Control Options

[dumbrill]

Having looked at the various options for boilers and controls I am keen to get the right controls as well as the right boiler.

I’m looking for the option to have either control on room temperature or weather compensation. In both cases I want a control in the living room with a wireless connection. So far the controls that most fit the bill are the Remeha iSense or the Atag WiZe, but neither of these are wireless. Either of these would allow me maximum flexibility to switch the ‘control strategy’, but they are both are hardwired.

I’ve put together a table of options below:

Untitled

• dumbrill
• 27 Nov 2010
• 2

Is there a wireless control that fits the bill?

I’m looking for a system boiler to work with an unvented cylinder and my boiler choices so far are either a Remeha Avanta 18S, Vaillant 618 or Viessman 200-W 19kW. I’ll finally decide on the boiler once I’ve found the controls I like. How would the price of an Atag boiler compare with the three listed?

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[YELLERBELLY]

the vrc 430f

 

[MJN]

If going for the Avanta I'd go for the iSense, buying from abroad if the wireless requirement is key. Whilst an inherent benefit of Opentherm is wide compatibility I think there are still some benefits of keeping the same manufacturer.

Mathew

 

[dumbrill]

If going for the Avanta I'd go for the iSense, buying from abroad if the wireless requirement is key. Whilst an inherent benefit of Opentherm is wide compatibility I think there are still some benefits of keeping the same manufacturer.

Mathew

I don't think the wireless iSense is compatible with the boiler sold for the UK market. I'd like to think that it was, but when I spoke to Remeha they said it wasn't and that I wasn't the first to ask if a Dutch purchased iSense would work.

 

[dumbrill]

the vrc 430f

Does it also optimise the startup times, ie. earlier on cold days, etc. I've seen references to this in the literature, but it doesn't seem to be explicitly stated anywhere.

 

[bengasman]

WC is more trouble than it is worth, the savings are minute.

 

[dumbrill]

WC is more trouble than it is worth, the savings are minute.

I've read enough comments on here to think that this might be the case. That's why I want to be able to switch back to control on room temperature if I need to. I don't mind paying a bit more to initially get all the options in place and then mess about with them to see what works.

I suspect that a Honeywell 957 would be exactly what I want since it would give me all that my 927 currently does plus the modulating bit as well.

 

[bengasman]

The folk who slag off weather compensation are those who can't be bothered to keep up with improvements in technology during the last quarter of a century, and who also can't be bothered to set it up properly.

That is a rather bold statement. As it so happens, I promoted he boilers before most others did, and dito for digital controls, programmable roomstats and wireless.

It is so simple, and so effective.

Simple, maybe. Effective? Adding wc to he boiler decreases the gasbill by a maximum of 2%. On installations with "ovesized" rads where the boiler is permanently set to a return temperature of below 50, the savings are virtually nil.
I would not call a saving of 0.something % very effective.

The heat requirement of a house is directly proportional to the temperature difference between outdoors and indoors.

True as that may be, it does not automatically make wc a useful addition.

 

[dumbrill]

The folk who slag off weather compensation are those who can't be bothered to keep up with improvements in technology during the last quarter of a century, and who also can't be bothered to set it up properly.

It is so simple, and so effective. The heat requirement of a house is directly proportional to the temperature difference between outdoors and indoors.

I want to try WC and I'm optimistic that it will work OK. I just want to be able to switch back to room temp control as well.

 

[bengasman]

I want to try WC and I'm optimistic that it will work OK.

I am sure it will work ok if you choose a good brand. It's just that it is unlikely that you will save much more than a tenner a year on an average gasbill.
That means supply and fit only will take about a decade to break even. If it fails once outside warrantee, it will take about 20 years to break even.
You can save an equal amount of money by turning the ch stat down 0.5 degrees.

 

[dumbrill]

the vrc 430f

I've read the instructions again and I can see that screen C8 allows the 'Switch-on room temp' parameter to be set to 'none', 'switch-on' or 'thermostat'. The 'switch-on' option seems to be one to go for as I assume it will ramp up the temperature when heating up the room from cold. The 'thermostat' option goes further and turns off the CH if the room temp exceeds the set point. I'm not sure if this is a good idea in reality.

I don't however see an option to drop the WC altogether and revert to a modulating thermostat. Is there one?

 

[D_Hailsham]

I don't think the wireless iSense is compatible with the boiler sold for the UK market. I'd like to think that it was, but when I spoke to Remeha they said it wasn't and that I wasn't the first to ask if a Dutch purchased iSense would work.

I have been doing some Googling to find out why this is.

Firstly: both the iSense and iSense RF are OpenTherm products. The only difference is that the iSense has OT built into the controller but with the isense RF it is built into the relay box, not the control unit.

Secondly: the relay box for iSense RF is powered from the OT connections on the boiler. The boiler has to meet the latest version of the OT protocol, which now includes a feature called "OpenTherm Smart Power". Unfortunately the Remeha boilers currently sold in the UK are not yet equipped with this version of the OT protocol. You can get it if you buy a Quinta Pro!

However all is not lost. Remeha in the Netherlands sell a power adapter for about €15. It very similar to the typical power adapter used for broadband modems etc. The spec is:

Primary AC: 230 V
DC Secondary 5 V
Max. Output current 0.4 A
Nom. Power: 5.5 VA
Stabilized: Yes
Short Circuit Protection: Yes

I reckon you should be able to purchase an adapter to meet this spec from Maplin etc. The DC output is bare wire, not a plug.

 

[mehran]

dumbrill ignore the FUD(Fear, uncertainty and doubt)

loads of manufacturers now have outside sensors for their boilers. it will allow you to have more efficient system.

also, I have a isense in my house + an outside temp sensor with my intergas boiler

 

[D_Hailsham]

I’ve put together a table of options below:

Untitled

• dumbrill
• 27 Nov 2010
• 2

You show the Honeywell as not having weather compensation; that is incorrect.

Outside temperature compensation is built into the OpenTherm Protocol so, provided the boiler is OT compliant and has a connection for an outside sensor, any OT controller can make use of the information.

 

[dumbrill]

I’ve put together a table of options below:

Untitled

• dumbrill
• 27 Nov 2010
• 2

You show the Honeywell as not having weather compensation; that is incorrect.

Outside temperature compensation is built into the OpenTherm Protocol so, provided the boiler is OT compliant and has a connection for an outside sensor, any OT controller can make use of the information.

Thanks for looking into iSenseRF.

I hadn't realised this about the Opentherm Protocol although it makes sense now that you've highlighted it. I was thinking of Opentherm as just a communication standard rather than as a complete standard for boiler control. I've changed the table.

Untitled

• dumbrill
• 28 Nov 2010
• 2

The idea of using the 957 is appealing as my guess is that it's the most user friendly. Although I guess using all one manufacturer's gear is also a good idea in the event of problems.

After thinking about this yesterday I've probably come round to the Vaillant controls because they offer a complete wireless solution straight out the box. They're not Opentherm, but then I'll be happy with a Vaillant boiler anyway. It seems to me that Vaillant offer the most complete and well thought out controls because of the RF options, HW temp integration, etc.