Worcester 24CDI boiler problems

[JONES-SMITH]

Hi

Ive searched the net for an answer to a problem i have with my worcester bosch 24cdi boiler but to no avail ! Rather then sign up to some random diy forum i thought i might as well try here, and while im at it i can see check out some savings accounts !!

Anyya, although the boiler works (or seems to) there are a few things that dont seem right...firstly, sometimes when running the hot water the water pressure will drop slightly and i think that if it drops out on the boiler too much the boiler stops firing (?). We live in a 1880 terrace house and think that there maybe a poor water pressure supply to the house anyway. After a short time the hw kicks in again and 'pumps' it out at full force. Am i right in assuming the drop in water pressure and subsequent re-firing could be due to the water pressure coming into the house fluctuating due to neighbours using the water? Or is there something else ?
Secondly and more of a problem is that if we turn the CH temperature dial to below half and try to run the boiler, the boiler seems to lockout and the CH light flashes and the
boiler fires, locksout, fires etc etc....Only when we turn the temperature dial to above half will the boiler fire and maintain heating the water. What could be causing this ? It is a bit frustrating (and potentially expensive) that we cannot turn the heating down to a low level as the boiler locks out. Any ideas ? From reading various other posts the PCB is mentioned quite a bit but im unsure.....

Apart from that the boiler seems fine-ish.

Any help or advice would be appreciated

Thanks in advance,

[HayZee518]

the drop in water pressure is dependant on the size you have coming into the house and how its reduced going to the boiler/ 1/2 inch should be adequate. if your neighbor opens his/her taps your pressure should not be affected. now I remember my dad's house in buffalo had a lead pipe for water. when the city replaced it there was all kinds of mineral crud inside the pipe. I take it you have a tankless water heater jacket in the boiler. maybe you need to rod out the heat exchanger. after all these years there must be a reduction in the tube sheath inside. I doubt it but check if you have a vane type flow switch in the water heater piping. this would account for the burner kicking in/out when water is drawn. not so much the aquastat because this is only for water temperature. if yours is a steam boiler, check the blow down valve. this is a black thing that looks like a T with a valve on the bottom. you should be able to crack this valve open and drain the brackish water out of the boiler - only need about a quarter turn. if you open it and nothing comes out then the blow down is jammed with scale - you'll need to take it apart and clean it. some old boilers need to have the inlet water opened about once a month to one-half a full gauge glass.

[THOMPSON]

The radiator temperature governs the temperature of the water in the pipes, not the temperature of the flame. If you turn it down, then it will go off and on as and when the water in the pipes drops below the required temperature. If the boiler is running constantly when heating, you've got problems!

Otherwise I agree that it sounds like your water pressure is low and that you're probably on a shared supply. Do you and each of your neighbours have stop cocks out in the street? If not I believe you can approach the local water board to get one fitted at price.