Conversion to hive

[AndyG_NI]

Hi, I'm a member of a sports club and we need to convert our heating programmer from a horstmann channelplus xl h27. I have attached an image of the wiring backplate. This system comprises a combi boiler, underfloor heating downstairs (2 thermostats) and radiator heating upstairs. There are two pumps one seems to be for the rads and one for the ufh. The hot water channel controls the ufh and the heating channel controls the rads.

I have found other threads showing converting to hive from the horstmann, but I'm stuck on point 5 of the horstmann backplate. A loop from live to point 5 and then a second connection at point 5, seems to me that they didn't need to do this and should just have gone direct to live... could anyone help me to map this to the hive connections?

 

[Stuckinarut]

If you look at the Horstmann wiring diagram it states a link from L to 2 and L to 5 is required. The Hive 2 channel doesn’t need it as it does it’s own switching internally.

 

[AndyG_NI]

Thanks, I saw that but there is another wire connected to point 5, which I think could just go to L? Or am I wrong

 

[Stuckinarut]

Thanks, I saw that but there is another wire connected to point 5, which I think could just go to L? Or am I wrong

Apologies, yes there’s another wire, but again looking in the wiring for the Horstmann could be a frost stat

 

[AndyG_NI]

And so to convert this to hive just put that connection to L on the hive backplate?

 

[stem]

As they are all connected together L = 2 = 5, so effectively they are all the same live connection.

As per @Stuckinarut the connections to 2 and 5 are made internally with Hive, providing you have a Dual Channel version, so the links I've marked with a red X can be removed and discarded.

However, I see a possible problem....

This system comprises a combi boiler, underfloor heating downstairs (2 thermostats) and radiator heating upstairs. There are two pumps one seems to be for the rads and one for the ufh. The hot water channel controls the ufh and the heating channel controls the rads.

You don't say which version of Hive you are considering. A Dual Channel version is the usual one to replace the Horstmann, but my concern here is that the Horstmann is designed to control 'one heating zone' plus 'heating of a hot water cylinder'. If you replace the Horstmann with a Dual Channel Hive, it will have only one room thermostat for its central heating zone, and will just provide simple on/off time control for the uhf (hot water channel) This may work for you, but you will only get control of the temperature relating to one zone from the Hive, and whatever is connected to the HW channel will need to retain the existing room thermostat/s.

To get full control, you would need to buy 3 single channel Hive's. Each would come with a thermostat giving you one thermostat for each heating zone. Unfortunately the system would probably need some considerable rewiring to achieve this. Maybe this is what you are planning to do anyway, but as you don't give details of the Hive product/s you are installing, I thought it worth mentioning. If you are using single channel Hives, then they do require a link between L and 1.

 

[AndyG_NI]

Dual channel is the version I was going for, leaving the wired thermostats in place, but controlling via home assistant and zigbee thermostats as I have done at our other site. With the rads as heating channel and ufh as hot water. So to confirm, from my picture: leave out the loops to 2 and 5. Take the other wire coming from 5 straight to live on the hive plate, the those in horstmann 1 go to hive 3, horstman 4 goes to hive 4?

Really all we want to achieve is better control of on and off and the horstmann battery is dead so if we get a power cut the programmer defaults to 8 hours or more on per day and this isn't always noticed for a while resulting in large gas bill

 

[ericmark]

As @stem points out, most thermostat/programmers are designed with one set of contacts for DHW, so for a two zone installation you need a three channel controller

so with a combi boiler either single or three channel, two channel does not help.

What puzzles me is why with a combi boiler is there a connection into the DHW? Since an orange wire, I wonder if there is some motorised valve?

 

[AndyG_NI]

Haven't seen any evidence of one. The cables coming through are 2 x t&e and 1 x 5 core of which 4 cores are used

 

[stem]

What puzzles me is why with a combi boiler is there a connection into the DHW?

The op explained that.

The hot water channel controls the ufh and the heating channel controls the rads.

 

[ericmark]

Sorry re-read see the DHW is feeding the UFH so that makes a little more sense.

 

[stem]

Dual channel is the version I was going for, leaving the wired thermostats in place.

OK, you could do that for the HW channel. For the HW channel, Hive does only provide simple timed on/off control (the same as the Horstmann does) so the existing room thermostat (upstairs rads) connected to the HW channel will work as now.

If you are planning on changing the existing room thermostats for Zigbee thermostats, be aware that some older wired thermostats don't need a 230V permanent supply for their operating power. If the Zigbee thermostats you are planning on using do need 230V and it's not present you will have to provide this, or use battery powered Zigbee thermostats instead.

However, the Central Heating channel of Hive also includes temperature control as well as time control (different to the Horstmann) The CH channel of Hive works in conjunction with the Hive wireless room thermostat, in that the thermostat sends a signal to the Hive receiver telling it whether heat is required or not. The receiver won't turn the CH on and off without the new Hive thermostat telling it to do so. If the CH channel only has one existing room thermostat connected to it, you could replace that thermostat with the Hive. A small wiring modification would be required to change the wiring to bypass the old wired room thermostat so that it can be removed. Although if I've understood your original post I think it has two thermostats (downstairs ufh) so that wouldn't work.

You could swap channels and use the Hive CH control with the Hive thermostat for upstairs rads, and the HW control for the two downstairs zones and keep the existing wired room thermostats.

Or alternatively, forget the Hive completely and install three new Smart Programmable Zigbee's one for each heating zone.

 

[AndyG_NI]

Thanks stem, the zigbee thermostats are battery powered and will be controlled via home assistant which can then tell the hive to turn off / on as required. Regarding the wiring of the hive backplate am I correct above? This location is only used a couple of times a week for a couple of hours a time through the winter so thermostats aren't really a big problem

 

[stem]

Regarding the wiring of the hive backplate am I correct above?

I reckon so:

Dump both links between L, 2 & 5 The remaining single wire in 5 goes to L as you worked out at the start.

Then move all of the remaining wires from the Horstmann terminals to the Hive terminals that provide the same function.

Horstmann E = Hive Earth Tether
Horstmann N = Hive N
Horstmann L = Hive L
Horstmann 1 (HW ON) = Hive 3
Horstmann 4 (CH ON) = Hive 4

I would be interested to hear how it works out and where you end up locating the Hive Room Thermostat and how it works in conjunction with the Zigbee's. I hope they don't fall out with each other.