DIYbanter - View Single Post - Karcher steam cleaner HDS 601 C ice damage

The Medway Handyman

wrote:
hi Dave

Thanks for your reply. I'll have a look tomorrow when there's more
light.

As far as I recall if you switch it on it's lowest temperature without
pressing
the lance trigger, the pump stops after about 10 seconds. If you wind
up the temperature
the pump runs forever. I suppose this means it never attains its full
operating pressure
or it does and the pressure cut-off sensor is buggered. However this
theory is
contradicted by the burner igniting, which can apparently only come on
when the
"water shortage safeguard" device senses adequate flow. The high
pressure sensor being
knackered would explain the water escape from the cyilinder head.

Look, forget the heater entirely for the moment. Unless the pressure
problem is sorted we can't even start on the heater.

Perhaps I'd better stop
running it otherwise I may screw the pump.

I would like to know how it works. For example what are the two
electronic devices on
the lhs of the cylinder head? I presume one is a pressure switch to
shut off the pump
at a certain pressure. What's the other one? Also the "water shortage
safeguard" device
has what appears to be a thermistor attached to it. Is that to track
temperature of water
flow back from the coil to the pump? Why are there apparently two
overflows, a skinny
transparent pipe from the top of the cylinder head and a thick black
pipe from the top rhs
of it?

Basic theory of hot water HPC's. The pump provides pressure & sends high
pressure water through the heat exchanger.

This usually has a pressure switch to stop/start the pump. Sometimes it
will use a bypass valve & flow switch.

The heat exchanger/burner/coil/whatever has a number of safety cut outs,
commonly;

1) A flow switch - unless water flows into the heat exchanger it won't
ignite.

2) A thermostat - which will cut the HE off if it gets over temperature.

3) A backflow heat sensor - if the HE overheats and very hot water starts to
get back to the pump, it will shut off the HE. These are usually not re
setable. If they trip once they are buggered.

4) A flame failure device - no flame after a certain time, it will shut off
the fuel, usually a photo cell.

As I said, and I can't stress this enough, forget the HE for the moment - it
will just confuse matters. That can't be sorted until the HP system
functions properly.

I can sort this for you, just need some more info.

--
Dave - The Medway Handyman
www.medwayhandyman.co.uk