Alpha SmartFlow worth the extra cost?

8 Oct 2015
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United Kingdom

I'm looking to replace my boiler (vented system currently). 4 bed house, 1 bath/shower (soon to be expanded to 5 bed, 1 baths, 1 shower ensuite). Only 2 adults 2 kids, rarely shower at the same time, if at all. Also going for water underfloor heating during the renovation. The boiler will be moved into the loft. The house has plenty of mains water pressure.

I plan to have a high end shower, so plenty of water, body jets etc. I'm also a sucker for efficiency which is why i've discounted a unvented system - i don't like the idea of paying to keep water hot.

I'm considering either the Alpha FlowSmart 50 or the Vaillant ecoTEC Plus 938. I like the idea of the FlowSmart pre-heating the water, and the potential to use a Solar PV immersion on it too, however the relatively small 50Ltr tank makes me wonder if it will last the length of a good shower.

Of course flow rate is the most important, will the FlowSmart give that much better than the Vaillant?

But is the extra cost worth it ? Over £1000 for the FlowSmart on top of the 938.

Are there any other combis i should be considering? Perhaps Worcester 42Cdi?


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Save yourself some moeny and get the vaillant 838 rather than the 938, the storage capacity of the tank on that boiler doest make much difference.

ie: the 938 and the 838 are the same power and hot water flow rate/temp rise, just without the 14 or so stored litres, once there running theres no difference. and it will power any shower I've seen.
If you're having body jets you'll be disappointed by any combi.
Thanks for the input. So if i say no to bodyjets, and just want a decent rain shower. Could a Vaillent 838 provide a good shower experience? Or am i going to be forced to consider unvented?
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I would be looking at unvented for anything over 2 people/2 bathrooms.

Even with very good flow a combi has its limits.
You can run a rain head off a combi depends how big.

Need to test some stuff on your water supply static and dynamic pressure and flow rate.
The combi especially an 838 will run a rain shower no problem, the problem with any combi as gassafe says is when other outlets are in use at the same time, then the flow rate to the shower has to drop, good mixers showers should keep the temp steady but they cant control the flow rat eif another appliance or outlet is stealing some of the pressure

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