Worcester Bosch Greenstar 28i Junior Combi Boiler - Help

Hi there,

Link to Manual: https://www.worcester-bosch.co.uk/support/literature/download/release/6720644741/12637

Not a plumber, just an infuriated owner of the subject boiler.

I had a oil to gas conversion done and this boiler installed late 2013 by what I perceived to be a competent installer, he gave me no reason to doubt otherwise. The installer told me that it the system had been power flushed and again, had no reason to doubt him. Had a few radiators replaced by the installer during the process. Also had an Adey Magnaclean pro2 filter fitted to the system. Its a semi-detached house with 9 rads, 1 shower and 2 hot water taps.

Admittedly stupid of me, every so often when the system pressure was low, I had been topping up / re-pressurizing the system without inhibitor, which is where I think a lot of my problems have stemmed from.

Irrespective of this stupidity my boiler had been performing mostly fine for years after until around 2016-2017 [3-4 years after install] where the Plate Heat Exchanger [87161066850] gave out.

Can't quite remember if I had replaced the plate then or not but I do know for sure I had it replaced and system flushed around mid 2017. Which for all intents and purposes was the starting point of constant boiler breakdown.

I replaced the plate again in late 2018 [2] then it broke down again in 2019 where I had the system flushed again and new plate [3] fitted in 2019.

Recently, within the last few months, the plate broke down on me again and the engineer cleaned it out with chemicals to no avail.

Since it was cleaned, we were pretty sure it was not the hot water side and when I replaced the plate with a 'refurbished' part a few weeks ago [4], I also had an Adey Limescale remover installed all of which to try and tie me over until I come up with a plan to resolve this once and for good, however, the boiler is already showing signs of breaking down.

It must also be stated that the past two times the symptoms of the breakdowns have notably been showers running cold and the boiler clocking out only. The central heating has been working just fine and the radiators get hot. So long as there is no sustained showering or hot water taps being used, the boiler works and does not clock out. However, about 10-15minutes into a shower, the boiler seems to overheat and clockout, suggesting the hot water side of the plate being blocked.

Apart from querying the obvious, which is: has this been correctly diagnosed and it isn't another well known fault? I wanted to ask you guys a few things in order to try and ultimately resolve this (costs aside):

Do I:

1. Replace the boiler, flush the system and replace all rads? The Ultimate Clean System

2. Convert to a system boiler with tank, flush system & keep rads?

If so, any boiler recommendations?


Other general questions:

A. Given my prior stupidity of topping up the system with fresh water and a lack of inhibitor, are my radiators compromised so much that this arguably what is causing me so much trouble and I would be better off just replacing them all?

B. Can 1-2 older / compromised Rads compromise younger rads? I.E is one Rad's rust going to cause damage to a more recent rad?

Any assistance in this matter would be much appreicated.

Thanks!

 

Your boiler model is well known for being very dirt sensitive, but with all that flushing you should have a very clean system. Was it the primary side of the heat exchanger or the domestic hot water side that was blocked when they were replaced? Has anyone looked at the pump? It could be that that isn't running as well as it should be, or is partially blocked. I wouldn't rush into replacing the boiler just yet. You can get your system tested to see whether it's contaminated, and Worcester Bosch offer a fixed price repair service for your boiler if you can't find a local chap you trust.

 

Hi,

Thanks for the reply - I appreciate the info on the boiler model being very dirt sensitive and I can 100% vouch for this! Haha! Its for that reason I am considering a new boiler, just unsure if I want to risk another combi boiler getting messed up.

Should also note that after the clean and prior to the replacement, the overflow was engaging [since been put right] and the colour of the water coming out was a rusty brown, which is why I'm thinking, despite the flush, somethings not right with the cleanliness of the system.

Then just after the last plate was replaced a few weeks ago I did notice one of the pipes for a downstairs Rad was dripping and closed the valve for it there and then. I've been told that even the tiniest of leaks can lead to contamination / sludge build up. Might also be worth mentioning that there are no cold spots on any of the Rads, they're topped up and run as per the temperature dial on the boiler which is to say that when the dial is 'Max', the Rads are piping hot and generally speaking the amount of heat given off by a particular Rad is a reflection of the dial on the boiler [I.E 4 is a 4 etc].

All of which makes me curious regarding your comment on the pump. The pump has never been mentioned by the engineer, so I'll bring that up to him next time. If it wasn't this, any other ideas?

I take your point on the WB fixed price repair - however I would hate for it to be in vain as I have convinced myself I have ruined the system beyond repair.

The engineer I go with I trust and in fairness he despairs as much as me... lol

In any case, you think I should query the pump?

Thanks!

 

Certainly worth looking at the pump. Have you got a Magnaclean or similar magnetic filter on your boiler?

 

I do indeed, and I have regularly serviced both the boiler and the filter. Was just in the process of building up the courage to go up into the loft to take a look at the magna clean myself.

 

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