It does take longer to heat up to maximum efficiency, but it's also more efficient. That means that when you set the timer, the house will remain warmer inbetween times as it were than it would with a radiator.
We have no radiators at all and find that simply setting the thermostat to 21 on a timer programme suitable for us (there should be several to choose from depending on whether someone is in the house all day or not) is absolutely fine.
The nice thing about underfloor heating is that it feels natural, there's no getting massively stuffy and feeling that you're either freezing or baking.
Depends on your insulation. Our radiators and wet UFH are on different timers: the UFH is set on a lower temp than the rads for less time, from an hour or so before we get up while the rads are more like on from 30 mins before we get up - but we usually have the rads on constantly anyway. The UFH is in the very well insulated extension and it's tonnes warmer in there than in the drafty rest of the house with the unreliable old radiators.
It is a hot water UFH system. As the house is brand-new it is insulated to the hilt - insulation in-between floors as well as in the walls and loft. Also the downstairs rooms all have individual thermostats so you can set the living room to be warmer than the kitchen, etc.
I'm not sure if the radiators (upstairs) are on a separate timer but will check.
asked my DH, he says "Yes, it will heat up more slowly. However, it will also cool down more slowly, due to the thermal mass of the concrete screed in which the pipes are laid. Typically expect to have to wait 24hrs before seeing a change in room temperature either up or down.
Depending on the heat source (oil boiler/gas boiler/heat pump etc.) you shouldn't have to change the target temperature during winter, as the heating will simply run for longer to compensate for the increased heat loss due to the colder outside climate. " HTH xx
We moved to a place with UFH (electric) heating last Autumn. I got rather a shock when I got my first bill, 3 months based on actual electricity usage. Our UFH basically cost us £10 per day, we turned it off and haven't used it since.
We also have gas radiators everywhere (not sure if this is normal for houses with UFH?!) so we basically used the UFH to take the chill off the tiles downstairs. Never again...
If it has the new reg insulation you wont believe how much cheaper it is to heat. Our ufh goes on for a short time each day in the winter and then because of the insulation it holds it really well. Even in the coldest -10 temps we never had to turn it up to the highest temp. The improvements in ufh over the past few years have made it much more efficient.