Manifold/TRV actuators - 24V or 240V?

[SimonHa]

I'm nearly at the point of finishing off my CH installation and have to sort out the actuators for the 7 port manifold that will run my radiator zones (picture on this post: http://www.navitron.org.uk/forum/index.php/topic,11586.msg129643.html#msg129643 ).

I will be controlling the zones using a HobbyBoards 1-wire 8 channel I/O board (http://www.hobby-boards.com/catalog/product_info.php?cPath=24&products_id=1554) which has 8 relays on it, each rated at up to 60W (0.25A@240V).

I can get both 24V and 240V actuators for my manifold. I was originally going to use 24V ones as they would be low voltage within whatever enclosure I find for the relay board. The 24V actuators are AC so I was planning to drive them from Maplin power supply (Maplin 1.5A L55BR http://www.maplin.co.uk/Module.aspx?ModuleNo=96964&OrderCode=L55BR).

However I am now thinking I'll need at least one 240V relay (to control the boiler demand) so maybe I should have all the actuators as 240V too? That would be about £33 cheaper (actuators + PSU), plus if a future owner wanted to use some other controls later (1-wire isn't very plumber-friendly!) I suppose 240V is far more common and could be easily rewired. A 24V AC PSU would be another thing to go wrong too.

Note: power consumption is about same - 24V supply uses about 4W when idle & according to spec the 24V actuators is 3VA whereas the 240V is 3.45VA. So for 7 valves open that's ~25W for 24V actuators and 24W for 240V ones.

What do people think? Stick to 24V and know everything is low voltage (and no Part P concerns) or go for the much more common 240V?


Simon (procrastinating again!  )

[fred bloggs]

Hi Simon

I'm going to be do the same as yourself with my house , Just brought a Viessmann 200W combi with weather compensation controls and was also looking at putting in zones for the rads, could you please post details of the actuators you are using as the ones I've looked at are very expensive! and another man views are always helpful.

Many Thanks

Fred

[BruceB]

No doubt both 230V and 24V will work OK, but I believe 230V is the industry standard.  I was supplied with a 4 manifold system from Continental for my own place and that was all 230V actuators without any alternative being discussed.  Also the Heatmiser system I have installed uses 230V actuator outputs as standard.

PS:  Part P and BS7671 apply to 24V as well as 230V.

Regards
Bruce

[Iain]

Hi
Surely the boiler demand will work with either. The 24 or 230 is just the relay coil operating voltage. The switch contacts are normally "volt free" and will work with any voltage, whatever you supply them with, and can be diferent to the coil voltage. So you can have a 24v control system operating the relays, which can then switch any voltage or combination of voltages
Iain

[SimonHa]

I'm going to be do the same as yourself with my house , Just brought a Viessmann 200W combi with weather compensation controls and was also looking at putting in zones for the rads, could you please post details of the actuators you are using
...snip...

I've got a Viessmann 100-W WB1B 26kW system boiler with weather comp (i.e. basic where you can change the slope but not the shape of the curve like on the 200) - just fitted the outdoor sensor (with 1-wire temp sensor alongside) last night! I'm using an Emmeti manifold from http://www.heatingcontrolsonline.co.uk* (mainly because they do a 15mm copper version of their monoblocco fitting) and am looking at the Emmeti actuators (http://www.heatingcontrolsonline.co.uk/multifit-thermal-actuator-24v-low-voltage-p-433.html and http://www.heatingcontrolsonline.co.uk/multifit-thermal-actuator-240v-p-396.html).

None of the actuators are cheap though - £20-30 seems pretty standard. If you like home brew I read somewhere an inventive person using a small resistor in a TRV head to melt the wax (probably Wookey   )

HTH


Simon
PS. * I've no involvement with this company - just a happy customer.

[SimonHa]

Surely the boiler demand will work with either. The 24 or 230 is just the relay coil operating voltage. The switch contacts are normally "volt free" and will work with any voltage, whatever you supply them with, and can be diferent to the coil voltage. So you can have a 24v control system operating the relays, which can then switch any voltage or combination of voltages
Iain

Hmmm - I didn't explain myself very well. My Viessmann has a contact (labelled "1") which is connected to 240V by a normal room thermostat when heat is called for. (There's also a Viessmann interface too for their own controllers). So what I was meaning was that I'd have to run 240V to my relay board for that, so I'd have one relay in there with 240V on its contacts (unless I put a 24V-coil relay in another sealed box). The appeal of 24V was not having 240V in the box if I was "tinkering," though perhaps there's not actually much to do in there once it's connected anyway and I'm being paranoid.

If I go for 240V actuators then I also need to decide whether to use the AUX switch on 4-wire actuators hardwired to 240V to control the boiler demand (simple, but then the 1-wire network wouldn't know whether the valve had actually opened or not), or do it in logic (which was the plan with 24V to limit the amount of 240V connections). Simple is probably best...

Simon

[fred bloggs]

Simon

Thanks for the links, just what I'm after, I'll have a good look tonight.

Again many thanks, I'll try and post pics of what I've done of the install, I've put under floor heating in the extension etc.

Best Regards

Fred

[hiccup]

Hi

I'm using Uponor manifolds and 24Vac actuators, and as for a power supply, a simple transformer is all that is needed,  not a power supply as such.

My control system (work in progress) uses 1-wire sensors, and modbus to link the various control nodes. The modbus master is an embedded controller (not a PC). The relays are all driven by 5V coils. Some switch 24Vac loads such as the actuators on the manifolds, and some 240Vac loads such as the boiler call for heat and the three position valves that determine where the heat goes from/to the boiler and thermal store.

Hope his helps

Hic!

[SimonHa]

Thanks for the replies so far & I'm glad to hear many others are doing the same sort of zoning.

Hiccup: 24V - presumably you just wired a 10:1 transformer to get 24V? This may actually be all the Maplin supply is (though it does have an LED). I don't really trust myself to wire up something like that - ideally I'd like to assemble the system from off the shelf units. The funny thing is I haven't seen any 24V supplies designed for actuators (I can only assume they're usually built into a wiring centre & control system).

Huccup: aside: Are you using opn-mbs (http://www.opnode.org) for your embedded controller? I know Daniel was moving towards modbus as his preferred HA protocol. I rather like the look of opn-one.

Back to the original question...
I think I'm leaning towards 240V actuators again (60/40 I'd say!). The Viessmann has a 4-pin proprietary interface for its programmers (labelled CH1, CH2, 24V and GND) - I suspect the channel control is 5V/TTL so I could, maybe, keep everything at low voltage, however for plumber acceptance I think 240V would be less puzzling. If a future owner wanted to they could rip out the 1-wire relays and connect the actuators to something like a Heatmiser UH1 wiring centre, or straight to a 240V programmer with all the zones connected together  . I've got a twin coil cylinder and so will buy solar next year so I suspect I'll need some 240V stuff for that.

Any further thoughts welcome (in fact, if anyone can also recommend a supplier for "mains rated" plastic enclosures, e.g. approx 20x15x3cm that would be great).

Simon

[Brandon]

more and more gear is becoming 24V solely, as this is becoming the European norm, and the 230V is (a bit like hot fill washing machines and 60^oC washes) reserved more and more for those of us this side of the channel.

[Alan]

Hello Simon

Quote “ However I am now thinking I'll need at least one 240V relay (to control the boiler demand) so maybe I should have all the actuators as 240V too? “

The relay contacts on your hobby board are totally isolated. You could switch some systems at 24 volts and some systems at 230 volts at the same time.

If you want to keep mains voltage off the hobby relay board then use the 24 volt actators and use the boiler start relay to send 24 volts to a remote start  relay mounted near the boiler.

The only down side of the 24 volt system is a permanent magnetic power wastage using the double wound transformer that is using power if the zones are calling for heat or not.

That is why I use optically protected solid state relays here to keep voltages at 5 volts on the control boards and avoid power loss with transformers / power supplies.

If you stick with 230 volts on the hobby board then no power loss is involved.

Time to Ponder

Regards

Alan

[hiccup]

Hi Simon

I'm using the Barix Barionet as the central controller with their R6 relay modules and X8 I/O modules (that do 1 wire and/or digital io or analog in). I've also designed and built my own modbus node that does analog in and out, 1 wire, digital i/o, and 4 relays - because that's what I needed for a couple of places in the system. Most of the hardware is built and some of the software, but I still need to finish the software before it can start doing useful stuff.

The transformer I'm using is from Newey and Eyre and has screw terminals - so no different to a packaged AC power supply really - there are some din rail mounted transformers around.

As for cases I use the modular enclosures from Newey and Eyre. It suits me as some of the stuff is din rail and some isn't.


Alan - good point re the power wastage on the transformer, even if very small it is still wasted power so I'll use a relay to turn off the 240V to the transformer when no 24Vac is needed - which is in reality most of the time.

Regards

Hic!

[SimonHa]

Oh-oh... I'm veering back towards 24V..! Afterall why have 240V flying around if you don't have to, especially when the control box will be almost directly under the manifold! (not much choice in siting)

I've picked up the Maplin 24VAC power supply - it seems to use 4-5W when nothing is connected (though my basic plug-in power meter always shows 1W so it could well be only 3W). It has a dazzling (can't look into) blue LED on the front... how much might that be wasting?! (OK, so probably not much).

That said according to the spec 240V actuators use 15% more power than the 24V so that would perhaps even them out. But then again that little extra heat might make the valve open a tad more quickly.

All a bit irrelevant compared to 26kW boiler of course...

Should I stop thinking now as there's a danger I might never actually get the heating finished (and it's supposed to be turning cold again soon)!


Simon

[Baz]

Of course you are making sure you are compliant with EU Lot 6 legislation for PSUs brought in June this year requiring standby power less than abut 0.5W (can't find the exact figure) and requiring on/off switch since Jan 7 2010.   

[SimonHa]

Of course you are making sure you are compliant with EU Lot 6 legislation for PSUs brought in June this year requiring standby power less than abut 0.5W (can't find the exact figure) and requiring on/off switch since Jan 7 2010.   

Heh heh - it never fails to amaze me the stuff people on here know! Less than 0.5W would be much better than 3W (maybe the ruling doesn't apply to transformers sold as standalone components). I can't see much use for an on/off switch to turn it off standby at night and having to get up a couple of hours earlier in the cold turn it on though!

Aside: my CRT TV started going purple recently finally giving me an excuse to buy a new one It is an LG LCD TV but I was dismayed that it didn't have a power switch (I forgot to check in the shop )... until I plugged it into a power meter and it was showed 1W consumption in standby (i.e. <1W since my meter shows 1W when nothing is plugged in). I can even switch off the red standby light which might save a few mW! Perhaps that's a result of this new legislation.