Combi with highest flow rate? I've got 25 lt/min dynamic...

[Masood]

As per title, need to quote for a property with 25lt/min dynamic flow rate and 3.5 bar. He is adamant that he doesn't want an unvented. So, what combi delivers that kind of performance???

I'm surprised and little dismayed that even the biggest of the Intergas range won't go higher than 18lt/min at 35 degrees delta...

 

[Killy Bing]

You're looking at a floor standing storage combi mas!

worcester highflow 550 cdi will do 25 lpm at 30 degree rise.

Above that then i can only think of ACV floor standers.

again for 25lpm at a 35 degree rise you're looking at a biggy.

so he will end up with an unvented regardless in effect!

you could put an atag in, 120 ltr unvented, blend the hot take off into the dhw side of the atag to give you preheat to boost up your flow rate.
but then you're gambling on getting it right yourself.

 

[Masood]

Trying to get him to go for unvented Billy, but he wants rid of the cylinder, so trying to sell him on the idea of a new cylinder is an uphill struggle!

Oh yeah, phoned Vaillant to see where they've hidden the tech data for the boilers, where you could compare the different models and their performance. And their suggestion was that they could give him a call to try and persuade him! Yeah right, like I'm going to give my prospective custards to them!!!

 

[gasmanrob]

Biggest vaillant I know of only goes to 16! To be fair I'd probably fit a pressure/flow limiting valve 25 is too much imagine the wastage! Not to mention the damage that will cause to taps and shower fittings unless you can guarantee they will be running 2 showers at a time every time it's pointless having that much flow and pressure! The pipe work will knock every time a quarter turn shuts assuming the ceramic holds back the pressure for more then 3 months of use I personally would reduce it

 

[gasmanrob]

But the calculation is kW x 14.33 divided by 35 that will give you the flow rate an appliance can handle so 40kw x 14.33 divided by 35 will allow a flow rate of 16litres a minute much more then that your heading into commercial territory

 

[IDCHAPPY]

Vaillant 937 plus storage combi, it's a wall mounted felly but a good beast

 

[Mike Jackson]

Viessmann Vitodens 111W or 222F

 

[IDCHAPPY]

ecoTEC plus 937 | Combination Boiler | Vaillant
20 l/m @ 42C temp rise(I think)

 

[TBServices]

937 is rubbish

 

[TBServices]

Just fit biggest combi you can and restrict flow with a wondervalve. On his head be it