Combi boiler size (ATAG or Vaillant)

[LankyPaddy]

Hi guys,

I'm trying to decide on what combi boiler to get and I have a couple of questions, wondered if you'd all be good enough to help!

1. What size boiler do I need?
EnergySavingTrust and Sedbuk says I need a 10kw boiler for my semi-detached house, however for combi boilers should I instead be looking at the DHW rating and make sure I get a boiler which modulates down to 10kw?

2. Should I get any extra capacity on the DHW rating?
The shower I'd like has a rating of 11 l/min, and my wife likes to have baths. Should we get as higher DHW as possible to cope with this?


The boilers I'm considering are below. The ATAG is currently my current "favourite" (highest DHW for lowest modulation). The Vaillants both cover either the higher DHW, or the modulation for the CH.

ATAG A325EC
DHW @dT35 - 15l/min
Modulation range CH kW - 6.1 to 30.9

Vaillant ecoTEC 831
DHW @dT35 - 12.7 l/min
Modulation range CH kw - 8.7 to 24

Vaillant ecoTEC 837
DHW @dT35 - 15.2 l/min
Modulation range CH kw - 12 to 28

Feel free to tell me if I'm barking up the wrong tree

Thanks for any help

 

[htgeng]

The atag with the EC (gas saver type device) is a no-brainer. You get a few extra litres/minute as it is using the flue gases to preheat the incoming water.

 

[mehran]

if the they are the only boilers in the running then atag wins hand down on technical grounds and performance figures.


I would have a look at intergas HRE 36/30 as well, not quite the modulation range of the atag but have few parts to go wrong and can condense in hot water as well

 

[gas4you]

Atag will blow the intergas out of the water every time.

It is the rolls royce of all domestic boilers

 

[LankyPaddy]

Thanks for all the replies.

Next task is to find a plumber in the Chesterfield area who will fit them. My plumber is a Worchester-Bosch man and has never fitted one before, ATAG say there aren't any warranty issues in getting him to do it. How happy would you be being asked to fit a boiler you didn't know?

ATAG have given me some numbers of people in Sheffield/Derby/Nottingham so they'll be the next stop

 

[Biggles..]

Atag will blow the intergas out of the water every time.

It is the rolls royce of all domestic boilers

I thought that till mine at home popped,flooding the entire boiler( not due to freezing just poor quality)only good thing was they sent a brand new boiler next day,only trouble now is I've got 2atags in the garage.
Wish I'd have stuck with vaillant.

 

[htgeng]

Wish I'd have stuck with vaillant.

those same vaillants with the rubber hoses connecting the pump that have popped and leaked in peoples houses over the years Ok, ok vaillant fans, I know they have replaced the rubber for copper now...

 

[mehran]

I agree the Atag would blow intergas out the water...unfortunately it would be in a flood of water

I find intergas a more elegant design concept than Atag. making a boiler more efficient but with few moving parts

http://www.intergasheating.co.uk/movies/

the impotent thing is not that my boiler is better than your, but that we both choose to fit a quality boilers...

 

[Biggles..]

Wish I'd have stuck with vaillant.

those same vaillants with the rubber hoses connecting the pump that have popped and leaked in peoples houses over the years Ok, ok vaillant fans, I know they have replaced the rubber for copper now...

Those hoses that normally fail through dirty water,not had one of mine split. unlike a burst atag that hasn't even ran for 5mins,it burst 10mins after being filled for the first time.

 

[namsag]

Lee could it be a keston in the making

 

[Biggles..]

Lee could it be a keston in the making

I bloody hope not.

 

[Agile]

Those hoses that normally fail through dirty water,not had one of mine split. unlike a burst atag that hasn't even ran for 5mins, it burst 10mins after being filled for the first time.

Yes Lee, but tell us what it was that actually burst on your Atag?

Tony

 

[Biggles..]

Best case is it left the factory with no o ring in between cold main and plate ,worst case is split plate.not sure as I've not stripped it down at the request of atag who want to test it back at their office just as it is.

No disrespect to those that think they're the bees knees but I wouldn't fit one anywhere it could be seen,the flow rate is no better than any Vaillant/Worcester but they are visually naff(huge with a crap plastic panel hiding the vessel),awkward to handle due to it being an odd shape,And I don't like the pipe arrangement underneath when trying to use the naff valves supplied.plus points are Efficency of the ec,customer service is exceptional and the ability to use ot controls.

I fitted mine because it was good Value and I thought I'd give it a try

View media item 29948View media item 27493View media item 29949

 

[LankyPaddy]

....

Eek, Lee would you consider that a freak one off that and still recommend an ATAG, or has that experience put you off, you mention sticking with Vaillant above?

 

[Biggles..]

That's my first atag which I've put in at home,that said I've fitted numerous strebels which come out the same factory but are badged different but are a commercial product.

Current failure rate for me with the atag is 100%,as a firm we must have fitted over 500 vaillants with less than a hand full of problems.

Loads of people in here have fitted numerous atags with no issues,it's one of those things.