More inteligent heating controls...

[flo]

We have a reasonably new central heating and unvented DHW system in our house. It consists of 6 heating zones (ground and first floor radiators in the older part of the house, and 4 underfloor heating zones, one with a floor probe thermostat in the newer bit). The underfloor heating manifold is fed from directly below the boiler, the 2 radiator zones and DHW via a y plan plus arrangement.

Heat input is provided by a WB Greenstar 30CDi system boiler, water storage in a 250l WB greenskies cylinder (solar thermal ready, but no solar thermal heat source installed yet).

The previous owners only had a basic control system installed. The radiators and DHW from a 3 channel timer, with two room stats, and a cylinder stat and the UFH from a single timer with 4 room stats. We want to improve things.

I like the look of the Honeywell CM900 range and prefer the wireless options as it seems to offer us a 'syncronised multi-zone' option. I have lots of questions, but the obvious one is does anyone have any experience with the honeywell controls set up like this on a system like ours, and how might I set it up, i.e. what do I need?

I've also read about the modulating version Honeywell do (CM957) and know that our boiler is capable of self-modulation based on heat demand (presumably it monitors the return temp and regulates accordingly?) - I'm assuming that putting modulating programmable stats in will just confuse everything?

I'm reasonably techincally minded, but I'm not involved in the trade so please be gentle!

thanks in anticipation...

Phil

 

[doitmyself]

I've also read about the modulating version Honeywell do (CM957) and know that our boiler is capable of self-modulation based on heat demand (presumably it monitors the return temp and regulates accordingly?) - I'm assuming that putting modulating programmable stats in will just confuse everything?

To answer your last question first, the CM957 would not be suitable as it is an Opentherm product and your boiler does not support Opentherm devices. Also the product is still not available in the UK.

As for you main query, do you want to be able to control all times and temperatures from a central point or are you happy with separate time/temperature controls in each zone?

I read somewhere that the CM921/927 systems will control up to four zones (each with its own CM921/927 unit). There is also the CMZone system, which can control to zones from one unit, but it relies on wireless thermostatic valves to on each radiator. Lastly there is the Honeywell Hometronic system, which can control up to 16 zones as well as other things like your lighting etc; it's very expensive.

 

[Mbear]

Do u live in a castle mate? 6 heating zones, I've never worked on a system that big(mind u I only work in domestic properties)

the biggest one I've seen was 3zones plus hw zone. It was set up as a multi S plan if u like. The guy had 3timers. 1 for 1heat zone and hot water. The other two where single channel timmers for the other two zones. All 3 had room stats and all the timers where neatly wired (and marked as to which zone etc, which was helpful) in the cupboard below the stairs.

I know this sounds alot but if I where ever to fit such a system I'd probably do the same. I tend to find the more one controller/timer/stat can do, then the more ridiculously complicated it can be to set up and operate.

The setup I explained would be much easier for the end user to operate IMHO

 

[flo]

@doitmyself
I knew I was struggling to find info on the CM957 for a reason! The sorts of things I want to do centrally are switch the system into holiday mode, boost the downstairs/upstairs zones, turn heating down if we are going out - the kind of global changes you would do every now and again when running round the house switching several controllers over would be a pain.

I know from reading the literature on the honeywell website that the CM900 range have the facility for a multizone syncronised arrangement, but I need to contact Honeywell's Tech help centre to get the relevant info. The enquiry I sent last week hasn't yet been responded to - they do warn that they won't provide support to consumers on their tech helplines, but when you speak to the consumer support people, the questions seem to be too difficult for their help systems.

I don't want to independently control each rad, the original house is quite old and has some nice traditional rads and matching trv's that we don't want to touch.

Controlling things (or at least monitoring the settings) centrally would be the ideal, but you can probably see that it wouldn't be a hardship to manage each zone separately, I can just see it getting confusing. I'm also concerned that with so many zones independently switched (esp as some are UFH with slow response times) we could end up with the boiler cycling, but something I read suggests that the sync'd multizone arrangement from honeywell are able to automatically manage this situation?

@mbear
It would be nice if it was a castle... but just a decent sized house with a mix of old and new parts. Essentially what you're suggesting is what I suspect I'm looking for, I'm just hoping that we are able to simplify the management of all the various settings - as you say 6 zones, it's not straight forward!

Thanks for the help so far...

Phil

 

[doitmyself]

The sorts of things I want to do centrally are switch the system into holiday mode, boost the downstairs/upstairs zones, turn heating down if we are going out - the kind of global changes you would do every now and again when running round the house switching several controllers over would be a pain.

Presumably each zone at present has a motorized valve which is controlled by the local thermostat/timer. You will still need a thermostat/temperature sensor in each zone.

I know from reading the literature on the honeywell website that the CM900 range have the facility for a multizone syncronised arrangement,

Multizone CM900 systems are only available if you use the wireless versions (CM921 and CM927). You need a complete set (control unit and relay for each zone) to control the zone valves. You also have an extra relay unit, which synchronises the boiler requirement from all zone controllers. I believe you can link a maximum of four units together. However you would still have to run around the house whenever you want to change anything.

 

[flo]

Presumably each zone at present has a motorized valve which is controlled by the local thermostat/timer. You will still need a thermostat/temperature sensor in each zone..

With the rad zones thats true, but all 4 UFH zones are off one timer and 4 stats, this is the element I really want to improve on, as a min we want to have a timer/stat upstairs for 2 zones and one downstairs for the other 2 zones.

You also have an extra relay unit, which synchronises the boiler requirement from all zone controllers. I believe you can link a maximum of four units together. However you would still have to run around the house whenever you want to change anything.

Are you saying that I can't change ANY settings on the linked units from the one master unit? If I wanted to set the holiday setting, I'd stilll need to switch each controller locally for example? Doesn't sound like the advantages of the system are that strong - unless the sync-ing of the boiler firing has significant benefit?

 

[doitmyself]

With the rad zones thats true, but all 4 UFH zones are off one timer and 4 stats, this is the element I really want to improve on, as a min we want to have a timer/stat upstairs for 2 zones and one downstairs for the other 2 zones.

You've lost me a bit. 🙁 The UFH zones have one timer but four stats, which makes sense as a stat has to be within the zone to work - though some stats are available with remote sensors. But you say you want to improve this, or do you mean you want to improve the rad zones and have a similar arrangement. But you still need a thermostat in each zone.

Are you saying that I can't change ANY settings on the linked units from the one master unit? If I wanted to set the holiday setting, I'd stilll need to switch each controller locally for example? Doesn't sound like the advantages of the system are that strong - unless the sync-ing of the boiler firing has significant benefit?

Yes. that is what I am saying. You still have to go round the house to change the temperature or turn on the holiday setting. The synching prevents one room controller turning the boiler off at the same time as another is trying to turn it on.

Horstmann make a four channel programmer, you would still need separate thermostats in each zone.