Ravenheat DHW problem

[Moonmaiden]

2 year old Ravenheat condensing boiler... hot water cuts in and out. The boiler can be heard firing up and the water starts to come hot... then the boiler can be heard to cut out... and it goes cold.

This problem has been getting worse over the past few weeks. Initially, the boiler would only cut out a couple of times and then a nice long shower could be taken.... then I learned to switch the shower on for about 5 mins before I wanted to get in it and it would be ok..... now I spend half my time stood at the other end of the bath, hair full of shampoo, freezing cold, whilst I wait for the boiler to kick back in and I can step back under the shower to rinse off.

It's really not funny anymore!

Any ideas what's causing the problem and is it something that could be fixed by a girl with fairly competent DIY skills?

 

[Agile]

You dont bother to tell us the model.

However as its two years old i assume you had it serviced at the end of the first year and that its now due for its second service.

Hopefully a service might solve the problem. Its difficult to make any guesses without more detailed information.

Modern boilers are complicated enough for many boiler engineers and I doubt you will have much chance!

Tony

 

[Moonmaiden]

You dont bother to tell us the model.

It's a Ravenheat CSI85T

However as its two years old i assume you had it serviced at the end of the first year and that its now due for its second service.

Unfortunately... no... it's never been serviced

Hopefully a service might solve the problem. Its difficult to make any guesses without more detailed information.

Modern boilers are complicated enough for many boiler engineers and I doubt you will have much chance!

Tony

I was hoping that it might be something fairly simple such as the microswitch/shunt valve (not that I actually know how easy that would be to replace! )

 

[Agile]

On a two year old boiler the only parts that might fail are the NTC and the PCB. All the mechanical parts are unlikely to but anything is possible.

You could change the NTC as thats cheap but if that does not solve it then you will probably need someone.

Trade tip. Get a new NTC but dont fit it, just plug the lead onto it and see what happens on test but dont leave it like that.

Tony

 

[Moonmaiden]

Thanks Tony!!

Have ordered a couple of thermistors (might as well replace both while I'm at it!)

Fingers crossed!

 

[Agile]

I would not recommend replacing anything that does not need replacing!

Just use ONE NTC to replace temporily without changing as I explained.

Tony

 

[Vinno]

Its the plate heat exchanger! I have just had excatly the same prob and cured it by taking out the PHE and cleaning out its inards. A better way is probably to get a good strong flush and give the system a good clean out and then replace the conditioner.

I replaced the thermisters and poteniometers with no luck. Getting out the PHE is torture and requires special spanner and the patience of a saint.

All regulars please feel free to post your hate filled message now!!!!

 

[Vic Spanner]

Personally you should be congratulated as this is a D.I.Y forum...Well done fella put your feet up open that tinny and enjoy the footy

 

[Vinno]

What a generous man you are Poxi!

 

[corgiman]

.

All regulars please feel free to post your hate filled message now!!!!

Just out of mild interest why would they?

 

[Moonmaiden]

Its the plate heat exchanger! I have just had excatly the same prob and cured it by taking out the PHE and cleaning out its inards. A better way is probably to get a good strong flush and give the system a good clean out and then replace the conditioner.

Ok... giving it a good flush can do no harm... only good... I'll give that a go while I'm waiting for the thermistors to arrive! Thanks!!

 

[ChrisR]

I'm curious why Tony didn't suggest the plate heat exchanger. It's blocking is probably the most common cause of the problem you have. We have covered it in many threads.
A dirty system can block a new one in a matter of weeks without difficulty.
Taking out and cleaning it is
between

and

depending on the boiler

 

[Vinno]

Please keep us updated Moonmaiden!!

 

[Agile]

I'm curious why Tony didn't suggest the plate heat exchanger.

Because he said:-

This problem has been getting worse over the past few weeks. Initially, the boiler would only cut out a couple of times and then a nice long shower could be taken....

So it was not an ongoing situation as would have been the case with a blocked plate HE.

Unfortunately she never updated us ! Women rarely do though!

Tony

 

[gas4you]

If its been slowly getting worse as OP has stated it sounds to me as there a blockage has been getting worse, system side or domestic side scaling up.

OP do you live in a hard water area?