Heating but no DHW

[opps]

Be careful, if the HW 2 port is manually latched, there will be no HW temp control. The cylinder stat controls power from the programmer to energise the valve and then shut's it down when the it reaches set point. If the valve is manually open and the boiler is being controlled by the room stat, the HW could get to an excessive temp, if the system water is hot enough.

Thanks for the heads up. Would that be hot enough to force the hot water to head up to the cold water tank via the "vent" pipe?
BTW, can you recommend a primer web page that explains how those systems work?

I have, thanks to this thread, only just discovered that the thermostat on the cylinder is supposed to to stop the flow of water to the cylinder (as per your post). I had always wondered how the heat source knew when to stop.

I love this site, I try to use my work related knowledge to help others but I am always grateful when other trades people (such as each of the contributors to my initial post) help me with regards to things outside of my ken. Long may it last.

 

[CountryFan]

BTW, can you recommend a primer web page that explains how those systems work?

Our very own Diynot.com wiki pages

 

[opps]

Our very own Diynot.com wiki pages

Cheers mate. I will read through the link later. Much appreciated.

 

[Madrab]

I had always wondered how the heat source knew when to stop.

Programmer sends 240V to the cyl stat > cyl stat sends that 240V out to the 2 port > that 240V powers the 2 port valves motor that opens the valve > the microswitch in the 2port valve is triggered by the valve opening and sends 240v, that is running in on the grey wire, over to the orange wire out > that orange wire is connected to the boilers switched live and switches it on. Once the stat reaches set temp it breaks that connection and the valve shuts, switching off the power to the orange wire and the boiler goes off.

Would that be hot enough to force the hot water to head up to the cold water tank via the "vent" pipe?

Normally only if it gets excessively hot