worcester 28i junior water problem

[jamesjones1980]

hello was hoping one of you very knowledgeable gasmen could give me some info please.

ive had a few gasmen to check my boiler over the last couple of months, and I seem to have one of those problems which is ok whilst they are at my house so I end up paying them for doing very little so was looking for a bit of ammunition for myself so that I have some sort of idea as to whats going on before they get here next time:

anyway the boiler is a Worcester 28i junior, couple of years old. started a while ago my water from my hot tap seems to get scalding hot and then the boiler just stops working for a bit. the boiler cools down and then I get more hot water then it turns to scalding and then eventually shuts down again and this keeps happening.

what I have noticed is the flow upstairs in my bathroom from the hot taps is terrible (water barely trickling out some times & not enough water coming out to wash yourself in the sink) and downstairs in the kitchen is poor but not quite as bad as upstairs.

I understand that the slower the flow the hotter the water is so am I right in thinking the water is so hot as the flow is so slow and so there is a blockage somewhere which is causing the hot water flow to be so slow coming out of my tap?

did a bit of reading on forums and people have mentioned things like plate heat exchanger being scaled up could cause the flow to be this poor and others have mentioned possibly the pump? does any of this sound feasible to you experts? would just like a bit of info myself like I said before as getting fed up of calling people out to check it and not much being done about it. cold water flow is absolutely fine and stop tap is fully open. all valves are open underneath the boiler.

any info would be greatly appreciated.

thankyou

 

[AngelesPlumbing]

Restricting flow of hot water is possible cause is scale and boiler overheats shut it down. Do you have scale reducer on mains to the boiler?

 

[jamesjones1980]

Thanks for responding, no I do not have one of these?

Is this worth doing to cure my problem or Isit better to just bite the bullet and have the plate heat exchanger changed for a new one?

 

[kidgreen61]

Is the cold flow OK to other outlets?

I can't remember if that model has an integral filter on the cold inlet, but if it has - check to see if it's clean.

After that, you will be looking for a blocked plate heat exchanger

 

[jamesjones1980]

Cold flow is absolutely fine, hot downstairs is very weak and upstairs is a dribble but is to hot to touch.

Sorry to sound stupid where and how would I check this filter?

 

[St0rmer66]

Filter is on the inlet to the flow turbine, not something you can check yourself but the first thing your seemingly incompetent "gasmen" should have checked. It's definitely some kind of restriction, no doubt about it. It's just finding where. I would expect that after 2 call outs you'd have had some inspection of the boiler internals by now.

 

[jamesjones1980]

Ok thanks, last call out was 3 weeks ago and even in that time the flow on the hot taps, especially upstairs has got considerably worse. Just to reiterate, checking this filter is not something I can do myself no?

 

[St0rmer66]

No, it's inside the boiler, not accessible from the bottom or anything like that.

 

[Agile]

hello was hoping one of you very knowledgeable gasmen could give me some info please.

ive had a few gasmen to check my boiler over the last couple of months, and I seem to have one of those problems which is ok whilst they are at my house so I end up paying them for doing very little so was looking for a bit of ammunition for myself so that I have some sort of idea as to whats going on before they get here next time:

thankyou

Your description is rather confusing.

Presumably you mean that the flow rate is fine when an engineer visits.

As soon as a plate becomes scaled up it stays like that until cleaned!

In any case surely you are in a soft water area?

Tony

 

[jamesjones1980]

Not sure as regards to hard/soft water area. Basically the flow of the hot water has got worse over the last few weeks. It's now at the point where upstairs the flow is barely a dribble. When the last gas engineer was here he said some areas have poorer flow rates which at the time I believed but this can't be the case as it is now considerably worse since then.

Like I said before boiler seems to be overheating then it stops working then working an hour or so later. The water from the hot tap is scolding hot.

Is this a plate heat exchanger change needed in your opinion?

I'd like to know the next guy who comes
Is changing the right thing. Thanks

 

[simond]

Assuming this is a 28iJunior, not a Greenstar iJunior, all the expert postings here seem to forget that this boiler doesn't have a plate heat exchanger (or a diverter valve), it has a bithermic heat exchanger.

In other words, in this case a finned copper radiator sitting above the flame with two separate water paths through it. One for HW, one for CH.

I could draw similarities with a certain other boiler being promoted on this site that draws on this design......but I've done that a few times already.

I believe there is a filter in the flow switch assembly, you would need another RGI to look at this, preferably armed with a set of O rings. Alternatively the main heat exchanger could be scaled up.

 

[jamesjones1980]

This may make absolutely no difference to diagnosing whether this was the plate heat exchanger or not but the last guy I had out said the plate heat exchanger was getting got so could not be scaled? Could be complete garbage but just a point I thought I'd make.

GC number of boiler is 4731187

 

[jamesjones1980]

That was supposed to read plate heat exchanger is getting hot not got sorry

 

[St0rmer66]

It's a GREENSTAR 28i Junior then... Completely different boiler. A lot of the advice still stands though. Filter is still in the flow turbine. There is also a small plastic part called a "flow adaptor" which often breaks down in the flow turbine (accessible once it is removed). It does have a plate heat exchanger by the way which could be scaled if the former is OK. You cannot tell if this is faulty by just feeling if it's hot... It's supposed to be hot!

 

[Agile]

There are two faults!

A restricted flow and then perhaps a poor temperature regulation.

Regardless, the flow problem needs sorting out first as that may well be all that is wrong!

Tony