Intergas...but which...

[hard-work]

My main critique of the Intergas is the thermal mass of the heat exchanger which has to be wasteful of heat when this mass of metal is heated to deliver a few litres of hot DHW and then cools down before the next few litres of hot water are drawn off a few minutes later.
By comparison the thermal mass of a coiled tube heat exchanger is small and much less heat is wasted in heating up the metal of the heat exchanger.

I have aked here and not yet been answered if anyone has a copy (or can quote from) the test procedure used to measure the efficiency of domestic boilers. ( BS 303 -5 ? )
Specifically I am looking for the answer to whether the boiler has to be run up until it is in a steady state condition before any measurements are made.

Bernard, all Intergas have done is revert back to the heavy cast-iron ways of making heat exchangers, however they use heavy copper and aluminium instead of cast-iron. It is good that they have the heat exchanger as the back panel saving space. They run a DHW coil through the heat exchanger which is not very efficient as the specs show. In winter when the boiler is operating the heat exchanger acts as very small thermal store keeping the DHW coil pre-heated. But in summer, as you noted, when the CH is off, there is a long lag DHW delivery at the taps as there heating of the whole heat exchanger. Also the CH coil inside the heat exchanger is being heated. This heat may rise up CH flow pipes heating radiators upstairs. So overall, annually the DHW side is inefficient.

 

[Dan Robinson]

They run a DHW coil through the heat exchanger which is not very efficient as the specs show

the same specs you can't understand - and have demonstrated aptly without any help from the professionals here. .

So overall annually the DHW side is inefficient.

It's not though is it .

 

[bernardgreen]

But the maths don't work. And you obviously think they have a hex that can add energy to the combustion process.

Zo is het mogelijk om tot 111% rendement te halen uit het gas op basis van onderwaarde. Wanneer nu de condensatiewarmte uit de rookgassen wordt benut,

Thus, it is possible to make up to 111% efficiency from the gas, based on lower heating value. Now, when the heat of condensation is utilized from the flue gases.

In DHW mode with the water supply temperature below ambient air temperature it should be possible for the boiler that :-
1/ has flue gases cooler than the ambient air
2/ has all the water produced by combustion recovered in the boiler and not ejected as water vapour that cools to form a mist of water droplets when it meets air below the dew point.

 

[Dan Robinson]

In DHW mode with the water supply temperature below ambient air temperature it should be possible for the boiler that :-
1/ has flue gases cooler than the ambient air
2/ has all the water produced by combustion recovered in the boiler and not ejected as water vapour that cools to form a mist of water droplets when it meets air below the dew point.

But that is not what happens. Even with PFHR.

 

[bernardgreen]

But that is not what happens. Even with PFHR.

It could happen
It doesn't happen
Why doesn't it happen ?

 

[Dan Robinson]

Because of how flues and combustion work. You'll always be losing energy through the flue gases in one form or another. You also need the water vapour condensing in the HEX not the flue to get that energy back into he primary water or domestic water (HEX technology depending).

 

[Agile]

In winter when the boiler is operating the heat exchanger acts as very small thermal store keeping the DHW coil pre-heated. But in summer, as you noted, when the CH is off, there is a long lag DHW delivery at the taps as there heating of the whole heat exchanger.

Also the CH coil inside the heat exchanger is being heated. This heat may rise up CH flow pipes heating radiators upstairs. So overall annually the DHW side is inefficient.

But you fail to mention that the boiler has a DHW preheat function which can be timed or just left to learn from previous DHW usage times.

Certainly the ali HE has a warm up time, but the specific heat of ali is quite low, so that is not all that long. Probably not much longer than some normal boilers with a plate HE.

With most CH piping arrangements the thermal gravity flow is not a problem. It was not on any of the nine IG boilers that I have fitted. But it is simple to deal with if there ever was.

 

[bernardgreen]

You also need the water vapour condensing in the HEX not the flue to get that energy back into he primary water or domestic water (HEX technology depending).

The water vapour can be condensed on a heat exchanger that uses the recovered heat to warm the air used for combustion air ( effective when ambient air temperature is below dew point temperature )

When heating water for DHW flue gas vapour can be condensed using the cold water supply thus pre heating the water. ( mains water temperature is almost always below dew point temperature ). In a boiler that is only providing DHW the heat exchanger can be designed to do that. To achieve that in a single heat exchange serving CH as well as the DHW would be possible but it wopuld be prohibitively expensive for the domestic market.

 

[bernardgreen]

With most CH piping arrangements the thermal gravity flow is not a problem

But on a warm day when no room heating was required this heating of water in CH pipework would be a heat loss and thus contribute to reduced over all efficiency

 

[Dan Robinson]

It would also make the boiler massive, and therefore defeat the purpose of a combi. The A325ECX was a massive beast by most combi boiler standards and we never volunteered one to a client unless it was going in a garage or utility room.

As I said above, we've had CLOSE to ambient flue gas temps with that, which (as Google will show you) has a plate heat exchanger in line with the flue exhaust. You still get a quantity of water vapour and increasing the surface area would also increase flue stack resistance with other side effects that are undesirable.

But on a warm day when no room heating was required this heating of water in CH pipework would be a heat loss and thus contribute to reduced over all efficiency

This is not what Tony was referring to. He is referring to nuisance heating via convection. Which is a very rare and very easily solved problem. In the hundreds I have fitted over the years I can think of only one that had it, and that mysteriously appeared 7 years or so after the installation.

 

[hard-work]

One of the reasons many people buy a combi is because combi boilers are being over sold by installers and heating "experts".

The concept of the combi boiler was developed to cater for flats and apartments where there was no simple way to install header tanks and hot water cylinders.

Bernard the combi was developed simply to save space, first one was by Chaffetaux in France, who also if I recall rightly, also made the first `system` boiler complete with pump and expansion vessel. The first combi in the UK was a floor mounted Worcester in the early 1970s. Most would not touch them as they didn't have a clue about them. The old Gas Board did not sell them and referred people to Worcester. They never took off immediately. `Plumbers` did not understand them. They have only just got around to accepting non-cast-iron boilers. The likes of thermal storage blows their minds out.

Flats usually had a communal cold tank in the loft, a hot water cylinder and small under counter boiler with F&E tank in the flat. Although I have seen all the F&E tanks in the loft spaces in small blocks. Some tower bocks had gas fires in U or C ducts with flame failure devices fitted and an Ascot multi-point water heater also into a U duct. So no large storage tanks, just one in the basement with a powerful pump. Where the mains pressure and flow was good enough no tank and pump was needed. My point was that the heating and hot water equipment did not take up that much space in flats as you might think prior to mass introduction of combis. Some newer flats are highly insulated and do not not need centralised heating in the flats themselves. Some have a communal boiler that pumps heat around loop to each flat. Each flat may have a box on the wall with plate heat exchanger and thermal meter. No gas inside the flats. Soem highly insulated flat have only electric heating. The heating is used so little the bills are minimal. I knew one highly insulted 5 floor timber framed block that not one flat had ever used the heating systems. They tended to have the vent extractors on getting rid of heat.

The idea of CH and DHW all inside one box which is easy to fit, naturally took off having a multitude of advantages to the fitter and home-owner. Improving technology was proving it could be done. The fitter need not know too much about CH and DHW design and unfortunately that shows today. That is a negative point as many are appallingly fitted in CH design and quality of fitting. Look a the comments on this forum.

But technology improved with combis becoming physically smaller, higher output in DHW and greater modulation of burners for CH. Even weather compensation is built in to many. Instead of storing energy in a space consuming complex cylinder, a combi (or multi-point) uses the energy pushed down a mains gas pipe, which is approx 62kW. Most homes only used about 12-15kW with even CH boiler - a fraction of what was available. A lot of instant energy was on tap and not used.

Up to 10 years ago tripe by installers was spouted that combis could only do one tap at a time. That was not true then and far less so today. When the combis like Ferroli Modena with a case of 600mm by 400m can deliver 16 litres per minute, the days of the tank/cylinder are over, as long as the mains water supply is adequate. So they are not oversold as long as a high flow rate model is fitted. A gravity tank & cylinder could only deliver around 16 litres min anyhow. There is no need to have that space cluttering expensive plumbing.

Look at the comments on this forum when a home-owner asks for a recommendation many come back with "fit an unvented cylinder, combis can only do one tap at a time", when a 16 litre per in combi is the superior choice all around. I think combis are being undersold. There is just too much ignorance about combis and how they should be fitted in the DHW pipework. Many have one 15mm hot water pipe snaking around the house. The same with cold supply to the combi. Then they wonder why the shower is affected when another outlet is opened. Few on the hot & cold side are `balanced`.

 

[Dan Robinson]

Bernard the combi was developed simply to save space, first one was by Chaffetaux in France, who also if I recall rightly, also made the first `system` boiler complete with pump and expansion vessel. The first combi in the UK was a floor mounted Worcester in the early 1970s. Most would not touch them as they didn't have a clue about them. The old Gas Board did not sell them and referred people to Worcester. They never took off immediately. `Plumbers` did not understand them. They have only just got around to accepting non-cast-iron boilers. The likes of thermal storage blows their minds out.

Flats usually had a communal cold tank in the loft, a hot water cylinder and small under counter boiler with F&E tank in the flat. Although I have seen all the F&E tanks in the loft spaces in small blocks. Some tower bocks had gas fires in U or C ducts with flame failure devices fitted and an Ascot multi-point water heater also into a U duct. So no large storage tanks, just one in the basement with a powerful pump. Where the mains pressure and flow was good enough no tank and pump was needed. My point was that the heating and hot water equipment did not take up that much space in flats as you might think prior to mass introduction of combis. Some newer flats are highly insulated and do not not need centralised heating in the flats themselves. Some have a communal boiler that pumps heat around loop to each flat. Each flat may have a box on the wall with plate heat exchanger and thermal meter. No gas inside the flats. Soem highly insulated flat have only electric heating. The heating is used so little the bills are minimal. I knew one highly insulted 5 floor timber framed block that not one flat had ever used the heating systems. They tended to have the vent extractors on getting rid of heat.

The idea of CH and DHW all inside one box which is easy to fit, naturally took off having a multitude of advantages to the fitter and home-owner. Improving technology was proving it could be done. The fitter need not know too much about CH and DHW design and unfortunately that shows today. That is a negative point as many are appallingly fitted in CH design and quality of fitting. Look a the comments on this forum.

But technology improved with combis becoming physically smaller, higher output in DHW and greater modulation of burners for CH. Even weather compensation is built in to many. Instead of storing energy in a space consuming complex cylinder, a combi (or multi-point) uses the energy pushed down a mains gas pipe, which is approx 62kW. Most homes only used about 12-15kW with even CH boiler - a fraction of what was available. A lot of instant energy was on tap and not used.

Up to 10 years ago tripe by installers was spouted that combis could only do one tap at a time. That was not true then and far less so today. When the combis like Ferroli Modena with a case of 600mm by 400m can deliver 16 litres per minute, the days of the tank/cylinder are over, as long as the mains water supply is adequate. So they are not oversold as long as a high flow rate model is fitted. A gravity tank & cylinder could only deliver around 16 litres min anyhow. There is no need to have that space cluttering expensive plumbing.

Look at the comments on this forum when a home-owner asks for a recommendation many come back with "fit an unvented cylinder, combis can only do one tap at a time", when a 16 litre per in combi is the superior choice all around. I think combis are being undersold. There is just too much ignorance about combis and how they should be fitted in the DHW pipework. Many have one 15mm hot water pipe snaking around the house. The same with cold supply to the combi. Then they wonder why the shower is affected when another outlet is opened. Few on the hot & cold side are `balanced`.

Ah Water Systems - we have missed you and your Drivel .

 

[hard-work]

the same specs you can't understand - and have demonstrated aptly without any help from the professionals here. .

Our one boiler wonder has not demonstrated anything. Get a grip man, get a grip! I can see a man falling into mental destitution right here on my computer screen. Look at this..
`Ah Water Systems - we have missed you and your Drivel`
Sad viewing indeed.

 

[Dan Robinson]

I smell bullschit. Are they saying their heat exchanger is 100% efficient?:

View attachment 115411

But that is a 39kW boiler, which the Intergas isn't so lets try and even things up and go to as close to equivalent outputs/inputs as possible. So lets take the Modena 32, which is 0.7kW under the Intergas 36/40 which is as we have established not 40kW to hot water, but actually 32.7kW. Ferroli claim this:

View attachment 115414

View attachment 115412
Again - they seem to think their heat exchanger is 100% efficient, but then it probably is the same as the 38C, so go figure.


Intergas:
View attachment 115413
(Obviously we're looking at the right hand column for each).

Laws of physics seem to be different for our Italian brethren. Especially as said laws, even assuming 100% heat transfer state that at input of 32kw, ΔT35 you can get 13.06 l/min.

So how the feck does Ferroli manage to get 15.3 at both ΔT's? If we take ΔT30, that gives us 15.24l/min.... but again at 100% transfer efficiency. Which we ain't gonna get. Ferroli manage to squeeze another 0.3 l/min on top of their 100%.

Now, we give the same calculations to the Intergas figures?..... This gives us 13.35 l/min at 32.7kw input and an assumed transfer efficiency of 100%. Put that to ΔT30 and that rises to 15.57 l/min. IF we use Intergas' figures of ΔT25, it is 18.69. Ferroli - a slightly more modest differential of 0.1 litre a minute. Again assuming 100% heat transfer.

Of course we can't have 100% so a bit of a reduction ius in order. Something Intergas has done. But Ferroli?


Now - a few pages back Hard On stated:




Where did he get 13.1 and 16 litres per minute from? Fecked if I know, but it was the actual figures from the performance tables.


He was also prattling on about modulation rates.... let's take a look shall we?

Ferroli:

View attachment 115416

Intergas:

View attachment 115417


Only 1kW in it. Not bad, but not great either, yet something that was acknowledged a loooong time ago.


Now, who is spanked by who? Where are Hard On's figures to counter these? Is he going to go on about the 40kW intergas (which doesn't exist) against the 38C Ferroli with its imaginary performance statistics? Probably, but that is, as said before and the reason for the likes of KIWA, comparing apples with oranges.

Like I said before though. Since when has fact got in the way of a Googleer and their rants/trolling? Twentyfour only appears now and again for a troll too - I've seldom seen him give any advice in other threads. So we can take his opinion with the vomit soaked vindaloo it's worth. Out of all this nonsense we have Bernard who does at least try and base some of his opinion on fact. Although more often than not fails (still waiting for that admission BTW dude). A simple "yes I was wrong" will do .

Just in case you forgot.... Hard On . Water Systems . Big Burner Dr Drivel Can't remember your other now banned aliases

You were a muppet then and you are a muppet now.

 

[Dan Robinson]

Funnily enough - just had this email from a lady coming up to her first annual service having spent a year with an Eco RF24, Honeywell Round thermostat that replaced her ideal Classic...

I think the remote monitoring facility would be something I’m interested in. I’ll call you tomorrow as I’m about to leave the house to do a recce.

The boiler has been great and has made so much difference to the warmth of my home with the thermostat. I haven’t suffered the cold this year like I did in the past and the hot water is great.