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James, Developer
Category: HVAC
Satisfied Customers: 6919
Experience:  I have a portfolio of renovated houses, including DIY projects from installing bathrooms and new heating systems to rewiring.
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I have a worcester greenstar boiler supplying hw and ch

Customer Question

I have a worcester greenstar boiler supplying hw and ch through seperate zone valves. Both work fine when running alone but hw stops when both are required. I have changed the drayton za5 actuator on the ch side and changed the synchron motor on the Honeywell zone valve for the hw, but no joy. Where do i go next ?
JA: Are you getting any error codes or blinking lights on your boiler? How old is it?
Customer: 6 year old oil fired serviced 2 months ago.
JA: How long has this been going on with your boiler? What have you tried so far?
Customer: started a few weeks ago when no hw was available. Switching off the ch allowed the hw system to operate
JA: Anything else we should know to help you best?
Customer: zone valve actuator on the ch was changed last week and syncron motor changed on the hw valve. Both systems work fine when running in isolation but hw valve closes when both systems required.
Submitted: 18 days ago.
Category: HVAC
Expert:  James replied 18 days ago.

Hello and welcome to JustAnswer!
This is James, I'm an appliance repair technician with over 10 years of experience, and I'll be assisting you today.

Sorry to hear your appliance is having issues, please stand by while I find the answer for you, this is not an immediate service however I will try and respond as soon as possible.
What do you mean by HW stops when there is demand for both CH and HW, does the HW zone valve close?

Customer: replied 18 days ago.
the honeywell valve on the hw line closes.
Customer: replied 18 days ago.
The valve on the Hw line will not open until the CH is switched to OFF.
Expert:  James replied 18 days ago.

Right and are you getting a demand from the programmer to the HW valve, and also from the cylinder stat?

Customer: replied 18 days ago.
Expert:  James replied 18 days ago.

I would check your wiring centre for demand as more likely than not its the programmer.

The boiler doesnt come into it.

Customer: replied 18 days ago.
Ok will check that out. Cheers