Another Ravenheat RSF 84ET Problem

[markdon]

Hi all, over the last two years the boiler has started playing up, after reading up about them, i was suprised it had lasted this long.

So far i have had the three way valve replaced, and more recently the pressure releif valve.

Now we have fitted some new taps (strange coinkydink) but the taps have a wider bore on them (where the water exits, not the pipes), but for whatever reason ( i have learnt not to understand this boiler) the water is starting to play up.

Right, here goes, not too hot with technical descriptions...

To run a bath, hot water would be nice, so turn the hot tap on, boiler pops to life, get hot water, hot water turns to cold. UNLESS you turn the water down to a trickle, it takes roughly 25mins to fill the bath!

The hot water dial is on max, and if when the bath is running (as it is now) i turn this down, the boiler stops, as expected.

So, what do i need to replace now so i can get decent flow of water, and it is hot?

Any help would be appreciated.

Mark.

 

[Joe 2017]

most likely a new system boiler with a cylinder, what is the flow rate of the water, what is the temperature. don't expect to have hot water if you have a flow rate over 15l/m

 

[markdon]

Even slightly more than a trickle causes the water to go cold, doesnt have to be fully open, if i turn the tap on, i have to turn it back to a trickle just to keep the water hot.

Flowrate, is that exiting the tap?

Temperature, at what point?

Thanks very much.

 

[Joe 2017]

does it happen in all your hot water taps, or just your bath taps

 

[markdon]

All of them, very annoying!

 

[Joe 2017]

in that case could be anything, could be heat exchanger, plate to plate h/ex, gas pressure, themister. get someone who knows what there doing

 

[Agile]

We cannot make any meaningful comments without technical information.

Ideally the DHW flow rate at which the boiler JUST turns on.

The DHW flow rate at which you are expecting to fill the bath.

The gas rate measured at the gas meter. See this site FAQ for how to measure it.

Tony

 

[Joe 2017]

yes his right, find out the flowrate of the dhw, measure the cold water temperature and do a gas rate from the gas meter, all that will tell you if your boiler is working as it should.

 

[markdon]

Sorry, i have just had someone to look at it.

The reason i was asking on here was to find out if there were any common problems to help figure out what could be wrong.

I have been advised that i need to change the heat exchanger, part number 0002SCA05005/0, could you reccomend me the best place to get it from, i figured i would buy it myself and get the plumber to fit it.

While its in bits, is it worth changing anything else (not the whole thing, as much as i'd like)?

Thanks.

 

[Agile]

We have not had any technical info so we dont know whats really wrong with your boiler.

The heat exchanger might be scaled but they are expensive, perhaps £170, and in any case can be cleaned by an engineer prepared to do that.

I am always suspicious of an engineer who does not expect to get the parts and fit them himself. It makes me think that he is not sure whats wrong and if YOU buy it and it does not fix the problem then he will not be in a position of buying a part which he cannot get the money from you.

Tony