Water wont come on without heating!!!

[neilnewby]

HELP!!!!!
I have recently moved into a new house and have encountered a problem with my central heating.

The HW wont turn on without CH. CH will run fine on its own. The only way which the 3 way valve will switch to HW is when both are turned off. As soon as I switch HW on, the valve moves to the mid position and the boiler does NOT ingnite.

Any ideas why the valve moves to mid when only HW is selected?????

I have checked the stat for the hw with my meter and it operates fine. Also i have physically switched the micro in the stat to switch between mid and CH.

I have replaced the whole of the 3-way valve/motor and the controller.

Just noticed the room stat isn't clicking, but i dont think this affect the HW side of things as it isn't affecting the operation of the CH.

Any ideas would be greatly appreciated.

thank you

 

[mysteryman]

Sounds like a faulty programmer or cylinder thermostat - or more likely, it's wired up wrongly and never worked.

Look in FAQs on three port valves. The valve should not motor at all in hot water only. Check that your immersion heater is not switched on!

 

[neilnewby]

Hi,

Should have said the 3-way valve is a Drayton ma1 and a Drayton lp522 controller. I have changed both for brand new units, neither have made any difference.

 

[kevplumb]

check the wiring then

y plan

• kevplumb
• 19 Sep 2009
• 22

this is honeywell but the principle is the same

 

[neilnewby]

Thanks for the diagram. Looks almost identical to the one I have. I have followed it through and everything appears fine going throughout both stats valve and pump. I'm not too sure on the wiring in the back of the controller, but it appears ok.

 

[Hugh Jaleak]

Not sure if this will help, but if you're confident with a multimeter this: http://www.jturnbull.net/c_heating/index.htm shows the paths the power takes depending on demand/status of the system.

 

[neilnewby]

Thanks for that. Great diagram very clear. I'll have a poke about with
My meter in the morning

Cheers