Re: Underfloor heating and HA control?

[Jim Noble <yahoo-groups@xxxxxxxxxxxxxxxxxx>]

Paul Gale wrote:
> Thanks John.
> How big is big?
>

Use the loading calculator here:
http://www.heatweb.com/techtips/flash.html
to work out your hot water load.

I don't know if it's necessary to then add some capacity for the UFH,
but if our heatbank is anything to go by, you'll have a tank full of
warm enough (>40C) water after you've run all your baths/showers.

I'd recommend going for more than the standard amount of insulation
though (normally 50mm of foam - go for 100mm if you have space for it).
I've noticed with ours that even if the hot water isn't run, the
temperature drops significantly over the course of the day. (Thermal
stores used for mains pressure hot water tend to run hotter than normal
tanks, so the heat loss is higher I guess. Plus, I think the normal
advice is to use a tall thin cylinder, to make best use of the
stratification effect. This gives you hot at the top of the cylinder for
DHW, and cooler water at the bottom for UFH. However, that will also
increase the surface area, which will make the heat loss worse.)

Jim


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