Raven Heat 100RSF hot water

[billy_smith]

Following from a previous thread, my next door neighbor has got his boiler working again after his flue problems. (he's just moved in)

He's been back at my door asking about the operation when on hot water, I went and had a look this evening (I'm not GS so didn't open anything up, my boss is GS so I do have some knowledge)

Anyway, when the hot water is run at the bath the boiler fires up as it should, the water gets really hot then begins to cool down (not cold though)

I went and had a look at the boiler when the bath tap was running and the flame disappears completely for say 10/15 seconds then fires up again, this sequence seems to continue until there is no H/W demand.

Is this a normal sequence of events for this boiler.

I did ask my gaffer but he didn't have a good word to say about the boiler and more or less said rip it out !!

 

[mcmoby69]

it has a fault.

 

[Timtam21]

Following from a previous thread, my next door neighbor has got his boiler working again after his flue problems. (he's just moved in)

He's been back at my door asking about the operation when on hot water, I went and had a look this evening (I'm not GS so didn't open anything up, my boss is GS so I do have some knowledge)

Anyway, when the hot water is run at the bath the boiler fires up as it should, the water gets really hot then begins to cool down (not cold though)

I went and had a look at the boiler when the bath tap was running and the flame disappears completely for say 10/15 seconds then fires up again, this sequence seems to continue until there is no H/W demand.

Dry run thermistors and clean plate to plate.check how doesn't go down ch pipes

Is this a normal sequence of events for this boiler.

I did ask my gaffer but he didn't have a good word to say about the boiler and more or less said rip it out !!

 

[locosaki1978]

I've just had a RSF100 with much the same symptoms, I replaced both thermistors and adjusted BP and so far so good.

 

[billy_smith]

I've just had a look at the manual online for this boiler, Can I ask why you changed both sensors mate, should it not just be the H/W thermistor here ?

 

[Timtam21]

I've just had a look at the manual online for this boiler, Can I ask why you changed both sensors mate, should it not just be the H/W thermistor here ?

You want 2 green thermistors,dry run them first before draining down and fitting.

 

[bazdaman]

I've just had a look at the manual online for this boiler, Can I ask why you changed both sensors mate, should it not just be the H/W thermistor here ?

Study the manual then ask yourself why it might need both replacing, look at their positioning and function,

 

[billy_smith]

I've had another look at manual today, if the heating thermistor is faulty I can now see why this would affect HW. The burner is going off and on, this could be down to the primary thermistor shutting it down

 

[richw]

From what I remember (when I had a similar model), during HW demand, the CH loop becomes 'short-circuited' so it is entirely internal to the boiler. The boiler heats that tiny CH loop directly, and the heat exchanger transfers the energy into the HW side. So if the CH sensor is not working, and/or the CH side is full of sludge, the HW can do as you say.

In my case, with a similar problem, it turned out to be a broken wiring loom between the PCB and the HW/CH thermistor (I forget which). Replacing that solved the problem. I would advise checking/replacing both thermistors, checking the quality of the CH water (bottle of X400?), and checking the min/max gas pressures are set correctly on the gas valve.

Oh, and check the position of the HW temperature dial. I found that if mine was much higher than the 12 o'clock position, t would cut-out. No logical reason for that, since everything was wiring properly to spec (as far as I could tell).