Worcester Bosch Greenstar / Boiler Mate III mating problems!

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Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Fri Mar 18, 2011 12:53 pm

Hello all, I've just registered with this forum so this is my first post!
Great to see a forum dedicated to Gledhill repairs, wish I'd have found this years ago!!

As my tiltle suggests I have electrical issues with a new Bosch Greenstar 18Ri (heat only boiler) I have just installed on a Boilermate III storage system, a Potterton Suprima used to reside in the kitchen but the owners want a conservatory fitted where the flue for this boiler terminated and also wanted a condensing boiler.

The install was going well untill it came to providing a pump over run for the Bosch, the boiler needs a permanent live for this and MI's state the pump HAS to be wired direct to the boiler to validate the warranty. Before doing anything else I called Gledhill tech (at 60p per min!!!) who said that the unit operates a 3 min pump over run (exactly the same time as the Bosch requirement, I thought 'great no need to run an extra cable to the pump from the new boiler location in the garage'). But the tech guy (Alan) said that I should check with WB as this may invalidate their 2 year warranty - I did and yes it would have! So I ran a new cable from the boiler back to the wiring centre in the airing cupboard with the BM3 in and took the pump L N & E into the wiring centre.

(How many of you have sussed out where this is going?!)

Once I was all commissioned I turned the room stat up, the boiler stat to max and then the power on, great the boiler fires up and the pump's running and the rads (eventually) heat up (BM3 gets to 60 degs first before any heat to rads I believe).
Next I try setting the timer to go off and then back on again a while later, whilst supping my tea and admiring my handy work, the timer clicks back on, mid position valve motors over and ...............nothing. Ah, right. I take off the BM panel, I see ON and the top bar on so I know i should have the heating fired back up but nothing on the SL out of the BM. After another call to Gledhill tech I'm told this is normal as the unit has got hot enough so wont send 240v out to the boiler. I was told there was probably an air lock. did all I could to get rid of the air lock but only managed to scald myself with 78 deg water hitting my hand whilst holding a PTFE'd hose pipe into the cold feed connected to the mains feed!!
This is getting annoying now........another cuppa and the penny drops........the unit wont send 240v to SL while the temp is above 78 (correct me if I'm wrong Mike, that's prob wrong!) so what would get rid of that heat? THE PUMP! But why is the pump not going? Because it's wired to the boiler and that isn't getting power from the unit because it's hot enough! (But while there was a demand for heat the Pump SL at the BM had 240v so that would have been getting the rads hot (this is how it was when the suprima was connected).

This appeared to be a vicious circle, so I wired the pump back into the BM3, away it goes! But now the boiler as it is isn't covered by a warranty (I'm sure in reality if the engineer came out to a fault and saw the cable connected to the PL, PN at the boiler that would be good enough for him??)
But it dawned on me as I drove away from the job - (boiler is now located in the garage with 10m of primary F & R pipe work) that when the boiler's auto frost protection would now not function as it's not wired to the pump directly. The pipe work is well lagged and I'd like to think that the cold snap is well behind us but who knows what mother nature has in store for us tomorrow?

So after all that waffle - my question is - How do I wire up the pump to the BM and the Bosch so that it's direct to both? The customer is adamant (stand and deliver ;0) that the system be left with frost protection - I agree, for my peace of mind the next time we get a frosty spell.

Any advice would be very gratefully received as Worcester Bosch don't appear slightly interested that their wiring cannot work with a BM3.

Or have I cocked the whole install up and I now look like a complete numpty!!

Thanks in advance,
Dave

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  mike on Sun Mar 20, 2011 3:52 pm

Have you looked at page 18 of the BM III book?
Mike
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Norfolk

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Sun Mar 20, 2011 3:59 pm

Hi Mike, the MI's are at the customer's house, I'm trying to find a PDF version on-line but no luck yet. Any advice as to where to find these instructions on-line?

Cheers,
Dave

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  MK Group Ltd on Sun Mar 20, 2011 4:08 pm

Dave,

Try here...


http://www.gledhill-spares.net/documents.asp

Regards

Gary
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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Sun Mar 20, 2011 4:34 pm

Cheers Gary, saved that as a bookmark now!

The schematic shows the system pump wired directly to the BM, which is how I have left the install. But the boiler also needs to be wired to the system pump so it can send power to it when the auto frost protection mode kicks in at 8 degrees and below.

How can I wire both boiler and BM3 directly to the one pump?

Cheers,
Dave

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  MK Group Ltd on Sun Mar 20, 2011 4:56 pm

Hi Dave,

Which Boiler Mate 3 is it single pcb or twin pcb?

Regards

Gary
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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  MK Group Ltd on Sun Mar 20, 2011 5:03 pm

The frost stat should be connected directly to the BM, PCB Terminal 21 & 28!
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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Sun Mar 20, 2011 5:16 pm

Gary, it's the single PCB model. The frost stat is built into the boiler, between 8 & 5 degrees c it spins the pump, 5 and under it fires up until 12 degrees is reached.

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  MK Group Ltd on Mon Mar 21, 2011 1:38 am

Let me have a think about it and I will take a look at WB instructions, will come back to you shortly.
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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Mon Mar 21, 2011 2:08 am

Cheers Gary appreciate your help. I couldn't find any other info on the auto frost mode in the WB MI's other than on the fault finding flow charts at the back of the instruction manual. Customer asked about frost protection as the boiler was going in a garage.

Seems like I've managed to pair up two appliances that just can't electrically operate together (if we wire up the WB direct to pump for frost protection)

Thanks again for any help Gary,

Cheers,
Dave

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  Daniels on Mon Apr 11, 2011 3:19 pm

hi, did you come to a verdict on this problem, ? can u wire both feeds to the pump? is there such thing as check valves in electrics to stop 1 back feeding the other.??? thanks lee

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Mon Apr 11, 2011 4:39 pm

Hi,
Yes I did manage to complete the job whilst still keeping Worcester happy providing a connection from PL to system pump.
Gledhill technical advised connecting both the Greenstar and BM3 to the system pump, as the boiler had a 3 minute overrun the same as the BM3's (rather than a temp governed overrun period which would have conflicted with the store's temp), 240v would then be present at the PL at the boiler and BM3 at the same time when there was a demand.

I hope this helps other's in the same situation. Or the chances of another engineer choosing to fit a Greenstar Ri to a BM3 may never happen again!

One thing's for sure - I will continue to quote for WB combi's but for heat only boiler's I will think twice if a Boiler mate is fitted!

Cheers,
Dave

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  Daniels on Tue Apr 12, 2011 4:45 pm

cheers dave

thanks for the quick reply, baxi do a boiler that doesnt require a pump over run, mite try that, but then it is a baxi.

thanks again

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Re: Worcester Bosch Greenstar / Boiler Mate III mating problems!

Post  DJ Heating on Wed Apr 13, 2011 12:28 pm

No worries bud, I guess it's all part of the learning curve! You've got to experience these problems to learn from them.
As they say, you can't learn experience from a text book!

Good luck mate!


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