Why range rate a modulating boiler?

[mrbg07546]

If you ever feel like you need a quicker temperature boost, what can you do? Do you simply increase the heating curve?

Yes. But I never really do. But increasing heating curve changes the target flow tempreture. It is a way to increase room temp quicker. I do find rad fans in larger rooms help speed up heat up times. The only time when the heating curve fails is when you have decent temps in winter but it’s windy. Like this week we have had 10 degrees with cold wind. Shame the boiler can’t use a “feels like tempreture”.

On another point. I do notice as weather gets colder(in months December etc) I can can reduce thermostat down from say 18-19 because heating on when it’s 18 degrees feels warmer then heating is off when it’s 18 degrees

 

[mrbg07546]

The curve above, 40C at 6C follows Curve 1 on the Vaillant? one above in post 22 which means that it looks for 53C at -5C ambient, this in turn means the rads are rated at 50% of their design output, so if you had say 20kw of installed radiators then you might range rate the boiler to 10kw, so if you need a quicker temperature boost by chaging to a higher curve then you also have to range rate the boiler to a higher output, no big deal I suppose as long as you remember it.

Now it’s 43 at 4 degrees

 

[vulcancontinental]

If you ever feel like you need a quicker temperature boost, what can you do? Do you simply increase the heating curve?

The thing about weather comp is why would you need a quick boost? A good system will swap between comfort and setback and the difference is 4 perhaps 5 degrees and that's the air temp, it hasn't got to heat the structure.

That's the advantage of dual temperature, many boilers are simply modulated flow or off which delays heat up. Viessmann 200 has a boost.

To get a temporary or permant change in either comfort or setback on our boilers simply adjust the heating flow temperature selector, that will recalculate the flow to give the new required internal temperature

 

[mrbg07546]

The thing about weather comp is why would you need a quick boost? A good system will swap between comfort and setback and the difference is 4 perhaps 5 degrees and that's the air temp, it hasn't got to heat the structure.

That's the advantage of dual temperature, many boilers are simply modulated flow or off which delays heat up. Viessmann 200 has a boost.

To get a temporary or permant change in either comfort or setback on our boilers simply adjust the heating flow temperature selector, that will recalculate the flow to give the new required internal temperature

I do notice my vsmart does not increase target flow tempreture based on tempreture I select for example if I put 19 degrees vs 24 degrees on vsmart the target flow tempreture doesn’t change. Shouldn’t it? I thought that’s the purpose of load compensation?

 

[JonathanM]

The thing about weather comp is why would you need a quick boost?

Sometimes I just feel really cold for no identifiable reason, even when the heating has just been on, and even putting on another layer doesn't help. It doesn't happen very often. Currently, I just turn the thermostat up a bit. I was wondering how I could get a similar, quick change if I have weather compensation. I know I can always use some sort of subsidiary heating.

 

[JonathanM]

On another point. I do notice as weather gets colder(in months December etc) I can can reduce thermostat down from say 18-19 because heating on when it’s 18 degrees feels warmer then heating is off when it’s 18 degrees

I've noticed that as well!

 

[vulcancontinental]

Sometimes I just feel really cold for no identifiable reason, even when the heating has just been on, and even putting on another layer doesn't help. It doesn't happen very often. Currently, I just turn the thermostat up a bit. I was wondering how I could get a similar, quick change if I have weather compensation. I know I can always use some sort of subsidiary heating.

That's when the wrinkle we have is useful because sometimes you're tired or a little run down and a degree or two increase just makes you feel more comfortable.

Without a WC sensor connected the heating flow selector on our boilers is used too set the maximum flow temperature but with the sensor detected the heating selector changes function automatically.

The boiler will calculate the flow temperature adequate to achieve the nominal comfort level of 20 degrees with the selector in the middle of it's travel or if digital will show zero, this represents 20 degrees.

If the user requires a short or long term adjustment of the internal temperature, adjusting the selector up or down by 5 degrees in one degree increments the boiler will recalculate a flow temperature to achieve the new desired setting. A parallel shift in effect. This works on either the comfort or setback temperatures.

 

[mrbg07546]

Today vsmart did 34 at 7 degrees outdoor tempreture. Against the curve. I wonder if something else is happening?

 

[mrbg07546]

I woke up this morning and at heating curve 0.8 it was giving me 34 when outside tempreture was 6. 34 really struggles to heat it up . So I’ve increased curve to 1.2 and it’s asking for 38

 

[JonathanM]

That's very interesting. Did the same happen in previous years?

 

[mrbg07546]

That's very interesting. Did the same happen in previous years?

well I had heating curv very high. So not really

 

[JohnOfChelmsford]

Hello,

Would range rating a modulating boiler serve to reduce start-up\operational noise?

I have a new 050-w 30KW Viessmann and one of the slight disappointments is that it makes more noise than the outgoing potterton 33 promax it replaced. To qualify, it's not making unusual noises, just seems to be a few db higher and of a different frequency than the old, and it's right under our bedroom. I think the ramp-up phase after a call for heat (Or a preheat cycle) is when it's loudest - then once it's in its stride and modulating down, it's all fine.

In a steady state it seems to like being about 40% modulation to give us 65 flow temps to retain 19C where we want it. So i'm wondering if that means i could experiment with range limiting which might reduce noise. Gotchas' i'm wondering about -

- Would Range limiting actually address the start-up phase noise ( could imagine that phase has it's own power preses)
- Would Range limiting affect DHW supply (call for DHW\shower usually requires 100% right?)

any tips\advice welcome. thanks

 

[mrbg07546]

Hello,

Would range rating a modulating boiler serve to reduce start-up\operational noise?

I have a new 050-w 30KW Viessmann and one of the slight disappointments is that it makes more noise than the outgoing potterton 33 promax it replaced. To qualify, it's not making unusual noises, just seems to be a few db higher and of a different frequency than the old, and it's right under our bedroom. I think the ramp-up phase after a call for heat (Or a preheat cycle) is when it's loudest - then once it's in its stride and modulating down, it's all fine.

In a steady state it seems to like being about 40% modulation to give us 65 flow temps to retain 19C where we want it. So i'm wondering if that means i could experiment with range limiting which might reduce noise. Gotchas' i'm wondering about -

- Would Range limiting actually address the start-up phase noise ( could imagine that phase has it's own power preses)
- Would Range limiting affect DHW supply (call for DHW\shower usually requires 100% right?)

any tips\advice welcome. thanks

View attachment 329573All range rating is doing is lowering the gas flame hence limiting the amount of kWh that it using per hour. In most cases modulate down to as low as possible until the radiators are taking way too long to get up to temp. You may not be bothered about that if your heating is on most of day. The noise usually comes from pump pushing the water round your radiator. Some boilers may have a separate pump setting others the pump is set to auto where The pump speed is based on themodulate. In other cases you have to set the pump manually. Yet again the lower the better with pump. And you want to stop if you find the furthest radiators are not getting warm

 

[JohnOfChelmsford]

Thanks - I had tried pump speed limiting option (75% max speed down from 100) which didn't seem to address noise i was hearing. I suppose i can just give range limiting a go and see if it causes any issues. My hunch is the noise that bugs me is the fan when at 100%. If this cycles down to match modulation then that would help.

I'm looking at giving weather comp a go - which would mean running boiler all night (i understand) so noise reducing given location would be helpful. I have a solid wall 3 bed semi with uninsulated suspended flooring - so it's pricey to heat currently

 

[mrbg07546]

Does the pump have a auto option? Then it would be set based on the range rating