Over a period of a few weeks my in cabin heat has been getting poor to say the least..
After reading various posts on here I have checked the valves they are clear and operating when power is applied..one of the metal pipes to the change over valve on the bulk head is red hot and the return from the matrix is cold very minimal flow..at my wits end now..does anyone have any further ideas.
Things checked.

Matrix blown through and clear..
All valves clear on the bulk head and ns inner wing..
Aux pump below the inner wing valves works when power applied...
The fbh has not worked for around 4years there is water flow through the unit.

Have I missed anything???🤔🤔🤔 First rr..I'm loving it at the moment until the bongs kick off..