Worchester Bosch E9 Error - It's not the boiler !

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Worchester Bosch E9 Error - It's not the boiler !

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MichaelwGroves

I have been getting an E9 error for a few years. We have replaced a many parts in the system but the fault persists. My engineer has replaced the Thermistors, main PCB and Auto purge Vent in the boiler and Worchester Technical are adamant it is not the boiler and must be a problem with the plumbing. On the heating side it is Y Plan vented system, we have replaced valve, Pump and cylinder thermostat. I also had reverse circulation which I fixed recently thanks to this forum.
The boiler is a Worchestwer Bosch Condensing 40CDi

So, to be sure the E9 error is an over heat. So I need to establish what is wrong with the central heating to make the boiler over heat. I've noticed that on hot water only it is fine. When on heating it errors. When I've watched it from cold, if the boiler get to max temperature within 7 minutes it trips. When it takes 15 minutes to hit max temperature it works fine. It only trips on start up. I've also noticed recently that I can bleed my highest radiator daily, expelling 5 seconds of fast air.
So I'm thinking maybe it's sucking in air and this is what causes boiler to trip, but i don't want to lead you.But if so from where?

The current system is made of two halves, origional 22mm copper to 15mm T to radiators. The new part is 22mm Hep2o Mainfolds to 10mm and 15mm to radiators. The pump is a Grundfos Magna 25. When I put this on auto the house does not get hot enough, but the boiler does not trip. So I have to set pump at constant flow No.7

I attach an image which show the layout almost exactly, including T's etc. If it looks wrong it may well be, or maybe an inaccuracy in the drawing. For instance, yes the cylinder is bottom feed!
Yes there is an unconventional vent just before the pump due to old pump being under powered and air getting trapped before the boiler. If it looks wrong please say.

I am really lost with this, Worchester are adamant it's not the boiler, and we have replaced all the parts they thought it might be, but I just can't see what is wrong with the plumbing. Any help would be much appreciated.

Capture.jpg

Thanks
Michael
 
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Looked at this on Saturday, gave it a lot of thought. Clearly Vent is in wrong place and this muct be where airs is coming from, but this is just pushed to the Bathroom radiator where it coolects. It can't get to th boiler. So bad installation by origional plumber but can't be why boiler is erroring. Also 3 way valve, yep agree too small for boiler on max, but if this were the problem I would get problems with radiators not gettinmg not enough. So would be a good upgrade but probably not causing bolier to error. It would just act like sevetral TRV's backing off.

So last idea is down rate the boiler as it's heating up too quickly. Okay, the only time the boiler errors is on start up, once it gets going its fine. So I down rated central heating to 27kW.
Well since then it's been fine, no problems at all. I have left the hot water at 40kW. The radiators are not as hot as they were and the house is on the edge of just being warm enough, so I might tweek to 30kW at the weekend if it behaves itself.
So my advise to anyone who gets an E9 error is down rate it as your very first jobas it only takes 2 minutes.

Thanks for all the advice guys :)
 
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That's a good way of looking at it, so if I removed the restriction by way of the 3 port valve, this might also solve it?

2 port valves was recommended, but to keep the job simple can I get a larger 3 way valve that will allow 40kW of flow ?
 
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What models would you recommend, all my pipe work is 22mm, so I would look to replace 3 way with 22mm T, striaght into 2 port valves ?
 
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Would I get a full 22mm flow from Honeywell V4043, not sure on difference for "B" and "H". or would I need 28mm valve to get full flow?
 
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MichaelwGroves said:
That's mad, why does Worchester Bosch only come off the boiler in 22mm ?
Click to expand...

Because in WB lab tests they found you can have upto 1m of 22 mm straight off the boiler before increasing to 28 mm, this has virtually no effect on heat capacity.....this keeps their costs down too! As they send same pipes as 30 kw version!

I would run 28 mm primary's, then fit 2 x 28 mm zones valves, with 22 mm honeywell ABV, then convert to sealed system, job done.....

Micheal you cannot have your heating set on 27 kw and hot water on 40 kw on the 40 cdi, so if you have adjusted to 27 kw, the hot water is set to this also!
 
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Sorry, don't mean to be argumentative but...........

I don't see how 28mm will give better flow if boiler is only 22mm. But, I can see upgrading pipe at valve to 28mm to get full 22mm through valve.

snip from Manuel, "Even if the heating output is limited, the full rated heat output remains available for hot water"
1.a is setting for CH, 1.b is setting for Hot Water.

What are the advantages/disadvantages sealed over vented?


What's the advantages/disadvanteges sealed over vented?
 
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MichaelwGroves said:
Sorry, don't mean to be argumentative but...........

I don't see how 28mm will give better flow if boiler is only 22mm. But, I can see upgrading pipe at valve to 28mm to get full 22mm through valve.

snip from Manuel, "Even if the heating output is limited, the full rated heat output remains available for hot water"
1.a is setting for CH, 1.b is setting for Hot Water.

What are the advantages/disadvantages sealed over vented?



What's the advantages/disadvanteges sealed over vented?
Click to expand...

Trust me on the pipe, it acts as a buffer, just like the outlet of a gas meter is only 22 mm, but is often increased to 28 or even 35 mm on some installs.....

the 1a and 1b rule above is only for the combi boiler version not heat only like you have, how do you think the boiler knows wether it is in hot water only or ch mode? It does'nt it has a common switched live sorry you are on 27 kw for both.

loads of advantages foe sealed system google it or search on here and save my finger it has been covered many times!
 
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Total system resistance is the sum of individual resistances in series. So you can compensate for high resistance somewhere (e.g. boiler) by lower resistances elsewhere.
 
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I get it now, coming straight out of the boiler in 22mm will have similar resistance as going round a 90 degre bend in 28mm. I have some further upgrades planned, so will look to upgrade pipe and valves at the same time.
 
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MichaelwGroves said:
I get it now, coming straight out of the boiler in 22mm will have similar resistance as going round a 90 degre bend in 28mm. I have some further upgrades planned, so will look to upgrade pipe and valves at the same time.
Click to expand...

Good gleen as much info as you can, remember we do this for a living :sunny:
 
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I hate to admit I am wrong, but Vern I reckon you were right about the boiler as well. Obviuos when you think about that one :)
So do I assume the hot water setting has no effect on my boiler, or should I set this the same?

Thanks
 
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MichaelwGroves said:
I hate to admit I am wrong, but Vern I reckon you were right about the boiler as well. Obviuos when you think about that one :)
So do I assume the hot water setting has no effect on my boiler, or should I set this the same?

Thanks
Click to expand...

Yes pal, 1A is the only KW power setting as yours is not a combi, altering 1B will do nothing, as the code plug on the mother board stops this for obvious reasons
 
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E9 error, I would be considering changing the heat cell mate. The primary flow sensor should cut the boiler out we'll before the overheat stat cuts in.

if you have surface thermometer or temp robe on your gas analyser tape or hold it onto the heat cell where the overheat stat is. If your getting a reading of 100 degree plus but the temp is displaying lower than 80 degrees on the boiler chances are its the heat cell.
 
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There are two overheat stats, flue and Heat Exchanger. Exactly where would you take the reading?
I'll be using infrared thermometer.
 
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unfortunately thats where the advice stops.

this forum will not tollerate any advice to d..i..y boiler repairs!.

otherwise this thread/members will be removed unless in the private gas section, please stick to the rules of the forum.

thank you,
 
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