yellow gunk in header tank

[fabgav]

From googling,
My boiler has a stat on the return so when that drops it kicks in.
The temp on flow are about 55' and reutrn 48' does that sound about right?
Its a Baxi Bermuda 45/4m back boiler.

The MV you can see there is for my central heating.

I think my best plan of action for the time being is to assertain if my exchanger bit is leaking. if yes, new tank, if no, clean header tank of gunk, then look at better controls for the system?

 

[JohnD]

It's quite usual to have the flow hotter than that, but with no cylinder stat, your HW would in time get very hot. I suppose you have to try to keep it below scalding. Most boilers have a temperature control knob.

The cylinder with yellow insulation is rather old, maybe 20 or 25 years. I don't know how long they typically last, but my old one had a leak (visible, external) before it was that old. The current colour is blue. You could certainly get faster HW heating and better insulation with a more modern cylinder, as they are designed to higher standards, but you ought to insulate the pipes too - nothing to stop you starting tomorrow. Insulate all accessible hot pipes, especially those between boiler and cylinder. Pipe insulation is available in two grades (thicker is better) and for pipe diameters 15mm, 22mm and 28mm (hard to find). http://www.wickes.co.uk/Products/He...ter-Cylinders+Tanks/Jackets+Lagging/c/1000529

New cylinder or not, you ought to have a cyl stat and valve, both to avoid scalding, and to save money.

I've lost track of what's been done already, but if you have a large tank and a small tank in the loft, tie up the ball float in whichever has the water level lower than the water in the other, verify the valve is not dripping, and see if the water level rises in the lower tank. You could alternatively turn off the stopcock that feeds both tanks, but that is better if you are going to be out of the house all day and not running any taps or flushing WCs, so there should be no drop in water level unless there is a fault.