Hot water only runs for 1.5 mins

[kbdiy]

I have a similar setup with a Suprima except my bypass is a heated towel rail. It works exactly like your's does and I see no reason to question it as it heats the cylinder and central heating just as I would expect. My boiler is also in the same location as the cylinder so I expect the short flow/return would cause the short cycling of the boiler as it cannot loose heat that quickly to the cylinder coil.

Works well for me anyway!

 

[bolshy]

Ok. If your boiler is controlling the circuit temperature, it's doing it's job. I misunderstood you and thought you had a DHW problem. Your boiler can only heat the cylinder by heat transfer through the coil, which of course is a finite size.
Perhaps a very fast recovery cylinder with larger coil would have been better suited to the boiler. The cylinder would then be almost up to temperature before cycling on and off, and the boiler would be firing for longer during cycles.
Increasing your flow and circuit temperature a little will speed things up slightly, but won't stop the cycling. If your bypass is set low or defective, it will make the cycling worse.

 

[Agile]

With a blue cylinder the coil output is pretty good and totally satisfactory for any normal domestic use.

That of course if it is correctly sized according to a minimum of 50 li plus 50 li per person living there.

Of course there are always the geeks who want to take 30 min rain showers using up 20 li/min but they are not concerned about the running costs!

Tony

 

[DP]

Tony are you having a senior moment or speculating. What geek has a cylinder capable of delivering 600l of water? A blue insulation 600l cylinder.......?.... Perhaps two megaflow 300 cylinders which would not have blue insulation? Must be a rich geek.

 

[DIYedboy]

I,ve checked the boiler and it's already close to max, I've opened the gate valve a bit, many thanks for all your advice.

The bottom line is, if boiler n cylinder are within 6 feet of each other cycling will be an inevitable consequence I presume.

 

[JohnD]

no, it's because your boiler is not able to modulate itself down to provide only the energy that the cylinder can absorb.

 

[DIYedboy]

Ahhhh, that's what modulation means, thanks John...........I see it clearly now