at the micro switches, just above the lever. You may have had a leak onto one of these.

Hi Andy. I already checked the micro switches. I replaced them earlier this year, but I removed it just to check. They seem fine and dry

 

[Agile]

The only test is electrical!

 

[Andygasman2010]

Yes, Tony. You've already suggested the most likely problem. Well done you.