Ravenheat 820/20T

[ashtonvillageuk]

Ravenheat 820/20T .....been reliable over the years.....the problem I have and I hope you can shed some light on why there's no hot water at the tap(?)....The central heating is working perfectly but for some reason there's no hot water.

I see thermistor gets mentioned a lot for this type of problem but I don't think the 820/20T is fitted with one - is that correct?

Many thanks.

 

[Agile]

The boiler has a thermistor but not likely to be your problem.

You need to check the diverter valve is moving and operating the DHW demand switches!

Tony

 

[ashtonvillageuk]

Hi Tony......thanks for the reply.....The movement of the demand switches, are they situated near to the diverter valve?

 

[Agile]

On the end of the diverter valve!

 

[ashtonvillageuk]

Hi Tony....the head of the valve(with micro-switch) faces to the back of the boiler and is impossible to see due to the position.

 

[Agile]

Yes, repairing boilers is not so easy!

 

[ashtonvillageuk]

That's very true - I think I'll have an engineer install a new diverter valve(with micro-switch) and cross my fingers......many thanks for your assistance, Tony......

 

[ianmcd]

That's very true - I think I'll have an engineer install a new diverter valve(with micro-switch) and cross my fingers......many thanks for your assistance, Tony......

why ? just get an engineer out to diagnose the fault rather than say it needs a diverter valve and micro-switch, most probably the DHW Diaphragm has perished on your boiler

 

[Agile]

It is a scraping knuckles boiler.

But I do just replace the diaphragm on that model!

Tony

 

[St0rmer66]

The boiler has a thermistor but not likely to be your problem.

Tony

It doesn't. It's a thermostat which switches a high and low gas rate at the gas valve (not fully modulating).

 

[DP]

It doesn't. It's a thermostat which switches a high and low gas rate at the gas valve (not fully modulating).

Lad, your post count is not even 3k. You need high 60k to carefully and precisely state a thermistor is same as a thermostat. you are not implying these components are different are you?

I am still trying to get to grips with capacitors and ECR meters. I think you need to get to grips with thermistors and thermostats- you will eventually realise there is no difference, once you get an oscilloscope

 

[Agile]

Yes, that is correct, its such an old design that it uses a phial type thermostat to give three different contact outputs.

As it was not related to the fault on the OP's boiler, in my haste I wrongly said it was a thermistor!

I am still keeping one of this old model going until the summer when I will replace it with an Intergas.

 

[DP]

Tony that is the closest you have come to saying you have made a mistake

 

[bernardgreen]

I think you need to get to grips with thermistors and thermostats- you will eventually realise there is no difference

 

[St0rmer66]

Whoosh! Over your head it goes!