condensing mode

[tomtom2]

to boilers condense on hot domestic hot water mode or is it just on central heating.

 

[kevplumb]

both

 

[mehran]

well actually a little known fact is that the sedbuk score is only for central heating. so the efficiency on the hot water side can vary wildly between boilers. a lot of condensing combi boilers condense poorly to not at all when heating hot water.

from what i understand it is one of the changes to part L building regs to include DHW % in the sedbuk score.

i believe intergas boilers would do very well if dhw score was included as they would get A score for both CH & DHW

 

[bengasman]

It depends on the make and model of the boiler, the workmanship of the installer, and the chosen settings of the user.

 

[fanboy]

To be honest most condensing boilers are a waste of money in my opinion, for the fact that a boiler will only condense under certain circumstances. On SE boilers the heat leaving the flue is somewhere around 170 or 180 degrees, condensing boilers being different, rather than letting the heat leave at that stage it passes it to another heat exchanger, which then condenses the water vapour down through the condensing pipe and into its trap. So the flow and return temperatures need to be maintained for the heat transference to occur from the flue to the water.

Something along the lines of that, man it all gets so confusing!

 

[bengasman]

Nothing complicated about it. Just a more efficient hex, or a second hex where manufacturers decided to keep the se boiler pretty much as it is, and achieve the higher efficiency by leading the poc through the second hex is a cheaper solution.
The flow temperature is not essential, only the return temperature; if you would use only 300 x 600 double panel rads with the lockshield almost shut, you could have the flow at anything you want, and the boiler would still run in condensing mode.

 

[transam]

I would suggest that there are alot of people out there who have a certain make (?)of boiler installed , that uses an alloy 'secondary heat' exc , (recuperator) are very fortunate that there boilers are not condensing all the time , I have fitted 4 of these boilers on installations were they are in the condensing mode 'all the time' .
The boilers , are in use 7 days a week , 16 hours a day 6 months of the year ! gallons of condensate were dumped down those heat exc , after approx' 12 months of use the heat excs were a write off 2 have been donated to a acs training centre . I have got photos will post them in due course . Incidentally for the boilers to condense the return temp must be below 57 deg' C dewpoint of gas comb' products . boilers produce 2 types of heat 1) sensible heat & 2) Latent heat condensers are able to extract latent heat , the word latent comes (I think), from the latin lattare meaning hidden, latent heat = hidden heat , use less piece of imfo but there you go.

 

[bengasman]

Publication of make and model would be very helpful methinks.

 

[transam]

I will have to admit , its the Ravenheat CSI primary A boiler , yep installed 35 of them , it seemed a good idea at the time , think I was suffering from brain fade at the time . 35 disasters , or disasters waiting to happen ?? I am trying to think of something positive to say about them I will go away & have a think.

 

[bengasman]

You won't have to worry about the phone going quiet.