v little hot water from vokera boiler

[shaman]

I have a vokera linea boiler and altho heating works fine I am having trouble with hot water it is a recently new system (complete) approx 18mth old it does not matter whether heating is on or off same problem occurs which is: with heating on and set at 60 . . . turn tap on temp drops to 36 boiler ignites and runs fine for 50/60 secs or so temp hits 45 and boiler goes out after 15 secs or so temp drops rapidly to 15/16 then boiler iginites and runs for 45/50 secs temp hits 46 and boiler goes out this continues all time so consequently tap runs alternate hot n cold !!! help could do with a hot bath not a lukewarm one!!!

 

[DP]

I suspect the installation is dirty i.e. was not chemically flushed and inhibited. Check Benchmark Logbook.

What is the water flowrate like. The fact that the boiler is cutting out would suggest the heat generated by it is not effectivly being transfered to cold water due to lockage on the primary side (due to above mentioned debris)

If that is the case, calll the "heating engineer" and ask for water quality report.

 

[shaman]

thx dp but problem ahs only recently started about 3weeks ago does this make a difference to your diagnosis???? which i must admit was beyond me lol have no becnh flow charts etc etc jus a little card stuck in boiler !!! with next to b*****r all info on it we are in a hard water area if that makes a difference? thx again shaman

 

[shaman]

ps water flow is fine just keeps running hot n cold bit like the missis really lol

 

[DP]

I would suggest the plate heat exchanger is choked. Descale or replace (after confirmation) and fit online descaler. Pity the boiler does not indicate the primary temperature when in HW mode.

 

[shaman]

just thx dp