Bosch-Worcester Greenstar issue

[Christian McArdle]

I've now got my Greenstar HE28 System boiler installed (thanks John!). Unfortunately, as it is connected to a heat bank, I need the flow temperature to exceed the normal 75C limit. According to the installation/commissioning manual, this is done by removing the yellow end cap from the temperature selection knob and reinserting it 180 degrees to the original. Unfortunately, it doesn't seem to want to budge and I don't want to apply more force than I am, as it might snap the PCB/knob. Has anyone ever been successful in this task? Any ideas?

Christian.

[andy.pevy]

Yes, use more force.... Seriously, I have a 29HE and it took a lot of force to shift the little B*&&%r.

AndyP

[Christian McArdle]

How do you stop the PCB and knob disintegrating? The front panel is already bulging alarmingly as I try to prise it off.

Christian.

[andy.pevy]

I will have a look tonight as to how it comes off, I think it was just very tight and a little screwdriver under the edge did the trick.

AP

[Christian McArdle]

Mine has an obvious screwdriver slot. I assume this is what you mean by "edge"?

Christian.

[Lawrence]

I do not have one.

Are you sure it is not just a rotary c>> I will have a look tonight as to how it comes off, I think it was

Lawrence

usenet at lklyne dt co dt uk

[Christian McArdle]

No. It is a little yellow dot that doubles as the pointer for the temperature control. I suspect is has a protruding lug that prevents the pointer being turned past 75C. By reversing the dot, I suspect the alleged lug will no longer prevent the pointer being turned. The slot is in the edge of the insert supposedly to give something for your screwdriver to grip on when prising it out. It's a weird concept anyway, especially as there is a software setting to limit the temperature as well. Both have to be set to get > 75C water.

Christian.

[Lawrence]

Oh thanks for the delights of oil boilers where. I have no PCB in sight just a handfull of interwired thermostats and switches. I lie probably, there is a high voltage source in the burner itself and some sequencing logic.

I like the KISS principle.

Good luck.

Lawrence

usenet at lklyne dt co dt uk

[John Stumbles]

Yes, but what are you using to send that message? ;-)

-- John Stumbles

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-+ Copyright (c) Sirius Cybernetics Corporation (formerly Microsoft)

[Neil Jones]

Christian, once you've got this working, would you mind posting a brief report on the recovery aspects of your Pandora heat bank, coupled with your boiler.

I'm considering the same model that you have installed and would be interested in some "real-world" data before I commit.

Many thanks

Neil

[Christian McArdle]

Well, it isn't brilliant with the boiler limited to 75C. However, it does actually heat enough to turn off the 75C cylinder stat eventually. I think the electric immersion was heating higher than 75C. When I get the flow temperature above 80C, then I'm sure the boiler heating will do the same.

I tried even harder to remove the dot last night. I'm sure I'll damage the boiler if I pull harder. I'm going to phone Worcester...

Christian.

[Lurch]

I've just fitted a 35HE and that yellow bit is tight, I ended up ripping it off with a pair of grips. Luckily the knob is fairly sturdy, a good tug was required. It went back in o.k. just got teeth marks on it, can't see til you look closely though!

SJW A.C.S. Ltd.

[Christian McArdle]

I could try mole grips. However, the thing is mostly buried, so I'm not sure what purchase I can get on it.

Whilst the knob itself looks sturdy, I'm not sure about the control it is attached to. It moves too much for my comfort.

Christian.

[Lurch]

Well, I'm just saying I managed it. It is of course entirely up to you as to whether you want to try it or not.

SJW A.C.S. Ltd.

[IMM]

Do you need to do something softwarewise to get it to stay at 80C? Can you have it at 80C for DHW and modulation on CH?

[Christian McArdle]

It's nice to know two people have managed it!

I think I'll give the grips a try. It's a shame that this problem has blighted an otherwise well designed boiler. Given that there is also a software setting for this, I don't even see why they bothered making it so difficult.

Christian.

[Christian McArdle]

No. The software is currently set for a maximum of 88C. Unfortunately, the little peg in the knob physically prevents you turning the thermostat that high. The peg is useless. They would have been better to have just had the default software setting at 75C which would have just ignored any thermostat knob setting above that value. I wonder how many Greenstars there are round the country with chewed up yellow pointer knobs...

No. They had an internal diverter valve option with separate temperatures for both sides, but the hot water flow is limited to 75C. Of course, it was only later that it occured to me that I could have run the radiators on the hot water circuit and the cylinder off the radiator circuit to bypass this. OTOH, this may have defeated some internal algorithms.

Christian.

[stefek.zaba]

Aha! Have we at last found a use for a Dremel for you - to grind the little peg off the knob (giggles)?

[Christian McArdle]

If I could get it out first. The peg is only presumed to stick out of the back as it is the obvious method of accomplishing its task. I haven't seen it yet!

Christian.

[IMM]

So it will modulate on the load compensation software, either in CHG or DHW mode?