It might be these new energy saving pumps. I’ve just put my boiler central heating temp up from 68 degrees to 71, forget condensing mode. A few years back on an energy efficiency course, we were advised to set the boiler to max and control the room temperature with the trv’s and room thermostat. Put it on max, it fires up once and gets up to temperature quick and then goes off makes sense. I’ll revert back to the old way and see if it makes any difference.
Worcester Bosch Greenstar 8000 Life problems....Or are they???
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I appreciate what you're say snb, but none of this applies to me. For example the boiler we have is 35KW for DHW and 30KW for CH and it runs 11 radiators max. We don't have any dripping taps at all. The system as per the advice on this forum was balanced, but this issue is simply the fact that if no one runs the DHW, the boiler runs fine, but if you make the mistake of opening the tap, then the boiler just pauses for ages before continuing the heat. That means if I run the heating for 3 hours and open the taps 2-3 times within those hours, it'll waste a good 20 minutes just sat there, waiting to switch back to CH. That's a waste of energy and resources IMHO as the rooms never properly heat up.
Yes it sounds about right that it's the new energy pumps. Isn't putting the boiler on max going to waste lots of energy? My boiler is set to 75C. Please do let us know how you get on.
If the unit is waiting 20 minutes to return to heating after a demand for hot water then either you don't have the boiler settings as per the changes i suggested or you have altered them from the factory default because that would give a max of 5 minutes between a demand for hot water and the heating resuming. These boilers when asked for a heating demand go straight to 75% of max heating power for 10 minutes before going to 100%. This is only throttled back if the difference between the flow and return is less than 20 degrees ( poor flow around a system or poorly balanced) if the flow temp gets to within 6 degrees of its set point then it will also start to reduce output. once it has reached temp it wont restart until the flow is at least 6 degrees below the set point. this is to reduce cycling. if difference between flow and return goes above 20 degrees it goes into 5 min waiting period.
The only other problem we have is with small systems like yours with only 11 rads and a central heating output at 30kw is that it would try to heat up too quickly at 75% of 30kw. 22.5kw is the kind of output we would be using on a system with about 25 rads dependant upon size.
How big is the overall size of your house in square meter and its age ?
If you were to reduce the output for heating in 3-b1 to 50% you may find that it heats up faster because it won't keep going into waiting periods. ( when we put a boiler in max rate it bypasses most energy settings and only stops when it hits the flow temp setting).
Everytime currently when your boiler has demand for hot water it will revert afterwards central heating input at 22.5kw but if it hits a flow and return differential above 20degrees it will put it into a 5min waiting period and the cycle just continues.
The only other problem we have is with small systems like yours with only 11 rads and a central heating output at 30kw is that it would try to heat up too quickly at 75% of 30kw. 22.5kw is the kind of output we would be using on a system with about 25 rads dependant upon size.
How big is the overall size of your house in square meter and its age ?
If you were to reduce the output for heating in 3-b1 to 50% you may find that it heats up faster because it won't keep going into waiting periods. ( when we put a boiler in max rate it bypasses most energy settings and only stops when it hits the flow temp setting).
Everytime currently when your boiler has demand for hot water it will revert afterwards central heating input at 22.5kw but if it hits a flow and return differential above 20degrees it will put it into a 5min waiting period and the cycle just continues.
Apologies if I wasn't clear snb, but I didn't mean that it stops for 20 minutes each time - I meant 20 minutes in total if we open the tap 2-3 times.
Unfortunately, I don't know how big our semi-detached house (built in 1935) is in square meters.
I have changed the 3-b1 setting which was on 100% to 50% now.
Unfortunately, I don't know how big our semi-detached house (built in 1935) is in square meters.
I have changed the 3-b1 setting which was on 100% to 50% now.
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Hi everyone, sorry to join this discussion with you all after so long on this thread. But I have just read through all the posts after scouring through the internet and have exactly the same issues and problems I just registered just to comment on this. I had the 8000 life installed about three years ago, as well as the whole central heating and its been bugging me ever since, literally running round the house telling everyone to only use cold water as the heating is on. What seems like an age, forever to heat up. Checked everything bleeding balancing etc. Would really appreciate if anyone has found a fix to this? Thanks in adavance!
Sadly I'm still stuck with this boiler as I can't afford to move to another one. Still the same issues and yes putting the CH on for an hour or two makes little difference. It needs to be on for 4-5 hours for the house to warm up reasonably. Even then we've all got to avoid opening the hot water taps between these times. I don't think anyone on this form has a clear solution to this issue
Not sure how much that will help. I wish someone knew, but I wouldn't hold my breath.
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After a one hour wait got through to customer services - technical support. They checked boiler output settings which are set on 100% already, then the radiator pump they told me to set to 6 from 3. Also checked the weather temperature is set to OFF. Then advised me to go into menu L1, 1-A1 which was at 200. Monitor for about an 1 hour when the flame goes off and callback with any fault codes. I’m guessing the last one was the fob off advice as it did nothing. I’m guessing they just read off a screen and click buttons so they don’t really know what they’re talking about. I think this is a software coding issue rather than a hardware fault. If there was a way to update the “boiler brain” I think that would solve it?!
I have a relative with the open vent (regular) version of this boiler. At times it has been a very frustrating and confusing machine. The problems are nowhere near as bad as yours. But several times I've seen it stall at about 45C for more than twenty minutes, when the set point is 67C. When I've brought up the info screen, the modulation it is between 10% and 20%. It just seems to be fannying around doing nothing. The thermostats and controls are the most basic type, so there is nothing fancy going in the background which would interfere with it. After twenty minutes or so I gave up so I don't know how long it took to resolve.
On your boiler, 1-b8 and 1-c2 should show you the actual modulation and pump outputs. Although, in my experience it doesn't really shed much light on what is going on. It's probably worth trying though, just to get some background information.
I've checked my settings 1-b8 is at 33% and 1-c2 is at 89%. But the issue is related to where the boiler diverts to DHW and back to CH
I thought you also had a general issue with the boiler not getting up to temperature and taking ages to warm the house?
Yes, sorry, that's still the case and since there doesn't seem to be any solution, like many other, I'm stuck.
Is it a 30KW boiler? If so, 33% would be 10KW, which should keep things toasty once you are up near the set point. It might be useful to track how it varies against temperature during a heating up phase.
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Balanced eh?
I'll get pelters but hey ho.....
If the rads are old, regardless off you having the system cleaned or not, take them off, take them outside and hose them and tickle them with a rubber mallet.
Do them all.
Whilst you are at it, with the system drained down, if you have a ABV, take it off, clean it, and check it works.
Put everything back together, flush through, add inhibitor etc. etc
Does the system have trvs?
If so, resolve the bypass issue.
Does the boiler need one? (Read the manual).
Does the system have one (manual, abv, etc)
Is it set correctly?
Is it in the right place?
Is your pump a PP pump?
You'll be surprised at the answers those questions generate.
But, get through that lot and you'll begin to ensure before fault finding, that the system is at least set up properly.
If you wanna give those answers here, I'll give you my opinion on what it means.
Finally, to the balancing.
I wrote a recent discussion post here about this in modern systems.
Mostly scorned by those who could follow or be arsed but it might give you something to think about.
Do the above, the system is clean, the rads are able to radiate properly, the flow goes where it should, when it should. The pump is set correctly for the system and components.
If.
If your system is thus reasonably installed, has a decent design (preferably with manifolds and separate feeds/returns and has TRVs everywhere, and won't heat up, thy this.
Unbalance the system.
When doing this, take a note of the turns to close each lockshield, and then, open them all up full.
Goes against the grain, but with various zones, a variable speed pump, a modulating boiler and dynamic trv on rads, I'm not at all convinced that throttling them down does what it is supposed to do.
You should see the boiler go full pelt, with the pump in tow, as they try to satisfy the temp/flow algorithms they have. the room with the highest rad output - heat loss ratio should heat up first. Maybe not, maybe they will all rise at a similar rate. Doesn't matter. The Trv closes. And the capacity in the system shunts to getting the next room upto temp (trv closed) and so on and so forth.
If you don't have a rad plumbed in a daft way (say in series) then you get a self balanced system which is able to use its full potential.
Any blips (room overuns, etc) can be tweeked after.
I did this for my system after going through similar problems. It worked wonders. Ymmv.
Best of luck
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