Intergas heat exchanger design

[vulcancontinental]

Thanks, again, for all the great information. And for explaining the compromises with all the various designs; things I would never have thought of. It's so helpful for when I replace my boiler.

I know we've talked mainly about primary heat exchangers. Are plate heat exchangers also made from various materials, or are they more standard?

I also noticed that Vokera's open vent boiler has a radial aluminium heat exchanger, like most of the stainless steel ones I have seen. Most other aluminium ones seem to be more sort of flat. Is that design unique to Vokera?

That's the exchanger the patent of which was sold and used in the comparison test with stainless. The boiler has few of the features you've mentioned elsewhere and is difficult to service but very efficient.

 

[vulcancontinental]

That's the exchanger the patent of which was sold and used in the comparison with stainless. Very basic features and difficult to service but efficient.

 

[JonathanM]

That's the exchanger the patent of which was sold and used in the comparison test with stainless. The boiler has few of the features you've mentioned elsewhere and is difficult to service but very efficient.

So, does Vokera, or its parent group, design and manufacture its own heat exchangers? I know other companies sometimes buy them in.

 

[Johntheo5]

Great info above, If/when the gas path(s) get obstructed then would think that it must affect the air/fuel ratio causing over rich combustion as the gas valve control is linked directly to the fan speed?

 

[vulcancontinental]

So, does Vokera, or its parent group, design and manufacture its own heat exchangers? I know other companies sometimes buy them in.

Riello, the parent company apparently went to a university and gave them a brief. They came up with that; large bore, no joints at all, a single extrusion.

It was after a look at the Gianonni/Sermeta and Viessmann exchangers (small bore and too complicated compared to large bore, too basic)

Extremely efficient, a competitor technical engineer said it was the most efficient on the market but if run constantly at condensing temperatures the tight heat exchanger will need a lot of servicing or block.

Remember the vast majority of people ran their systems above 70 degrees back then, that exchanger gave them great efficiency but continual running at 50 degrees will be problematic.

We always used company called Valmex in the past and they've designed the current stainless exchanger.

Italy has a huge H&V industry.

 

[vulcancontinental]

Great info above, If/when the gas path(s) get obstructed then would think that it must affect the air/fuel ratio causing over rich combustion as the gas valve control is linked directly to the fan speed?

Yes, and by the time that happens getting into the exchanger to clean the coil is very difficult.

 

[JonathanM]

Riello, the parent company apparently went to a university and gave them a brief. They came up with that; large bore, no joints at all, a single extrusion.

It was after a look at the Gianonni/Sermeta and Viessmann exchangers (small bore and too complicated compared to large bore, too basic)

Extremely efficient, a competitor technical engineer said it was the most efficient on the market but if run constantly at condensing temperatures the tight heat exchanger will need a lot of servicing or block.

Remember the vast majority of people ran their systems above 70 degrees back then, that exchanger gave them great efficiency but continual running at 50 degrees will be problematic.

We always used company called Valmex in the past and they've designed the current stainless exchanger.

Italy has a huge H&V industry.

That explains a lot of things for me.

Something which springs to mind, though, can the passage through a large bore stainless steel exchanger be too easy for the water, so that it passes through too quickly, and doesn't give up/absorb enough heat?

 

[vulcancontinental]

Yup, everything has an effect on something else. An advantage in one area is a negative in another.

 

[sxturbo]

I'm pretty sure you can do this on the cheaper Rapid+ boilers, these are cheaper than the eco RF range.

you can do it on all of the intergas combi boilers

 

[dilalio]

That explains a lot of things for me.

Something which springs to mind, though, can the passage through a large bore stainless steel exchanger be too easy for the water, so that it passes through too quickly, and doesn't give up/absorb enough heat?

You have to remember... Transfer of energy is never 100% efficient.
There will always be losses to forms of energy you are not trying to capture.