vaillant turbomax

[townfanjon]

Gents, Pal rings me up this teatime, he's looked at a old Turbomax this afternoon that is going to be changed this summer anyway, his customer just wanted it to see the winter out, but its developed a fault
HW working ok /no probs
HTG works for around a 2/3 mins and knocks off, and just keeps repeating that cycle
Customer says its only just gone like that but he is not convinced.
he wants to check the thermisters but says there is only one spade terminal on them not the normal 2.
That sound's more like a sensor to me but I have never come across them, but I may be wrong or guessing lol
Has anybody any idea how to test them ???

Thank you

 

[dave1]

Check rad valves are switched on.

 

[wards]

check the divertor/actuator.

 

[Nostrum]

Check resistance between terminal and the body of the thermistor. Circulation would be my first look, is the heat getting away, pump proving switch etc

 

[townfanjon]

Check resistance between terminal and the body of the thermistor.

many thanks, that was the only way I thought, just have never seen one with one terminal.
As far as I know pumps going (quietly) and diverter is ok.
Hes back in the morning, I am still off for a while and not driving so I cant go, just would have helped the custard if it would have just lasted a bit longer, but there you go !!

 

[albatross]

I think they may have had a filter in the return. Blocks up restricting pump flow so boiler gets to temp and shuts off quick

 

[Ermintrude]

Pumps my guess in this old girl

 

[ambrosia]

I'm betting pump,
I think resitance on those should be about 180 if you put your multi meter on it