CH System suitability for Hive

Alun

I'm thinking of getting a Hive system for our gas central heating, but there's one thing that's always bugged me about the way our current system works that makes me wonder if it'll work properly.

The problem is that at present, if I select CH only on the programmer (a Landis & Gyr RWBXP) nothing happens, i.e. the boiler doesn't fire up (assuming the thermostat is set high enough for it to do so) and I have to select HW as well to get it to fire.

There's a conventional thermostat in the hallway, and in the hot press there's a two way motorized valve. The valve only operates to divert hot water to the radiators if the thermostat is active and CH has been selected on the programmer. The boiler is an Ideal Classic NF 250 if that matters.

So can the Hive system cope with such a setup, i.e. can it be set so that the receiver calls for CH and HW when it needs heat, and HW only otherwise, or is my system just wired up wrongly in the first place?

DGOBS

As long as the wiring behind your existing clock has both live wires going to a) the boiler (which is there) and b) the live wire going out the the thermostat.

Your system sounds like it only uses the thermostat to control a single motorised valve as a 'summer valve'

So the way you need your Hive installed it this:

1.Install a 'Dual Hive Receiver'
2. Wire the live for the boiler as HW (channel 3)
3. Wire the live for e the room stat as CH (channel 4)
4. Loop out your existing thermostat (will be replaced by the Hive stat)
5. Once Hive is installed and paired up, change it to 'Gravity Mode' (i.e. Hold the HW button on the receiver for 10-12 seconds, then release, the green light should change to a blue light = gravity mode)

So now when you use Hive, and call for HW , the boiler will fire up, but the CH motorised valve will stay closed.
When you call for CH, both HW and CH will come on together (i.e HW will call the boiler on, CH will open the motorised valve)

Unfortunately you do not have the ability to have CH on without heating your HW, but at least you will be able to time HW on its own during the summer moths as you would want it.

Hope that helps

yes your system is typical for here, that the installer did not do the proper job of putting in a dual system with 2 motorised valves properly wired with interlock back to your boiler, but the above description will gove you the maximum control available to you with what you currently have

Alun

Thanks, that's really helpful. I wasn't aware of this gravity mode, but even if I had, I wouldn't have thought it would have been a solution to my problem. Long term I suppose I could also get a second motorized valve fitted but getting the wiring installed back to the programmer / boiler would be a bit of a pain.

Regarding the existing thermostat, when you say loopback, I assume you mean just connect the two wires together? Alternatively I suppose I can just turn it up so high it'll never turn off.

I'm lucky in as much as the existing backplate looks identical to the one Hive uses so it should be a really simple installation.

DGOBS

Regarding the existing thermostat, when you say loopback, I assume you mean just connect the two wires together? Alternatively I suppose I can just turn it up so high it'll never turn off.

Yes connect them.

Gravity mode for that install is my trick!

Alun

Got it installed now, working perfectly, thanks! Only disappointment is that the thermostat itself is battery powered only, no mains power option. Would be nice to have it mains powered and have the display permanently on.

DGOBS

I have Hive for nearly 3.5years, I don't think I have looked at the sat more than a dozen times, phone for everything!