Vaillant turbomax 837E Luke warm water not dhex

[nutty_jah]

Help me please guys.

Diagnosed this boiler as blocked dhex, changed but still same problem.

Water runs like warm, boiler Temp shows 45 even though control on Max.

When demand is turned off, it jumps to 70 before pump switches off.

Tried reducing cold water pressure onto boiler, still holds Luke warm.

Thanks.

 

[Dotty]

Moved to the private forum.

 

[nutty_jah]

Thanks Croppie. Bloomin Tapatalk, I thought it had posted on the private.

 

[nutty_jah]

Bit more info.

Before dhex change, Dom water was cycle Luke warm / cold.

After new dhex, now constant Luke warm.

Pump is working, circulating CH three floors up without issue.

I think phex is not performing, now that dhex is passing through fine. Phex can't keep up with flow of water through it. The property has great pressure and flow. When refusing flow at taps, water runs hot on constant.

Just need back up confirmation from you guys, what do you think?

 

[harrygashull]

Diverter passing?

checked thermistors?

Is the board interpreting signal from thermistors correctly?

 

[nutty_jah]

Hi harrygashull,

Checked diverter, not passing.

Didn't check thermistor, but Burner flame went high to low with temp control setting.

 

[harrygashull]

My bet would be a faulty thermistor, they go out of range often enough and tend to still modulate up and down even if not sensing the 100% correct temporature..

The chances of it being the P2P after you just changed it for a new one are very low, any reason for not just descaling it?

Is there a bypass built into the boiler and if so it could be bypassing the heat ex?

 

[Masood]

Turbomax have a built-in bypass, check that it isn't stuck open..

 

[nutty_jah]

Thanks guys. I'm back there on Monday, I'll check thermistor and bypass.

Have a great weekend.

 

[nutty_jah]

Hi guys, just to bring this to a close. It was the flow sensor turbine, where the impeller had sheared off the spindle! You live and learn.