On Thu, 30 Dec 2004 23:20:20 +0000, Dave
wrote:



Thanks Andy, email sent.

On its way.


Do you happen to know whether the U values in the myson software are
correct?

The ones that I used were, but I didn't check all of them and had to
add a couple.

Estimating air exchange is tough, any suggestions on how to approach it?

I used the standard numbers given in the program, which are an
industry standard. If the house is exposed or the windows are older
sash types or you have gaps in the floorboards then it would be an
idea to up the numbers a bit.

You can also look at the various correction factors and adjust to your
pattern of use and location.

You don't need to include the typical 3kW or so for the hot water.
This is used for older cylinders with basic coil.

Are you going for a condensing boiler? If so, you can design the
radiator provision around a 70 degree flow and 50 return. This will
keep the boiler at the efficient end of the scale and also give you
plenty of head room for very cold weather. It does imply larger
radiators of course. Don't forget the correction factors from the
manufacturer data tables. These are normally 0.89 for 82/70 degree
operation and 0.6 for 70/50.




--

..andy

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