How old is the boiler?? Do you no anyone in the trade, ie friend,friend of friend that will have a look and advise for you.
Double HE = simple combi. Do you ever hear a buzz of the gas valve???? I bet a tenner it's the gas valve!!!! Are you in Scotland???
Not what i would of said going off what has been said. Although you got to be there to see it haven't you.
I will go up against you Dick, if the temperature is fluctuating its 99% sure to be the sensor. Bottle of scotch on it.
Have a look at the 'flow function diagram' for this appliance!!! Double HE remember!!! They were good wee boilers, but the HW delivery was **** poor!! A lot fitted in social housing around our way, so you needed to repair them fecking quick....Phewwwwwwww!!!!
He has swapped the sensors round but if they are both not 100%, then only way to find out would be too buy new and fit them see what happens. Definitely worth replacing before looking any further.
The only way to solve this issue is to see what is going on electronically. Connect a digital multimeter across the gas valve modureg at the same time as taking the burner pressure. If the voltage decreases at the same time as the burner pressure then you can rule out the gas valve and you know the pcb is being told by the thermisters that the hot water is hot enough. Thermisters arnt always easy to test as they may read correct a say 35c but wrong at 55c so you could replace them just to see, or i usually fit a variable resistor in place and set the resistance acordingly weathers an ntc or ptc. My guess would be the heat exchanger is scaled up causing a lack of heat transfer and the residual heat is then traveling to the ch sensor and this is causing the decrease in bp pressure. Ps no diverter valve on this model just a guess but hope its of help
Thanks silversurfer, I will give the pressure/resistance theory a test. As for the heat exchanger being scaled up, I did give this some consideration at first but due to living in Birmingham (Soft Water) I ruled it out, do you think that there is a possibility that it could be scaled up after all, and should I just give it a flush anyhow.
Hmmm to be honest i dont know if you lived in in a hard water area i would say your symptoms are a scaled up H/E but if your area is soft water i would guess that that cant be the case. Like i said measure the voltage on the modureg part of the gas valve and watch the burner at the same time if the voltage decreases at the same time as the burner modulates down then you know the pcb is being to asked to drop its output voltage and the gas valve is proved ok. You then need it establish why this is the case. If one of the thermisters has gone open circiut then swaping the leads over can prove this but with your problem i wouldnt say it wil help. Its not pressure/resistance its heat THERMister. There is a pre set potentimeter on the pcb controling the hw temp but i doubt this is causing the problem. I think id have to try changing the thermisters and fingers crossed. Ps ntc means negative temperature coefficent (resistance decreases on temperature) ptc is just the opposite. j
Hey 'smithp60' this is the one I want, it would be an insult to a Scotsman to buy him anything less!! http://www.thedrinkshop.com/products/nlpdetail.php?prodid=2162
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