Boiler backplate - Hot water needed for heating

[ianmcd]

That certainly works, it's what we did with the SM2. I just want to make better use of the thermostat and avoid using gas when the temperature is already good

You dont get it, only pluming alterations can do this electricerty wont make any difference whatsoever

 

[TimboTwo]

"You dont get it, only pluming alterations can do this electricerty wont make any difference whatsoever"
@ianmcd it looks like plumbing alterations have been carried out already.

OP is that motorised valve on the pipe going to / coming from the cylinder?
Is it a 28mm pipe?

I believe that it probably is as I note your cylinder has a thermostat attached to it. If this is the case, you will be able to control the water independently from the heating. It was quite a common conversion in the '80s and '90s.
The 28mm valve has a spdt microswitch, which allows the system to be wired up for the "16 program" system.
Honeywell call it the "C-plan".
Page 12 on the attached guide.

 

[matburton]

You dont get it, only pluming alterations can do this electricerty wont make any difference whatsoever

Sorry, still not sure I understand why would turning on HW when the CH is turned on not be sufficient?

If I did that wouldn't that mean that if the room thermostat called for heat then both CH and HW would be turned on and hence would work? Then once the room thermostat was 'happy' then CH and HW would be turned-off, turning off the boiler?

If this is the case, you will be able to control the water independently from the heating.

Ah I'm sure you're right!
I previously assumed that cylinder thermostat was disconnected or broken as it didn't seem to do anything.

Should the cylinder thermostat cause the boiler to stop once the cylinder temperate is reached?

Or does it mean that the valve is simply closed to the cylinder and the radiators will then start to warm up?

Should the cylinder thermostat dictate the maximum temperate of just the hot water or both the hot water and heating?

 

[TimboTwo]

Can you answer the question, please, before start getting ahead of ourselves.

 

[ianmcd]

Should the cylinder thermostat dictate the maximum temperate of just the hot water or both the hot water and heating?

once the cylinder thermostat is satisfied the boiler will shut down but the pump will keep running, you cant re-invent the wheel just do it properly

 

[oldbutnotdead]

I can feel a deal coming on here...if you can post pics of all the wiring for your system (cylinder stat, motorised valve on dhw primary, wiring centre if any and of course your programmer backplate) I'll knock up a couple of relay cards in return for you hacking the scripts to find out how I can use a Wiser radiator stat to control a Wiser DHW channel (I have 2 real heating zones and a couple of rads that were originally bypasses for the woodburner. With the thermal store in place i'm getting thermal syphon through them permanently so replacing std valves with wifi trvs & a real bypass, as above i'd like the hot water zone to use these valves as room stats)

 

[matburton]

Can you answer the question, please, before start getting ahead of ourselves.

OP is that motorised valve on the pipe going to / coming from the cylinder?
Is it a 28mm pipe?

Sorry. The pipe has a diameter of 28mm yes.
The pipe on one side goes through a wall and leads to the back of the boiler.
On the other side it goes through a wall that's in the direction of the hot water cylinder.

once the cylinder thermostat is satisfied the boiler will shut down but the pump will keep running

Ah! OK I'll try setting the cylinder thermostat low soon and check if it's working. Thank you.

you cant re-invent the wheel just do it properly

Sorry I know this must be frustrating. I know these are excuses, but here's where I'm at.

• I want to replace the whole system, likely with a combi, but I need to budget and save for that (I suspect the work might be invasive, e.g. the boiler cupboard has no external walls)
  
• I had an SM2, but it was becoming unreliable as a timer, so bought a second had Wiser to replace it (knowing I could drop it in place myself)
  
• I got excited that I now have a room thermostat and wondered if I could make it useful and avoid running the hot water all the time.
  
• I don't have any plumbing expertise, can only do very minor electrical work and I'd rather save for the big job than spend any further money on what I have.

I get it, the simple answers are:

• Check the cylinder thermostat I assumed didn't work actually does, then just leave the hot water on most/more of the time
• Don't bother with the bonus room thermostat, just set the timer as before

I can feel a deal coming on here...if you can post pics of all the wiring for your system (cylinder stat, motorised valve on dhw primary, wiring centre if any and of course your programmer backplate) I'll knock up a couple of relay cards in return for you hacking the scripts to find out how I can use a Wiser radiator stat to control a Wiser DHW channel

That's very kind, but I fear I couldn't safely install a relay card myself. Hence why I was hoping there was something trivial I could do within just the back plate originally.

However I'm more than happy to see what is possible with your Wiser setup!

I don't have any smart TRVs, so maybe if I first send you something (with some instructions) to see what data the Wiser Hub gives us about your setup?

You might have to be a bit patient, going back in to the working week I'm going to be slower.

 

[oldbutnotdead]

Not a problem, i'm just about to start my week ramming stuff in a hole for Amazon. Exploring IFTTT at the mo, that may provide the linking i need, may even let me link to my existing wifi controllers...thats why it would be a card, with marked terminals, no more complex than that backplate

 

[matburton]

I'm more than happy to see what is possible with your Wiser setup!

Maybe if I try to get the ball rolling with some manual steps? Do you have a PC with WiFi?
If so maybe we could use a browser extension like RESTED in Firefox to get started?

If you press the Setup button (on the left) of the Wiser Hub it creates a temporary WiFi network.
Note down the name, I think it'll end in an underscore followed by 6 characters.

If you connect your PC to that then you should be able to visit http://192.168.1.1/secret
Save the response somewhere but don't post it here. It doesn't seem to change unless you do a factory reset.
You can now re-connect to your normal WiFi network and press the Setup button again on the hub to make it exit that mode.
You might need to wait a while for it to reconnect to your WiFi network.

Next we'll ask the Hub for a overview of what it knows.
If you open RESTED and add these Headers:

• SECRET with the value set to what you saved previously (careful around spaces)
  
• Content-Type with the value set to application/json

We want a GET request to http://TODO/data/domain/ (trailing slash is required)
Replace the TODO above with WiserHeatXXXXXX where the X's are the 6 characters from the WiFi network.

Make the request and you will hopefully get a 200 OK with a load of data.
Could you post that here, but remove anything that looks sensitive like the "GeoPosition" stuff etc.

I hope that works, I've made a bit of an assumption about the host name format that might be wrong.

 

[oldbutnotdead]

Cool, ta. I'll give that a try...