Glow worm 30ci hot water not getting

[moony]

As title, hot water getting warm but not hot, improves if the stop tap is closed to reduce flow. Any thoughts.

Cheers

 

[SimonJohns]

Flowrate is too high across plates

Use a weir gauge to check flow rate. Lookin for about 13lpm

Anything more will lower temp of hw

 

[armourer]

check the gas max / min gas rate and ensure it is modulating.

 

[fixter1]

as simonjohns says flow rate to high,,, would be my first check

 

[moony]

Right ..... Update

Flow gets hot when only hot water running.

Divertor/3 way valve passing?

 

[fixter1]

could be dv or plate heat blocked

 

[moony]

Why would the plate being blocked cause the flow to warm up?

 

[armourer]

Why would the plate being blocked cause the flow to warm up?

If this is the case the bypass pipe will be getting hot.
(if the plate is totally blocked, internal bypass will open and it will bypass to CH circuit)

Not very likely though.

 

[moony]

I can get hot water if flow is restricted at stop tap. The problem being I don't want to fit a dhw plate if the divertor is faulty and passing.

 

[armourer]

Just use a weir cup at a tap and see what flow rate you have and compare to mi.

Then compare gas rate to mi.

That will tell you straight away if flow is too high or you are not getting enough heat into the system.

Also you can normally touch the bypass to see if it is getting hot and this will tell you if it is bypassing or if it is cold the
diverter is passing (or could just be stuck, remove the actuator and manually move the valve).

 

[dave1]

its quite common when the plated is blocked to let the heat down the flow, just take it out and check... after checking flow rate etc

 

[moony]

Ok thanks lads. Plenty to get on with there.

As for checking plate, I take off and look for black bits coming out, any of you guys use a more scientific approach ?