Mine is an air source, not a ground source. Apart from the expulsion unit, or whatever it's called being mounted in the wrong place, meaning I walk into a freezing gale when I go out the front door(it was mounted too low) and the housing association refusing to alter it, it's not bad. Certainly much wamer than the old storage heaters. It also heats the water, and gets it realy hot!
I think it's worth it, I think it's cheaper in the long run than storage heaters. The house needs to be really well insulated for it to work economically, otherwise it's on all the time. It works by sensing the temperature of the house, and kicking in automatically when it gets one or two degrees below the temperature you set.
Each radiator is also able to be set to a different temperature, so if you dont use a room much, such as a spare room, you can set it realy low, or not heat that room at all if you wish.
Water temperature is set by the engineers, and once a week gets so hot that it can scald.
That is apparently to kill any possible leigonaires disease bacteria that could be lurking in the system.mine does it overnight on a friday, so I have hot to warm water all weekend from the tap, all year round. That cant be turned off.. I live alone so I never heat the water at any other time.
All in all I'm very happy with it, apart from where they have sited the outside unit.
The radiators are also a bit bulkier, but no worse than the big old Victorian ones. If you want slimline heaters in the room, then that wont happen.!
Money wise, they are cheaper to run than storage, I'm on a single tariff now, I used to spend more at cheap rate, heating the storage heaters while I was asleep than during the day, and realy needed the wood burner in the evenings, so that was extra fuel on top.
My bills may be very slightly higher, but when you take into consideration the fact I only now light the fire occasionally, more for ambience than heat, it actualy is much cheaper in the long run. I was spending an extra £50 a month on top of electricity to keep warm in the evenings. Now, it's probably that for a whole winter season. And I'm warmer too!
It will need a yearly service which you'll have to factor in too.