Vaillant Ecotec 937

[hasski]

My plumber advises me that this is adequate for my needs. I prefer a combi to a conventional boiler as I like the idea of hot water on demand while not losing energy heating a whole tank which I usually don't need. My house is a large detahced (4 bedroom, 4 receptions) with 14 radiators and 2 bathrooms. Will this combi provide enough heating power for winter and enough water for showers and kitchen use?
Is my only alternative a conventional boiler with pressure cylinder/
Thanks

 

[Gasguru]

Don't believe the nonsense about combis being more efficient over a conventional cylinder setup....I've yet to see any substantiated independent evidence. Remember many combi owners have the warmstart/preheat enabled wasting fuel. In addition each time the boiler fires up heat energy is lost warming up the boiler instead of a steady continous burn of a conventional boiler. Heat loss from modern cylinders is minimal and the little heat given off is often put to use in an airing cupboard (that combi owners miss).

For that size of property a combi is a mad idea....you have no backup when it breaks down. Most owners would expect an immersion heater backup and a combi is just a cheap job.

I hope the dynamic pressure and flow rate have been measured before a mains pressure system (combi or unvented cyl) is contemplated.

 

[simond]

I think there are too many variables for an accurate result.

I always ask my customers whether they use their airing cupboard for it's intended purpose. If they don't, then the heat from the cylinder is wasted.

Many customers do not like the idea of heating water on the basis that it might be used. These are drawn to the combi or hybrids like the Vaillant.

Also, if the customer wants mains pressure performance but only has 20 litres per min incoming mains, a Vaillant 937 will offer a performance matching an unvented for a smaller outlay, and smaller footprint.

OK, so they could upgrade the main or fit an accumulator, burt this is all extra outlay which may not pay back if they are not planning on using multiple outlets. Used sensibly, a Vaillant 937 or a Worcester Highflow 440/Viessmann 333 is a worthy solution.

A big combi that combines the flow of an unvented, the heatstore advantages, all in one box is the ACV Heatmaster TC. Shame about the UK customer service though.