Vaillant EcoTec Plus 630 Pump Curves

[Johntheo5]

Can someone explain or throw some light on the above, this boiler's hydraulic settings can be set to several modes, constant speed, dp constant pressure (between 100mbar & 400mbar) and dT Temperature Spread (between 10C & 20C). This boiler is having problems in running in either dP or dT modes so is running in constant speed mode until problems resolved.
The EcoTec 430 gives the actual HEX pressure loss so relatively easy to calculate the Residual Head with any known circ pump, I have done a few calcs based on using a 6M (Wilo) pump.
THe EcoTec 630 does not give this very useful info, nor do they give the boiler's installed pump head, it does give a "Pump Curve" (see attached) which shows flow rates of 25.8LPM @ 100mbar head, 23.0LPM @ 200mbar and 19.0LPM @ 400mbar which makes no sense to me as the flowrate is apparently decreasing with increased pump head, hence the query. The boiler comes in a default dP mode set to 200mbar.
The D parameters show flowrates of 11.65LPM @ 50% pump speed, 20.6LPM @ 80% and 25.47LPM @ 100%.
This boiler has a Vaillant LLH installed.

 

[MNW67]

it does give a "Pump Curve" (see attached) which shows flow rates of 25.8LPM @ 100mbar head, 23.0LPM @ 200mbar and 19.0LPM @ 400mbar which makes no sense to me as the flowrate is apparently decreasing with increased pump head, hence the query.

How is that any different to constant pressure mode on the Wilo shown in the first chart below? I think it just means that the maximum flow the Vaillant boiler can produce at a constant 400mbar is 19.0LPM, and the maximum it can produce at a constant 100mbar is 25.8LPM.

Also, if I am reading the Vaillant manual correctly, it seems to mention that constant speed is the correct mode for use with a low loss header.

 

[Johntheo5]

The Wilo will flow 19.0LPM at 4M (400mbar) and will flow ~ 55LPM at 1M (100mbar), the HEX has a head loss of 2.6M @ 21.5LPM, if you tried to force 55LPM through it then the head loss is ~ 17M, if the Vaillant pump curve is just that (a pump curve) and assuming its ~ a 6M pump like the Wilo then, while it does show 19.0LPM @ 4M it should show ~ 50LPM @ 1M??.
Also when tested on a 100mbar dP setting it showed something like 12.5LPM at 49% pump speed, close enough to the 11.66LPM @ 50% showing in fixed speed, this, again assuming a 6M pump means its running at a head of ~ 4.2M with HEX dP of ~ 0.76M which still leaves around 3.4M residual head.
I think all this was discussed in some other thread?, Its very disappointing IMO that there isn't a accepted "standard" for all makers that just states the residual or remaining head available when the boiler is running at its rated output and flowrate, after all, they do give the flowrate, all these are based on a 20C dT, ie a 30kw boiler's design flowrate is, 1290LPH (21.5LPM). Installers can then reasonably make a decision on whether or not a LLH or whatever is required.
Or, even more useful, just show a Residual Head Graph like I just posted?.

 

[MNW67]

Or, even more useful, just show a Residual Head Graph like I just posted?.

I think the Vaillant graph actually is a residual head graph. But for some reason they haven't called it that. It shows how much pump head the boiler can produce after it has forced the water through the heat exchanger.

 

[Johntheo5]

I think the Vaillant graph actually is a residual head graph. But for some reason they haven't called it that. It shows how much pump head the boiler can produce after it has forced the water through the heat exchanger.

Yes indeed, with probably a ~ 6.5/7M pump and assuming the 630 Hex head loss is the same as the 430 but what's completely misleading is stating that 200mbar is the factory setting on dP mode which I interpret that the pump runs with a fixed constant pressure of 2.0M, you won't circulate a lot of water at that head.

 

[MNW67]

Yes indeed, with probably a ~ 6.5/7M pump and assuming the 630 Hex head loss is the same as the 430 but what's completely misleading is stating that 200mbar is the factory setting on dP mode which I interpret that the pump runs with a fixed constant pressure of 2.0M, you won't circulate a lot of water at that head.

The pump is probably something like this. Most system and combi boilers use UPM3, I believe. If you subtract the heat exchanger loss from the top curve, then you might get something close to the curve published in the manual.

 

[MNW67]

assuming the 630 Hex head loss is the same as the 430

The graphs look very similar. But I think the heat exchangers are actually totally different (one is aluminium and the other stainless steel).

 

[Johntheo5]

We are too posh, Remaining Head would have thrown up more, see attached where they provided the proper charts in 2021. However it seems that 250mbar, 2.5M is the remaining/residual head used throughout the range.