I'm not quite sure if I've got this. Is the problem no water from the taps or are you getting water but its not hot/heated?

For the first, could be airlock or sludge/blockage. Try the old hose between the taps at the kitchen or connect the two w/m valves together and blow through for a few seconds. Make sure the valve next to the H/W Cylinder(the one in the airing cupboard) is not turned off.

If you are getting water from your taps but its not heated, check your boiler is working(are rads getting hot, can you see the pilot light/boiler firing up).
If the boiler is working check any thermostats.(Make sure its set to call for heat. Listen for a "click" as you change the setting.) There is commonly one strapped to the cylinder for hot water. If a thermostat is broken it will need replacing(usually inexpensive).
If all these checks leave you scratching your head, you might have sludge in the flow or return pipe to the cylinder or a broken diverter valve. If you know where your valves are(next to or near the boiler usually) check those for operation.

hope this gives you some ideas.
Quote:


Not quite, yes the heating water is seperate from the H/W but it's not "layered" in the cylinder.  If you look at it you will see 4 main connections on the cylinder, one from the top, one very low on one side and two, one above the other on the other side(you may have others too) it is these two pipes that are your flow/return pipes from the heating system. The water flows in one pipe and out the other, but it doesnt really go "in" your cylinder. these two pipes are directly connected through a long coil of pipe wrapped inside the cylinder. Its this coil that heats your hot water. (the coil has a far higher surface area than your stratofying method, therefore more heat goes between it and the water to be heated.)


btk

balancing your system is definately a good starting point. Sounds like there might still be a problem with your diverter/3-port valve(s) though. Your rads should not come on when calling hot water only. On some systems hot water will come on when calling for heating only but not the other way round....
Do your balancing first then see how its running. You could be on the right track with that especially if some radiators arent heating at all. The ones that are heating(very hot) could just be using all the water for themselves, not allowing the hot water or other rads to get any... lol

How do you know what pipes are flow and what ones are return when you say some rads have the TRV on the wrong side, as they could come in at either side? I'm sure you have a method but just saying just in case... lol

btk

[quote author=welldweller  link=1113386357/0#4 date=1113410216]Put the CH on at lunchtime and checked which side the hot is coming into. On some rads its coming into the lockshield valve side. [/quote]

wtg now sort it!! lol

btk

Changed the valves around. The TRVs are all on the correct side of the rads now. CH is running fine and i've balanced the lot.
But still no hot water. Now reverted to using the immersion, until my new combi is installed.

THanks btk, but, um, what do these valves look like, where are they, how will I know if its working, etc.
The tank is in a cupboard on the first floor, the baxi back boiler on the ground floor. When I call for central heating on the controller the boiler fires up as normal.

Ha! Found it! Was at the side of the chimney breast next to the controller. When calling for water the lever doesn't move. If I move the lever by hand when the boiler is fired up, then turn it off at the controller, the lever moves back. Whatever happens, the pipe either side doesn't get hot so doesn't look like there's any flow. I take it that the lever should move when I call for water and therefore its knacked. Don't think I'll bother replacing it as the new boiler should shortly be installed.
Thanks for all you guy's help. It was much appreciated. At least I TRIED to solve the problem.