Heating only working when hot water permanently on????

[glowboy77]

Hi all,

The facts;-
House built circa 2006, potterton suprima 50 boiler, 3 storey house, boiler on ground floor with programmer off it, hot water cyl and expansion tank on 1st floor with two MV's etc, sunvic digi programmable room stat in hallway.

Had few issues recently with heating ie boiler keeping firing up and only on for 30 secs or so before turning off, hence taking an eternity to get house up to temp if at all. Repaced thermistor, latest thing is to replace PCB which i know are problematic on these but this boiler has the upgraded one? However, i am not sure it is a pcb issue.

Generally HW just controlled at programmer by boiler by kicking in for few hours a day, CH left permanently on at this programmer but controlled by digi room stat in hall. Anyway, having played about with it last few days it seems that if the hot water is on permanently the heating is fine, however when i program the water to come on for say 2 hrs in am and same in pm, the heating is affected and i get the problem above ie rads, flow pipe etc get warm but never toasty and water temp at taps is lower??

Surely i can have the heating on without needing the hot water permanently on can't I? Is there a problem here and if so any ideas how i remedy it?

 

[picasso]

if the microswitch in the 2 port valve isint making contact it wont switch on the boiler when you call for heat but it will still open the valve, when you switch on the hot water the other valve opens and switches on the boiler so you get the rads coming on with the hot water, if its a honeywell valve with a small dimple on the cover you can just change the head.

 

[glowboy77]

Hi,
Thanks for response,

They are "range" valves, simply click on top of valve coupling. when water off the heating valve does open in response to stat and boiler does fire, just that it fires for 30-40 secs at time. However, when heating on on programmer, but valve for heating may be closed as temp in cyl reached, boiler fires for several minutes at a time and heats rads etc.

I don't understand it?

Could there be a wiring issue ie my hot water needs to be on for CH to work?

 

[picasso]

However, when heating on on programmer, but valve for heating may be closed as temp in cyl reached, boiler fires for several minutes at a time and heats rads etc.

I don't understand it?

me neither, is the above exactly what you meant to write ?

 

[glowboy77]

What i am trying to say is,

when hot water permanently left on at programmer but no call for it to be heated by cyl thermostat as it is up to temp ie 55 degrees so HW valve is closed, the heating works fine and rads etc are v hot. However, when HW is off at programmer ie out of time setting to be heated, the heating seems to be affected.

With my type of system above ie boiler, room stat etc, do i need to have the HW permanently on to obtain heating or is there a wiring issue here?

Surely i can have HW without heating having to be on and vice versa?

Left HW permanently on last night, heating working fine this am. When HW on programmed times the night before, heating affected ie only warm rads and taking eternity to heat up, also water temp on cyl stat right down to around 30 degrees??

Help please??