Is This a Modulating Boiler? etc.

[Lucky Luke]

Hello again, C.H. pundits. Our house has only three radiators (that's how we chose to heat it, mixing gas "fires", electric convection heaters and radiators, and we are quite satisfied with this). The combi boiler currently installed is a Vaillant EcoTEC Plus 824, and I am on the point of changing this for a new Vaillant EcoTEC Plus 826 26kW (the nearest in output and quality, to what is already installed). When the 824 was installed, the engineer said that, in view of the low output it needed because of the few radiators, he had reduced its output accordingly. I understand that this is called "modulation".

My questions, then, are: 1) is the boiler that I am thinking of having installed a modulating boiler also? (I need to know for sure, because the man that is coming round to give me a price does not seem to know. I was not satisfied with the way he seemed to duck my question).

2) If it is a modulating boiler, will it be in keeping with best practice if I also had a modulating timer/thermostat installed? At present, the timer/thermostat is a Honeywell CM 907. I think that this is just an ordinary timer. Would it make a big positive difference to change it for a "modulating" thermostat/timer?

3) Even if the Vaillant 826 were not a modulating boiler, would a modulating timer/thermostat be enough to keep the output stepped down, regardless?
With thanks in advance, for any helpful and informed replies,
L.L.

 

[cross thread]

Your choice can be range rated (this is the maximum output you need )
Some other makes have a lower minimum rate than the vaillant ,
Add weather comp to your control will help,

 

[Harry Bloomfield]

Even if the Vaillant 826 were not a modulating boiler, would a modulating timer/thermostat be enough to keep the output stepped down, regardless?
With thanks in advance, for any helpful and informed replies,

The 826 has a modulation range of 1:10, 26Kw on Max, 2.5Kw on minimum.

Without the Vailant controls, it will only modulate itself, based on what it sees as it's flow temperature. Add Vaillant controls, and it can go the extra stage and modulate based upon what it sees as the actual demand for heat.

 

[Lucky Luke]

The 826 has a modulation range of 1:10, 26Kw on Max, 2.5Kw on minimum.

Without the Vailant controls, it will only modulate itself, based on what it sees as it's flow temperature. Add Vaillant controls, and it can go the extra stage and modulate based upon what it sees as the actual demand for heat.

Thanks very much for that, Harry! I can now order the boiler with confidence.
L.L.

 

[Mottie]

Thanks very much for that, Harry! I can now order the boiler with confidence.
L.L.

Although I don’t doubt what Harry says as I believe he also has a Vaillant with Vaillant controls, you should also do your own research and not rely solely on the answer of a stranger on t'internet!

 

[Madrab]

Modulation and range rating are 2 different thing.

Typically when the CH is being called for, a boiler starting from cold will fire @ max output until the system warms up. Range rating means a boiler's CH max output can be 'turned down' so when the boiler starts up from cold then it won't exceed that set max, keeping fuel bills down. As suggested the 826 can be range rated down to ~ 2.5Kw.

Modulating is when the boiler's system temp reaches is set point, the burner will modulate (turns) down and maintains that set heat - most, if not all modern boilers will modulate. Your boiler has a modulation ratio of 1:10 therefore it can modulate down to 10% of the CH standard output

A smart system using Open Therm can control the system temps/times etc, very specifically. Coupled with specific sensors they can fine tune and control the system temps etc again helping greatly with efficiency and costs.

 

[Lucky Luke]

Although I don’t doubt what Harry says as I believe he also has a Vaillant with Vaillant controls, you should also do your own research and not rely solely on the answer of a stranger on t'internet!

Ah, Harry is a good hearted chap, but I had an impression that he was also a C.H. tech wallah. You do have a point, Mottie, but Harry was quoting specific figures, and that implies that he knows a thing or two about that boiler, regardless.
L.L.

 

[Harry Bloomfield]

Typically when the CH is being called for, a boiler starting from cold will fire @ max output until the system warms up. Range rating means a boiler's CH max output can be 'turned down' so when the boiler starts up from cold then it won't exceed that set max, keeping fuel bills down. As suggested the 826 can be range rated down to ~ 2.5Kw.

Modulating is when the boiler's system temp reaches is set point, the burner will modulate (turns) down and maintains that set heat - most, if not all modern boilers will modulate. Your boiler has a modulation ratio of 1:10 therefore it can modulate down to 10% of the CH standard output

With the Vaillant specific controls, you get the best of both worlds. You could say the Vaillant controls self adjust the range rate, to match the demand for heat precisely.

Although I don’t doubt what Harry says as I believe he also has a Vaillant with Vaillant controls, you should also do your own research and not rely solely on the answer of a stranger on t'internet!

Very true! The advice on here, is only worth what you pay for it

My Vaillant began with basic on/off controls, until I did the research and realised that Vaillant's integrated controls were so much more sensible. So I replaced with the Vaillant controls. Instead of the boiler running flat out, in complete ignorance of how much heat it needed to supply, until the stat clicked off, instead....

It knew the actual room temperatures, knew the desired temperature, and could calculate just how much heat it needed to produce to precisely hit the desired temperature and no more. After that, it gently maintained the desired temperature, by continuous modulation.

 

[Lucky Luke]

With the Vaillant specific controls, you get the best of both worlds. You could say the Vaillant controls self adjust the range rate, to match the demand for heat precisely.


Very true! The advice on here, is only worth what you pay for it

My Vaillant began with basic on/off controls, until I did the research and realised that Vaillant's integrated controls were so much more sensible. So I replaced with the Vaillant controls. Instead of the boiler running flat out, in complete ignorance of how much heat it needed to supply, until the stat clicked off, instead....

It knew the actual room temperatures, knew the desired temperature, and could calculate just how much heat it needed to produce to precisely hit the desired temperature and no more. After that, it gently maintained the desired temperature, by continuous modulation.

For anyone else besides Harry that is still interested, I enquired of a firm that sells the boiler I was enquiring about, and this is how they replied:
The newer ecotec Plus models are self modulating (this means they modulate the output to suit the temperature set on your thermostat as well as other factors). Nearly all modern boilers ‘flow temperatures’ can be reduced (I am assuming this is what your installer will have reduced).
In summary, the new ecotec plus can have its flow temperature reduced, it is also self-modulating so should be more efficient than your existing boiler. I hope this helps.

It seems to me (dunce though I am about these matters) that there is no good reason not to install the boiler in question.
L.L.

 

[Mottie]

For anyone else besides Harry that is still interested, I enquired of a firm that sells the boiler I was enquiring about, and this is how they replied:
The newer ecotec Plus models are self modulating (this means they modulate the output to suit the temperature set on your thermostat as well as other factors). Nearly all modern boilers ‘flow temperatures’ can be reduced (I am assuming this is what your installer will have reduced).
In summary, the new ecotec plus can have its flow temperature reduced, it is also self-modulating so should be more efficient than your existing boiler. I hope this helps.

It seems to me (dunce though I am about these matters) that there is no good reason not to install the boiler in question.
L.L.

I have a Vaillant 418 EcoTEC plus (18Kw) boiler. I have the flow temperature set to 61° and the max output set to 14Kw. After it has been running for a while, it modulates down from 14Kw.

 

[Harry Bloomfield]

I have a Vaillant 418 EcoTEC plus (18Kw) boiler. I have the flow temperature set to 61° and the max output set to 14Kw. After it has been running for a while, it modulates down from 14Kw.

It will do that, as the flow temperature begins to increase.

My boiler is not range limited, it's control system determines how many Kw the demand needs.

 

[Madrab]

With the Vaillant specific controls, you get the best of both worlds. You could say the Vaillant controls self adjust the range rate, to match the demand for heat precisely.

That's OT rather than Vaillant, where it will fine tune output in line with the smart control settings and what it's sensors are doing and then how the system is setup to compensate and interact.

Cant say I've spent much time playing with a Vaillant controlled by Vaillant smart control so not sure if there is anything more specific to their interaction as against any other OT enabled smart controlling a Vaillant.

 

[Harry Bloomfield]

Cant say I've spent much time playing with a Vaillant controlled by Vaillant smart control so not sure if there is anything more specific to their interaction as against any other OT enabled smart controlling a Vaillant.

Vaillant don't use Open Term, they use a proprietary ebus system. You can/could get an ebus to OT adaptor, but not available in the UK. So, buy a Vaillant, you are stuck with Vaillant controls, if you want the system optimised.

I think Mottie, uses a basic on/off, demand/no demand control system.

 

[Madrab]

There you go, every day's a school day, I don't know why these manufacturers don't get on the same page, pain in the a$$ - shows how many Vaillants I install

Same a WB which is even stranger as I believe they were right at the forefront when the OT interface and protocol was being developed, pure money grab so people have to use their own overpriced controls and then invalidate their warranty's when using 3rd party OT adapters.

Don't see the point

 

[Lucky Luke]

There you go, every day's a school day, I don't know why these manufacturers don't get on the same page, pain in the a$$ - shows how many Vaillants I install

Same a WB which is even stranger as I believe they were right at the forefront when the OT interface and protocol was being developed, pure money grab so people have to use their own overpriced controls and then invalidate their warranty's when using 3rd party OT adapters.

Don't see the point

The contribution above, by Madrab, seems to be a good point at which to come in on this conversation once again. After obtaining an answer to a question about the Vaillant EcoTech Plus 826 26kW boiler, I asked the people that told me (see a little earlier in this thread) that that boiler is self-modulating, another question — one that occurred to me later. I asked them whether that boiler is self-modulating in its own right, or whether it can self-modulate only with an additional Vaillant control. They diplomatically declined to answer. So, I now put the same question (which is very important to me) to this forum. Can anyone tell me, with certainty, whether this boiler will self-modulate even if I keep my Honeywell timer/thermostat, and don't use additional controls sold by Vaillant?

I hope someone can tell me!
L.L.