Nest 3rd Gen / Heat Link not Turning on Hot Water...

[AndyMcCall]

Hi All,

I made a post a few days ago about how to wire my Nest 3rd Gen Heat Link. User jackthom kindly replied and everything seemed great. However I've noticed that the Heat Link isn't turning on the hot water. The central heating work fine.

The original wiring of the programmer was:

http://imgur.com/WDTM5Pp

On my original post I thought the black was the central heating and the grey was the hot water, but after I wire it I noticed when calling hot water the central heating was turning on.

My current wiring of the heat link is:

http://imgur.com/a/KiM3O

When the central heating turns on there is a click from the heat link and a radiator symbol (circled in green on the image below) that flashes on the boiler display. When the hot water is turned on there is a click from the heat link and I can also hear some winding noise from some sort of motorised valve on the side of the hot water tank, but the tap symbol (circled in red on the image below) on the boiler display never flashes, the radiator symbol doesn't flash either:

http://imgur.com/a/1eoPS

For reference, the programmer has the wiring on the back as this:

http://imgur.com/a/VPzpa

So, it seems simple and that the wiring should be working as 5 is getting its power from 2, which is wired to 1 - if this wasn't connected the central heating wouldn't turn on. I'm pretty sure I've got the Nest programmed correctly as if I swap the grey and black cables around I can turn the central heating on by asking the hot water to boost. However I can't get the hot water to turn anything on under any circumstance.

The hot water works fine with the original programmer (which I have replaced because the remote thermostat is broken).

Can anyone help me? Does this seem like the Nest Heat Link is broken??

Thanks in advance,

Andy

 

[jackthom]

Andy can you connect the black wire directly to the Live terminal in the Heatlink. Make sure there is no demand for heating and see if the boiler fires up for hot water.
Is the hot water cylinder cool and it's thermostat demanding heat?

If nothing is happening I think we need more details about the system and pics of the wiring centre if there is one.

Are there two motorised valves in the system?

 

[AndyMcCall]

Jackthom,

I think its me being totally dumb.

I tested by removing the central heating wire (grey) and firing up the water. The boiler kicks into life and the radiator symbol flashes. Hmmmm.... thats strange! So I wire up the old programmer and do a call for heating and the radiator symbol flashes NOT the tap symbol. So I think the radiator symbol is more of a demand/hot symbol rather than a central heating symbol.

I have put the Heat Link back in and test again, yes, call for hot water flashes the demand/hot symbol.

At this point I am guessing that the default Nest hot water programming times are not long enough to keep up with demand for our wasteful family of four. I put the Nest in on Thursday and its only today that I've noticed that we haven't got boiling hot water out of the taps. I am guessing that we slowly used more than the current times can supply.

I'll increase the how water times on the website and see how I go.

Sorry for bothering you and thanks a lot for replying!!

Andy

 

[jackthom]

Glad you've got it sorted. My Nest only controls the heating so the hot water is 'on' 24 hours, controlled only by the cylinder stat.
Having a large family who are using water at all times of the day and night it's probably just as well.