Hive system no hot water

[cforsythe]

Hello

I have bought a house with a Hive system but it did not work and the wiring was a mess.

Rewired it based on the y plan installation drawing, heating is working but not the hot water only or the three port valve.

When no heating / hot water is required the drayton valve sits in the heating position not what I thought it should be in the mid position?

Attached is the electrical schematic including cable numbers. I have checked the cabling twice and all seems to be connected correctly.

1st table shows the voltages at each position. Issue seems to be on the HW off from the hive dual receiver always at 240v, my thinking this is not correct. I disconnected this cable from the block as feedback from the valve etc could be causing this but there is 110v here when calling for hot water.

That does not seem to be right or am I missing something obvious in the cable installation or that the hot water thermostat is faulty? The more I look at it, the more of sore head I am getting!

Thanks

 

[ericmark]

The valve has diodes and resistors in it, so it can give what seem strange readings. But DHW does not move the valve and not trigged by the valve. It is controlled by the tank thermostat. So you should be able to disconnect all wires to the valve, and still get DHW.

 

[cforsythe]

Hello.

Thanks for coming back.

Assume the picture of the internals of the Honeywell valve are the same as the Drayton?

In this case if you feel the voltage from the Hive is okay and the wiring diagram is correct would this point to a fault with the tank thermostat? If so what is the best way to confirm this and it not being something else?

Thanks

 

[CountryFan]

You shouldn't have 240vac on the grey when both are calling, so something is amiss. Can you post a photo of the wiring at the hive and the wiring center?

 

[stem]

Have I missed something?

The grey wire is the 'hot water not required' signal and is connected to Hive 'HW Off' terminal 1, and the 'Satisfied' terminal of the cylinder thermostat. (fed via HW on) so the OP's wiring diagram looks right to me.

When no heating / hot water is required the drayton valve sits in the heating position not what I thought it should be in the mid position?

With mid position valves, the valve will stay in the place in which it was last used. Which means if the heating was the last thing to be used it will sit in the heating position. If it was the water only then it would remain in the water only position.

If the main isolator was turned off, the valve would return to the water only position (CH outlet closed) as it's pulled there by a spring. So if the valve is faulty, normally the spring does its job and you would only get hot water and no heating....Is it possible that the valve has been installed the wrong way around?

 

[Harry Bloomfield]

With mid position valves, the valve will stay in the place in which it was last used. Which means if the heating was the last thing to be used it will sit in the heating position. If it was the water only then it would remain in the water only position.

A MOMO actuator will, but a spring return actuator will return to the hot water position, as soon as the central heating demand is satisfied.

 

[Harry Bloomfield]

In this case if you feel the voltage from the Hive is okay and the wiring diagram is correct would this point to a fault with the tank thermostat? If so what is the best way to confirm this and it not being something else?

The three wires on the tank thermostat - Try swapping over the wire connection on the NO terminal, with the one on the NC terminal, then report back.

 

[stem]

A MOMO actuator will, but a spring return actuator will return to the hot water position, as soon as the central heating demand is satisfied.

When the Heating and Hot Water are both off, the grey wire remains live. Therefore, if the valve happens to be in the Heating & HW, or Heating only positions, the microswitch SW1 shown in the drawing posted by @ericmark will have operated, so the motor will still get power, and the valve will wind to open the Heating port and stay there. The boiler won't operate because the orange wire that controls the boiler won't be live as its supply comes via SW2 and the white wire which isn't live.

This is a disadvantage of this sort of valve as the motor will still be drawing power unnecessarily when the heating is the last thing to go off in the evening. i.e. most of the time. Not a problem in the summer though when the Heating isn't being used at all as the valve will sit unpowered continually in the HW only position all of the time.

The three wires on the tank thermostat - Try swapping over the wire connection on the NO terminal, with the one on the NC terminal, then report back.

Good call. Could be incorrect connections. OP if you are unsure post back the details of the cylinder thermostat and someone will be able to confirm. Not all manufacturers use the same numbers for the same terminals, so you may have the right connections in your diagram, but the wiring terminal numbers may be different for your type of thermostat.

For example this thermostat below shows terminal 1 as the Common, your diagram shows the Common as terminal 3, which may or may not be right for your thermostat.

Personally I prefer the thermostats that are marked C, 1, & 2 at least you know the function of one of the terminals

 

[ericmark]

I have come across thermostats with a dip switch, so normally closed can be heat on, or heating off, the idea is to have normally open power the device, so it will fail-safe (off) so if used for air conditioning the dip switch is moved. I often check with meter to make sure.

 

[cforsythe]

Hello Everyone

It was just the thermostat wired incorrectly on the block, swapped them around and all working okay. I had checked this a number of times and was pretty sure it was correct but there you go...

Thanks all for taking the time out to help me with this.