BoilerMate 2000 calling for heat, boiler pump running all night, ACBs replaced twice!

Hi all, sorry for the long post but please bear with me.
I've scoured the topics on this forum to see if anyone has the same issues but have so far been unsuccessful. I'd appreciate some help as this problem is literally giving me sleepless nights!

System is a Gloworm 50ff coupled to a Boilermate 2000.

Issue 1 (fixed): LEDs 1, 2 and 3 randomly came ON (even when there was no CH demand and store was upto temp). This was fixed with a new ACB on the Boilermate 2000.
Issue 2 (fixed): PHE return sensor error, fixed with a new sensor
Issue 3 (partially fixed): LEDs 1 and 2 remain ON thereby demanding heat from the Gloworm 50ff boiler. The boiler was firing but not delivering water at a high enough temperature causing the desired store temps to not be met. This was investigated by checking temps of feed and return from boiler. The problem seems to have been fixed by replacement of the thermistor in the boiler, now the store temps are satisfied (around 72-76degC).

Issue 4 (NOT FIXED): This is the major issue and is driving me insane. There are 2 parts to this problem:
PART1: LEDs 1 and 2 remain ON irrespective of whether the store temp has been met, Store Temp Bar on LCD display is lit. Therefore BM2000 continues to call for heat and the boiler pump continues to run for hours on end. Eventually the store temp will fall below the lower set value, but the boiler does not fire, even though BM2000 continues to call for heat.
However if the room thermostat is set to a high enough demand, the boiler will fire (all of this time the LEDs 1 and 2 remain ON).

PART2: After several hours of running (5 hours this evening!), the boiler pump will eventually turn off, along with the call for heat. I suspect this is coincident with when the desired store temp range moves to a lower range i.e from 71-75degC desired the range shifts to 61-69degC, but the actual store temp is 75degC and this seems to cause the pumps and the call for heat to switch off. HOWEVER, Store Temp Bar is STILL lit on the LCD (indicating the store is not upto temp, even though it clearly is).
At some point during the night (usually around 3am) the store temp falls low enough for BM2000 to call for heat and start the boiler pump, this time the boiler fires, delivers heat and turns off after a while but the call for heat remains, alongwith boiler pump and does so for the next 2 hours atleast and so the whole cycle begins again............

The ACB has been replaced (twice) as it was thought that the first ACB may have been faulty (even though it was brand new).

I could really do with some help on this matter as every single boiler technician I have spoken to seems to be clueless about this unit and I've spent a small fortune getting it to this point! I'm now completely lost and don't know what to do.

Many thanks and sorry for the long post.

Is the boiler a Micron?

Have you checked the fault codes on the BM 2000?
Store sensor?

I presume the boiler is on MAX
Is the boiler putting out 80c?
Is 80c reaching the unit?

I presume you have the jumpers on the ACB (1,3 & 4) ?

Have you tried re installing the ACB to the unit / boiler?

Mike

Hi Mike apologies for the late response life got in the way! I still have the prpblem (been home all day and the pump has been running continuously today.

Have you checked the fault codes on the BM 2000?
There are no fault codes on the BM2000, there was one earlier for the PHE ensor but that has been replaced and the fault has gone.

Store sensor?
There is no fault relating to the store sensor thats showing on the BM2000 lcd screen

I presume the boiler is on MAX
Yes

Is the boiler putting out 80c?
Yes

Is 80c reaching the unit?
Yes

I presume you have the jumpers on the ACB (1,3 & 4) ?
Yes

Have you tried re installing the ACB to the unit / boiler?
Yes, twice and the board has been changed twice

Right
The bars / led display.

Example;

Put heating on timer / room stat
It will show on the display.
But if below 60c heating pump will not run.
It is showing an indication that it is on.

Hard with out seeing it.
Is the boiler a MICRON?

Sometimes the flow and return from the boiler to the unit can be part blocked.
Or even the left hand side of the BM can be blocked.
Email me and I will send you pictures of a BM opened up / exposed.

Mike

Hi Mike yes the boiler is a Gloworm MICRON 50ff

The store DOES get upto temp, originally the boiler output was quite weak at around 60degC and the store would never get to the requested set point. The boiler thermostat was replaced and this cured the issue.

The problem now is that the boiler pump almost never stops running.

Well you need to get the unit up to temperature.
Check the codes etc.
You can read the temp setting on the ACB
Watch it rising up.

Check with a meter or test leads.

1 Has the boiler pump got a supply / voltage?

2 Has the boiler switched live (at the unit) giving a voltage reading.

Can you go through the fault codes ok?

Mike
MGC/H2O

Hi I this link is to a youtube video showing the basic operation of the GT155 pcb on a boilermate 2000 setup it might help you shed some light on what is or is not happening. As you know by pressing SW2 once you will see the store temperature and you can manipulate this by using a hair dryer or similar to artificially warm the store sensor once it is out of its pocket. This might aid diagnosis as you can make changes without waiting for the boiler to warm/cool etc. Once the store has reached the target temp. the boiler should switch off and after a few minutes of overrun (to remove residual heat from the boiler) the pump should stop (the store temp must stay in the target figure otherwise if it drops the boiler sill switch back on again). If artificially manipulating the store sensor it would probably be a good idea to temporarily turn the boiler off and just use the green LED's to see what is happening. Hope you get it sorted.

https://www.youtube.com/watch?v=EaRdpx5LFd4

Hi Octane83,

I am experiencing similar issues to you. Did you manage to resolve the issue with your Boilermate and the boiler pump?

Cheers,
Andy

Hi couple of quick checks, is the display on the GT155 pcb showing -on or =on if not the pcb is faulty. Are all the green led's at the bottom of the pcb constantly on, or does the heating come on and off when it feels like it then the pcb is probably faulty. Finally if you have a pump running constantly is it the right-hand one in the cabinet which is the one for the plate heat exchanger, if so the GT155 needs replacing. Please check out my website where there are videos showing how to check the pcb and how it should work if working correctly. https://murraymartin.yolasite.com/

Octane83 did you ever find a solution to this please?

I am having the exact same issue as the OP. After going through all steps suggested above (including new ACB, error code checks, testing voltage on pumps etc), the boiler pump still remains running for hours.

I believe it is to do with the boiler pump overrun, which should usually only last for a few minutes, whereby the pump is removing heat from the boiler after it has been used (either for heating or hot water).

My final guess is that it maybe the plate heat exchange thermistor in the boiler but am not certain, reluctant to replace anything else.

Any help from the OP or anyone else would be appreciated. Thank you.

Sweet_Baby_Jebus wrote:Hi Octane83,

I am experiencing similar issues to you. Did you manage to resolve the issue with your Boilermate and the boiler pump?

Cheers,
Andy

Did you find a solution for this Andy? Cheers in advance.

I would check what temperature water the boiler is putting out ideally it needs to be 82 degrees but the unit will scrape by as low as 76 degrees according to the manual.  Also have you checked the sensor temperatures using SW2, pressing SW2 once will show the current store temperature, if you then press Sw1 it will show the set cut in and cut out temperatures for the tank.  Pressing SW2 again and then again will show the hot water sensor temperatures, if any show -err or daft readings like 00 or 99 they are probably faulty.

Might also be worth just watching it for a while with no heating on, with the bottom two LEDs on one the tank is up to temp the boiler LED bottom one will go off and then after three minutes ish the boiler pump should go off.  Question is does the boiler kick back in briefly before the 3 minutes is up?

Sorry if you have already tried these just some ideas to try to figure out the issue.

You might have seen my video on how the system operates if not it is here:  GT155/GD131

Hi Murray, (I recently swapped my gt155 with you last week, ref Stallard)

Thank you for your reply.

Sensors checked with sw2 (haven't checked the sw1 cut in/out temps.. Will do when I next get a moment)

According to Gledhill, 00,85,99 and 'err' are the ones to watch out for.

Your idea to look at if the boiler kicks back in around the 3 minutes I haven't tried. The boiler certainly doesn't tick or fire up but I'll have a look to see what's going on with LED 1.

I have managed to fix the issue temporarily, which sometimes works, by turning the heating thermostat up to demand and then off again. This then performs the usual cycle without issue. This is a Nest thermostat... Wiring appear correct but another thing to look into.

Thanks for your help.

My workaround for the boiler pump over-running issue is a simple one; once the boiler has gone off and the boiler mate has reached the highest temperature it will get to, I simply turn on a hot water tap (about 1/3 open) for around 12 to 15 seconds. This results in the boiler light going off on the boiler mate PCB leaving only one green LED. This last LED stays on for the built in 3 minute pump over-run and then it all goes off as per normal. No idea why this works, but it does!

It seems to me that this phenomenon is not a physical hardware issue, but rather issues with the programming that controls how the boiler mate functions when it can only reach the lower inbuilt boundaries (e.g 61/68 or 63/70).

Thank you Sweet_baby for your reply... Interesting I've also found a work around... But I've been turning the room thermostat up (Nest), to call for heat and allow the boiler to fire up. I then turn the thermostat back down, so the boiler them stops and everything else goes through the usual shutdown and 3 minute pump overrun.

My thoughts with it are I'm now looking at the Micron 40ff boiler circuit board being the issue. I replaced this some years ago and am reluctant to throw more money at it.

If I get a chance, I'll do some electrical testing to see if I can identify any faults on the micron board or any of its sensors (PHE sensor perhaps).

I'm getting the feeling the boilermate 2000 seems to think the boiler is still on, when it isn't, hence why the pump keeps going.

If I find get anywhere further I'll let you know. Nice one.

When I was having this looked into when it first occurred back in January 2020, British Gas replaced all the major components of my Micron boiler, including the PCB, fan and thermistor, as well as the PCB and the tank thermostat on the Boilermate. None of it made an iota of difference, unfortunately.

I have now had several different PCB’s in the Micron Boiler and the Boilermate, as well as most of the mechanical components replaced to no effect, which is what leads me to believe it’s a software problem rather than a hardware problem.

The boiler gets up to its maximum temperature and switches off, but the Boilermate keeps asking for more heat, which is why the boiler circuit stays open and the pump stays running. I’m not sure why supplying a demand for hot water (either via running the hot tap or turning the heating back on momentarily) triggers something to make the Boilermate cease its demand for more heat from the boiler, but it does.

My boiler is able to heat the water to 78 degrees, but the Boilermate refuses to register much above 71 degrees. I was told by Gledhill that this was likely due to limescale buildup around the slot where the thermostat is inserted. I still don’t see why this should prevent it operating correctly (e.g. automatically) between the 61/68, 62/69 and 63/70 temperature settings that it can achieve with the manual intervention workaround.

I have swapped the hardwired mains on the Boilermate for a regular socket and now use a smart plug to allow me to setup a routine that turns on the power, lets the tank heat up for 10 - 12 minutes and then runs the heating as required and switches everything off a few minutes after the heating has gone off. I use this if I am going to be away and it seems to work well enough.

Hi, with the store sensor never going above 71 degrees an interesting experiment, maybe when the weather is better, would be to get the tank sensor out of the pocket and with the PCB on the tank temperature reading play a hair dryer on it to see if it will pop over 71 degrees.

Also, it sounds as though you may have several Gledhill PCBs in your collection if you would like to send me one I can pop it on my test jig and run it through its paces to see if it is behaving, no charge. Message me if you want to do that.

Regards Murray

Thank you for the offer, but both BG and Gledhill always made sure to take the ‘old’ PCB’s away with them when they left!

I have seen the Boilermate tank thermostat read as high as 74 after the CH has been on for a long time, but generally the boiler shuts off as it reaches 70 and the tank temp tops out at 71.

I don’t have much electrical knowledge, but I’ve wondered if it would be possible to add a component (e.g a resistor or some such) into the wiring between the Boilermate tank thermostat and PCB to artificially increase the reading from the thermostat by about 8%, thus moving it back into the desired operating range of the system. I could then see if the system then resumed ‘normal’ operations..?

Apart from this problem the system itself works fine, delivering CH and HW without issue. The Boilermate and boiler were installed when the house was built in 2000.

Hi, the tank sensor and in fact all the temperature sensors are digital devices so adding resistors will not be possible as they send a digital signal that indicates the temperature to the PCB.

Regards Murray

Hi chaps
Thank you both for replying on this thread. You've stopped me buying more components that may have been throwing money down the drain (no pun intended)..

I did infact buy a couple of sensors for cheap that I might test and replace... I'll take a look if there's any limescale build up as mentioned by Gledhill, though I agree it with you about why it wouldn't still work.. But they've mentioned it for a reason I suppose.

The only reason I'm not convinced it's software, is that I've been living with this system for 8 years and it's only recently started doing this.

Anyway.. Like you, we have HW and CH, so can't complain too much.

Have a great Christmas and Happy New Year.

Have you managed to get it sorted out now Tommy?