No Hot Water when HW switch is on but radiators stay on HOT

[MikeDee]

Hi.

I have a conventional gas fired Boiler/CH system:
Boiler: Ideal Elan 2, around 17 y/o.
Horstmann H425 programmer.
Hot water storage tank.

Last week i had my system drained as i accidently damaged a radiator pipe when lifting it off. This was quickly fixed. Then, after initial problems with the boiler making noises, re. air locks, this was also resolved and all appeared to be fine - no noises, radiators all very hot and heating working fine. I didn't really test the HW at this stage (we have a dishwasher, elec shower and i don't shave much!).

However, i have since noted i have no Hot Water after leaving the HW switch on for hours (the CH switch was left OFF). The burner in the boiler stays on, the radiators heat up very hot, but NO hot water at all. (I still have the odd little air block in the rads but i have sorted them out).

This problem did occur before my troubles last week, i got both HW and CH with just the HW switch on. I'd say the problem has been there periodically for a good 5 or 6 months now.

Can anyone shed any light? I'm not too confident at replacing parts, what could be the matter? Does it have anything to do with the small expansion tank in the attic after it was refilled? Will this be expensive?
Many thanks guys.
Mike

 

[hi-spec plumbing heating]

your motorized valve is sticking.

 

[MikeDee]

your motorized valve is sticking.

thanks mate, where do i locate this and what does it look like? Is this the small plastic box unit near the pump up beside the HW tank?

 

[hi-spec plumbing heating]

thats it you can remove the top and turn the spindle on valve to check it moves freely

 

[MikeDee]

i will do.
Can you tell me, what are the 2 black plastic "switches" on it? (One on the top, the other at the side). What do they do?
Is this easy fixed? Do i need to drain the system again?
Many thanks again.
Mike

 

[hi-spec plumbing heating]

draining depends on if you can get away with changing the top or you may have to change whole valve.

lever on side can be pushed in and top will come off then you can check spindle.
end lever that moves when the valve is switched onto hw/heating.

 

[MikeDee]

i got the plastic cover off but there is nothing resembling a spindle mate.
There is a circular metal thing but it is enclosed/sealed, around 40mm diameter and is still hot to the touch. Anything else i can check?
thanks

 

[hi-spec plumbing heating]

if you can watch it as someone turns off heating onto hw only you should hear it move and that metal circle is a motor.

and try heating only
then both
then hw only

 

[hi-spec plumbing heating]

if you push the side lever in it will all come off not just the plastic case.

 

[MikeDee]

Right, i tested it with a helping hand there....

Switched both ON.

Then, turned off CH. The small plastic switch moved (think it was up)

Then, turned on CH. The small plastic switch moved (think it was down)

Then, turned off HW. The small plastic switch moved inwards and upwards.

Then, turned on HW. The small plastic switch moved outwards and downwards.

Note, the small plastic switch moved VERY slowly and indeed the motor sounded very slow inside that metal drum. (Not sure if this is normal or not?)

Any more clues?

Many thanks again,
Mike

 

[MikeDee]

got it off.

I take it i just poke a screwdriver in the back where it would meet the spindle and see if it moves freely?

 

[hi-spec plumbing heating]

no don't do that bit turn the spindle on the pipework valve ( brass bit )

with a pair of pliers.

 

[MikeDee]

no don't do that bit turn the spindle on the pipework valve ( brass bit )

with a pair of pliers.

ok, done it.

It only turns around 1/4 of the way (if that). Any more clues?

thanks again mate

 

[hi-spec plumbing heating]

they don't turn much put the top back on valve.
and just switch hw on
does boiler fire up or not ?

 

[hi-spec plumbing heating]

reading your post
i can't see how your got hw on heating off and your rads are hot.
when your valve apeers to be working ok. strange.