Heating Has To Be Fired Up To Get Hot Tap Water. Help PLEASE

[Ry]

Hi experts,

I have a gravity sys in a small house.
Potterton Fuel Saver boiler in Kitchen.
Tank and EP2002 controller in Upstairs cupboard.
A few weeks ago we started to not be able to get hot tap water unless the heating was also put on.
The slider seems ok and infact the controller was new a year ago anyway.
The red light comes on the controller, but the boiler wont fire unless the heating slider is also moved into timed or on.

Im about to change the controller again for another new one but would love some advise.
The tank has a bimetallic dial themostat attached to it that only seems to have effect on central heating operation. ie it shuts the boiler down if it is turned to a low temp setting.

I cant understand whats going on?

 

[ChrisR]

COuld be a sticky valve - what motorised valve(s) have you got?
Here's a pic with a 3 pipe one, some have two...
http://content.honeywell.com/uk/homes/Catalogue/Sundial Plans/3.4 Y Plan.pdf

 

[Ry]

Not sure what the valve is. I tried to take a pic but how do I put this into the reply?[/img]

 

[Ry]

how do you att a pic?

 

[Ry]

As in, I know what a valve is and where mine is. Its in a bitch of place. Is this the cause then chaps?
I will be changing the ep2002 now any way as one of the sliders had gone friction'less so was annoying me. I'll push the advance button from now on to save wear-n-tear on the delicate little sliders.

Why have I got a water temp dial on the front of the glow worm in the kitchen and a thermostat dial thing strapped to the tank upstairs?

What water temp do they regulate> tap water or Heating water?

Will I change the valve next then?

 

[Gasguru]

Is the valve a mid-position type ie with 3 ports as shown in the link above.

The cylinder thermostat controls the temperature of the tap hot water in the cylinder.

The thermostat on the boiler controls the water flowing from the boiler.

This water indirectly heats the stored water in the cylinder. If the system had no thermostat on the cylinder the only way of controling the hot water temperature would be to use the boiler thermostat.

 

[ChrisR]

Upload a pic to photobucket.com then copy the link to your posting.

Unless we know what sort of valve(S) you have we can't advise, but if it's 3 pipe one like shown above, it'll probably need replacing at least in part, for your symptoms.
That's sod's law for you if it's hard to get at.

 

[Ry]

How much average will the unit cost in your experience chap?

 

[Ry]

http://i75.photobucket.com/albums/i301/ry29_2006/Photo-0282.jpg
http://i75.photobucket.com/albums/i301/ry29_2006/Photo-0283.jpg
http://i75.photobucket.com/albums/i301/ry29_2006/Photo-0284.jpg

doesnt show its pipes. It does have three. the blue brick has a round copper extrusion that has three pipes. 22mm. on to center of tank with an air bleeder. On to the bottom of the pump area, and another looking like it goes down stairs maybe toward the boiler.

Shall I change this valve then? or does it get serviced somewhere.

I do every thing myself if I can, always have done.

Thank you for your help very much

 

[ChrisR]

I think that's an old ACL/Drayton valve - see if you can read a name on the "top" ie the leftfacing face.
If it's Switchmaster you will be embarking on an adventure (it would have a round part you can turn manually), because the pipes will have to be altered.

If it's the former it's almost certainly meant to "spring return" to HW, so the valve (in the brass bit) is probably stuck, if it ever DID work ok.

Either way it means a whole new valve, which will be a hard thing to change in there.

Also your pump looks like a Myson Unit 3??? In which case it's 20 years old and due for a change.

It might be worth your while sketching the pipe route so we can check the logic of the failure.

 

[geoff@cetltd]

I think that's an old ACL/Drayton valve - see if you can read a name on the "top" ie the leftfacing face.
If it's Switchmaster you will be embarking on an adventure (it would have a round part you can turn manually), because the pipes will have to be altered.

It's a Switchmastrer VA1 or VA5

I used to repair them, but not any more

it's a re-plumb job