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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...
 
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.
 
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!!!
 
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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
 
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
 
Just fit biggest combi you can and restrict flow with a wondervalve. On his head be it
 
ive fitted a few 937's, they are very, very big. Not something you want on your kitchen wall thats for sure.

any room in the loft space for a cylinder?
 
COMBIPLUS 42kW – modulating CH output from 7.9 – 35.5kW and DHW flow rate of 19.5 litres/minute @ 35ºC rise

Ravenheat............

:lol:
 
[DLMURL="http://www.acv.com/gb-en/03_04/87/app.rvb"]HeatMaster 201 - ACV[/DLMURL]

(y)
 
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stick in an andrews water heater alongside a small system boiler, tell him its the latest combi design :)
 
IDCHAPPY said:
COMBIPLUS 42kW – modulating CH output from 7.9 – 35.5kW and DHW flow rate of 19.5 litres/minute @ 35ºC rise

Ravenheat............

:lol:
Click to expand...

Are Ravenheat still making BBBB boilers,:001_9898: surely not
 
Still don't see why the flow can't be restricted most logical option in my opinion
 
gasmanrob said:
Still don't see why the flow can't be restricted most logical option in my opinion
Click to expand...

Because he has had that kind of flow and pressure for around 12 years, since the state was built. He is used to it and likes it, so I am trying to find a way that he can keep as much of that as possible. I'd rather talk him into an unvented and take a hit on the labour to make it affordable than restrict the flow to around half of what he's currently got. Every time he opens a tap he'll hate it, and me...
 
Mas you will never please this guy :)

Point him in the direction of the ACV boilers and put £££ on the chunky gas re run!

what is the current set up?
 
Have you got room for a small system boiler and a worc green spring water heater?

Or a Baxi DuoTec heatsaver advance thing?
 
TBServices said:
Have you got room for a small system boiler and a worc green spring water heater?

Or a Baxi DuoTec heatsaver advance thing?
Click to expand...

Plenty of space for standard unvented, in the utility room where the boiler is going. Just some moron has told him combis are the be-all and end-all and I'm having to show him the error of their ways LOL. The frustrating thing is that he's pretty much given me the job as long as I don't take the mickey on price. Just want to give him the right solution for his situation, which IMO is an unvented & system boiler...
 
TBServices said:
Just fit biggest combi you can and restrict flow with a wondervalve. On his head be it
Click to expand...

Do you mean one of these mate? Not fitted one before - do you set the flow rate you want, or can you buy them with different rates preset?
 
Yeah just pick the right restrictor.

But we all know the route he should go down really.

Green spring does almost 21lpm but it's a dead horse if he won't budge on a combi
 
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