No central heating - twin pump heating system

[morrismob]

We have a floor mounted boiler in the garage, this has twin pumps fitted, possibly as we have 13 radiators in the house ? Dunno..
There is one pump either side of the boiler, a room stat in the dining room and a tank stat on the hot water tank - hot water seems to work fine..
When the heating is turned on, we get nothing. And feeling the pumps, only 1 pump runs - is this correct or should both run together ?
When I turned the silver centre screw, the running pump had water come out, but the pump which soesn't run just had steam hissing out..
The room stat can be turned to max and still no heating, the boiler fires up, runs for approx 2 mins and then cuts out again..
I am wondering if this is a room stat problem, and/or a pump fault or even the 3 way valve faulty..
Most of the radiators last year seemed only warm at the top 3/4 and didn't get as hot as would be expected.. Should we remove and flush all radiators too ?
Any ideas or info on testing what should work and when would be most appreciated before my kids finally freeze to death - as they keep telling me.
Many thanks, Andy.

[The Heating Doctor]

Too many variables, impossible to answer on a forum. Time to bite the bullet and call in a heating engineer