Vaillant ecoTEC plus 940 vs Viessman Vitodens 111-W Boiler vs Something Else?

[eveares]

Quick question, out of the two boilers below, what would you say is the better and more reliable one?

1) Vaillant ecoTEC plus 940 Boiler

2) Viessman Vitodens 111-W Boiler

3) Or how about the Vaillant EcoTEC Pro 24 which is not a storage combi, but has the "aquaCOMFORT System" which is supposed to deliver hot water near instantly. No idea how that works.


I am after a combi boiler which can:

1) Deliver hot water a decent-ish* rate for a combi boiler.
2) Provide no slug of cold water should the hot tap be turned off for a minute or two and then opened back up.


*I know Combi boilers are limited in their DHW flow rate, but what's the best out there.


Any recommendations? This is for a 3 bed terraced house.


Regards: Elliott.

 

[CountryFan]

How many bathrooms? What is litres per minute? Personally I like the Ideal Logic combi 35kw. I believe there’s some on here that recommend the Vokéra pinnacle - @muggles being one of them, I can’t vouch for it as I haven’t seen them or worked on them. Vaillant are a good boiler, spares a generally reasonable. Veissmann unsure.

 

[eveares]

No many bathrooms? What is litres per minute? Personally I like the Ideal Logic combi 35kw. I believe there’s some on here that recommend the Vokéra pinnacle - @muggles being one of them, I can’t vouch for it as I haven’t seen them or worked on them. Vaillant are a good boiler, spares a generally reasonable. Veissmann unsure.

1 Bathroom and 1 Kitchen currently as is, may add 2nd bathroom via loft conversion way down the line.

Litters per second is unknown at this stage as have not moved in yet.

 

[muggles]

Your requirement 2 is virtually impossible. Hot water left static in pipes will cool down. You could ensure all the hot water pipework is insulated in very thick lagging to mitigate the effects but you'll never eliminate them.

You need to know your incoming flow rate & pressure before specifying a boiler. There's no point going for a 40kW boiler if your mains is only running at 10l/min, for example. You can't get more out than is going in.