What temp should my Greenstar be pushing around?

[Brass Monkey]

I saw the thread on "non condensing boiler condensing" and wondered what is the most efficient temp for my 30CDi to be providing. TIA.

[BigWallop]

You would only turn it up to full on the main boiler thermostat, but your room stat and radiator thermostat valve would regulate the heating into each area of the house. However, I have found that the boiler can be reduced to around three quarters of the way up the boiler 'stat, and the systems usually keep going without any detrimental effects on heating comfort.

Whether turning the boiler 'stat down a little is any type of energy saving concept, I have no idea. I only know that the boiler doesn't fire up for as long as it did with the thermostat fully on. Though it may be firing up more often than it did at full temperature.

Me thinks someone with a little more expertise, should get a grip of this to tell us either way.

[ransley]

Why dont you go to the manufacturers site and see for yourself, Im in the US and all condensing boiler specs I have read show the peak efficency is under 140f, at 180f they are about 6% less efficent. I find alot of "pro" installers idiots. They dont read. My "pro" installer who has been installing and repairing maybe 40 years I just found sets Steam units very wrong, trust yourself and read manufacturers specs.

[Brass Monkey]

Why dont you go to the manufacturers site and see for yourself, Im in the US and all condensing boiler specs I have read show the peak efficency is under 140f, at 180f they are about 6% less efficent. I find alot of "pro" installers idiots. They dont read. My "pro" installer who has been installing and repairing maybe 40 years I just found sets Steam units very wrong, trust yourself and read manufacturers specs.

Worcester Bosch don't seem to offer any suggestions on this point. At least, I can't find it.

[Mike]

The most efficient is as low as you can go whilst providing enough temperature rise to heat your hot water and heat your rooms.

Long fuel burns at low flow temperatures are always much more efficient than short high output burns at high temperatures.

[Kevin]

is the burn/flow rate any different between boiler temps? its not on mine the burn/flow rate is identical it just stays on longer for a higher boiler temp

[ransley]

The condensing design has limits and all are designed from the same principle, this information on operating temp and efficency is all over, Google it and go to different boiler manufacturer sites, even contact Bosch, Its a fairly linear degradation over 139f or less than

135f, there is an optimal temp you want to try to not go over, the aquastat under the boiler cover or on the boiler should be easily adjustable to lower it. The less a boiler cycles, the longer run times also keep it most efficent, unless you pump the water 24x7 and the pump is old an inneficent. My new pump uses 50% less power.

[Mike]

If you have no room thermostat and a non modulating boiler you are bang on the mark.

On a boiler such as the 30CDi mentioned by the original poster the amount of gas and air admitted to the burner will alter on a continuous basis to maintain the return flow temperature to that set on the boiler thermostat. If the boiler thermostat temperature is set low enough the boiler will run for very extended periods, most of it in condensing mode and maintaining optimum room comfort.

[Kevin]

ah I have not moved on to a condensing boiler yet, I never thought a boiler was that clever