Advice on new heating system

noncom_2

Hi all

My family's moved into a new house, and the whole of the heating system is very different from our old one, so I'm looking for advice on how to run it most effectively and efficiently.

(Previously we had a standard non-condensing combi boiler running the radiators and hot water.)

In the new house we have:

A condensing Ferroli system boiler in the garage, an unvented hot water tank upstairs, radiators (with thermostatic controls) in most rooms, and underfloor heating (hot water fed, not electric) in two large-ish areas downstairs.

I've had all sorts of (conflicting) advice on how to set it up, so would welcome any more opinions (especially if you can explain WHY you advise a particular course of action).

In particular:

1. On the boiler I can set the temperature of the outgoing water heating. What is an appropriate temperature to set? Presumably it needs to be above 60degrees so that the hot water tank can reach the temperature its thermostat is set to. But for the heating itself (ie rads and underfloor) is there an optimum temperature - is it more efficient to have it hot (and therefore things heat up quickly) or cooler and therefore needing to come on for longer?

2. If I understand correctly, there needs to be a certain difference in temperature between the outgoing temperature of the CH water from the boiler and the return in order for it to run efficiently in condensing mode. How can I ensure that this is the case? (My boiler only displays the return temperature in Standby Mode, ie when there's no heating demand, so it's hard to work out what the drop is when it's actually running). Or does the boiler handle this automatically somehow by pumping faster or slower to maintain the ideal temperature drop?

3. Someone advised me to leave the hot water tank heating all the time. I'm pretty sure this can't be right, as it must lose more heat by trying to maintain its maximum temperature all the time than it would if it is heated to a certain level and then allowed to cool gradually. At the moment it's set to heat for a short period in the morning and again in the evening, and even with 5 of us in the house, we're never finding the water is running too cold.

4. The underfloor heating - how long typically do these take to heat up and cool down? It seems to be a couple of hours for one area, and longer than that for the other (which is bigger). Again, someone advised us to leave it on permanently (controlled by its own room thermostats), which seems a wasteful way to run it (I don't need the kitchen to be heated to 18degrees all night!).

5. On the input to the Underfloor system from the main Central Heating pipework, there is a thermostatic valve similar to the ones on the radiators. What is this for? It shouldn't be measuring the external temperature of the room (like a radiator one would do) as it's in a cupboard and how hot it is in there is irrelevant. But surely it can't be closing down if the temperature of the actual heating water is "too high" either? Any ideas?

Many thanks if anyone is able to help in any way.

Cheers
Andy