Question re Intergas/Atmos Combi

[dmdm272]

Tibbot- We only have a small bungalow so wanted a combi in the loft so we can gain an extra kitchen cupboard and get the space of the old HW tank back in the 2nd bedroom.

I know combis are less reliable than the old style (which worries me) but that's why I'm looking for the most reliable combi! (and hoping that these newer ones are more reliable than older ones).

A question for Dan_Robinson if I may?

Over at this thread (ATAG vs Intergas): //www.diynot.com/forums/plumbing/atag-a325ec-or-intergas-combi-compact-hre-36-30.378845/

Dan (you) says early on that "if size isn't an issue then ATAG all day" and since he (you) are a massive supporter of Igas this speaks volumes.

Dan- were you talking efficiency or reliability here? As I've said all things considered I think I have to go with reliability as a first consideration as if one thing (eg a diveter valve) goes and has to be replaced that will most likely cost more than 5years of theoretical efficiency savings!

Obviously ATAG sounds great with fantastic reputation, quality, performance and efficiency so if its also as reliable as the Igas then I would probably plump for that, but if Igas was more reliable I think I'd go for that! How does their new RF ECO model compare to ATAG 325ECX? Does that get closer to its efficiency?

Another consideration is (the old combi dilema) that I only have a 2bed 1 bath small bungalow so I will only need a small amount of power for heating but want good hot water flow... I don't want to end up with an over powered boiler that short cycles but see that these models modulate so have 6kw minimum....is this minimum enough for me to avoid this or should I go for a smaller (eg 24kW) boiler and put up with slower hot water?....

Dean- sorry for over thinking! That is my nature! But since I'm looking at a good £2k to change the boiler and I want to live with this decision for the next "many" years (ideally forever ) I want to get it right!

Many thanks!

 

[dmdm272]

So....all in all I'm favouring the ATAG at the moment but I'd welcome your thoughts on this.

The only other dilemma I can think of is balancing good hot water flow with min CH output as I don't want the boiler to be constantly short-cycling. The A325ECX modulates CH output down to 6.1kW...is this low enough for my needs?

 

[St0rmer66]

It'll be fine. All combi's end up cycling a bit! Only boiler I can think of with a properly low minimum is the Vokera Linea One.

 

[Agile]

If you want efficiency and good hot water then get ( or keep ) a hot water cylinder and you get the best hot water without any cycling problems.

Combis are NOT the best thing, just a convenient single unit which does the job and useful for builders and for very small flats.

Although often recommended by installers there is rarely any benefit in converting from a stored system to a combi.

Tony

 

[dmdm272]

The reason we want a combi is that we have a small 2 bed bungalow and want the space that the hot water cylinder takes up (especially my wife) in the (tiny) second bedroom. Also it will be nice not to have hot water running out on us eg half way through filing a bath etc. Also it seems mad to have a huge tank of hot water for the majority of the time when most days we only need to wash our hands (I mostly use cold water for this anyway), have a shave etc.

 

[doitall]

Run a normal bath, then measure how much water you used.

Next consider an average combi say 12 Ltrs/min and work out how long it will take to fill the bath

 

[dmdm272]

Well however long it takes with a combi son't it take longer if you run out of Hot Water and have to reheat your tank? How long does it take to reheat an average HW tank?

TBH though I think my choice to switch to a combi has been dictated by my wife and space considerations and I just have to find the best, most reliable combi for a hard water area (nr Brighton UK).

 

[Agile]

Have you considered a boiler/cylinder in the loft?

Tony

 

[doitall]

Well however long it takes with a combi son't it take longer if you run out of Hot Water and have to reheat your tank? How long does it take to reheat an average HW tank?

TBH though I think my choice to switch to a combi has been dictated by my wife and space considerations and I just have to find the best, most reliable combi for a hard water area (nr Brighton UK).

The difference being a cylinder heats up when you not waiting for a bath, whereas a bath can take 10-15mins to run.

For a hard water area I would definitely go with Intergas and a Hyrdoflow 38 scale preventer.

 

[Agile]

And to complete the comparison, a cylinder will usually fill a bath in about 4 minutes!

But it will usually take about 30 minutes to reheat which is why I always recommend they are correctly sized.

Tony

 

[DP]

But it will usually take about 30 minutes to reheat which is why I always recommend they are correctly sized.

I do not know where you get your figures from Tony, but 30 minutes to reheat? You cannot be serious

Here is an example

If you want some help, here is an example...........A Megaflow 145i will reheat
in 19 minutes if heated by a boiler supplying the cylinder 17.6kW

 

[Agile]

I quote typical approximate times.

Manufacturer's figures have usually been fiddled to look better such as increasing the flow temperature above what would be better for economy on a condensing boiler.

But on a forum we are not dealing with any particular known cylinder but an unknown make/size and boiler temps.

 

[DP]

Think not Tony. In that case all the makers will be telling lies as coils rated at 20kW plus would appear to be normal and reheat times typical of what Megaflow suggest.