On Sat, 2 Dec 2017 13:20:31 +0000, (Roger Hayter)
wrote:

T i m wrote:

On Fri, 1 Dec 2017 07:58:58 -0800 (PST), whisky-dave
wrote:

snip

I said nothing about stoping, what's wrong with reducing cycling. ?

Because it means the heater won't be on, will be cooling down, so
giving off less heat.

Just what we want in a cold lab,

That's good as that seems to be what you've got. Luckily *you* are
monitoring it all and know all the answers (not).

a heater that gives off less heat,

Yup, but that's what you want. You want an overpowered heater cycling
and giving off less heat than one that isn't.

For any given lower power heater there will only be a narrow band of
ambient temperatures where its average surface temperature is higher
than that of a cycling heater.

I can't remember the exact numbers (and CBA to search) but I think
dave measured ~75 - 100 Dec C or so.

Any warmer and it will cycle,

Yup.

significantly cooler and it will suffer from insufficient power compared
to the cycling heater.

Yup.

So I don't agree with you that this is a useful
objective.

But could be a useful experiment, given the lack of alternative
solutions?

I don't think cycling is actually too much of a problem.

No, it may well not be but it was a question that would be easy to
answer and may well yield *a* solution towards the problem?

So, if we know the 'from hot' cycle time when set at ~2kW and then to
see if it cycles (at all or the cycle time) we can then determine any
advantages of say switching down to the 1300W setting.

Remember, not only might this yield the best practical output for a
given input *but also* limit the maximum draw on the (poor) supply and
therefore allow for the addition of some extra heaters whilst keeping
within the capacity of the supply.

What you are effectively doing is increasing the surface area of these
cheaper rads to the point where they should be able to heat the space
better (overcoming their shortcomings to a degree). ;-)

Cheers, T i m