I'm trying to find a central heating controller for multiple zones.

I have an underfloor heating system, which leaks. (It's an old (~10 years)
Nu-Heat system with Contraflo rubber hoses. They don't use that material
anymore, but that doesn't stop mine rotting - so far mostly at the manifolds,
but it's going to spread.)

I am planning to replace upstairs with radiators, because I can't cope
with the idea of taking down every downstairs ceiling in order to fit
underfloor heating (nor of taking up all the carpets, routing grooves
in the T+G chipboard for new pipes, putting a hardboard floor on top of
that and taking a bit off all the doors to allow for the raised floor).

(Downstairs i) isn't leaking yet and ii) is wood block floor which is
easier to take up to get at the pipes, so the current plan is to keep
that as underfloor, replacing with new style pipes next summer.)

I did get a plumber in to quote for doing the radiator conversion,
but since he didn't pay attention and only quoted for half the job,
and given the amount of time I've spent fixing other plumbers work
in the past, I decided to do it myself.

At the moment upstairs has three heating zones, each with a Danfoss TP5
5/2day programable thermostat connected to the central control box,
which controls the zone valves at each manifold, and switches the
heating circuit pump when any zone thermostat switches, and is supposed
to switch the boiler pump when the cylinder thermostats switch, but
actually runs it the whole time at the moment (so the cylinder temperature
is actually set by the boiler thermostat - not ideal).

(The cylinders (two, paralleled) are thermal store types:
http://www.diyfaq.org.uk/plumbing/he...s.html#thermal
(except they are a sealed circuit, not open vented).)

What I would like, or at least what I think I would like, is to leave
the existing controller switching just the underfloor heating circuit
pump (based on the downstairs zone thermostats), and keep the upstairs
zone thermostats with two-port zone valves and a controller that will
switch the boiler circuit pump if any of the zones or the cylinder
thermostats are calling for heat.
Explaining this to local plumbing supplies results in quite a lot of
blank looks (having spent 15 minutes explaining the existing system
to a plumber with both a schematic and the actual pipework in front
of us before he finally got it, this didn't surprise me).
The Danfoss and Honeywell brochures I have only cover simple systems.

Any suggestions? A Danfoss FH-WC looks like it might do the job, is
there any reason not to use it for radiators rather than underfloor
zones? (http://tinyurl.co.uk/n4nk)