Idratek and Heating

[Andrew Millne]

Im just about to start getting quotes from plumbers for a central heating system so I need to consider my options with regards to zoning control.

The most common approach seems to be using the RVA-001 : Radiator Valve Actuator but what is the best way to provide power to them? Also presumably they are connected to an Idratek spur in the same manner as other modules?

Would this be the best approach for a completely fresh central heating installation or am I missing a more obvious option?

[jpdw]

I've been looking at trying out a couple of these on the (only) 2 of my rads that currently have TRVs. From what I've seen on the specs, the actuators dont directly connect to idranet - they are simply motorised actuators driven by a 24v input (ac or dc I think). So they would need to be connected to an idranet controlled output -- ie relays on a DRB for instance.

For powering them, I think idratek sell a 24v din rail PSU but I would guess this is resold just to match the actuator's power requirement (as all the rest of the idratek kit uses 12v) and that "any 24v PSU" would probably do the job. My intention for trying out just a couple of rads was to get two cheapy plug-in-the-wall type PSUs from somewhere like Maplin and then use an Idratek drb to enable/disable the mains power to the PSUs. I figured this would work for testing but is not ideal for long-term install.

Someone else on the ukha_d group mentioned the idea of having a central PSU (like the one idratek sell, I guess) then running the 24v power out to each rad over a run of c-bus cabling (but not the same actual piece of cable used for the idranet bus). If doing this you'd still need to switch the 24v spurs going to each rad... I guess it could either be done locally to the rad (ie DRB relays) or a bank of DIN-rail relays alongside the 24v PSU unit. So that may be another option to consider; certainly a central PSU seems to me to be more power-efficient, yet the downside is more cabling & installation work.

Depending on what you mean by "completely fresh" you might be able to use bog-standard zone valves instead of on-radiator actuators? Zone valves tend to cost more & take up more space, but they DONT rely on having a TRV body already there, and done need a PSU. They would still need power (this time mains) switching to open/close.

The RVA-actuator driven TRV body method you are thinking of using is probably also easier to "back out" should you have any reason to want to remove it all ... simply replace all the actuators with old-style TRVs and it's job done. Backing out many zone valves would probably be more difficult.

I'd be interested to hear how you get on.... as I said, I wanted to try some and hoped to do so before Christmas... but crikey where did the time go?

[Andrew Millne]

they are simply motorised actuators driven by a 24v input (ac or dc I think). So they would need to be connected to an idranet controlled output -- ie relays on a DRB for instance.

Sorry I'm having difficulty getting my head around this. If the actuators don't connect to idranet and are simply switched by a relay does this mean the valve must either be fully open or fully closed or does cortex handle the timing? Also I presume two relays must be used per actuator valve?

In this document (http://www.idratek.com/public/datasheets/RVA001_DS.pdf) there seems to be different versions for 230v/110v/24v unless I am misunderstanding.

Someone else on the ukha_d group mentioned the idea of having a central PSU (like the one idratek sell, I guess) then running the 24v power out to each rad over a run of c-bus cabling (but not the same actual piece of cable used for the idranet bus). If doing this you'd still need to switch the 24v spurs going to each rad...

2 spurs per radiator?

The RVA-actuator driven TRV body method you are thinking of using is probably also easier to "back out" should you have any reason to want to remove it all ...

I totally agree and thus will probably remain investigating this approach.

I'd be interested to hear how you get on.... as I said, I wanted to try some and hoped to do so before Christmas... but crikey where did the time go?

I've set up a blog (http://www.millne.com) but haven't yet added anything beyond a basic wishlist, you can follow my progress there. I've also just added a link to your blog.

Thanks

[jpdw]

Sorry I'm having difficulty getting my head around this. If the actuators don't connect to idranet and are simply switched by a relay does this mean the valve must either be fully open or fully closed or does cortex handle the timing? Also I presume two relays must be used per actuator valve?
Thanks

The actuators appears to be like the TRV actuator (ie the bit you twiddle to set the temperature, not the valve bit the water flows throw). BUT, rather than twiddle the top to set the temperature there's a motor do push the valve pin and thereby "open" the valve.

The TRV valves are spring... apply pressure & the valve opens. Release, and it closes. So the actuator needs to be powered to open the valve & hold the valve open. Disconnect the power and the valve will close. So only 1 relay would be required - unless you want to be double-safe and disconnect both the + & - of the 24v supply to the actuator in which case you need a double-pole relay or 2 single pole.

Although Idratek sell the valve, I guess they just re-sell a product that they know well, unlike most of their products which they actually design and make themselves. In fact the datasheet references Sauter and some web searching will find the vendor's own information (which has the same data sheet).

In this document (http://www.idratek.com/public/datasheets/RVA001_DS.pdf) there seems to be different versions for 230v/110v/24v unless I am misunderstanding.

I think Sauter make a number of configurations of this actuator, incluing the 230v/110v versions you mention. Idratek appear to only stock the 24v one (which makes most sense as the idratek equipment is generally low voltage). The pricing PDF gives the specific Sauter part number which is listed on the data sheet as the 24v version.

2 spurs per radiator?

No, for power the suggestion from the other person (sorry, I forget who) was to run a cable spur, possibly in c-bus type cabling from a central PSU to the sauter valve. This would carry the 24v "open the valve" supply. As closing the valve is done by disconnecting the supply, only one spur is needed. HOWEVER, if you want to put the relay device (ie DRB etc) by radiator then you would need another spur to take the idranet signal to the DRB. Essentially the 24v c-bus type cable is just carrying the RVA's power supply.

Hope that makes sense

I've set up a blog (http://www.millne.com)

Good stuff... If you've not already found them, there are several very very good comprehensive blogs... Look out for Dave Gumbrell's in particular. He's done a lot of Idratek install work and it's very very informative reading.

[Karam]

IDRATEK basically resell a Sauter radiator valve actuator and a 24V supply which can power a number of these. The actuator is a heated wax based technology so either open or closed (takes about 3 minutes to go from state to the other but this is a relatively small time compared to heating time constants). Motorised and proportional type actuators do exist but are more expensive. Neither the actuators nor the 24V PSU need be purchased from IDRATEK.

IDRATEK do not resell any valves (the bit which actually connects the radiator to the hot water pipe) since these are widely and cheaply available as part of off the shelf TRVs. Fitting TRVs in the first instance then provides an easy fall back/uninstall route. It is important to check that the TRV valve fits properly to the Sauter actuator. Some known suitable units are listed on the IDRATEK web site: http://www.idratek.com/HWMisc.htm#RVA001

The actuators can be switched via IDRATEK relay modules. A convenient method is to use something like a QRI-002 located in a convenient location. Then a single CAT5 cable can carry the switched 24V to 4 actuators (for example). I say CAT5 simply because it is low cost, will likely be to hand, and will have sufficient cores and current carrying capacity for this purpose. You have to imagine the cat5 daisy chaining between one radiator and the next. This makes for minimal wiring.

As for the control side of things, well each controlled zone should have one or more temperature sensors relevant to that zone. The sensors and the actuator are then the basis of a feedback loop which Cortex (or Reflex) can use to regulate the zone temperature. Typically the control is simple ON/OFF which generally works ok, but Cortex also offers more sophisticated options such as fuzzy logic and linear parametric. These can make use of proportional actuators or can achieve pseudo proportional action by Pulse Width Modulation of ON/OFF actuators. The rule of thumb though is that the more sophisticated the control algorithm the more twiddling it needs and less tolerant it is to parameter innacuracies. But anyhow these features are available so that people can experiment and to try and achieve even better regulation.

Karam
IDRATEK LTD

[Gumby]

I have cabled ready for RVA type actuators. I actually cabled 1.5mm T+E and also a pink Cat-5 run to an outlet near each rad valve, the other end terminated at an upstairs and downstairs junction enclosure which will contain the 24V PSU. This was because at the time it wasn't clear whether I would need mains power or not. I was looking at Oventrop valves, which appear to be the same as the Idratek/Sauter ones, but for some strange reason were much more expensive in 24v version. However, final purchase was 24V version.

So I will run 24v over the T+E, but I have the flexibility of choosing which end to switch the power at. One reason to put DRBs near the radiator would be to have some local buttons for a "natural" control surface (eg +/- set point by one degree). On the other hand, the relay click may be audible and irritating. So it is most likely I will use a DIN mount relay unit to switch the valves at the junction box.

I guess in the back of my mind I could imagine a future Idratek product consisting of a solid state switching unit, 2 push buttons and temperature sensor (or two), allowing direct feedback of rad temp, room temp and also a valve body switch if present to directly support these applications and implement proportional control :-)

Since it's DC I would have thought you could get away with using the spare pair of conductors in Idranet CAT-5 for 24V DC power. I'd suggest dedicated runs to rad points if doing this to avoid danger of accidentally connecting them to something else if you are typically doubling up the Idranet power conductors. But really, running a second cable would be better.

[Gumby]

So this weekend I actually got the RWAs connected up. Instant improvement over simplistic demand + TRV setup, much tighter control. However, some tuning on setpoints required to account for ceiling mounted sensors, which will take some time through trial and error, although I do have a sneaky idea ...

Initial post up on the blog, more details as I get time ...

http://www.gumbrell.com/archives/200...ng_control.php

[hargraverch]

Hi Gumby
I have the upstairs heating fully automated using the sauter rad valves supplied from Idratek as the RVA-001 AXT 111-F202 and also the AXT116F-212 which is also 24v but is a little larger it has two extra wires i suppose to interogate the valve. Each room has a temp module and each room has it own temp set, ive found that a little bit of tuning here and there can get the upstairs rooms practically all the same temp, give or take half a degree. I also found, the landing tends to aquire a lot of rising heat from downstairs, and therefore re-adjusting the havc, the landing radiator shuts down quicker. Iam using the QRI-002 units mounted on some din rail to power rva.
I have been made aware through the data provded by the temp modules that one of my bedrooms has some serious heat insulation issues compared to the other rooms, which i may have ignored ,if not for Idratek system Cortex.

My next project is to controll the downstairs heating, and if all goes to plan add a multifuel boiler in conjuntion via a neutaliser to a gas boiler.

Ron

[Gumby]

So far I have been pleased with the improvement over pure TRVs, which really didn't seem to work very well.

However, the temptation to be a tight g*t and turn the temp right down on unoccupied rooms at night has led to complaints that rooms are cold. Can't win on that one until Idratek bring out their new sensory unit:MRM-001*.








* Mind Reading Module

[KirasHome]

Can't win on that one until Idratek bring out their new sensory unit:MRM-001*.
* Mind Reading Module

Great idea, but I have a feeling that SWMBO would veto my installing an MRM on the basis that it would allow me to be right far too often ... perhaps I could fit it as a stealth ugrade :-)