Atag A325EC or Intergas Combi Compact HRE 36/30 ?

[Corgigrouch]

I can't comment on the intergas as I have't fitted one, I'll bow to Dans superior knowlage on these boilers... But last year I did run a head to head with one of the ATAG A325ECs that I had just fitted against my own Worcester 30Si Greenstar, the flue temerature from the Worcester was 65c against 24c from the ATAG when both were at full DHW flow.... Not exactly scientific but interesting nontheless

 

[Dan Robinson]

Tell you what; it is odd that I am defending a boiler that:

A - doesn't need it

and

B - I'm not even recommending for the OP's situation



At least I give SEDBUK more credit than i do Which? magazine.

At least they try and be scientific .

 

[sadanorakman]

I understand what you are trying to say just fine Dan.

I suppose any boiler could be forced to run inefficiently... too small radiators, or setting too high a system temperature that puts the boiler out of condensing mode a lot of the time.

I think I'm just more willing to give the SEDBUK figures a bit more credit. In my opinion, it is a pretty fair attempt at scientifically measuring the relative efficiencies of many hundreds of different boilers... I think that effort is to be commended.

The SEDBUK Data tells me that if installed, operated, and maintained correctly my unreliable old Ravenheat in my old property was expected to be 89.4% efficient. I know that house was reasonably well insulated, and it turned out to be quite cheap to heat.

The same database tells me that both the Intergas and Atag have a similar approx. 90% seasonal efficiency for central heating, which gives me confidence that either of these boilers will be nice and cheap to run in my new house central-heating wise. (Just hopefully be a lot more reliable!!!)

The same Database showed a reasonably low DHW performance for the Intergas (56% compared to the 63% of my old Ravenheat). This just made me a little more cautious about making sure to check out the true performance of the Intergas DHW-wise.

Again, thanks for your advice along the way!

 

[Dan Robinson]

It has raised an interesting question which I shall put to Intergas next time I speak to them.

Frankly though SEDBUK is something I haven't bothered with in years as far as work is concerned.

Like i said - the Atag was always going to be more efficient that the Intergas for hot water. because of the flue recovery unit; and i am approved for both brands as well as Vaillant.

It would still be interested to know how they reach this hot water figure - especially for boilers that do not heat water directly; and possibly not at all.

 

[sadanorakman]

It would still be interested to know how they reach this hot water figure - especially for boilers that do not heat water directly; and possibly not at all.

I wouldn't even go there... I've just opened an 18 page pdf about the SAP efficiency testing of two Gas combi's compared to two oil burners... I regard myself as quite a techy-nerd, but even I was bored sh**less by about the third page!!!

Thanks Again!

 

[sadanorakman]

It has raised an interesting question which I shall put to Intergas next time I speak to them.

I first started to look at Intergas boilers about a year ago Dan. I sent a few questions to Steve Merry, and he forwarded them to John Stanford. I particularly wanted to understand what they meant by a 'double high efficiency' heat exchanger, as I felt that was a bit of marketing free-licence taking place.

John replied that:

1.The term ‘’double high efficiency’’ refers to both circuits being capable of condensing on the combination boiler. This is unique amongst condensing boilers currently. The top sensor registers the burner temperature which modulates either to the outgoing ch temperature (via sensor 2) or the DHW temperature (via sensor 3) . This is not the case with other condensing combination boilers.
This is not hype suggesting double the efficiency of other boilers. Rather a reference to condensing in DHW mode as well as CH.

So we know that it condenses in DHW mode, which is great. It just doesn't seem to extract as much heat out of the gas in DHW mode as perhaps it could do if designed differently.

 

[sadanorakman]

Corgigrouch wrote:

I can't comment on the intergas as I have't fitted one, I'll bow to Dans superior knowlage on these boilers... But last year I did run a head to head with one of the ATAG A325ECs that I had just fitted against my own Worcester 30Si Greenstar, the flue temerature from the Worcester was 65c against 24c from the ATAG when both were at full DHW flow.... Not exactly scientific but interesting nontheless

Thanks Corgigrouch... So agreed, not very scientific, but sounds like a pretty good advert to me for the Atag. Those temperatures say a lot!

 

[Dan Robinson]

So we know that it condenses in DHW mode, which is great. It just doesn't seem to extract as much heat out of the gas in DHW mode as perhaps it could do if designed differently.

Hot water mode:




Heating Mode:



Sadly I don't have a sample from an Intergas running at full tilt in heating mode. Nor can I remember the flue temperature when it is running full tilt in hot water mode - 75 rings a bell. But don't quote me on it.

 

[sadanorakman]

Interesting chart data thank you Dan... What is it meant to be showing me? ...That in DHW it's regulating sensor 3 (and therefore the DHW) to 42.9, so condensing? ...erm no Craig, sort yourself out, that doesn't make sense!

 

[Dan Robinson]

It means less than it should due to the lack of a flue temp sensor, but S2 is the bottom of the main heat exchanger.

S3 is the domestic water temperature.

S1 is the top of the main heat exchanger.

 

[sadanorakman]

Sadly I don't have a sample from an Intergas running at full tilt in heating mode. Nor can I remember the flue temperature when it is running full tilt in hot water mode - 75 rings a bell. But don't quote me on it.

erm... does the above count as quoting you on it?

If the flue temp is up at 75 degrees, and dew-point is somewhere around 55, then it can only be partially condensing if condensing at all?

 

[sadanorakman]

It means less than it should due to the lack of a flue temp sensor, but S2 is the bottom of the main heat exchanger.

...Ah, good, so if S2 is sat at 45 degrees, then the boiler should be condensing nicely.

But in your chart, in Heating mode, S2 is up at 54.4, and seeing as it is a sensor bolted to the heatsink, the gasses passing the bottom of the heatsink will be hotter than the temperature registered by that sensor (as heat is being constantly drawn from the exchanger by the water-loop). So the boiler isn't condensing, or only partially condensing at that time.

Be interesting to see what the flue temps would have been!

 

[Dan Robinson]

Yes - like i said I don't have a decent chart of the boiler running in heating mode. I can't remember why i even took that screen grab.

Looking at the title I can see it was running for some prior to the screen in hot water mode. Although after that amount of running time it should have dropped a little. In know that that property only has a likely heat loss of 4 kW or so so the poor boiler will not be losing much heat to the system.

 

[sadanorakman]

I only wish my latest house had a 4kW heat-loss!

I'm in a 1965 bungalow... the owner was a builder, and didn't trust those new-fangled cavity walls, so he built solid 9 inch walls instead!

I plan to systematically insulate them internally with 75 or 100mm of PIR, one room at a time, but am converting the garage at the moment, so have only managed to insulate the kitchen so far.

 

[sadanorakman]

Just a little bump... Just before I make my purchase... any other comments or recommendations in favour of the Atag A325EC over the Intergas HRE 36/30, or visa-versa please?

All comments welcome thank you.