Vaillant EcoTec Pro 824 Modulate Heating temperatures?

[Unklian]

Hi All Again.

Just wondering......

My ancient heating system has now been replaced. All new rads & a
Vaillant EcoTec Pro 28 Combi boiler.
When it's making DHW, I can hear it running "flat out". No problem.

When it's providing water to the radiators, in the summer, they seemed to heat up quickly. Now, as the weather is cooler, the radiators seem to be taking longer to get up to temperature.

The question......Does the boiler modulate output depending on return temperature?
ie, When the heating first comes on, should the boiler run at maximum, then as the return water nears it's set temperature, should the boiler idle back? Would I be able to hear the difference? Or, does the heating work at a set level & the boiler only modulate "up" for DHW?

I've looked through all the brochures & operating manual & can't seem to find a simple yes / no answer.

Or is it just that the radiators are losing heat quickly & I'm being paranoid?

Cheers.

Ian.

 

[Agile]

You have not told us hob big your property is and number of rads.

The d0 setting in the boiler controls the CH power and its POSSIBLY set too low.

You should do a whole house heat calculation to see how much power you need. Usually about 1.5 kW or so per rad.

Tony

 

[Unklian]

Hi Tony.

No exact figures but......
3 bed, well insulated semi.

5 radiators at (very) approx. average 600 x 800mm single panel with fins.
TRVs set at 2 in bedrooms, 3 in kitchen, 4 in bathroom.
1 radiator, 2400 x 500mm high double panel with double fins. Under large living room window. (with thermostat on wall).

Boiler is EcoTec Pro 28.

The house is fine & warm, set at 17 degrees while we're out all day,
20 degrees 4-5pm. Then 21 degrees, 5pm to 11. 16 overnight, then 19 degrees for an hour in the mornings.

d0 setting?......I'll look that up now......If it's not something I can mess with, I'll leave well alone. The house is warm, I was just wondering if the "heat-up" time is supposed to be quicker......EDIT......looked d0 up, As far as I know, it hasn't been altered. According to manual, factory setting is "Maximum".

As usual, ANY advice, tips are appreciated.

EDIT: BTW, boiler is set at 60 degrees, is it better to run at that for longer
or set at 75 degrees and run for shorter times? Still new to stuff like this.
I'm in North Sheffield and the water is (I believe) fairly hard, I believe this temperature was set to try and prevent scaling in the heat exchanger?

Cheers.

Ian.

 

[Dan Robinson]

The boiler starts low then ramps up over time dependent on a few things.

 

[Unklian]

@ Dan......

I've done a couple of EDITs. don't know if they shed any light.

Ian.

 

[Agile]

You need to look at the boiler to see what the d0 setting actually is!

Set it at about 10 kW if set at a higher figure.

With only 60 C the rads are not going to heat the house so quickly but it will be far more efficient to run like that!

Tony

 

[gasman1987]

is it a 824 or a pro 28, also is this the new design for 2012

 

[scoobydo123]

Also very relevant is what controls you have? Perhaps you may have smart controls. Please can you give the make and model of roomstat/programmer

 

[Unklian]

is it a 824 or a pro 28, also is this the new design for 2012

Boiler is EcoTec Pro 28. (I BELIEVE it's the new model. The fitter was surprised at all the copper pipework inside and mentioned "They've changed it this year").

 

[Unklian]

Also very relevant is what controls you have? Perhaps you may have smart controls. Please can you give the make and model of roomstat/programmer

It's a Danfoss TP5000Si (Wireless with a RX1 receiver).

16 overnight.
18, 5:30 - 7:30.
17 through day.
20 at 4:00
21 at 5:00
back to 16 at 23:00

Ian.

 

[scoobydo123]

this stat has proportional control and will on off cycle the boiler before the room comes up to temp to stop overshoot and keep return temp down I believe. You may be able to turn this off. between 4 and 5 you only have a 1c increase the logic on the stat will not let it call for long with only this rise. Override this with an artificially high target temp and rise and it should stay on and get hotter. Got no experience of this stat and haven't read the manual in full as on a mobile device

 

[baxiengineer]

Hi , I know what you mean, it is preferable to turn the boiler on and have it heat the rads red hot and then modulate back. Unfortunately most boiler makers now use a software platform that will not allow this as it does not fit neatly in to the efficiency side of things, in reality as soon as the return reaches a quite low temperature, it modulates back.Would be nice if we could have a 5 minute time delay on this when the boiler runs full tilt to get the rads hot at start up as quite clearly, it takes longer to warm the house up with the boiler modulating back. One thing is important in all of this, if the system is designed correctly and balanced correctly then all of the rads should heat up at once at the same rate. But if this is not the case, the first rad on the circuit will send return water back to the boiler at a higher temperature than say the ones further down the line. This will trick the boiler in to thinking that the system is reaching or near the design temperature set. So both balancing the flow rates to the rads and sizing of pipes is important.

I have to say though if you are not a registered installer, then you should not alter the settings within the programmer as these are safety critical parameters.

Out of interest, did a registered installer fit it? and why did he not set the heating load when he commissioned it?

 

[Unklian]

this stat has proportional control and will on off cycle the boiler before the room comes up to temp to stop overshoot and keep return temp down I believe. You may be able to turn this off. between 4 and 5 you only have a 1c increase the logic on the stat will not let it call for long with only this rise. Override this with an artificially high target temp and rise and it should stay on and get hotter. Got no experience of this stat and haven't read the manual in full as on a mobile device

Yes, it DOES have that facility.
I currently have it switched off as the house temperature is quite stable.
The options are, brief heating for (I think) 3, 6, 9 or 12 times per hour.
I thought best to leave off as it will cause more boiler lighting / heating / cooling cycles. The house seems to heat up then the boiler doesn't come back on for ages, perhaps twice in 5 hours.

Ian.

 

[Unklian]

Hi , I know what you mean, it is preferable to turn the boiler on and have it heat the rads red hot and then modulate back. Unfortunately most boiler makers now use a software platform that will not allow this as it does not fit neatly in to the efficiency side of things, in reality as soon as the return reaches a quite low temperature, it modulates back.Would be nice if we could have a 5 minute time delay on this when the boiler runs full tilt to get the rads hot at start up as quite clearly, it takes longer to warm the house up with the boiler modulating back. One thing is important in all of this, if the system is designed correctly and balanced correctly then all of the rads should heat up at once at the same rate. But if this is not the case, the first rad on the circuit will send return water back to the boiler at a higher temperature than say the ones further down the line. This will trick the boiler in to thinking that the system is reaching or near the design temperature set. So both balancing the flow rates to the rads and sizing of pipes is important.

I have to say though if you are not a registered installer, then you should not alter the settings within the programmer as these are safety critical parameters.

Out of interest, did a registered installer fit it? and why did he not set the heating load when he commissioned it?

Agree with all the first statement, seems common sense.

I'll leave the settings alone, all seems to be working fine, I just expected it to behave more like you've suggested, ie, flat out until nearing the desired temp. then throttling back. (It MAY actually be doing this, I just expected more of the "flat out" noise like when it's making DHW. Perhaps it's water rushing through the heat exchanger I can hear? I'll listen more carefully next time).

The fitter was a registered installer and (don't know what it's worth) had been on a Vaillant course of some kind which enabled him to give me a longer guarantee / warranty. (2 years instead of 1).

Ian.

 

[Unklian]

Deleted. Duplicate post.