Brittony 28SE

[mario500]

DHW fine

CH Warm rads, but not up to temp. Large house but rads furthest away getting warm (at top).

Temp differential on flow and return seem quite high - but couldn't measure properly due to time. Will measure accurately tomorrow.

With CH temp selector on full the boiler gets up to temp (80 degree led on) and the burner is 12 mbar - then after 30 secs or so the gas valve steps down to 2 mbar low flame - this then repeats up and down as temp changes. I did notice that when it steps down the temp drops from 80 degree light to 50 or 60 fairly quickly.
Turn the CH selector down a bit and the flame drops out like it should.

Was thinking possibly a lazy pump or CH thermistor gone out of tollerance.

This is the model with the three solenoids on the gas valve.
Is there a way of testing the solenoids? resistance for example


Al

 

[mario500]

Update


Second visit I measured flow and return temps - flow was only 68 degrees even though the leds said it was 80 degrees.
The temp differential was between 24 and 18 degrees!! too high I thought.

With a 10 k ohm pot connected instead of CH thermistor It was possible to get the boiler up to full temp - so hot it locked out until I lowered the pot a little.
So - I though new thermistor - changed both thermistors like a good lad and refilled - result - no difference.

Actually the DHW was vastly improved even though this wasn't the fault reported.

So symptoms are the same - boiler thinks it is at 80 degrees when in fact it is only 68 degrees???

Any help much appreciated.

Al

 

[cso30]

Hi,

Change the thermistors anyway because they are quite cheap.

The easiest way to test a pump is to electrically isolate the boiler disconnect the live and neutral wires, set a multimeter to resistance (ohms) and measure the resistance over the live and nuetral terminals.

150 - 200 ohms - ok, the closer to 150 the better

Anything over 250 ohms or less than 100 ohms replace the pump

 

[mario500]

Cheers Cso30

Thermistors for these are 25 quid plus vat each. But I did change them both anyway.
The pump head is only a year old - in fact I put on for the guy.
I will test though when I am there next.

The thing that has had me struggling is the temp differance! why does the boiler think it is up to temp.

Hoping someone who works on chaffs alot might know some fix


Cheers

Al

 

[numpty1]

these boilers are funny in the way they modulate,hence the three solenoids if you are getting min burner and maximum i would be looking at the middle one.i am no expert on these if fact i refuse to work on any french sh1te.

 

[cso30]

I bought a thermistor for about £5 last week maybe the price varies in regions.

Is the system clean?

 

[mario500]

Cheers fella's

I did wonder about the middle solenoid - i was wondering if there was a test for them. Although If I pull off the wires to them the boiler either goes to low flame or no flame. I don't know if there if a mid set flame modulation, but would really like to

Yes fella - the system seems very clean. The guy said it was cleansed and inhibitor added when installed - about 3-4 years ago.


Al

 

[mario500]

Ok finally got back to this one due to difficulty obtaining parts
I found that the diverter valve was stuck in the DHW mode - so when in CH the flow was just flying around the plate hex. Changed the hydraulic block along with new valve - refilled and at last rads warmed up nicely.
Then - I ran DHW to make sure all ok there and it was.. Until boiler resorted to Ch again - and then back to original symptoms arrrgghh

I had already tried a new pump head because I suspected a restriction in the flow, but no difference.

So why oh why did Ch work fine at first but as soon as dhw was on the original symptoms came back. ie cold rads and hot plate hex???

Any ideas men?


Al

 

[mario500]

Fixed this ages ago but forgot to update.

Replaced dv and flushed ch flow and return with mains pressure.
Connected back up and all tickety boo.