Atag A325EC or Intergas Combi Compact HRE 36/30 ?

[Dan Robinson]

Indeed 0 you have spotted the margin of error in the SEDBUKlistings can completely destroy many of the differences between the various models out there.


Atag's FHR module is the killer feature as it is included in the price of the boiler whereas all the other makes that have it as an option bend you over on price often making it impractical.

 

[sadanorakman]

Indeed 0 you have spotted the margin of error in the SEDBUKlistings can completely destroy many of the differences between the various models out there.


Atag's FHR module is the killer feature as it is included in the price of the boiler whereas all the other makes that have it as an option bend you over on price often making it impractical.

Unfortunately not much in life comes for free... THE A325ECX still cost me about £200 more than the non-X model that doesn't have the FHR, so it's still going to take a few years for the FHR to pay for it's self in savings.

having said that, an external FHR unit could have cost me £800, and would practically never have paid for it's self!

I know you believe strongly in Intergas Dan, and boy my Atag is Ugly on the wall in comparison, but only time will tell me if I've chosen the right one of the two or not!
The Atag does have so much more to go wrong with it than the Intergas, but yes it is certainly giving me better DHW efficiency.

It is also immaculately behaved with its OWC sensor input and OpenTherm control... I have to say I'm incredibly impressed with my final system. Room temperatures don't overshoot, it only warms the rads gently if that's all that's required, and the DHW temperature is brilliantly regulated from a small trickle to full pelt.... I'm REALLY happy with it right now.

With respect to the previous poster, I know that Vaillant were regarded as pretty solid boilers five years ago, I don't know if that reputation still persists, but I hear not such good things about WB reliability and build quality. I doubt I would have ever entertained the WB.

 

[St0rmer66]

The Intergas isn't much to look at either, so I wouldn't complain too much about how the Atag looks . I think things like the flue heat recovery are the way to go for boiler manufacturers to gain more efficiency. It's just a shame that Atag don't get a look in when it comes to market share with Worcester and Vaillant having such aggressive marketing, if they were more popular the others would have to follow suit. I know you "can" get FHR separately but being built into the boiler has got to be better.

 

[sadanorakman]

Yes I agree, it's the way to go, and a shame every manufacturer doesn't offer built in FHR... if it were to become the norm, it would drive the costs way down too.

It's not like you've often got the choice with external units; intergas for example said they did not support any type of external flue heat recovery, and I can understand why... they would cause a restriction to the flow of exhaust gasses, so will effect the burn to some extent.

In fact I wonder how they calculate the size of their main heat exchanger, as the more surface area it has, the more energy it would transfer, but there must be rather rapidly diminishing returns beyond a certain point.

 

[St0rmer66]

There's a Baxi/Potterton FHR for their combi's but I've never seen one fitted and didn't know it existed until I was looking for weather compensation (which is also barely mentioned). It's external though and sits on top of the case, looks bloody stupid! Wouldn't even fit where I've got mine.

 

[sadanorakman]

Well the extra parts have got to go somewhere, like on the Atag: The FHR fits in a space that could have housed a slender expansion vessel, so instead the expansion vessel gets slapped under the boiler, adding a foot to the overall height, and making it look fugly at the same time!

It seems that there are a few external FHR units around, but they are expensive, generally tied to that particular manufacturer's boiler, and as you say sit above the boiler, where most people wouldn't have the available space!

I think the industry could do a lot better, but instead are happy to make small incremental improvements with each boiler incarnation, and let the technology creep along, instead of challenging the status quo, and developing something that is head and shoulders in advance of the market-place.

 

[dmdm272]

Re-reading the start of this thread it seems the initial dilemma was that Igas seemed to have a poor HW score on sedbuk. Since this has now been found to be false (ATAG also had a poor score which was false) and the Igas and ATAG seem to be more evenly matched efficiency-wise which is the one to go for reliability-wise?

Thanks!

 

[St0rmer66]

Reliability alone probably the intergas but the Atag is more efficient due to the flue heat recovery built in.

 

[sadanorakman]

Reliability alone probably the intergas but the Atag is more efficient due to the flue heat recovery built in.

That pretty much summarizes the situation. The Intergas is different to most current combi's, in that it has no secondary heat exchanger for the DHW, and therefore no diverter valve. It's Aluminium heat exchanger has two separate pipes embedded/running through it, one for the CH loop, and a narrower one for DHW. This mechanically-elegant design means fewer parts to go wrong compared to other combi's.

The intergas's concept is not a new one, as my mother has a 20 year old Combi using the same principle. Of course the technology employed in the intergas is much newer.

Apparently the heat exchanger's DHW pipe can suffer a build up of limescale, as the water sitting in it is heated to a high enough temperature when the central heating burns to bring the minerals out of solution. I don't know practically how much of a problem this may be; Dan will advise you accordingly. I have also heard that the Wilo pumps used on the intergas are not great reliability-wise, but stand to be corrected on that.... again Dan?

The Atag conversely has a stainless steel primary heat exchanger, and is like most other combi's, with a diverter valve which upon demand diverts the system's water through a secondary heat exchanger to instantaneously heat the DHW. More parts to fail than the intergas, but only a comparable number of components to most other combi boilers.

I believe that failed diverter valves are often attributable to crap floating around the system (Sludge, and non-metallic particles etc...), which is one reason a boiler manufacturer may insist your existing system is power-flushed for their boiler warranty to be valid. Most also either mandate or at least recommended a system filter on the CH return pipe close to the boiler, and an inhibiter chemical in the system.

Ultimately I opted for the roughly 10% greater DHW efficiency of the Atag, knowing that there are more mechanical components that could fail in comparison to the Intergas.

With all of the above considered, the manufacturing quality of both of these Dutch boilers is regarded as first rate, so you are buying a damned good boiler regardless of which one you go for.

You pays your money, you takes your choice.

regards

Craig

 

[vulcancontinental]

I haven't got the EN standard to hand but it's a pattern of usage throughout a day; 10 minutes here, 20 minutes there for example and the energy consumed is measured against the hot water output.

I may be wrong but the Appliance Database which quotes the DHW efficiencies I believe uses the EN pattern.

I think the Intergas does poorly because of the high mass of the heat exchanger and plate heat exchangers on low water content boilers do better.

Flue gas temperature is fine but that depends on where it's measured and on the IG it's quite away from the HX though that's common on many boilers.

Lastly, the EU had a technical committee that reviewed test procedures for arriving at boiler efficiencies and found the current ones not very useful at all and not at all representative of how a boiler is used, I think it dropped the 90% figure into the high 70's.

A German study also slated the way boilers are used inasmuch as little account is made of the inefficiencies of cycling and how oversizing a boiler for the loads affects annual efficiency. Going by memory again they gave the overestimation of boiler efficiency at 11% due to cycling unnecessarily due to poor control strategies and burner turn down.

Just get a decent boiler, which most are, follow the instructions and get it put in by a conscientious installer and you're good to go. One failure due to saving £200 on the install and you've lost that 'saving' but expensive doesn't always mean better.

dmdm72, how was the HW efficiency found to be false? I missed that bit.

 

[dmdm272]

Well I emailed Building Energy Performance Assessment - Support Website

Building Energy Performance Assessment - Support Website
Type Index number Status Gas and oil fuel boiler 016135 Normal Brand Model name Model qualifier Intergas Combi Compact HRE 28/24
View on www.ncm-pcdb.org.uk

Heres my email:

Hi,

I was comparing boilers as I need a new combi and I noticed that the Intergas HRE 28/24 (and Atmos HE32 which is apparently similar or identical) score very poorly for the "Comparitive Hot Water Efficiency" at 62.1% and 62.2% respectively.

This alarmed me as my other boiler options from their obvious competitors were getting more like 75%.

I called them (Intergas technical support) and they couldn't understand why this is as they say they provide "the only true condensing of hot water on the market" so they should be considerably more efficient than this.

As I only use central heating for about 5 months of the year the hot water efficiency of my boiler will be very important to me.

Am I understanding the importance of this figure correctly?

Do you think this low figure seems likely given your knowledge of their boiler or may it be misleading or a mistake?

Many thanks,

And they replied:

Dear

Thank you for your email, all I can say is that unless a manufacturer has submitted Hot Water data the boilers will received a default value. I am sorry I cannot give specific details about manufacturers submissions.


So it looks like both I gas and atag were low as default values were used. Atag knew about it and are in the process of getting it corrected. Igas did not know about it.

 

[vulcancontinental]

I'll try to look out the EN test sheet on Monday.

I'm afraid I don't see how you can arrive at the conclusion you have from the reply you received but it is of no matter. If your DHW bill came to £200/ annum which I would think a reasonable guess, 15% reduced efficiency is £30 over a year, who cares? Buy the boiler you have most confidence in and spend as much time choosing the installer as you do researching the boiler.

I work for a manufacturer although not one so highly regarded on here but frankly, in my experience, no manufacturer will send in anything but the very best data they can get certified by a test house. If they don't then I'd worry about the organization although from what others say about IG they do seem short on numbers.

I'm sure these boilers are fine and would be trying one of each myself if I still installed.

 

[dmdm272]

I came to the conclusion I came to as they stated that "a default value was used" which would suggest that it was not the correct one or even a properly calculated one. Also both Atag and Igas said their dhw efficiency was much higher than that value and they we're going to look into correcting it on that website (but there will be a delay).

I agree about the efficiency though. From a personal financial perspective reliability and price trumps all that. Not so great for global warming though as 15% multiplied by the whole population soon adds up! Unfortunately, like most of us I'm not in a position to be able to budget for that!

 

[vulcancontinental]

I came to the conclusion I came to as they stated that "a default value was used" which would suggest that it was not the correct one or even a properly calculated one. Also both Atag and Igas said their dhw efficiency was much higher than that value and they we're going to look into correcting it on that website (but there will be a delay).

I agree about the efficiency though. From a personal financial perspective reliability and price trumps all that. Not so great for global warming though as 15% multiplied by the whole population soon adds up! Unfortunately, like most of us I'm not in a position to be able to budget for that!

Ah, thank you for the reminder, I forgot Monday and am off today. Will look tomorrow.

I do not think the manufacturers give anything but the very best figures they can so I would take what they say on a phone line with a pinch of salt. The thing is you have to treat them like the MPG figures in a car brochure, presented in the best possible light, and the EN doesn't do that for them.

 

[dmdm272]

well yes I would trust the SEDBUK to be impartial but they said they used "default values" god knows what they are or where they got them but they seem unlikely to be correct.