Valiant 837

[marsaday]

I have a 2 yr old valiant and it is very efficient. my gas bill has really come down in that time.

however i have been doing some reading and it seems we all buy combis too big for what our heating systems need. my boiler is 37kw and the heating uses 12-28kw. my house is 120sqm and i think it only needs 10kw to heat it.

so can i turn down the kw requirement on my boiler? my this i mean can i reduce the factory setting to run a lower kw requirement for the heating. will this affect the water output too?

 

[Agile]

You can and should reduce the boiler output power to better match your heating needs.

You do thin in the d0 setting on the boiler and if the heat loss is 10 kW then you can set the boiler to 10 kW.

It will increase the efficiency a LITTLE as it enables it to condense a bit more but will only give a saving of perhaps an extra 2%.

The real problem with a boiler like yours that is sized for DHW delivery is that it cannot modulate down enough and so just reduces power by switching on/off. Thats perhaps 5-10% less efficient than when it can cover the heating load within its modulation range.

Tony

 

[marsaday]

ok thanks, i will have a look

 

[dfaz]

I agree setting the heating load keeps the boiler in the condensing mode longer but the savings are greater than 2% it also helps the life of the heat exchanger and makes your system quieter,be aware when you reduce the heating load below 60% the pump automatically reduces down to speed one as it thinks its a small system if your system is on drop pipes you may need to fix the pump speed in the diagnostics, if you are after more fuel savings check out the weather compensation unit vr400.
Dave.