no hot water

[caveman720]

Hi all i am with out hot water through the hot taps. I have a copper cylinder which does not appear to be allowing water from the boiler to pass through the coil (heat exchanger) the in let pipe is slightly warm to the touch. I suspect the coil is blocked,or air locked. I have forced water via a hose pipe down the outlet pipe in the header tank in the attic to flush through . The vent pipe acted as a over flow and returned water back into the header tank but still no hot water this has worked in the past.

 

[Armo74]

Do you have any motorised valves? If you have a 3 port it is more than likely stuck in the central heating position(assuming your heating works), if you have a 2 port it could be a failed motor.

 

[caveman720]

I dont think there is a motorised valve ,the heating works fine. I have a old timer which shows 24 hr clock with red and blue pegs which you rotate around the dial for on and off times on the side off this unit there is a toggle switch with 3 positions 1 hot water, 2 off ,3hot water and central heating. I am wondering if the hot water part could be faulty .

 

[ukrobj]

Cold feed blocked further down?

 

[caveman720]

uk rob j suggested cold feed blocked further down, furthe down in the cylinde? I have turned the toggle switch on the timer to hot water only this has resulted in bathroom rad geting hot and feed into the cylinder becoming warm i am waiting to see if this can turn into hot water at the taps . I have also increased the rpm on the boiler pump to aid water flow /wash any blockage away!.

 

[Hugh Jaleak]

If you're sure there aren't any motorised valves then you may well have gravity HW/pumped CH, in which case turning the pump up is unlikely to have any effect on the HW primary. Excluding gas supply, how many pipes come from the boiler ?

 

[caveman720]

ok the boiler is a glow worm floor standing there is a 22mm pipe coming from the bottom of the boiler to the pump i guess ther must be a return pipe therr as well and that is it .Today i have hade the toggle switch over to the hot water only position this has resulted in warm water now coming from the hot taps . The bottom of the cylinder is cold and the top is warm suggesting a build up of silt/crud i plan on draining this to flush out . but i still cannot have ch and hw at the same time i am looking for a diverter valve its not in the airing cuboard or in with the boiler .A bit of a mystery.

 

[Hugh Jaleak]

Top of cylinder will be warmer than bottom, hot water rises. What little heat that is getting through has managed to warm up the top of the cylinder. Whilst there may be crud in the bottom of the cylinder it is highly unlikely to be half full of rubbish....

There may not be a valve on your system, the timeclock suggests you may have the older type of gravity HW/pumped CH, where basically the cylinder is heated from the boiler using gravity circulation through 28mm (1") or larger pipes, and the rads rely on the pump to get the water round. I would suspect a blocked pipe or coil on the gravity circuit. Try a magnet on the pipes in the side on the cylinder, if it attracts this can indicate a blockage.