Posted By: tehorodonI'm interested in how people with zone control use it

A good question. My plumber gave me a UFH system with many room stats, then I read here how maybe it was a useless waste and 1 zone would suffice. I hope to discover they are wrong, given my specifics. After 1 heating season partly occupied I am still learning the best strategy for using it. My 500L thermal store is heated by WBS, solar thermal panels and immersion (as a last resort), so my experiences may be a lttle different from your ASHP. UFH in 50mm screed above 250mm EPS above slab.

My first observation is that the (expensive) Heatmiser stats are very course with 1 to 2 degress of hysterisis - separate adjacent thermometer ususally reading at least 1C different from the stat, so micro-management is not possible. Next is just how slow a low temp UFH system is to respond compared to old fashioned high flow temp convective radiator. If a room gets cold (because you have not heated it for weeks in winter) then to heat it up quickly best get a fan heater or light a fire! Partly this is down to human perception too, currents of warm air and a definable (glowing?) source make you feel warm quicker.

But, contrary to some expectations, I can keep a 3 to 4 deg difference between different rooms (warm lounge, cooler bed) so the stat settings do do something. I also seem to tweek lots especially in the in-between days at start and end of winter. This is mostly to make use of lower grade solar thermal heating - I circulate the UFH for say 10 mins (usually a room or so at a time so as not to cool the tank too much and kill my DHW) to swap the "water" in the pipes into the bottom of the store for the sun to heat. Slowly heating the slab up too. I also found that the stats will say a room is warm when it isn't (hysterisis) so I manually force up the stat (and then be patient).

Very glad to have a network based controller for it all - running around the rooms was tedious. Looking to automate with some overall thermostatic control i.e. stop circulation regardless of stats calling if the source store temp is too low to do anything, or run towel rail when store is nice and hot throughout etc. But don't think weather sensors etc. will be appropriate (too changeable here in Cornwall, and my demands vary too).

Anyone else??