It is an ecoTEC pro 28 - a condensing combi boiler. The room thermostat is a Danfoss programmer - the Vaillant controls were expensive and online rumours suggested they are unreliable. The main temperature control is by the Danfoss programmer. Most radiators have TRVs, so that gives some local control. The boiler has its own control loop to achieve a particular output water temperature (currently set to 70C). The issue with outside temperature is that in warmer weather the boiler runs at lower power so it takes a lot longer to reach 70C. This was unexpected; there was a sentence in the manual about automatic rating control but this did not mean much to me and our installer never mentioned it. I was puzzled to see that the boiler output temperature was much lower than the setpoint, yet the boiler was not running at full power to achieve the setpoint.jean-paul said:
The error code for a broken sensor is something I saw in the manual, not something the boiler has reported. It was my first clue that the boiler is capable of sensing the external temperature. I had read that some boilers elsewhere do this as a main control input, but this is not normally the case in the UK.
Why we call the thing a boiler is unclear, as it certainly does not boil the water - in fact there is an over-temperature trip to prevent boiling! Similarly, what we call a condensing boiler is not necessarily something which always condenses; it is just that it can safely condense moisture from the flue gas without causing undue corrosion. Of the 10% increase in efficiency in going from a modern non-condensing boiler to a condensing boiler, about half is due to latent heat of condensing and half is due to cooler flue gas taking less heat away.
Till now every New high efficiency gas boiler I installed has been more economic than the previous one. Since 2015 minimum efficiency has been defined as 107% (due to condensing efficiency can be higher than 100%). We are not far from the absolute maximum obtainable 111% with dutch natural gas.
Modern gas boilers also use less electrical power as pumps are rpm controlled. Thankfully most attention goes to more efficient combi devices where many significant efficiency improvements have been made. Gas burner producing companies have changed hands to obtain valuable know how.
Will try to make myself familiar with the Ecotec later.
Modern gas boilers also use less electrical power as pumps are rpm controlled. Thankfully most attention goes to more efficient combi devices where many significant efficiency improvements have been made. Gas burner producing companies have changed hands to obtain valuable know how.
Will try to make myself familiar with the Ecotec later.
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I live in Perth where summer days are commonly 35-40C and more.
The tricks here are to insulate the ceiling, and even better is to insulate directly under the roofing also.
The other trick is to seal the house during the day and then open windows and doors come late afternoon/evening and use the dependable sea breeze to cool the house.
During the winter I use the aircon to warm the living space first thing in the morning and then that's it until the next morning.
This combined with solar hot water and my energy costs are around $20.00/week.
Dan.
I have found that the gas industry seems to have its own peculiar definitions of 'efficiency'; and in the UK these definitions can be difficult for the layman to discover. How much these vary from country to country I do not know, but any definition which can entertain more than 100% (apart, perhaps, for a heat pump) must be regarded as unhelpful. Condensing should not push the figure above 100%, as the latent heat was always there in potential form.jean-paul said:
In the UK the minimum efficiency now allowed (under normal circumstances) is just under 90%, but I doubt if this figure can be compared to your figures.
We use european definitions as EU members together have defined and all should adhere to. In this definition heat loss via the exhaust is not taken in account. Odd but collectively defined. I have heard (so dangerous assumption) that this is because heat loss via the exhaust is a variable hard to estimate. Dutch gas industry objected as efficiency normally can not be defined above 100%. At least that is not something we are used to. Whatever, a collectively made decision is the rule.
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We must be using a different definition; maybe the EU standards give a choice of definitions? Probably equally daft, but less obviously so.
I have recently been investigating gas fires. The UK definitions mean that 'net efficiency' is a bigger number than 'gross efficiency'; this always confused me. I have recently stumbled upon an explanation: 'net' includes the (typically false) assumption that the heat in the flue gases will somehow find its way back into the building, perhaps via the chimney passing through other rooms above the gas fire. Needless to say, gas fire brochures always major in the larger, more meaningless, figure.
I have recently been investigating gas fires. The UK definitions mean that 'net efficiency' is a bigger number than 'gross efficiency'; this always confused me. I have recently stumbled upon an explanation: 'net' includes the (typically false) assumption that the heat in the flue gases will somehow find its way back into the building, perhaps via the chimney passing through other rooms above the gas fire. Needless to say, gas fire brochures always major in the larger, more meaningless, figure.
The boiler put an error code on its display panel and, presumably, ignored the command to start (or stop - whichever it was). Each time the boiler starts or stops it starts a timer and will not respond to any command to do the opposite until the timer has expired. The time depends on boiler temperature. I assume the aim is to prevent repeated temperature cycling of the boiler components. It makes an exception for a request for domestic hot water - this is always satisfied, but presumably in a typical household this will happen far less often than a TPI controller (which on default settings will demand a change 12 times an hour).
Mine does this also.
I was told by the engineers that there is not enough thermal mass in the boiler (for want of a better word) to dissipate residual heat, same reason it needs a sink radiator.
This is the first time I've tried dividing a quote....hope it's worked
Short cycling typically means the heater or AC is oversized for the load under that condition. It is very common (at least in the US) for heating and AC to be oversized and it can make for an uncomfortable house.. Alternating hot and cold in winter and too humid in summer...causing mold issues.
Boiler short-cycling does not usually lead to room temperature alternation, as there is enough thermal mass in the circulating water and radiators to smooth the boiler output. Air systems may be different, but they are rare in the UK.
The annoying thing about TPI is that it can ask for heat when the room is already too hot, and it can stop heat when the room is too cold. This is because the proportional band is typically 1.5C or 2C. A narrower band would correspond better to human temperature awareness, but a narrower band might lead to loop oscillation.
Those contemplating TPI should be aware that some of the advertising compares an electronic TPI with a mechanical bimetal on/off control. TPI might not look so good if compared with a modern electronic on/off thermostat with precise setting of hysteresis. In any case the best option is to buy a thermostat which can do both, and then you can choose.
The annoying thing about TPI is that it can ask for heat when the room is already too hot, and it can stop heat when the room is too cold. This is because the proportional band is typically 1.5C or 2C. A narrower band would correspond better to human temperature awareness, but a narrower band might lead to loop oscillation.
Those contemplating TPI should be aware that some of the advertising compares an electronic TPI with a mechanical bimetal on/off control. TPI might not look so good if compared with a modern electronic on/off thermostat with precise setting of hysteresis. In any case the best option is to buy a thermostat which can do both, and then you can choose.
With your Ecotec 28 pro modulating gas boiler the original Vaillant thermostats are (of course) modulating and can be set to on/off if one wants this desperately. In all my experiments with most recent Vaillant modulating thermostats and boilers in the here more or less standard scheme with TRV regulated radiators gas consumption was higher with on/off control.
It was a surprise to read that you habe a Danfoss controller. Till now any attenpt to use a different brand with Vaillant was a failure. With Remeha I have used several "smart" Opentherm thermostats without a hitch. Always set the parameters and Till now never experienced microcycling.
Even distributors advise to use only Vaillant stuff with Vaillant boilers. Maybe the things you describe are caused by the Danfoss.
It was a surprise to read that you habe a Danfoss controller. Till now any attenpt to use a different brand with Vaillant was a failure. With Remeha I have used several "smart" Opentherm thermostats without a hitch. Always set the parameters and Till now never experienced microcycling.
Even distributors advise to use only Vaillant stuff with Vaillant boilers. Maybe the things you describe are caused by the Danfoss.
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Vaillant uses their own Ebus protocol and refuse to adapt to the Opentherm protocol. It is a simple 2 wire connector block affair and works OK in 99% of cases. There are, however, slight differences in versions of the very same thermostat due to firmware changes. Also some features seem to be country restricted like DCF77 which I haven't been able to get to work on non-german Vaillant boilers.
Their built in 10 litre expansion vessels are notoriously non-reliable though. Die within a few years. Too small too for most installations (which often already have an external expansion vessel) so removal is often wiser than replacing.
Their built in 10 litre expansion vessels are notoriously non-reliable though. Die within a few years. Too small too for most installations (which often already have an external expansion vessel) so removal is often wiser than replacing.
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The boiler has the ability to respond to a conventional on/off heat command, via either a relay contact or a 12V signal. Hence it can be used with non-Vaillant controls. In the UK it is normal for the boiler and controls to be made by different people.
When looking for controls I wanted sufficient flexibility to do what I wanted, and sufficient simplicity to allow my wife to use it too. This combination seemed to be rare. I considered the Vaillant controls, but decided they were not what we wanted.
Thanks for the warning about the internal expansion vessel. I have purchased an extended warranty so hopefully it will be Vaillant's problem and not mine.
When looking for controls I wanted sufficient flexibility to do what I wanted, and sufficient simplicity to allow my wife to use it too. This combination seemed to be rare. I considered the Vaillant controls, but decided they were not what we wanted.
Thanks for the warning about the internal expansion vessel. I have purchased an extended warranty so hopefully it will be Vaillant's problem and not mine.
Using a modulating natural gas boiler (made by a typical vendor lock in company that has its own protocol) with on/off control will make an interesting case when talking to a professional heating company that installs these and knows their way of operating 
They classify this as user error, trust me This Ecotec has Ebus communication meant to communicate with an Ebus device sending many parameters over to the gas boiler. Hot tap water also has its own parameters controlled by the Calormatic device meant to be used with Vaillant gas boilers. I strongly suggest to read the extensive documentation that came with the Ecotec. It can be used otherwise but it is not meant to be used otherwise.
Calormatic thermostats (350,370, 370f, 470 or 470f depending on room sensor or outside sensor) are so simple a child can operate them. Complicated parameters are behind a password to allow normal users simple operation. They are expensive but work very good and can be programmed for days, weeks, holidays etc. I think your problems are self explanatory as this Ecotec is meant to be used modulating. The way it is done now will cause an expensive repair within 5 years and higher gas usage than normal.
The built in 10 litre expansion vessel can be removed easily. It is connected with a flexible hose which can be blocked wthout much hassle. A new vessel costs around 100 Euro so not worthwhile at all when 99% of installations need a way larger one. I would have preferred a lower price and no 10 litre expansion vessel but Vaillent reacted quite comical to this remark. If you google a bit there is a chance you will find the service manual of yours.
They classify this as user error, trust me This Ecotec has Ebus communication meant to communicate with an Ebus device sending many parameters over to the gas boiler. Hot tap water also has its own parameters controlled by the Calormatic device meant to be used with Vaillant gas boilers. I strongly suggest to read the extensive documentation that came with the Ecotec. It can be used otherwise but it is not meant to be used otherwise.Calormatic thermostats (350,370, 370f, 470 or 470f depending on room sensor or outside sensor) are so simple a child can operate them. Complicated parameters are behind a password to allow normal users simple operation. They are expensive but work very good and can be programmed for days, weeks, holidays etc. I think your problems are self explanatory as this Ecotec is meant to be used modulating. The way it is done now will cause an expensive repair within 5 years and higher gas usage than normal.
The built in 10 litre expansion vessel can be removed easily. It is connected with a flexible hose which can be blocked wthout much hassle. A new vessel costs around 100 Euro so not worthwhile at all when 99% of installations need a way larger one. I would have preferred a lower price and no 10 litre expansion vessel but Vaillent reacted quite comical to this remark. If you google a bit there is a chance you will find the service manual of yours.
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The boiler is modulating; it just isn't modulating according to room temperature. Instead it is using water temperatures and external temperature; radiator TRVs ensure that water return temperature is a proxy for room temperature. On/off control is easier on the boiler than TPI. A modulating thermostat would have been nice, but the Vaillant one was expensive and did not meet our needs; we could not use an alternative because Vaillant does not support the industry-standard protocol. Any expensive repair in 5 years will be paid for by Vaillant, as the warranty is for 10 years.
It works. Gas consumption has reduced as expected; perhaps slightly better than expected. I am happy with it.
It works. Gas consumption has reduced as expected; perhaps slightly better than expected. I am happy with it.
I was tempted to send you a free "install, program and forget"" Calormatic 470 (between all words I thought to conclude you have an outside sensor) but since you are happy it is not necessary.
It works yes. You may have reduced gas consumption in the out of spec operation by some improvements yes. It can work better also yes
* You remark that on/off control is easier on the burner simply is not correct. Please ask Vaillant or a repair man. 10 year warranty on the burner ?!
It works yes. You may have reduced gas consumption in the out of spec operation by some improvements yes. It can work better also yes
* You remark that on/off control is easier on the burner simply is not correct. Please ask Vaillant or a repair man. 10 year warranty on the burner ?!
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The Calormatic 470 is known here as the VRC 470. It has a reputation for being difficult to get the settings right - especially 'heat curve'. People complain of serious undershoot or overshoot on room temperature. That may be because everyone in the UK is too dim to understand efficient central heating, or maybe all our houses are poorly constructed.
On/off control should be easier on the boiler than TPI because TPI is frequent on/off whether needed or not, while on/off is occasional on/off when needed. The Vaillant boiler appears to be sufficiently intelligent to do its own modulation.
Tests done by heating manufacturers and UK universities in test rigs show that TPI gives a few % improvement in efficiency. Tests done in hundreds of UK homes show that TPI gives no improvement on average, and is as likely to make things worse as it is to make things better. TPI may cause a small increase in electricity consumption. The people organising the tests were naturally somewhat baffled by this, but I suspect the reason is that the test rigs are not representative of actual UK domestic practice.
On/off control should be easier on the boiler than TPI because TPI is frequent on/off whether needed or not, while on/off is occasional on/off when needed. The Vaillant boiler appears to be sufficiently intelligent to do its own modulation.
Tests done by heating manufacturers and UK universities in test rigs show that TPI gives a few % improvement in efficiency. Tests done in hundreds of UK homes show that TPI gives no improvement on average, and is as likely to make things worse as it is to make things better. TPI may cause a small increase in electricity consumption. The people organising the tests were naturally somewhat baffled by this, but I suspect the reason is that the test rigs are not representative of actual UK domestic practice.
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