Vaillant ecoTec Plus 630 boiler not reaching target temp

[windsor-tg]

I recently had a new 2023 Vaillant ecoTec plus 630 (30kW) system boiler installed along with a Low Loss Header (LLH) in my house. I have 21 rads in the house and a room with UFH. The LLH was introduced as I was finding (before the LLH was fitted) that my old boiler (Vaillant heat-only boiler) was anti-cycling as the demand from the UFH was too low for the boiler to remain firing. This issue has gone away since the introduction of a new boiler & LLH.

I have noticed in the last couple of days that with the boiler target temp set to 65 degrees, the boiler flow temp (d.40) takes an age to get to 60+ from cold. Even when the boiler was running continuously (with just CH on) for 2 hours this morning, the boiler flow temp reached 61C (d.40), boiler return temp - 52C (d.41)

d.00 on the boiler is set to "Automatic".

The boiler displays 5 modulation levels and it is currently displaying level 2. Is there any reason on why the boiler is not reaching its target temp and/or why the boiler is not modulating at a higher level to get the boiler flow temp close to the boiler target temp ? Even now with both, CH and UFH, demanding heat from the boiler, the modulation level is at 2.

Any suggestions on why the modulation level is not going above 2 will be much appreciated.

 

[ShaunCorbs]

What’s the flow and return temps both sides of the llh ? Sounds like it’s sensing the heat isn’t getting away fast enough

 

[windsor-tg]

What’s the flow and return temps both sides of the llh ? Sounds like it’s sensing the heat isn’t getting away fast enough

thanks @ShaunCorbs. Stupid question but I would I meassure the flow & return temps on both sides of the LLH?

 

[ShaunCorbs]

thanks @ShaunCorbs. Stupid question but I would I meassure the flow & return temps on both sides of the LLH?

Clip on temp guages or a ir temp gun with some black electrical tap on the copper eg test on the temp due to copper being shiny / reflective

 

[windsor-tg]

sorry @ShaunCorbs, I thought I had responded to this. Since my last post, I changed d.00 to 28kw. The speed of the boiler immediately increased and the modulation level went up to 4. I was finding that the boiler flow temp was reaching the boiler target temp of 65C and the rads were heating up nicely.

However, from reading my IHD linked to my smart meter, I am finding that I am using approx £16 per day of gas in the last few days of this cold weather spell. I took some readings earlier today, with boiler target temp set at 64C, and with just my CH on, D.40 was 64C, D.41 was 53C, and the modulation level had dropped down to 3 (since the CH was on for at least 3-4 hours).

Trying to find ways in reducing my gas consumption. Suggestions I have read on another forum (where I posted about my initial problem) is to use Vaillant controls. Without vaillant controls, comments are "you are wasting the modulating tech of your boiler by not using the ebus system from vaillant to control the boiler, this is why your system it not running properly and probably wasting loads of gas". Here's the link to the post on that forum Vaillant ecoTec Plus 630 boiler not reaching target temp - https://forum.buildhub.org.uk/topic/36747-vaillant-ecotec-plus-630-boiler-not-reaching-target-temp/#comment-533644

 

[ShaunCorbs]

agree vaillant controls are best but there not cheap and you would save on average max £25-30 if you switch on gas

 

[windsor-tg]

agree vaillant controls are best but there not cheap and you would save on average max £25-30 if you switch on gas

@ShaunCorbs - do you mean £25-30 max saving for the month or year?

 

[ShaunCorbs]

@ShaunCorbs - do you mean £25-30 max saving for the month or year?

Year sorry

 

[windsor-tg]

Year sorry

Well that’s a negligible saving in my mind. How did you arrive at that?

 

[ShaunCorbs]

Well that’s a negligible saving in my mind. How did you arrive at that?

Just experience in changing over it’s more to do with the features that It could bring more so than gas saving etc

 

[windsor-tg]

Just experience in changing over it’s more to do with the features that It could bring more so than gas saving etc

well, I really cannot see what extra features the Vaillant controls can provide (over and above 3rd party controls like Heatmiser, Hive, Nest, etc) to warrant such an expenditure, and not provide much of a saving in gas consumption