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Discuss No Heating and Hot water after 4 weeks, 6 engineer visits, a power flush and new pump - HELP!!! (please) in the Central Heating Forum area at PlumbersForums.net

Messages
6
We have a Glowworm BBU56F (back boiler). Its well-maintained/serviced and since we’ve been in the property (15 years) only the Thermocouple was replaced in July of this year, otherwise has been running fine.

We’ve not had heating/hot water for a month now, and with 2 young kids/unwell missus I’m almost on my knees, after 6 engineer visits (including a full day power flush and a new pump), still no joy with getting it working again. Below I have outlined the problem first, thereafter some more history as to what’s been said/done/diagnoses to get us to present day etc.. Unfortunately unable to afford a replacement boiler due to covid situation so need a fix and desperately seeking some advice/help before xmas

Frustrating thing is fellow tradesman are say saying previous engineers are not advising/doing a proper job and I’m being passed around in recent weeks… Any thoughts would be great, I know people are busy… but I would be willing to have a chat to anyone wanting to advise if easier…

Current Problem
  • The HOT WATER will warms up to being lukewarm after being on constant for a few hours (far too long)
  • The HEATING has different patterns:
    • Won’t work at all, despite being on from the controls
    • Or boiler will go on for 20-30mins continuous, the whole system/all radiators will heat up (very quickly since power flush), but then will switch off and go back on say in 5 minute intervals but for only 1 minute each time, and the radiators will cool down, so boiler is cutting out)
    • A few times has fired up and a couple of radiators will only go lukewarm…
    • A few times 1 radiator has been piping hot and a couple lukewarm and others cold
    • I sense from a cold start there is a higher chance the whole system will heat up for a short burst (but not always the case)
For some of the the above latter points you may think there’s a blockage/air, but as the whole system SOMETIMES still heats up fully and air has been checked for/radiators bled don’t think this is the case + since the new pump and powerflush has been, the boiler system is running quieter and smoother when it wants to work! The engineer that did the power flush said BEFORE the job my issue could only be the pump or power flush – but now hes saying it actually the boiler ): Note AFTER the powerflush everything was working, so I paid in full and one hour after he went, the system shutdown and experiencing the above issues described! I cant seem to get his help now! Note he did the powerflush by hooking his machine to where the pump goes, used chemicals and did one radiator at a time.

Some more history/background on engineer vists past month
To put the above in context, some notes below on engineers visits from when the problem first started a month ago to where we are currently present day (note a combination of plumbers and gas safe engineers):
  1. First visit, gas engineer said air in the system was diagnosed and released – worked for half an hour after he went and then packed up
  2. Next day same engineer came and said you could have a leak, causing air to get into the system, he marked expansion tank and came back 3 days latter (having tied the ball so it doesn’t fill), and on his return said you lost a pint of water in 3 days - told me I need a plumber (I also marked the tank water level at this point)
  3. Plumber came in following week and said no leak your pump is knackered (from listening to it), need to change it! I didnt not a tank water level drop either!
  4. Following week gas engineer came and actually said pump is fine, and how can a plumber determine in one visit for an hour you don’t have a leak, you need to call the plumber back!
  5. Another plumber came back and fitted a new pump (as he thought also no leak) – pump did not resolve the issue, in fact from having a tiny bit of heating there was nothing at all, he said there could be a blockage and its backing up to the pump and to get a powerflush done (which is what we’ve done last week per above opening comments)
To be honest losing the will, and above is the whole story in short. Look forward to any advise or thoughts please….
 
Messages
863
Clearly it's very difficult to provide an accurate diagnosis without seeing system. However:
1. It sounds as if the boiler is firing up (on occasion at least), running for a short while, then stopping again. Sounds like some form of blockage in the system.
2. Given that the pump is new, that's unlikely to be the culprit.
3. Given that the problem occurs on both heating and hot water, it is not so likely to be a problem with the 2 x single port or 1 x two port motorised valve(s).
4. My first suspicion would be a blockage in the feed from the small feed and expansion (F&E) tank into the system. This would be particularly so if the system has been recently drained without the F&E tank being cleaned out first. Ways to check:
4a. Run a magnet over the pipework leading from the base of the F&E tank into the system (normally close to the pump). If the magnet is attracted, it suggest there is magnetic material in the pipe, possibly a blockage. Only solution is to cut out the pipework and renew.
4b. Clean out the F&E and start draining the system. If the flow from the drain point is very slow, it again suggest a blockage. Same remedy as above.
5. Make sure there is an adequate flow of water into the F&E. Push down the float and water should enter.
6. After that I'd check the motorised valve(s).
 
Messages
6
What Controls/motorised valves do you have, and have they been checked?
Hello
I will double check, but off the top of my head I know

1) there is one thermostat for room temperature (a manual dial/Honeywell branded)
2) the timer control panel/to switch the heating on/off is digital
3) there are 2 motorised valves I believe (thats the silver boxes (one for heating and hot water) that open and close i'm if right - sorry a bit of a novice here!).

For points 1 and 2, no ones really check apart from just using as normal to switch the system on and off, and adjust the temperature to get the boiler to kick in!

For point 3, the last engineer said they are 'opening and closing' as they should...
 
Messages
6
Clearly it's very difficult to provide an accurate diagnosis without seeing system. However:
1. It sounds as if the boiler is firing up (on occasion at least), running for a short while, then stopping again. Sounds like some form of blockage in the system.
2. Given that the pump is new, that's unlikely to be the culprit.
3. Given that the problem occurs on both heating and hot water, it is not so likely to be a problem with the 2 x single port or 1 x two port motorised valve(s).
4. My first suspicion would be a blockage in the feed from the small feed and expansion (F&E) tank into the system. This would be particularly so if the system has been recently drained without the F&E tank being cleaned out first. Ways to check:
4a. Run a magnet over the pipework leading from the base of the F&E tank into the system (normally close to the pump). If the magnet is attracted, it suggest there is magnetic material in the pipe, possibly a blockage. Only solution is to cut out the pipework and renew.
4b. Clean out the F&E and start draining the system. If the flow from the drain point is very slow, it again suggest a blockage. Same remedy as above.
5. Make sure there is an adequate flow of water into the F&E. Push down the float and water should enter.
6. After that I'd check the motorised valve(s).
Thanks Steady on. The expansion tank is in the loft and pipework goes into the main bedroom, where the cylinder and new pumper are... i will try and take a look tomorrow in the day... thanks again
 
Messages
6
hello all

just thinking ahead for my boiler model (Glowworm BBU56F) any recommendations on where to source parts from please? I did google and various suppliers came up but just want to ensure i go to the 'right place', esp given its an older boiler and not had much luck so far

thanks so far
 

Last Plumber

Esteemed
Plumber
Gas Engineer
Messages
4,185
You need a competent Engineer by the sound of it. There is no reason why the component parts of the system can't be tested. especially things like pumps, stats, motorized valves, boilers etc.
I think you would be better off starting a fresh with a recommended person. I know that isn't much help on its own but it is difficult to diagnose this type of issue without testing various things.
 
Messages
6
Thanks for the various suggestions - appreciated, below is an update/progress made noting some thread responses also... and lastly ‘In summary what's happening now…’

Update...

1) The power flush engineer installed an 'automatic air vent' last week, which saw no real improvement, he said 'could be' the boiler thermostat, but having lost some confidence in him, called out someone new recommended by my uncle to get a fresh opinion as suggested by 'Last Plumber'***

2) The new engineer spent 30-40mins assessing/checking and concluded the boiler Thermostat!

3) Someone from the same company came out 48 hours later and installed the part... note it was xmas eve and all a bit hectic/rushed, had to grovel to get the work done on time.

The replacement thermostat didn’t actually improve things, nice chap he was, he checked the f & e tank/flow/valves/pump again, and said to let the system 'bed down' as there could be air in the pump (sealed) which will slowly discharge and could take hours... a bit speechless at this point tbh...

After several hours, no real joy... however, hot water appeared to be working, but noticed 3 or 4 radiators UPSTAIRS were again warm/hot - so I called someone I know who's handy/experienced! He said close those UPSTAIRS radiators to push the flow downstairs (eliminate a blockage/air etc)*** after doing this downstairs warmed up! I then did a bit of googling and re-opened the upstairs valves by a 1/2 or 3/4 of a turn (wasnt very scientific more on gut) - switched the system off for a bit and then fired it up again, and like magic the whole system warmed up... read on (not finished :))

In summary what's happening now
1) The heating from a cold start heats up the house amazingly, boiler stays on for circa an hour... but then goes into a frequent stop/start cycle with only a few radiators staying warm/hot (mainly upstairs and one or 2 downstairs rads - note this is after my valve adjustment above) - so we have some heating, using sparingly/wisely, not ideal but in a better space than last week. Scared will conk out all together...

2) Hot water seems to be working 🥳

3) I've been trying different things, here’s the interesting thing I noticed, after an hour of heating, and when it goes into this stop/start mode of a few warm radiators, if I 'boost the hot water for an hour' with the heating still on constant, then after after 15-20mins (there is a delay) the entire heating system starts to come on and the house gets baking hot - i noticed this by fluke and replicated last night… could just be a coincidence that on 2 occasions same result...

Any further thoughts/ideas again welcome. Had some good feedback here and private messages - v helpful, so thanks again


Lastly I had a slight doubt on the thermostat in our hallway (radiator temperature), but might be getting paranoid...
 
Messages
6
Thanks for the various suggestions - appreciated, below is an update/progress made noting some thread responses also... and lastly ‘In summary what's happening now…’

Update...

1) The power flush engineer installed an 'automatic air vent' last week, which saw no real improvement, he said 'could be' the boiler thermostat, but having lost some confidence in him, called out someone new recommended by my uncle to get a fresh opinion as suggested by 'Last Plumber'***

2) The new engineer spent 30-40mins assessing/checking and concluded the boiler Thermostat!

3) Someone from the same company came out 48 hours later and installed the part... note it was xmas eve and all a bit hectic/rushed, had to grovel to get the work done on time.

The replacement thermostat didn’t actually improve things, nice chap he was, he checked the f & e tank/flow/valves/pump again, and said to let the system 'bed down' as there could be air in the pump (sealed) which will slowly discharge and could take hours... a bit speechless at this point tbh...

After several hours, no real joy... however, hot water appeared to be working, but noticed 3 or 4 radiators UPSTAIRS were again warm/hot - so I called someone I know who's handy/experienced! He said close those UPSTAIRS radiators to push the flow downstairs (eliminate a blockage/air etc)*** after doing this downstairs warmed up! I then did a bit of googling and re-opened the upstairs valves by a 1/2 or 3/4 of a turn (wasnt very scientific more on gut) - switched the system off for a bit and then fired it up again, and like magic the whole system warmed up... read on (not finished :))

In summary what's happening now
1) The heating from a cold start heats up the house amazingly, boiler stays on for circa an hour... but then goes into a frequent stop/start cycle with only a few radiators staying warm/hot (mainly upstairs and one or 2 downstairs rads - note this is after my valve adjustment above) - so we have some heating, using sparingly/wisely, not ideal but in a better space than last week. Scared will conk out all together...

2) Hot water seems to be working 🥳

3) I've been trying different things, here’s the interesting thing I noticed, after an hour of heating, and when it goes into this stop/start mode of a few warm radiators, if I 'boost the hot water for an hour' with the heating still on constant, then after after 15-20mins (there is a delay) the entire heating system starts to come on and the house gets baking hot - i noticed this by fluke and replicated last night… could just be a coincidence that on 2 occasions same result...

Any further thoughts/ideas again welcome. Had some good feedback here and private messages - v helpful, so thanks again


Lastly I had a slight doubt on the thermostat in our hallway (radiator temperature), but might be getting paranoid...
Sorry above might be unclear (as another long post!), but we're getting heating but only for around an hour max (may be less) if we use as normal, whilst better than before boiler thermostat was changed still an issue as the house cools down with a couple of rads (mainly upstairs) remaining either mainly warm or rarely hot! So we're using heating sparingly morning and in the evening... allowing the system to 'rest'/cool down between usage!
 
D

David Graham

Sounds to me like there might be air in the boilers heat exchanger, you need a heating engineer (not a gas engineer or plumber) to connect a hose at a point on the system below the boiler and push water back through the system into your F & E tank, if that doesn’t work it sounds like the boiler is going off on high limit (temp too high) and I would recommend having the wiring and motorised valves checked on your s plan/y plan as they may be sticking and causing the boiler to “kettle”
 

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