Need Urgent Help on Lochinvar Noble Combi-

[domsue]

I have radiant floor heating and my lochinvar noble combi is not staying ignited. the thermostat calls for heat-it was short cycling (on for about 8 minutes then off) constantly. Now, each time it goes to run it gets to 100%, flame is about 7.2 -8.4. then it shuts down, purges, pre-purges and does that 4 times before going into lockout running mode.

we are in montana and temps are supposed to go below zero tonight. i have water in my radiant heat tubes, (not glycol) and am very very concerned....
any help would be greatly appreciated .
thank you