Ravenheat Boiler Fails To Fire Up

Poisonata · 26 Jan 2008

Hello,

I have a Ravenheat RSF 820/20 combi boiler. This morning both the heating and the hot water failed and I'm stumped.

The pilot light is on and gives a strong flame. I inspected and cleaned the internal extraction fan and it is rotating as normal. I blew into the plastic tube (connected to the fan) while it fired up (until it clicked) incase the fan wasn't achieving enough pressure. These things are the 'usual suspects' and have resolved the issues many times before.

You activate either the hot water/ heating, it makes all the right noises as it clicks into action but just doesn't fire up.

I think this time it is something more sinister however if I have missed something obvious or there is something else worth checking I would be most grateful for any suggestions.

I will check the thread incase I have failed to provide enough information.

Thank you in advance to anyone who responds.

Norton.

Poisonata · 26 Jan 2008

More information - just spotted something I missed before.

The fan does work correctly when the pilot light is on and it is idling.

However when you active the heating/water rather than the fan speeding up, it actually slows down until it stops.

Is this an issue with the fan or some fan controlling device ?

So to clarify, the fan spins normally when the boiler is idle, you active the boiler, the fan seems to lose power and stop altogether. You switch off the boiler, the fan goes back to spinning slowly on idle mode.

Hope someone has an idea

Norton.

Slugbabydotcom · 26 Jan 2008

Poisonata said:
The fan does work correctly when the pilot light is on and it is idling.

However when you active the heating/water rather than the fan speeding up, it actually slows down until it stops.

Is this an issue with the fan or some fan controlling device ?

So to clarify, the fan spins normally when the boiler is idle, you active the boiler, the fan seems to lose power and stop altogether. You switch off the boiler, the fan goes back to spinning slowly on idle mode.

So the high speed coil of the fan has burnt out

OR

Relay 2 on the pcb isn't sending the required current to the fan for high speed.

I'll bet 50p on the latter

Checking the voltages of the wires leading to the fan as you give a call for HW/CH will point you to the culprit. Wire 39 should go live for high speed.
There should be 50+/-5 Ohms between the terminal that wire 39 goes on to and wire 37

Poisonata · 26 Jan 2008

Thank you very very much .

I will go and buy a voltmeter today to check this and let you know the outcome.

As the fan (in the UK) is not cheap I really didn't want to buy a new one only to find out this wasn't the cause.

If indeed it is relay 2 on the printed circuit board, is it possible to replace this one item or must i replace the whole pcb. I guess the latter and I bet this will cost even more than the fan.

Once again MANY thanks, at least I can get on with the repair.

Kindest Regards, Norton.

Slugbabydotcom · 26 Jan 2008

I cant guarantee a repair unless I fit a new part. So generally I don't do it unless the circumstances are exceptional.
I don't recommend that you try a repair on the pcb unless you are skilled at it.
Part number for pcb is 5021160
Fan part number is 5021305 and you lost your bet as the PCB is cheaper

Poisonata · 26 Jan 2008

How very silly of me thinking you were actually from Pakistan. Oh well.

Anyway (thanks to you) I am now convinced it is the PCB. When I depress the ignition switch to fire the spark this actually engages the fan on high speed mode. So the motor isn't burned out.

Furthermore when I measured the Ohms from the terminal 39 to 37 after engaing the HW/CH the reading slowly died to nothing.

I will order one later tonight from the site you recommended.

Could I ask you to eMail me (if your happy to do so) your address as I have a small gift for you to pop in the post as a thanks for your time helping me today.

Kindest Regards, Norton.

Bamber gaspipe · 26 Jan 2008

[quote="Poisonata";p="810488

could I ask you to eMail me (if your happy to do so) your address as I have a small gift for you to pop in the post as a thanks for your time helping me today.

Kindest Regards, Norton.

I wouldn`t, it`s probably poison, poison from Poisonata Geddit? oh! please yerselves.

Slugbabydotcom · 27 Jan 2008

Poisonata said:
Anyway (thanks to you) I am now convinced it is the PCB. When I depress the ignition switch to fire the spark this actually engages the fan on high speed mode. So the motor isn't burned out.

Good move. The power comes instead from the microswitch behind the gas valve button and proves the fan can work ok at high speed.

Poisonata said:
Furthermore when I measured the Ohms from the terminal 39 to 37 after engaing the HW/CH the reading slowly died to nothing.

Bad move but at least you are lucky. Resistance is best measured with the component disconnected from the circuit and no power on! Going back a very long time ago I blew a couple of multimeters up by running current through them. You nearly learned the hard way like I had to.
A fan that is out of range can draw too much power through the pcb and take it out. A check prevents you losing another pcb

Poisonata said:
How very silly of me thinking you were actually from Pakistan. Oh well.
Could I ask you to eMail me (if your happy to do so) your address as I have a small gift for you to pop in the post as a thanks for your time helping me today.

No probs. Bacon sarnies are welcome as well as dark chocolate, brothel vouchers or anything decent out of a skip as per my profile

Your precise information has helped me to steer you on the right track.

Slugbabydotcom · 30 Jan 2008

Two bars of Bournville gratefully received and already consumed.

Thank You

diynot

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Ravenheat Boiler Fails To Fire Up

Bamber gaspipe

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