Heating comes on with hotwater demand

[BladeC]

Hi All,

I have just spent all day trying to fix this issue but with no luck. It was installed by a specialist and was working fine until someone worked on the boiler ever since then I have had this issue and I can't seem to resolve it.

My system is a Saidie Heatrae electromax which is an Electric wet flow system with hot water storage cylinder.

I have two BDR91s , 1 connected to hotwater (Hotwater valve only) and the other is connected directly to the boiler(boiler wireless relay) and I have 4 radiator valve zones and each with an HR92UK. My configuration is similar to Figure 4 in the installation guide. There aren't any motorised valves on my setup.


Whenever I switch on the hotwater , the BDR91 for C. heating also comes on. I have read on here that when set as a "boiler relay"
, this switches on both hotwater and the boiler. I have also tried setting it up as a heating valve but nothing happens when there is a demand for hotwater.


What configuration am I to use to prevent the heating coming on when hot water is switched on ?

[dty]

It could be double bound. Clear the bindings first, then bind it just as a boiler relay.

That said, what do you mean by "the heating comes on"? There is only one boiler, and it should be on when the hot water is on. You say you don't have a central heating valve, so what does "the heating comes on" mean?

[BladeC]

It could be double bound. Clear the bindings first, then bind it just as a boiler relay.

That said, what do you mean by "the heating comes on"? There is only one boiler, and it should be on when the hot water is on. You say you don't have a central heating valve, so what does "the heating comes on" mean?

I did a full reset of the system today and reconfigured everything. I don't think it is double bound but I can redo it.

The heating and DHW are independent of each other on the Electromax. The Electric boiler is only for switching on the Central Heating and for the hotwater it uses an immersion heater in the hotwater cylinder.

By "the heating comes on" I meant the BDR91 relay for the boiler comes on and then the Central Heating comes on (See extract from the installation manual )

"
2.1 General description
The Electromax is a combined electric
central heating boiler and unvented storage
water heater. The electric boiler provides
heat to the water that is pumped around
the radiators / underfoor heating system in
your property thus warming it up. The water
heater operates independently to the boiler
and provides a full tank of domestic hot
water heated by Off-Peak electricity.

[dty]

So it's essentially two completely separate things? One "water heater" for the hot water, and one "electric boiler" for the heating? Does it have two separate flows? What is the hot water valve you referred to in your first post?

[BladeC]

So it's essentially two completely separate things? One "water heater" for the hot water, and one "electric boiler" for the heating? Does it have two separate flows? What is the hot water valve you referred to in your first post?

Yes there are two separate things. I assume they use different flows...don't know enough about that.

The hot water valve I was referring to is the hotwater configuration on the evohome controller. Hotwater only valve instead of 2 or 3 port valve.

[dty]

OK, so I’m making (at least) two assumptions here:

1) That you have two separate outputs - one that feeds the hot taps, and one that feeds the radiators
2) That you have two separate switched lives to turn the system on - one for the hot water side, and one for the heating side

If that’s right, I’d try setting the system up without boiler control and as if it has two zone valves, but connect the BDRs that would normally connect to the zone valves to the appropriate inputs of the boiler instead. Make sure you properly clear the existing bindings first.

If that’s not right, you’ll need to share more details of how your system is plumbed and wired.

[BladeC]

OK, so I’m making (at least) two assumptions here:

1) That you have two separate outputs - one that feeds the hot taps, and one that feeds the radiators
2) That you have two separate switched lives to turn the system on - one for the hot water side, and one for the heating side

If that’s right, I’d try setting the system up without boiler control and as if it has two zone valves, but connect the BDRs that would normally connect to the zone valves to the appropriate inputs of the boiler instead. Make sure you properly clear the existing bindings first.

If that’s not right, you’ll need to share more details of how your system is plumbed and wired.

I removed the existing bindings on both BDR91 for Hotwater and heating

On the controller , I went to system devices

For Boiler setting - > Changed it from Wireless Relay to None
For Hotwater configuration -> I bound the bdr91 for hotwater to Hotwater valve and the BDR91 for the boiler to Heating Valve.

Switched on the hotwater on the controller and only the BDR91 for hotwater came on(green led)
Switched it off and then switched on demand for heating and the BDR91 did not come on immediately. (I think it takes a few minutes for the controller, HR92s and BDR91 to sync up)

I ran out of time and had to catch my train. I did a remote test from the train, I turned on the heating for two zones and 30mins later the temperature had increased by a few degrees, so it looks like it is now working. I will confirm when get home.