Hive wiring queries

[IJWS15]

Fitted a hive system last week and while the hive is working it isn’t switching the system as expected.

The boiler is a Potterton Kingfisher (about 45 years old) previous controller was a Potterton EP2000 (heating and water switching at the same time). Y plan with 3 way valve.

We get hot water and heating but only if both are on, boiler doesn’t strike up if only HW is on.

We have L, N, HW ON, HW OFF and HEAT ON connected at the hive replicating how the old controller was connected. The room stat is disconnected and a link fitted at the wiring centre.

Diagram showing how the old controller was wired, and feeds into it from Fcu, boiler and wiring centre. I did not replicate the link from L to T5 as there is no T5 on the hive

I don’t fully trust the house wiring as the previous occupant had fitted a second room stat using twin&earth and in doing so left the neutral from the first thermostat loose in the wiring centre (live at times)

Plan for tomorrow is to rewire the wiring centre to a known diagram and see if it works as I can’t see anything wrong at the new hive switch. Tracing feeds is not easy as the boiler is about 40ft and one floor away from the wiring centre .

Am I missing something obvious?

ps I think the neutral from the cable top left is connected to the neutral at the hive baseplate (there definitely three wires connected to neutral but the diagram shows 2 - heating is on so don’t want to take the controller off again to check)

 

[CountryFan]

Was it working the same before you replaced the Potterton? Have you tried hot water only from cold?

 

[ericmark]

With the Y Plan, the DHW only does not power or move the motorised valve,

The red line shows the DHW connection to give us DHW when we have no central heating, if the red line is completely missing, we will still get DHW when the boiler is running to give CH.

The grey wire, into the zone valve, stops the DHW getting too hot, and also allows us to turn DHW off.

So with no DHW wiring at all, you will still get DHW when the central heating is running.

 

[IJWS15]

It worked before we changed it …… But. …….. It was always with heating and hot water at the same time. Single channel clock so couldn’t run them at different times so it may have had the same behaviour before without us noticing as both were generally on. When heating wasn’t wanted we used the immersion heater for hot water (the boiler puts out a lot of waste heat!)

Been thinking, when we did use it just for water we had hot radiators in the bathrooms and some bedrooms. One reason why we used the immersion heater.

With HW only on the boiler doesn’t fire up.

 

[IJWS15]

Was it working the same before you replaced the Potterton? Have you tried hot water only from cold?

Possibly doing what it is doing now - HW and heating generally used at the same time. Hw on only and the boiler doesn’t strike up.

 

[ericmark]

I have worked out, in summer, cheaper to use the immersion heater, at least with my house. In winter, I have no option, but my DHW will stay hot for 3 days, so hard to say what heats the water in winter.