Hive Active heating single channel receiver replacing time clock

[stem]

First of all you shouldn't believe everything you read in a forum

In the post you refer to, there isn't any other information given about the rest of the system, so electrically it might work if the poster doesn't have a gravity circulation plumbing system that relies upon the hot water side of the Hive to control the boiler. But you do. [For oil and gas systems, gravity circulation was generally superseded by fully pumped systems in the early 1980's so there aren't all that many left.]

In addition, some electricians have a good knowledge of wiring as they should, but not a clue about the many variants of central heating. I have often had to sort out some very strange installations as a result.

Given what you have said I don't think that even the 2 channel hive will work for me without rewiring the boiler and pump

Most systems will require some rewiring, but yours shouldn't be that difficult. Your system has only 2 components to connect to the Hive. A modern fully pumped system will have at least 5 items, some considerably more. The two components are wired to the Hive terminals 3 and 4 as I described earlier. Some boilers (not all) also require a permanent live.

N=Neutral/s
L=Permanent Live Supply
1. Not used
2. Not used
3. Hot water on (NO) = The switched live supply to the boiler
4. Heating on (NO) = The switched live supply to the central heating pump

However if you don't understand how it works, or feel competent to do the work, you should get a professional to do it for you. Provided that the existing boiler and pump cables can be used, it shouldn't take longer than 2 hours to install.

I forgot to say the only thermostat on the hot cylinder is for the immersion, so there would be no means of controlling the hot water temp.

That's usual with gravity circulation hot water systems, whenever the boiler is on, hot water circulates around the hot water cylinder. That is why you can never have just the central heating on.

 

[Peter Slevin]

Hi, thank you for sharing your knowledge, if I'm understanding you correctly all I need to do is have 2 SL feeds from the hive to the boiler, 1 for the boiler and 1 for the pump. Is that right? Oh and the installtion of a motorised valve because it's the same pump that pumps to hot water cylinder.

 

[ericmark]

You said it has blown the fuse, that to me rings alarm bells, to blow the fuse some wire has been incorrectly installed.
There are three ways for a thermostat to control a boiler.
1) 230 volt AC.
2) Extra low voltage often around 24 volt.
3) Varying voltage to the ebus
Getting them mixed up will not only blow a fuse, it will likely damage the boiler, some boilers have the option to use any one of the three, so even if we know boiler make and model it does not always help.

Hive single channel can work with 1) or 2) Hive double channel can only work with 1). Nest Gen 3 and Nest e can work with all three methods.

Wire colours mean nothing, you can have a line wire which is blue, commercial may use white, purple and orange to show control circuit voltages but not domestic.

There are a number of plans, Y, W, S, C etc. However often the system only part follows the plan, I have an oil boiler which roughly follows a C plan with thermo syphon domestic hot water, but it has two pumps, and two motorised valves, and two thermostats and with all that only control for domestic hot water is time the boiler runs for and temperature of circulating water.

So most thermostats (Not Smart type) will have 2, 3, or 4 wires a few odd ones will have 5. (Not including the earth) With 2 wire it is simple on/off (Except for Nest e where it could be opentherm) it does not really matter if 24 volt or 230 volt as 99% of thermostats using 2 wires it is either pure mechanical or battery powered. With 3 wires likely one is neutral, it may be required to make the thermostat work, or to work a small heater to reduce the hysteresis (over shoot), with 4 wires in the main two power the thermostat normally 230 volt, and 2 are extra low voltage normally either 24 volt AC or 24 volt DC.

There may be the odd system where both NO and NC contacts are used, but that is rare.

So you have 4 wires, and you have blown a fuse, so the chances that you have in some way fed 230 volt onto the 24 volt system is high, looking at thermostat removed clearly not opentherm, but it does seem likely it was switching 24 volt.

So there comes a point where one has to admit defeat, and I would say you have reached that point, if you know how the old thermostat was wired then putting the old one back may be an option and see if it works. If so then may be we can still help. However I suspect it will not work, and it's time to get an expert to correct what ever you got wrong.

 

[Peter Slevin]

Hi Ericmark, thanks for the reply, sorry if I've caused some confusion but it's not a thermostat that I'm replacing it's a simple on off timer RWB7 fed by 3amp switch fused spur, on the switched side it's just a 3 core wire going to the oil boiler, then it splits out to oil burner, boiler thermostat and integrated circulator pump and that’s it. I was hoping that I could gain a little more control over the central heating rather than just timed on and off which is all I can do with it at the moment. I don’t have any internal room stat.

I wired up as per your last reply and hive receiver appeared to be functioning as it should, however when the flame light was on the boiler hadn’t fired up.

I have refitted the original RWB7 so heating is back working again, but can only have it coming on or off at specified times, but have no control other house temperature. Again sorry if I caused confusion.

 

[stem]

Originally I asked...

I believe that you have gravity circulation of the hot water and only pumped central heating.

...and you confirmed this.

Hi Stem, thanks for the reply, yes you are spot on my system is pumped heating and gravity fed hot water.

So we have been discussing a system with gravity circulation of hot water and now you are telling me that it's...

it's the same pump that pumps to hot water cylinder.

Gravity circulation of the hot water is how the water circulates between the boiler and the hot water cylinder, it's either by gravity circulation, or circulated by a pump, not both.

I think you are getting confused and calling it gravity because there's a tank in the loft that fills the whole system. If so, that is a different thing altogether.

So, if the the hot water is pumped most of what I've written above is irrelevant now. Except that you do still require a Dual Channel Hive and now a 3-port motorised and cylinder thermostat as well. The wiring will be more complicated too.

 

[Peter Slevin]

Hi, your right again of course, and I must sincerely apologise for the confusion the boiler is gravity fed from the tank in the loft.

Stupidly I thought I could replace the time switch with the hive acting as a time switch and switching the boiler on as required with additional functionality of it only switching boiler on according to the set temperature of the thermostat.

Again I appreciate your input and apologise for the confusion.

Not sure if anything can be done without replacing whole heating system as there is only a flow and return to the boiler, so I think as it stands even a 3 port motorised valve may not be an option
I’ve arranged for a plumber and electrician to call out next week to see what’s actually required.

 

[Deleted member 267285]

I’ve arranged for a plumber and electrician to call out next week to see what’s actually required.

Good man.

 

[Peter Slevin]

Thanks again for sharing your knowledge and your Patients

 

[ericmark]

In view of what has now been said, there are some options, it will likely mean a manual swap from summer to winter mode, however some ideas.

First let me say what I think you have, the pump, and boiler are integral there is a third part that might be required, that is a by-pass valve, however if there is no way to turn the domestic hot water off, then likely you will not need the by-pass valve as there is some where for the water to go.

So as the water hits a pre-set temperature the boiler will switch off, on mine there is a dial on the front to set that temperature, so if the boiler is left switched on 24/7 the boiler will switch off/on as the water being circulated heats up and cools down.

So the simple control is the thermostatic radiator valve (TRV) this will limit the room temperature, clearly it will not make the boiler fire up, but it will cause the off time to increase as the circulating water warms up, swapping the heads on the TRV for electronic heads will allow you to also set a schedule so rooms are only heated when required. This is a motorised valve, however it is missing one thing the normal motorised valve has, and that is the micro switch to turn the boiler off/on, but the boiler will do that anyway.

The problem is when summer arrives the boiler will still switch off/on even when all electronic TRV heads are closed, so if used for domestic hot water then you would need to set the time the boiler runs for.

So one of these

on each radiator will control the room temperature, the valve is about £6 (if not already installed) and the head around £10, and no wiring to do, and likely better control than a single thermostat. (One shown is the eQ-3 there is also the Terrier i30 does the same, and there is a bluetooth version of the eQ-3)

You could use a more expensive version, at around £50 you can buy versions which connect to internet, and/or link to a wall thermostat, as to if worth it, not so sure, the only reason I mention the more expensive option, is if you want the "Smart" version then the old one becomes redundant, but I am using 5 of the heads shown and they work well.

For Hive to work to best it can, it also needs electronic TRV heads, the head tells the thermostat when to run, I am not sure about the Hive head

, but I think is can be used as a stand alone, without the Hive thermostat, however I have Nest, this uses MiHome Energenie

these have a problem to my mind, you have to use a phone, tablet or PC to set them, and they need a hub, so I can't walk into a room, simply press the moon/star button and flick from eco to comfort mode, I have to use my phone. However I just want to point out if you want to add a motorised valve for domestic hot water and a programmable "Smart" thermostat, then get the head that will work with the unit you want to use.

I have an oil boiler, two pumps, two motorised valves, two thermostats, 4 Energenie heads, and 5 eQ3 heads and 5 standard heads and the domestic hot water has no control other than time, and it all took a lot of setting up, but is can be done, however even for me as an electrical engineer who has programmed large PLC controlled machines, it was not easy, and I did make some mistakes.

 

[Peter Slevin]

Many thanks for your reply; I have fitted standard TRV’s to almost all rads on the system, I suppose I thought if I could use something like the hive and effectively run the CH more or less 24/7 that the boiler would only be used to maintain a more comfortable temp throughout the house.

I had originally looked at the hub controller; don’t know if you know of it, that basically according to their site does what I want, however it’s just one unit and has to go exactly where the existing time clock is. https://www.thehubcontroller.com/happy-features I thought if I used the hive I would have a little more control.

Your very good to try and help and I'm very greatful for the information received

 

[Peter Slevin]

Update managed to get it working proerly today with the single zone receiver, I will however take the good advice given here by Stem and ericmark, I have ordered a dual channel receiver and will get modifications done to split HW from CH, many thank for the support

 

[ianmcd]

Thanks again for sharing your knowledge and your Patients

I thought that was a spelling error but for most of the posts that @stem perseveres with I dont think it is

 

[Peter Slevin]

Ha ha very funny, I stand corrected patience.

 

[ianmcd]

Ha ha very funny, I stand corrected patience.

No offence meant , just digging at Stem as he is the most patient person on here , most of us give up and just leave it to him, hope you get it all sorted out

 

[Peter Slevin]

No problem it is all sorted apart from splitting the hw from ch. But very happy with hive so far.