All of a sudden no heating. HELP

Chrisneill

All has been working fine. Last night no heat to rads although app was demanding and light on Wireless receiver indicated CH on. Rads will heat if HW and CH are both on but HW will not heat!! As said if CH only selected message is getting to wireless receiver but not firing up the boiler.

Chrisneill

Hi. More detailed description below. Any help appreciated as Tado are saying that it must be a problem with my system which I cannot see as everything works but the control system (receiver) is not sending correct messages to operate.

The problem manifested itself yesterday evening for no apparent reason ie there has been no work whatsoever on the system. In short.

1. If ch is selected and hot water is off the boiler will not fire up

2. If ch is selected and hot water is turned on the 3 port valve will select ch, the boiler will fire, the rads heat but not the hot water.

3. If hw is selected with ch off the water heats with the 3 way port moving to hw.

4. If hw is on and not ch, and then ch is turned on the 3 port valve moves to mid point (heating water and ch). The minute hw is turned off the port moves to ch but then turns the boiler and pump off. The only way to reengage ch is to turn the hw on but that then keeps the way valve at ch only.

If I change the setting on the wireless receiver to gravity feed the system heats both hw and ch. since installation I have been on Y/S setting as that is the system I have.

Chrisneill

Hi any thoughts here would be appreciated. Only way I can have ch is to have hw running in parallel all the time!!

GrilledCheese2

The most likely explanation is a faulty switch in the 3-port head unit, or the valve in the 3-port body is partially obstructed by debris.

There’s a micro switch in the head unit which is activated when the valve moves to the CH only position. This switch is providing the switched live to power on the boiler. It’s also possible that the valve is unable to move fully over to the CH only position and so the micro switch is never activated. If it’s just a faulty switch the head unit can be replaced, otherwise it’s the whole valve and a drain down of the system.

If you speak to your plumber they will recognise the fault - it’s fairly common.

Chrisneill

GrilledCheese2 - thanks for responding - appreciate it. Would a good start be to tap the unit with a hammer? Unsure if we are talking about the plastic box with the lever that moves between CH/M/W or the brass unit? Assume if microswitch we are talking about the plastic box?

GrilledCheese2

Yes, the switch is inside the plastic box. You can unclip or unscrew the box from the brass body and give it a tap, but it may not help if the contacts have corroded. Turn the electric off first.

While the plastic box is off you can rotate the valve spindle to check it moves freely. The amount of movement is quite small. Before moving the spindle memorise it’s position as you will need it to be in the same position before you reattach the plastic head.

Chrisneill

Thank you - very much appreciated.