grant combi 90 - hot water - cold

[Robdiy48]

Hi , I'll try and answer as much as I can
CH fine -
changed 3 way valve 2 year ago, changed pump around year ago along with air vent and recent PRV.

HW flow always been low, pulled of the Flow valve & the CW in filter was blocked, a little scale inside bottom of the valve itself, valve seems to be moving when turning, put back on and still no HW but loads more pressure.
3 way valve pin out after HW turned on. so believe the valve is fine

Heat ex below the 3 way valve is luke warm to touch, front pipe from boiler is hot.

Would this be the Heat Exchanger ? do I need to pull that off and give it a flush? or replace,or something I have missed.

No other areas have been changed.

thanks in advance

 

[Robdiy48]

Grant Combi 90 MKII

 

[Terrywookfit]

Is the divertor operating the microswitches.

 

[oilhead]

On Hot water only, does the burner fire when there is a demand?
Is the heatstore hot?

 

[Robdiy48]

Divertor valve is operating micro switch

Boiler fires up when HW demand

 

[Robdiy48]

Heat store is hot, pipe from there to Heat ex is hot - Heat ex is warm.

Update:
CH is on - Pipe into Heat Ex is hot, Heat Ex is Hot pipe to Mixer Valve is hot - water out of mixer valve is cold

Possible mixer valve ?

 

[Robdiy48]

mixer valve = Blending Valve

 

[Terrywookfit]

If the hot to TMV hot then TMV is faulty

 

[Robdiy48]

TMV.. will replace this,

Keep you posted and thanks