No hot water on y plan system
Help most appreciated. Installed Tado and CH works a treat. However HW control doesn't. Tado says it's on. I can hear the Tado switching it on. However the boiler doesn't fire up.
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The default state for a 3-port valve is hot water only. Even if the motorised valve is unpowered the system switching the boiler on will still work. Three potential explanations are:
1) The motorised valve is jammed in the CH only position.
2) The cylinder thermostat has failed.
3) The wireless receiver is not wired correctly.
If you switch on both HW and CH together does the HW cylinder heat up? You'll probably need to feel the copper pipe between the 3-port valve and the cylinder to determine if it is heating.
Post a picture of the wireless receiver wiring now, before if you've got it.
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Any idea how post photos please?0
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If you're using a mobile you need to force your browser to load the desktop version of the web page. Otherwise use a PC. At the bottom of the comment box is a button for uploading photos.
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Cheers. Here we go. Replaced a honeywell st9400c.
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On the Live terminal you have a purple wire. I cannot see in the photo where the other end is attached, it should go to CH COM.
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Yes it does. So I've been a felt the pipes and listened to the 3 port valve. All works. The valve moves and directs the flow to where needed. Pipes warm up as appropriate ie just to tank or ch or both.
However could the reason the boiler does not start up for just hw be as simple as the ch water temp is set higher than the hw temp so the boiler doesn't need to fire up until the water temp of the ch has dropped to that set of the hw?
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Your boiler is unaware if the call for heat is coming from the heating thermostat or the cylinder thermostat. There will be a single switched live input to turn the boiler on.
The cylinder thermostat will determine if the boiler switches on. When testing HW function you need to turn the cylinder thermostat up to maximum, at the same time as switching HW on in the app.
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It seems to be working. Not sure what the difference is between yesterday and today. I did raise a ticket for support yesterday. I'll keep testing. Bit reluctant to turn up cylinder thermostat if it's all working.
Think boiler just doesn't fire up as much with hw as opposed to ch. Gets up to 69c very quickly than turns off until water circulating temp drops again.
Ch more demanding of boiler?
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Most boilers go through a cool down cycle after the heating turns off, or if the temperature difference between flow and return exceeds 30°C. During this time some boilers will not respond to new inputs until the cool down cycle is complete, so there can be a few minutes delay where the boiler appears to be idle.
Give it a few days and see if you notice the HW coming from the tap is cooler than expected. It may be that your system is working normally.
Long term you shouldn't need to adjust the cylinder thermostat - just keep it on the previous temperature.
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Thanks very much for your help. Most appreciated. Think just going to listen to the valve moving and feeling the pipes heat up has clarified what's going on.
Cheers
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