It isn't too clever once people understand that all you do is hook up simple sensors back to the boiler. The thinking is done for you. DHW sensor has it own terminals as does the room influence and outside weather sensors too......and also the zone valves as well. Super simple to wire up.
The C55 (55 kW) is £1821. Two Qudos 28 kW boilers is £1576. ...and a back up boiler in case. With the right boioper sequence controller this will modulate from about 6kW to £56 kW.
Is that a good thing? ;-)
"Doctor Drivel" wrote in news:4772d38d$0$47116$ snipped-for-privacy@authen.yellow.readfreenews.net:
Err... The programmer badged by Keston is the Theben Ramses 850 OT. See:
The reference to OpenTherm has nothing to do with the Honeywell Chronotherm, but to the OpenTherm protocol used for data communication between the boiler and the controller. See:
Kind regards
Here is the Chrontherm on the Keston site:
In the manuals they specifically state Chronotherm.
I said, "Opentherm standard", which is a "open" standard used by those who sign up to it, as the opentherm link you gave explains. Currently is only a protocol between boiler and room temperature sensor. Two microprocessor based devices connected via a common "open" protocol so all makers equipment using the protocol can talk to each other. The boiler and an intelligent room temp sensor (this may have a sophisticated clock in it as in a clock stat, like the Chronotherm). There was talk of it 5 years ago, but only recently have a number of makers started to incorporate it into their pcbs (Maxie will have to get to know it as he fixes pcb's).
A number of boiler makers use it, mainly German and Dutch, I believe an Ideal boiler can use the Opentherm protocol. Honeywell, Danfoss, Siemens, Landis, etc make room temperature sensors which will connect onto these boilers and modulate the burner or switch the boiler off/on, optimise the start stop of the boiler, etc (the Honeywell Chronotherm optimises switching on). Then no rip-off proprietary room sensors to buy, as any makers sensor will do.
I am sure a Chronotherm using the Opentherm protocol can be bought for under £133 if you look around. If the Opentherm protocol is implemented further it will fully simplify boiler wiring and give commercial levels of modulated burner/pump, etc, control.
Few people in the heating industry have heard of "Opentherm", so many opentherm compatible boilers will not be used to their maximum efficiency and I see this boiler being one of them. If pushed properly, even dumb plumbers could even understand it, it is that simple, with all the control done on the pcb, not in crude electrical devices external to the boiler, as is now. The contol is thought out for them, all they have to do is connect up the devices with wires directly back to the boiler using two core wires which don't care what way around the wires go in the terminals.
"Doctor Drivel" wrote in news:47732ad2$0$47115$ snipped-for-privacy@authen.yellow.readfreenews.net:
Indeed. The description and part number are: Keston Chronotherm Room Controller C.17.4.21.00.0
The device supplied to me approx 18 months ago under this description and part number is the Theben Ramses 850 OT and its details can be found at the link I gave.
The name confused me when I was speccing the system, and I spoke to the Keston Technical Department who confirmed that it was not a Honeywell product. Unsurprisingly, they did not offer any more info on where I could get a lower cost alternative but did confirm that any OpenTherm (OT) device would do.
The fact that Keston calls it a Chronotherm does not imply that it is a Honeywell device. The manual that you linked to on the Keston site is indeed for a Honeywell product (the CX51), but the PDF is dated
2002 and there is no reference to it that I can find on the Honeywell UK site. Perhaps it's out there somewhere, but the Keston-badged device that I have is certainly a Theben product.As you say, OT devices are uncommon - I couldn't readily find a cheap one, and opted for the Keston-badged device.
I have the Keston C36. I confess that I was hoping for more from the OT controller, but perhaps I was over optimistic. Given that OT is a two-way protocol, it offers:
- display of boiler and pump info, including burner and pump status, flow temp etc
- display of outside temp
- reasonably comprehensive time programming
- optimised temp control (rather than directly programmed room temp) via the external temp sensor and return flow temp [but this is poorly explained in the manual]
However, whether this is much better than an external temp sensor + normal switched live controller I'm not sure, since with just the external temp sensor the boiler implements weather compensation directly...
I'm pleased with the running costs - my gas bill is currently running at £30 per month for a 12-rad system.
Kind regards
In article , Richard Perkin writes
Thanks for the information Richard which was mostly new to me.
Seconded. Interesting stuff.
It appears, Keston are using the Honeywell Chronotherm for the current unit.
"Any" OpenTherm device will do, that is the beauty of the OT protocol, you may not have realised that at the time. The temperature sensing device can have far much more funtionality and sets the boiler temperature from 0C to
82C, as you found out.
You will find the name "Chrontherm is heavily trademarked and legally protected. The Keston link is to the Honeywell product. It will be the Honeywell.
The Chronotherm modulation controller is sold openly on the Continent for less than £133. The Opentherm protocol was a Dutch/German initiative. I heard the Atmos Multi is supposed to use OpenTherm to its controller, but it does not state in the manual that it is. I assume if you sign up to OpenTherm you make it clear it is OpenTherm.
How is the DHW flowrate from the C36?
The problem with current OpenTherm controllers is that they are too complex for the average user. Simple to use, connect and fire up devices should be made, then the nerd aspect of the OpenTherm protocol will disappear and the dumb plumber will use them as the electronic control settings can be pre-set.
Some Danfoss, and others, OpenTherm room sensors look like normal room stats with normal knobs. And yes using these when you turn up the knob the burner will modulate up as most people think happens with normal on-off room stat. The time clock aspect is usually done via a switched live at the pcb and separate clock usually on the boiler.. Yet how many of these boiler will have normal crap on-off stat fitted instead of an OpenTherm room sensor (looks like a stat), because of ignorance and the OpenTherm device will be more expensive - yet it delivers full burner modulation of boiler giving superior economy and comfort conditions.
It will be, as the room temperature is supposed to influence the burner too. First stage is outside weather temperature then the room temp influence to control the burner - cascade.
Appears the electronic controls are doing their job. Does it maintain a constant room temperature?
Keston are only doing what the Germans and Dutch have been doing for a number of years in a limited manner. Vaillant do OpenTherm, yet only on selected models and not across the range, and up until recently nothing sold in the UK that I was aware of. The OpenTherm protocol appeared only to be for Continental models.
Here are the makers who implement OpenTherm. The boilers and the peripheral devices. It may be slightly out of date:
The more small third party companies make OpenTherm devices the cheaper they will become. The hope was that third party pcb makers would make a range of "standard" OpenTherm pcb's and many boiler makers would use them for their models. This would also drive down pcb costs too. Then pcb's could be bought anywhere and fit many boiler models. Just like when you buy parts for your car and there is a long list of models the part fits. Then a pcb may be a user replaceable slide in part.
Brilliant thread, it will help me choose a new boiler/ controller in the spring.
I had a Camray 70/90 Oil boiler in my previous house controlled by a Honeywell AQ6000, a brilliant controller unfortunately no longer made. I installed and commissioned it in August 1996, never had any problems with the boiler or controller and AFAIAA the new owners (4Yrs) have had good service from it. However, new technology, we must move on, am looking forward to getting to grips with it.
Regards Don
"Doctor Drivel" wrote in news:47739c48$0$47105$ snipped-for-privacy@authen.yellow.readfreenews.net:
Of course I realised it - that's one of the reasons why I spoke to Keston. I (like you) also realised that the asking price for the 'Keston' controller was high - but the company couldn't/wouldn't suggest an alternative, and I struggled to find one. Perhaps you know of others readily available in the UK? Or (for the rcord) where the Honeywell OT device can be purchased?
The same name and part numer are in the C36 manual. The same product info was also on the Keston site 18 months ago. When I ordered the controller, what was delivered was the Theben device *not* a Honeywell.
Perhaps things have changed - you could try ringing them up...
It's best described as 'adequate'. I was hoping for better - indeed, a major reason for selecting the C36 was its high output (CH output OTT for my house, although of course it's fully modulating so no problem there) and consequent high DHW flow rate. The spec is: 14.5 l/min @ 35deg C rise, 17 l/min @ 30 deg C rise.
However, despite this it is still slower than I would like to fill a bath with 'properly hot' water. However, the flow rate for a drencher shower is truly excellent, as you would expect.
The bolier is sited some distance from the bathroom, and the length of pipework has a significant impact as there is a considerable 'slug' of cold water to come from the tap before the hot water flows well.
But these are well known consequences of using a combi, so I'm not surprised.
No, it doesn't quite work like that. The Theben controller has two modes of operation: you can set a target room temperature, or (if the external temp sensor is present) use weather compensated control.
Weather compensated control is the default when the sensor is fitted, or more accurately, since the snsor is connected to the boiler system, when the boiler tells the controller via OT that it is present. When it is used, the controller uses a predefined heating curve, but it is possible to set the start and end points. This is very poorly explained in the manual (read it at the link above) and I am using the default settings.
This seems to work OK. All rads but the usual suspects (hall, bathroom) are fitted with TRVs and the controller is in the hall. If it were set for a fixed target temp I would use 21 deg C - in practice it works automagically with a displayed temp of around 21 -
22 deg. Room temp is controlled by the TRVs, but the controller + weather compensation ensure that the CH flow rarely rises above 65 deg (although the max would be 82 deg).As I write this the controller says the (hall) room temp is 22.6 deg and the flow temp is 43 deg against an outside temp of 8 deg.
The house is always comfortably warm. In fact many visitors find it hot, but having spent a very cold Derbyshire childhood I vowed never to be cold again, so we like it like that :)
Quite how the device implements the control I'm unclear (which is unlike me - I like to know the nitty gritty) and I'd prefer to 'play', but the default setting works well and the running costs are low.
Kind regards
Try Honeywel first. :-)
14.5 litres/min is not starting.
Dead leg pipe is well ...dead-leg pipe and will be the same whether from a combi or a cylinder.
That is probably the function of the pcb. It appears it can't do weather compensation "and" room temperature influence on the compensation.
It "appears" it is either or. Weather compensation or room temperature control depending what sensor is connected.
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