Ideal logic combi 35 - not reaching higher temperatures

[TCLITE]

Hi I have an ideal logic combi 35 with a Honeywell cm907 digistat installed in my new build. The problem is the boiler struggles to get up to 23degrees then won't go any higher. The property is a 2 bedroom mid terraced house so I'm sure the 35kw output is plenty. I have 3 downstairs rads and 3 upstairs all have TRV's apart from the main radiator in the livingroom where the digistat is. I have bled and balanced the system and the boiler temp is turned up to max. Any suggestions on how I can fix this?

 

[Agile]

I presume the boler flow temp is 70 C and you have 23 C in the rooms?

Most heating is designed for 21 C and those who do it at 23 C are wasting about 20% of their gas!

We need to know the boiler flow and return temperatures! That's for a start!

Tony

 

[TCLITE]

I don't have a contact themoneter on me at the moment but if we assume that its a standard flow and return of 70 and 50 would that infer a maximum possible temperature of 23degrees?

Edit: I will get measurements on flow/return tomoz for you

 

[gigz]

Are your radiators sized correctly ?

 

[TCLITE]

This is one of my theories, all radiators are k1 apart from the living room which is a k2. All rads are less than 550mm apart from the living room which is 600*1200

 

[Agile]

If rads were correctly sized then 70/50 C would give 21 C in the room.

But most programs oversize rads by about 10% to aid warm up ( and cover up inaccuracies ).

Its not immediately obvious to me what you are aiming to achieve!

Tony

 

[Dan Robinson]

Little terraced house with a 35kW boiler?


23 degrees?

Boiler turned up to max?



Titchy rads with small water volume?


I think you get my drift .

 

[TCLITE]

Maybe it's my fundamental lack of understanding on these condensing boilers but should it not be possible to raise the room temperature above 21-23degrees?

 

[Agile]

Its your fundamental lack of understanding of the design criteria for heating systems!

And to spend hundreds extra on your gas bill and to spoil the ozone layer!

Tony

 

[TCLITE]

Let's try be mature about it Tony, you can clearly see I'm not knowledgeable in this area, you are. The most productive thing to do here is impart your expertise so I can learn. I'm assuming that's why you're a member of a forum which supports people because you derive satisfaction from it? Or do you enjoy belittling people?