So does the 6 series, though nominally the timeout can be adjusted by changing one of the d-registers. Whether it actually does anything or not I don't know; changing the partial load d-register didn't make any difference.
Just why would you want it serviced? All most only need is a visual check
- and a sniff of the flue gas to make sure it is burning OK. So the same for all.
Fixing a broken one might be a different matter.
I'd call that a basic electric boiler. And am surprised you can still buy them. Given you need sophisticated management to get the best efficiency.
BTW, why do you think an external pump is not going to be an 'over priced paraphernalia that can go wrong'?
Really? Wouldn't that depend on how accessible it is? In both cases?
They look like normal gas boilers to me; they are readily available from most manufactureres. The difference between a system boiler and a regular boiler is that the system boiler will have a pump and expansion vessel in the case while with a regular boiler they are external. Can't see that a system boiler will have more sophisticated controls than an equivalent regular boiler.
I've recently replaced our regular boiler with a Viessman which has the option of weather compensation and an opentherm interface, IOW the regukar boiler has controls which are just as clever as they would be in a system boiler. The programmer can be as sophisticated as you like. As it was a drop in replacement there was no value in replacing it with a system boiler. Did consider a combi for about 2 seconds, but as it would involve considerable plumbing upheaval, probably couldn't provide the hot water supply rate (2 baths at 30l/mnute each), and I've never come across a good combi system it wasn't an option.
On the 4 it's adjustable but not to zero. If the plumbing is sluggish that caan be a problem.
Yup you can limit max power out, and the modulation range is quite broad as well.
If you have established that is what is happening, then you would need to fix the system balancing to make it work correctly.
If it can reach the flow temp quickly and easily, you won't be dumping much heat into the system - since it will spend lots of time cycled off.
You mean one that does what you tell it to do rather than one that does what you want it to do?
If you are running a fixed flow temp, that it will at best only warm it as fast as the setting allows. With more sophisticated controls then it could indeed take into account things like the magnitude of the error between demand temp and actual temp and set higher flow temps.
I think in the circumstances I would go to the effort of balancing the rads properly, and dispense with (or close off) the bypass circuit altogether (Vaillant boilers have an internal bypass). Then see if you get proper operation.
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